* [PATCH v3 00/17] Remap tree
@ 2025-10-09 11:27 Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 01/17] btrfs: add definitions and constants for remap-tree Mark Harmstone
` (16 more replies)
0 siblings, 17 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:27 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
This is version 3 of the patch series for the new logical remapping tree
feature - see the previous cover letters for more information including
the rationale:
* RFC: https://lore.kernel.org/all/20250515163641.3449017-1-maharmstone@fb.com/
* Version 1: https://lore.kernel.org/all/20250605162345.2561026-1-maharmstone@fb.com/
* Version 2: https://lore.kernel.org/all/20250813143509.31073-1-mark@harmstone.com/
Changes since version 2:
* Addressed the points that Boris mentioned in his reviews
* Moved fully_remapped_bgs list from the transaction to fs_info
* Chunk sub_stripes now set to 0 when num_stripes is
* Fixed crash with RAID0
* Made it so changing a block group's flags feeds through to the
block_group_item on commit
* Added discarding of fully-remapped block groups
For async discard, we set a new flag on the block group item,
BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING, in the transaction in which
the last identity remap is removed. We then queue up async discard of
the whole of the range in the usual way. Once the block group has been
fully discarded, we remove the device extents, remove the chunk stripes,
and clear the STRIPE_REMOVAL_PENDING flag.
If we encounter a block group with this flag set when we walk the block
group tree on mount, we queue it up for discard again - that way it's
not possible for the discard of a block group to be missed.
For sync discard we don't set this flag, discard happens at the same
time as the transaction commit. But if we encounter it on mount we still
queue the BG up for discard, it just happens on the commit of the first
transaction after mount.
If you are trying the btrfs-progs patches I linked to in the other cover
letters, bear in mind that btrfs-check doesn't like the fact that
BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING gets set on the block group
item but not the chunk item. There didn't seem much point in setting it
on both, but I can change this if anybody has strong feelings on the
matter.
Mark Harmstone (17):
btrfs: add definitions and constants for remap-tree
btrfs: add REMAP chunk type
btrfs: allow remapped chunks to have zero stripes
btrfs: remove remapped block groups from the free-space tree
btrfs: don't add metadata items for the remap tree to the extent tree
btrfs: add extended version of struct block_group_item
btrfs: allow mounting filesystems with remap-tree incompat flag
btrfs: redirect I/O for remapped block groups
btrfs: release BG lock before calling btrfs_link_bg_list()
btrfs: handle deletions from remapped block group
btrfs: handle setting up relocation of block group with remap-tree
btrfs: move existing remaps before relocating block group
btrfs: replace identity maps with actual remaps when doing relocations
btrfs: add do_remap param to btrfs_discard_extent()
btrfs: allow balancing remap tree
btrfs: handle discarding fully-remapped block groups
btrfs: add stripe removal pending flag
fs/btrfs/Kconfig | 2 +
fs/btrfs/accessors.h | 29 +
fs/btrfs/block-group.c | 272 ++++-
fs/btrfs/block-group.h | 22 +-
fs/btrfs/block-rsv.c | 8 +
fs/btrfs/block-rsv.h | 1 +
fs/btrfs/discard.c | 70 +-
fs/btrfs/disk-io.c | 107 +-
fs/btrfs/extent-tree.c | 131 ++-
fs/btrfs/extent-tree.h | 3 +-
fs/btrfs/free-space-cache.c | 84 +-
fs/btrfs/free-space-cache.h | 1 +
fs/btrfs/free-space-tree.c | 4 +-
fs/btrfs/free-space-tree.h | 5 +-
fs/btrfs/fs.h | 10 +-
fs/btrfs/inode.c | 2 +-
fs/btrfs/locking.c | 1 +
fs/btrfs/relocation.c | 1867 ++++++++++++++++++++++++++++++-
fs/btrfs/relocation.h | 10 +-
fs/btrfs/space-info.c | 22 +-
fs/btrfs/sysfs.c | 4 +
fs/btrfs/transaction.c | 13 +
fs/btrfs/tree-checker.c | 94 +-
fs/btrfs/tree-checker.h | 5 +
fs/btrfs/volumes.c | 302 ++++-
fs/btrfs/volumes.h | 19 +-
include/uapi/linux/btrfs.h | 1 +
include/uapi/linux/btrfs_tree.h | 30 +-
28 files changed, 2901 insertions(+), 218 deletions(-)
--
2.49.1
^ permalink raw reply [flat|nested] 38+ messages in thread
* [PATCH v3 01/17] btrfs: add definitions and constants for remap-tree
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
@ 2025-10-09 11:27 ` Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 02/17] btrfs: add REMAP chunk type Mark Harmstone
` (15 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:27 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone, Boris Burkov
Add an incompat flag for the new remap-tree feature, and the constants
and definitions needed to support it.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: Boris Burkov <boris@bur.io>
---
fs/btrfs/accessors.h | 3 +++
fs/btrfs/locking.c | 1 +
fs/btrfs/sysfs.c | 2 ++
fs/btrfs/tree-checker.c | 6 ++----
fs/btrfs/tree-checker.h | 5 +++++
fs/btrfs/volumes.c | 1 +
include/uapi/linux/btrfs.h | 1 +
include/uapi/linux/btrfs_tree.h | 12 ++++++++++++
8 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
index 99b3ced12805..95a1ca8c099b 100644
--- a/fs/btrfs/accessors.h
+++ b/fs/btrfs/accessors.h
@@ -1009,6 +1009,9 @@ BTRFS_SETGET_STACK_FUNCS(stack_verity_descriptor_encryption,
BTRFS_SETGET_STACK_FUNCS(stack_verity_descriptor_size,
struct btrfs_verity_descriptor_item, size, 64);
+BTRFS_SETGET_FUNCS(remap_address, struct btrfs_remap, address, 64);
+BTRFS_SETGET_STACK_FUNCS(stack_remap_address, struct btrfs_remap, address, 64);
+
/* Cast into the data area of the leaf. */
#define btrfs_item_ptr(leaf, slot, type) \
((type *)(btrfs_item_nr_offset(leaf, 0) + btrfs_item_offset(leaf, slot)))
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 0035851d72b0..726e4d70f37c 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -73,6 +73,7 @@ static struct btrfs_lockdep_keyset {
{ .id = BTRFS_FREE_SPACE_TREE_OBJECTID, DEFINE_NAME("free-space") },
{ .id = BTRFS_BLOCK_GROUP_TREE_OBJECTID, DEFINE_NAME("block-group") },
{ .id = BTRFS_RAID_STRIPE_TREE_OBJECTID, DEFINE_NAME("raid-stripe") },
+ { .id = BTRFS_REMAP_TREE_OBJECTID, DEFINE_NAME("remap-tree") },
{ .id = 0, DEFINE_NAME("tree") },
};
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 81f52c1f55ce..857d2772db1c 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -291,6 +291,7 @@ BTRFS_FEAT_ATTR_COMPAT_RO(free_space_tree, FREE_SPACE_TREE);
BTRFS_FEAT_ATTR_COMPAT_RO(block_group_tree, BLOCK_GROUP_TREE);
BTRFS_FEAT_ATTR_INCOMPAT(raid1c34, RAID1C34);
BTRFS_FEAT_ATTR_INCOMPAT(simple_quota, SIMPLE_QUOTA);
+BTRFS_FEAT_ATTR_INCOMPAT(remap_tree, REMAP_TREE);
#ifdef CONFIG_BLK_DEV_ZONED
BTRFS_FEAT_ATTR_INCOMPAT(zoned, ZONED);
#endif
@@ -325,6 +326,7 @@ static struct attribute *btrfs_supported_feature_attrs[] = {
BTRFS_FEAT_ATTR_PTR(raid1c34),
BTRFS_FEAT_ATTR_PTR(block_group_tree),
BTRFS_FEAT_ATTR_PTR(simple_quota),
+ BTRFS_FEAT_ATTR_PTR(remap_tree),
#ifdef CONFIG_BLK_DEV_ZONED
BTRFS_FEAT_ATTR_PTR(zoned),
#endif
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index c10b4c242acf..9c03aeb6f2c7 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -913,12 +913,10 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
length, btrfs_stripe_nr_to_offset(U32_MAX));
return -EUCLEAN;
}
- if (unlikely(type & ~(BTRFS_BLOCK_GROUP_TYPE_MASK |
- BTRFS_BLOCK_GROUP_PROFILE_MASK))) {
+ if (unlikely(type & ~BTRFS_BLOCK_GROUP_VALID)) {
chunk_err(fs_info, leaf, chunk, logical,
"unrecognized chunk type: 0x%llx",
- ~(BTRFS_BLOCK_GROUP_TYPE_MASK |
- BTRFS_BLOCK_GROUP_PROFILE_MASK) & type);
+ type & ~BTRFS_BLOCK_GROUP_VALID);
return -EUCLEAN;
}
diff --git a/fs/btrfs/tree-checker.h b/fs/btrfs/tree-checker.h
index eb201f4ec3c7..833e2fd989eb 100644
--- a/fs/btrfs/tree-checker.h
+++ b/fs/btrfs/tree-checker.h
@@ -57,6 +57,11 @@ enum btrfs_tree_block_status {
BTRFS_TREE_BLOCK_WRITTEN_NOT_SET,
};
+
+#define BTRFS_BLOCK_GROUP_VALID (BTRFS_BLOCK_GROUP_TYPE_MASK | \
+ BTRFS_BLOCK_GROUP_PROFILE_MASK | \
+ BTRFS_BLOCK_GROUP_REMAPPED)
+
/*
* Exported simply for btrfs-progs which wants to have the
* btrfs_tree_block_status return codes.
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 65b02a93db31..2e144ebd56ac 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -231,6 +231,7 @@ void btrfs_describe_block_groups(u64 bg_flags, char *buf, u32 size_buf)
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_DATA, "data");
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_SYSTEM, "system");
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_METADATA, "metadata");
+ DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAPPED, "remapped");
DESCRIBE_FLAG(BTRFS_AVAIL_ALLOC_BIT_SINGLE, "single");
for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 8e710bbb688e..fba303ed49e6 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -336,6 +336,7 @@ struct btrfs_ioctl_fs_info_args {
#define BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2 (1ULL << 13)
#define BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE (1ULL << 14)
#define BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA (1ULL << 16)
+#define BTRFS_FEATURE_INCOMPAT_REMAP_TREE (1ULL << 17)
struct btrfs_ioctl_feature_flags {
__u64 compat_flags;
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index fc29d273845d..4439d77a7252 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -76,6 +76,9 @@
/* Tracks RAID stripes in block groups. */
#define BTRFS_RAID_STRIPE_TREE_OBJECTID 12ULL
+/* Holds details of remapped addresses after relocation. */
+#define BTRFS_REMAP_TREE_OBJECTID 13ULL
+
/* device stats in the device tree */
#define BTRFS_DEV_STATS_OBJECTID 0ULL
@@ -282,6 +285,10 @@
#define BTRFS_RAID_STRIPE_KEY 230
+#define BTRFS_IDENTITY_REMAP_KEY 234
+#define BTRFS_REMAP_KEY 235
+#define BTRFS_REMAP_BACKREF_KEY 236
+
/*
* Records the overall state of the qgroups.
* There's only one instance of this key present,
@@ -1161,6 +1168,7 @@ struct btrfs_dev_replace_item {
#define BTRFS_BLOCK_GROUP_RAID6 (1ULL << 8)
#define BTRFS_BLOCK_GROUP_RAID1C3 (1ULL << 9)
#define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
+#define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
#define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
BTRFS_SPACE_INFO_GLOBAL_RSV)
@@ -1323,4 +1331,8 @@ struct btrfs_verity_descriptor_item {
__u8 encryption;
} __attribute__ ((__packed__));
+struct btrfs_remap {
+ __le64 address;
+} __attribute__ ((__packed__));
+
#endif /* _BTRFS_CTREE_H_ */
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 02/17] btrfs: add REMAP chunk type
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 01/17] btrfs: add definitions and constants for remap-tree Mark Harmstone
@ 2025-10-09 11:27 ` Mark Harmstone
2025-10-15 3:37 ` Boris Burkov
2025-10-09 11:27 ` [PATCH v3 03/17] btrfs: allow remapped chunks to have zero stripes Mark Harmstone
` (14 subsequent siblings)
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:27 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Add a new REMAP chunk type, which is a metadata chunk that holds the
remap tree.
This is needed for bootstrapping purposes: the remap tree can't itself
be remapped, and must be relocated the existing way, by COWing every
leaf. The remap tree can't go in the SYSTEM chunk as space there is
limited, because a copy of the chunk item gets placed in the superblock.
The changes in fs/btrfs/volumes.h are because we're adding a new block
group type bit after the profile bits, and so can no longer rely on the
const_ilog2 trick.
The sizing to 32MB per chunk, matching the SYSTEM chunk, is an estimate
here, we can adjust it later if it proves to be too big or too small.
This works out to be ~500,000 remap items, which for a 4KB block size
covers ~2GB of remapped data in the worst case and ~500TB in the best case.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/block-rsv.c | 8 ++++++++
fs/btrfs/block-rsv.h | 1 +
fs/btrfs/disk-io.c | 1 +
fs/btrfs/fs.h | 2 ++
fs/btrfs/space-info.c | 13 ++++++++++++-
fs/btrfs/sysfs.c | 2 ++
fs/btrfs/tree-checker.c | 13 +++++++++++--
fs/btrfs/volumes.c | 3 +++
fs/btrfs/volumes.h | 11 +++++++++--
include/uapi/linux/btrfs_tree.h | 4 +++-
10 files changed, 52 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
index 5ad6de738aee..2678cd3bed29 100644
--- a/fs/btrfs/block-rsv.c
+++ b/fs/btrfs/block-rsv.c
@@ -421,6 +421,9 @@ void btrfs_init_root_block_rsv(struct btrfs_root *root)
case BTRFS_TREE_LOG_OBJECTID:
root->block_rsv = &fs_info->treelog_rsv;
break;
+ case BTRFS_REMAP_TREE_OBJECTID:
+ root->block_rsv = &fs_info->remap_block_rsv;
+ break;
default:
root->block_rsv = NULL;
break;
@@ -434,6 +437,9 @@ void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
fs_info->chunk_block_rsv.space_info = space_info;
+ space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_REMAP);
+ fs_info->remap_block_rsv.space_info = space_info;
+
space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
fs_info->global_block_rsv.space_info = space_info;
fs_info->trans_block_rsv.space_info = space_info;
@@ -460,6 +466,8 @@ void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
WARN_ON(fs_info->trans_block_rsv.reserved > 0);
WARN_ON(fs_info->chunk_block_rsv.size > 0);
WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
+ WARN_ON(fs_info->remap_block_rsv.size > 0);
+ WARN_ON(fs_info->remap_block_rsv.reserved > 0);
WARN_ON(fs_info->delayed_block_rsv.size > 0);
WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
diff --git a/fs/btrfs/block-rsv.h b/fs/btrfs/block-rsv.h
index 79ae9d05cd91..8359fb96bc3c 100644
--- a/fs/btrfs/block-rsv.h
+++ b/fs/btrfs/block-rsv.h
@@ -22,6 +22,7 @@ enum btrfs_rsv_type {
BTRFS_BLOCK_RSV_DELALLOC,
BTRFS_BLOCK_RSV_TRANS,
BTRFS_BLOCK_RSV_CHUNK,
+ BTRFS_BLOCK_RSV_REMAP,
BTRFS_BLOCK_RSV_DELOPS,
BTRFS_BLOCK_RSV_DELREFS,
BTRFS_BLOCK_RSV_TREELOG,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f475fb2272ac..102e5e0ad10c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2815,6 +2815,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
BTRFS_BLOCK_RSV_GLOBAL);
btrfs_init_block_rsv(&fs_info->trans_block_rsv, BTRFS_BLOCK_RSV_TRANS);
btrfs_init_block_rsv(&fs_info->chunk_block_rsv, BTRFS_BLOCK_RSV_CHUNK);
+ btrfs_init_block_rsv(&fs_info->remap_block_rsv, BTRFS_BLOCK_RSV_REMAP);
btrfs_init_block_rsv(&fs_info->treelog_rsv, BTRFS_BLOCK_RSV_TREELOG);
btrfs_init_block_rsv(&fs_info->empty_block_rsv, BTRFS_BLOCK_RSV_EMPTY);
btrfs_init_block_rsv(&fs_info->delayed_block_rsv,
diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index 814bbc9417d2..c4dba7e7ce5a 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -485,6 +485,8 @@ struct btrfs_fs_info {
struct btrfs_block_rsv trans_block_rsv;
/* Block reservation for chunk tree */
struct btrfs_block_rsv chunk_block_rsv;
+ /* Block reservation for remap tree */
+ struct btrfs_block_rsv remap_block_rsv;
/* Block reservation for delayed operations */
struct btrfs_block_rsv delayed_block_rsv;
/* Block reservation for delayed refs */
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 04a07d6f8537..22bc95f33a6f 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -215,7 +215,7 @@ static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
if (flags & BTRFS_BLOCK_GROUP_DATA)
return BTRFS_MAX_DATA_CHUNK_SIZE;
- else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
+ else if (flags & (BTRFS_BLOCK_GROUP_SYSTEM | BTRFS_BLOCK_GROUP_REMAP))
return SZ_32M;
/* Handle BTRFS_BLOCK_GROUP_METADATA */
@@ -343,6 +343,8 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
if (mixed) {
flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
ret = create_space_info(fs_info, flags);
+ if (ret)
+ goto out;
} else {
flags = BTRFS_BLOCK_GROUP_METADATA;
ret = create_space_info(fs_info, flags);
@@ -351,7 +353,15 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
flags = BTRFS_BLOCK_GROUP_DATA;
ret = create_space_info(fs_info, flags);
+ if (ret)
+ goto out;
+ }
+
+ if (features & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
+ flags = BTRFS_BLOCK_GROUP_REMAP;
+ ret = create_space_info(fs_info, flags);
}
+
out:
return ret;
}
@@ -590,6 +600,7 @@ static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
DUMP_BLOCK_RSV(fs_info, global_block_rsv);
DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
+ DUMP_BLOCK_RSV(fs_info, remap_block_rsv);
DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
}
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 857d2772db1c..f942fde1d936 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -1973,6 +1973,8 @@ static const char *alloc_name(struct btrfs_space_info *space_info)
case BTRFS_BLOCK_GROUP_SYSTEM:
ASSERT(space_info->subgroup_id == BTRFS_SUB_GROUP_PRIMARY);
return "system";
+ case BTRFS_BLOCK_GROUP_REMAP:
+ return "remap";
default:
WARN_ON(1);
return "invalid-combination";
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 9c03aeb6f2c7..62f35338a555 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -748,17 +748,26 @@ static int check_block_group_item(struct extent_buffer *leaf,
return -EUCLEAN;
}
+ if (flags & BTRFS_BLOCK_GROUP_REMAP &&
+ !btrfs_fs_incompat(fs_info, REMAP_TREE)) {
+ block_group_err(leaf, slot,
+"invalid flags, have 0x%llx (REMAP flag set) but no remap-tree incompat flag",
+ flags);
+ return -EUCLEAN;
+ }
+
type = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
if (unlikely(type != BTRFS_BLOCK_GROUP_DATA &&
type != BTRFS_BLOCK_GROUP_METADATA &&
type != BTRFS_BLOCK_GROUP_SYSTEM &&
+ type != BTRFS_BLOCK_GROUP_REMAP &&
type != (BTRFS_BLOCK_GROUP_METADATA |
BTRFS_BLOCK_GROUP_DATA))) {
block_group_err(leaf, slot,
-"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx or 0x%llx",
+"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx, 0x%llx or 0x%llx",
type, hweight64(type),
BTRFS_BLOCK_GROUP_DATA, BTRFS_BLOCK_GROUP_METADATA,
- BTRFS_BLOCK_GROUP_SYSTEM,
+ BTRFS_BLOCK_GROUP_SYSTEM, BTRFS_BLOCK_GROUP_REMAP,
BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
return -EUCLEAN;
}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2e144ebd56ac..e14b86e2996b 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -231,6 +231,9 @@ void btrfs_describe_block_groups(u64 bg_flags, char *buf, u32 size_buf)
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_DATA, "data");
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_SYSTEM, "system");
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_METADATA, "metadata");
+ /* block groups containing the remap tree */
+ DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAP, "remap");
+ /* block group that has been remapped */
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAPPED, "remapped");
DESCRIBE_FLAG(BTRFS_AVAIL_ALLOC_BIT_SINGLE, "single");
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 2cbf8080eade..b0fa8eb38060 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -58,8 +58,6 @@ static_assert(const_ilog2(BTRFS_STRIPE_LEN) == BTRFS_STRIPE_LEN_SHIFT);
*/
static_assert(const_ffs(BTRFS_BLOCK_GROUP_RAID0) <
const_ffs(BTRFS_BLOCK_GROUP_PROFILE_MASK & ~BTRFS_BLOCK_GROUP_RAID0));
-static_assert(const_ilog2(BTRFS_BLOCK_GROUP_RAID0) >
- ilog2(BTRFS_BLOCK_GROUP_TYPE_MASK));
/* ilog2() can handle both constants and variables */
#define BTRFS_BG_FLAG_TO_INDEX(profile) \
@@ -81,6 +79,15 @@ enum btrfs_raid_types {
BTRFS_NR_RAID_TYPES
};
+static_assert(BTRFS_RAID_RAID0 == 1);
+static_assert(BTRFS_RAID_RAID1 == 2);
+static_assert(BTRFS_RAID_DUP == 3);
+static_assert(BTRFS_RAID_RAID10 == 4);
+static_assert(BTRFS_RAID_RAID5 == 5);
+static_assert(BTRFS_RAID_RAID6 == 6);
+static_assert(BTRFS_RAID_RAID1C3 == 7);
+static_assert(BTRFS_RAID_RAID1C4 == 8);
+
/*
* Use sequence counter to get consistent device stat data on
* 32-bit processors.
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 4439d77a7252..9a36f0206d90 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -1169,12 +1169,14 @@ struct btrfs_dev_replace_item {
#define BTRFS_BLOCK_GROUP_RAID1C3 (1ULL << 9)
#define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
#define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
+#define BTRFS_BLOCK_GROUP_REMAP (1ULL << 12)
#define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
BTRFS_SPACE_INFO_GLOBAL_RSV)
#define BTRFS_BLOCK_GROUP_TYPE_MASK (BTRFS_BLOCK_GROUP_DATA | \
BTRFS_BLOCK_GROUP_SYSTEM | \
- BTRFS_BLOCK_GROUP_METADATA)
+ BTRFS_BLOCK_GROUP_METADATA | \
+ BTRFS_BLOCK_GROUP_REMAP)
#define BTRFS_BLOCK_GROUP_PROFILE_MASK (BTRFS_BLOCK_GROUP_RAID0 | \
BTRFS_BLOCK_GROUP_RAID1 | \
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 03/17] btrfs: allow remapped chunks to have zero stripes
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 01/17] btrfs: add definitions and constants for remap-tree Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 02/17] btrfs: add REMAP chunk type Mark Harmstone
@ 2025-10-09 11:27 ` Mark Harmstone
2025-10-15 3:47 ` Boris Burkov
2025-10-09 11:27 ` [PATCH v3 04/17] btrfs: remove remapped block groups from the free-space tree Mark Harmstone
` (13 subsequent siblings)
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:27 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
When a chunk has been fully remapped, we are going to set its
num_stripes to 0, as it will no longer represent a physical location on
disk.
Change tree-checker to allow for this, and fix a couple of
divide-by-zeroes seen elsewhere.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/tree-checker.c | 65 ++++++++++++++++++++++++++++-------------
fs/btrfs/volumes.c | 13 ++++++++-
2 files changed, 57 insertions(+), 21 deletions(-)
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 62f35338a555..59b1393e5018 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -816,6 +816,41 @@ static void chunk_err(const struct btrfs_fs_info *fs_info,
va_end(args);
}
+static bool valid_stripe_count(u64 profile, u16 num_stripes,
+ u16 sub_stripes)
+{
+ switch (profile) {
+ case BTRFS_BLOCK_GROUP_RAID0:
+ return true;
+ case BTRFS_BLOCK_GROUP_RAID10:
+ return sub_stripes ==
+ btrfs_raid_array[BTRFS_RAID_RAID10].sub_stripes;
+ case BTRFS_BLOCK_GROUP_RAID1:
+ return num_stripes ==
+ btrfs_raid_array[BTRFS_RAID_RAID1].devs_min;
+ case BTRFS_BLOCK_GROUP_RAID1C3:
+ return num_stripes ==
+ btrfs_raid_array[BTRFS_RAID_RAID1C3].devs_min;
+ case BTRFS_BLOCK_GROUP_RAID1C4:
+ return num_stripes ==
+ btrfs_raid_array[BTRFS_RAID_RAID1C4].devs_min;
+ case BTRFS_BLOCK_GROUP_RAID5:
+ return num_stripes >=
+ btrfs_raid_array[BTRFS_RAID_RAID5].devs_min;
+ case BTRFS_BLOCK_GROUP_RAID6:
+ return num_stripes >=
+ btrfs_raid_array[BTRFS_RAID_RAID6].devs_min;
+ case BTRFS_BLOCK_GROUP_DUP:
+ return num_stripes ==
+ btrfs_raid_array[BTRFS_RAID_DUP].dev_stripes;
+ case 0: /* SINGLE */
+ return num_stripes ==
+ btrfs_raid_array[BTRFS_RAID_SINGLE].dev_stripes;
+ default:
+ BUG();
+ }
+}
+
/*
* The common chunk check which could also work on super block sys chunk array.
*
@@ -839,6 +874,7 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
u64 features;
u32 chunk_sector_size;
bool mixed = false;
+ bool remapped;
int raid_index;
int nparity;
int ncopies;
@@ -862,12 +898,14 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
ncopies = btrfs_raid_array[raid_index].ncopies;
nparity = btrfs_raid_array[raid_index].nparity;
- if (unlikely(!num_stripes)) {
+ remapped = type & BTRFS_BLOCK_GROUP_REMAPPED;
+
+ if (unlikely(!remapped && !num_stripes)) {
chunk_err(fs_info, leaf, chunk, logical,
"invalid chunk num_stripes, have %u", num_stripes);
return -EUCLEAN;
}
- if (unlikely(num_stripes < ncopies)) {
+ if (unlikely(num_stripes != 0 && num_stripes < ncopies)) {
chunk_err(fs_info, leaf, chunk, logical,
"invalid chunk num_stripes < ncopies, have %u < %d",
num_stripes, ncopies);
@@ -965,22 +1003,9 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
}
}
- if (unlikely((type & BTRFS_BLOCK_GROUP_RAID10 &&
- sub_stripes != btrfs_raid_array[BTRFS_RAID_RAID10].sub_stripes) ||
- (type & BTRFS_BLOCK_GROUP_RAID1 &&
- num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1].devs_min) ||
- (type & BTRFS_BLOCK_GROUP_RAID1C3 &&
- num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1C3].devs_min) ||
- (type & BTRFS_BLOCK_GROUP_RAID1C4 &&
- num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1C4].devs_min) ||
- (type & BTRFS_BLOCK_GROUP_RAID5 &&
- num_stripes < btrfs_raid_array[BTRFS_RAID_RAID5].devs_min) ||
- (type & BTRFS_BLOCK_GROUP_RAID6 &&
- num_stripes < btrfs_raid_array[BTRFS_RAID_RAID6].devs_min) ||
- (type & BTRFS_BLOCK_GROUP_DUP &&
- num_stripes != btrfs_raid_array[BTRFS_RAID_DUP].dev_stripes) ||
- ((type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 &&
- num_stripes != btrfs_raid_array[BTRFS_RAID_SINGLE].dev_stripes))) {
+ if (!remapped &&
+ !valid_stripe_count(type & BTRFS_BLOCK_GROUP_PROFILE_MASK,
+ num_stripes, sub_stripes)) {
chunk_err(fs_info, leaf, chunk, logical,
"invalid num_stripes:sub_stripes %u:%u for profile %llu",
num_stripes, sub_stripes,
@@ -1004,11 +1029,11 @@ static int check_leaf_chunk_item(struct extent_buffer *leaf,
struct btrfs_fs_info *fs_info = leaf->fs_info;
int num_stripes;
- if (unlikely(btrfs_item_size(leaf, slot) < sizeof(struct btrfs_chunk))) {
+ if (unlikely(btrfs_item_size(leaf, slot) < offsetof(struct btrfs_chunk, stripe))) {
chunk_err(fs_info, leaf, chunk, key->offset,
"invalid chunk item size: have %u expect [%zu, %u)",
btrfs_item_size(leaf, slot),
- sizeof(struct btrfs_chunk),
+ offsetof(struct btrfs_chunk, stripe),
BTRFS_LEAF_DATA_SIZE(fs_info));
return -EUCLEAN;
}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e14b86e2996b..6750f6f0af59 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6145,6 +6145,12 @@ struct btrfs_discard_stripe *btrfs_map_discard(struct btrfs_fs_info *fs_info,
goto out_free_map;
}
+ /* avoid divide by zero on fully-remapped chunks */
+ if (map->num_stripes == 0) {
+ ret = -EOPNOTSUPP;
+ goto out_free_map;
+ }
+
offset = logical - map->start;
length = min_t(u64, map->start + map->chunk_len - logical, length);
*length_ret = length;
@@ -7088,7 +7094,12 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
*/
map->sub_stripes = btrfs_raid_array[index].sub_stripes;
map->verified_stripes = 0;
- map->stripe_size = btrfs_calc_stripe_length(map);
+
+ if (num_stripes > 0)
+ map->stripe_size = btrfs_calc_stripe_length(map);
+ else
+ map->stripe_size = 0;
+
for (i = 0; i < num_stripes; i++) {
map->stripes[i].physical =
btrfs_stripe_offset_nr(leaf, chunk, i);
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 04/17] btrfs: remove remapped block groups from the free-space tree
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (2 preceding siblings ...)
2025-10-09 11:27 ` [PATCH v3 03/17] btrfs: allow remapped chunks to have zero stripes Mark Harmstone
@ 2025-10-09 11:27 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 05/17] btrfs: don't add metadata items for the remap tree to the extent tree Mark Harmstone
` (12 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:27 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
No new allocations can be done from block groups that have the REMAPPED flag
set, so there's no value in their having entries in the free-space tree.
Prevent a search through the free-space tree being scheduled for such a
block group, and prevent discard being run for a fully-remapped block
group.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/block-group.c | 21 ++++++++++++++++-----
fs/btrfs/discard.c | 9 +++++++++
2 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index cd51f50a7c8b..19a129c54200 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -933,6 +933,13 @@ int btrfs_cache_block_group(struct btrfs_block_group *cache, bool wait)
if (btrfs_is_zoned(fs_info))
return 0;
+ /*
+ * No allocations can be done from remapped block groups, so they have
+ * no entries in the free-space tree.
+ */
+ if (cache->flags & BTRFS_BLOCK_GROUP_REMAPPED)
+ return 0;
+
caching_ctl = kzalloc(sizeof(*caching_ctl), GFP_NOFS);
if (!caching_ctl)
return -ENOMEM;
@@ -1248,9 +1255,11 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
* another task to attempt to create another block group with the same
* item key (and failing with -EEXIST and a transaction abort).
*/
- ret = btrfs_remove_block_group_free_space(trans, block_group);
- if (ret)
- goto out;
+ if (!(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
+ ret = btrfs_remove_block_group_free_space(trans, block_group);
+ if (ret)
+ goto out;
+ }
ret = remove_block_group_item(trans, path, block_group);
if (ret < 0)
@@ -2472,10 +2481,12 @@ static int read_one_block_group(struct btrfs_fs_info *info,
if (btrfs_chunk_writeable(info, cache->start)) {
if (cache->used == 0) {
ASSERT(list_empty(&cache->bg_list));
- if (btrfs_test_opt(info, DISCARD_ASYNC))
+ if (btrfs_test_opt(info, DISCARD_ASYNC) &&
+ !(cache->flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
btrfs_discard_queue_work(&info->discard_ctl, cache);
- else
+ } else {
btrfs_mark_bg_unused(cache);
+ }
}
} else {
inc_block_group_ro(cache, 1);
diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
index 89fe85778115..1015a4d37fb2 100644
--- a/fs/btrfs/discard.c
+++ b/fs/btrfs/discard.c
@@ -698,6 +698,15 @@ void btrfs_discard_punt_unused_bgs_list(struct btrfs_fs_info *fs_info)
/* We enabled async discard, so punt all to the queue */
list_for_each_entry_safe(block_group, next, &fs_info->unused_bgs,
bg_list) {
+ /* Fully remapped BGs have nothing to discard */
+ spin_lock(&block_group->lock);
+ if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
+ !btrfs_is_block_group_used(block_group)) {
+ spin_unlock(&block_group->lock);
+ continue;
+ }
+ spin_unlock(&block_group->lock);
+
list_del_init(&block_group->bg_list);
btrfs_discard_queue_work(&fs_info->discard_ctl, block_group);
/*
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 05/17] btrfs: don't add metadata items for the remap tree to the extent tree
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (3 preceding siblings ...)
2025-10-09 11:27 ` [PATCH v3 04/17] btrfs: remove remapped block groups from the free-space tree Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 06/17] btrfs: add extended version of struct block_group_item Mark Harmstone
` (11 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone, Boris Burkov
There is the following potential problem with the remap tree and delayed refs:
* Remapped extent freed in a delayed ref, which removes an entry from the
remap tree
* Remap tree now small enough to fit in a single leaf
* Corruption as we now have a level-0 block with a level-1 metadata item
in the extent tree
One solution to this would be to rework the remap tree code so that it operates
via delayed refs. But as we're hoping to remove cow-only metadata items in the
future anyway, change things so that the remap tree doesn't have any entries in
the extent tree. This also has the benefit of reducing write amplification.
We also make it so that the clear_cache mount option is a no-op, as with the
extent tree v2, as the free-space tree can no longer be recreated from the
extent tree.
Finally disable relocating the remap tree itself, which is added back in
a later patch. As it is we would get corruption as the traditional
relocation method walks the extent tree, and we're removing its metadata
items.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: Boris Burkov <boris@bur.io>
---
fs/btrfs/disk-io.c | 3 +++
fs/btrfs/extent-tree.c | 31 ++++++++++++++++++++++++++++++-
fs/btrfs/volumes.c | 3 +++
3 files changed, 36 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 102e5e0ad10c..92cb789957b4 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3049,6 +3049,9 @@ int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info)
if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2))
btrfs_warn(fs_info,
"'clear_cache' option is ignored with extent tree v2");
+ else if (btrfs_fs_incompat(fs_info, REMAP_TREE))
+ btrfs_warn(fs_info,
+ "'clear_cache' option is ignored with remap tree");
else
rebuild_free_space_tree = true;
} else if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE) &&
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index dc4ca98c3780..d964147b8097 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1552,6 +1552,28 @@ static void free_head_ref_squota_rsv(struct btrfs_fs_info *fs_info,
BTRFS_QGROUP_RSV_DATA);
}
+static int drop_remap_tree_ref(struct btrfs_trans_handle *trans,
+ const struct btrfs_delayed_ref_node *node)
+{
+ u64 bytenr = node->bytenr;
+ u64 num_bytes = node->num_bytes;
+ int ret;
+
+ ret = btrfs_add_to_free_space_tree(trans, bytenr, num_bytes);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+
+ ret = btrfs_update_block_group(trans, bytenr, num_bytes, false);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+
+ return 0;
+}
+
static int run_delayed_data_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_head *href,
const struct btrfs_delayed_ref_node *node,
@@ -1746,7 +1768,10 @@ static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
} else if (node->action == BTRFS_ADD_DELAYED_REF) {
ret = __btrfs_inc_extent_ref(trans, node, extent_op);
} else if (node->action == BTRFS_DROP_DELAYED_REF) {
- ret = __btrfs_free_extent(trans, href, node, extent_op);
+ if (node->ref_root == BTRFS_REMAP_TREE_OBJECTID)
+ ret = drop_remap_tree_ref(trans, node);
+ else
+ ret = __btrfs_free_extent(trans, href, node, extent_op);
} else {
BUG();
}
@@ -4896,6 +4921,9 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
int level = btrfs_delayed_ref_owner(node);
bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
+ if (unlikely(node->ref_root == BTRFS_REMAP_TREE_OBJECTID))
+ goto skip;
+
extent_key.objectid = node->bytenr;
if (skinny_metadata) {
/* The owner of a tree block is the level. */
@@ -4948,6 +4976,7 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
btrfs_free_path(path);
+skip:
return alloc_reserved_extent(trans, node->bytenr, fs_info->nodesize);
}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6750f6f0af59..0abe02a7072f 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3998,6 +3998,9 @@ static bool should_balance_chunk(struct extent_buffer *leaf, struct btrfs_chunk
struct btrfs_balance_args *bargs = NULL;
u64 chunk_type = btrfs_chunk_type(leaf, chunk);
+ if (chunk_type & BTRFS_BLOCK_GROUP_REMAP)
+ return false;
+
/* type filter */
if (!((chunk_type & BTRFS_BLOCK_GROUP_TYPE_MASK) &
(bctl->flags & BTRFS_BALANCE_TYPE_MASK))) {
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 06/17] btrfs: add extended version of struct block_group_item
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (4 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 05/17] btrfs: don't add metadata items for the remap tree to the extent tree Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag Mark Harmstone
` (10 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone, Boris Burkov
Add a struct btrfs_block_group_item_v2, which is used in the block group
tree if the remap-tree incompat flag is set.
This adds two new fields to the block group item: `remap_bytes` and
`identity_remap_count`.
`remap_bytes` records the amount of data that's physically within this
block group, but nominally in another, remapped block group. This is
necessary because this data will need to be moved first if this block
group is itself relocated. If `remap_bytes` > 0, this is an indicator to
the relocation thread that it will need to search the remap-tree for
backrefs. A block group must also have `remap_bytes` == 0 before it can
be dropped.
`identity_remap_count` records how many identity remap items are located
in the remap tree for this block group. When relocation is begun for
this block group, this is set to the number of holes in the free-space
tree for this range. As identity remaps are converted into actual remaps
by the relocation process, this number is decreased. Once it reaches 0,
either because of relocation or because extents have been deleted, the
block group has been fully remapped and its chunk's device extents are
removed.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: Boris Burkov <boris@bur.io>
---
fs/btrfs/accessors.h | 20 +++++++
fs/btrfs/block-group.c | 101 ++++++++++++++++++++++++--------
fs/btrfs/block-group.h | 14 ++++-
fs/btrfs/discard.c | 2 +-
fs/btrfs/tree-checker.c | 10 +++-
include/uapi/linux/btrfs_tree.h | 8 +++
6 files changed, 127 insertions(+), 28 deletions(-)
diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
index 95a1ca8c099b..0dd161ee6863 100644
--- a/fs/btrfs/accessors.h
+++ b/fs/btrfs/accessors.h
@@ -239,6 +239,26 @@ BTRFS_SETGET_FUNCS(block_group_flags, struct btrfs_block_group_item, flags, 64);
BTRFS_SETGET_STACK_FUNCS(stack_block_group_flags,
struct btrfs_block_group_item, flags, 64);
+/* struct btrfs_block_group_item_v2 */
+BTRFS_SETGET_STACK_FUNCS(stack_block_group_v2_used, struct btrfs_block_group_item_v2,
+ used, 64);
+BTRFS_SETGET_FUNCS(block_group_v2_used, struct btrfs_block_group_item_v2, used, 64);
+BTRFS_SETGET_STACK_FUNCS(stack_block_group_v2_chunk_objectid,
+ struct btrfs_block_group_item_v2, chunk_objectid, 64);
+BTRFS_SETGET_FUNCS(block_group_v2_chunk_objectid,
+ struct btrfs_block_group_item_v2, chunk_objectid, 64);
+BTRFS_SETGET_STACK_FUNCS(stack_block_group_v2_flags,
+ struct btrfs_block_group_item_v2, flags, 64);
+BTRFS_SETGET_FUNCS(block_group_v2_flags, struct btrfs_block_group_item_v2, flags, 64);
+BTRFS_SETGET_STACK_FUNCS(stack_block_group_v2_remap_bytes,
+ struct btrfs_block_group_item_v2, remap_bytes, 64);
+BTRFS_SETGET_FUNCS(block_group_v2_remap_bytes, struct btrfs_block_group_item_v2,
+ remap_bytes, 64);
+BTRFS_SETGET_STACK_FUNCS(stack_block_group_v2_identity_remap_count,
+ struct btrfs_block_group_item_v2, identity_remap_count, 32);
+BTRFS_SETGET_FUNCS(block_group_v2_identity_remap_count, struct btrfs_block_group_item_v2,
+ identity_remap_count, 32);
+
/* struct btrfs_free_space_info */
BTRFS_SETGET_FUNCS(free_space_extent_count, struct btrfs_free_space_info,
extent_count, 32);
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 19a129c54200..d3433a5b169f 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -2375,7 +2375,7 @@ static int check_chunk_block_group_mappings(struct btrfs_fs_info *fs_info)
}
static int read_one_block_group(struct btrfs_fs_info *info,
- struct btrfs_block_group_item *bgi,
+ struct btrfs_block_group_item_v2 *bgi,
const struct btrfs_key *key,
int need_clear)
{
@@ -2390,11 +2390,16 @@ static int read_one_block_group(struct btrfs_fs_info *info,
return -ENOMEM;
cache->length = key->offset;
- cache->used = btrfs_stack_block_group_used(bgi);
+ cache->used = btrfs_stack_block_group_v2_used(bgi);
cache->commit_used = cache->used;
- cache->flags = btrfs_stack_block_group_flags(bgi);
- cache->global_root_id = btrfs_stack_block_group_chunk_objectid(bgi);
+ cache->flags = btrfs_stack_block_group_v2_flags(bgi);
+ cache->global_root_id = btrfs_stack_block_group_v2_chunk_objectid(bgi);
cache->space_info = btrfs_find_space_info(info, cache->flags);
+ cache->remap_bytes = btrfs_stack_block_group_v2_remap_bytes(bgi);
+ cache->commit_remap_bytes = cache->remap_bytes;
+ cache->identity_remap_count =
+ btrfs_stack_block_group_v2_identity_remap_count(bgi);
+ cache->commit_identity_remap_count = cache->identity_remap_count;
btrfs_set_free_space_tree_thresholds(cache);
@@ -2459,7 +2464,7 @@ static int read_one_block_group(struct btrfs_fs_info *info,
} else if (cache->length == cache->used) {
cache->cached = BTRFS_CACHE_FINISHED;
btrfs_free_excluded_extents(cache);
- } else if (cache->used == 0) {
+ } else if (cache->used == 0 && cache->remap_bytes == 0) {
cache->cached = BTRFS_CACHE_FINISHED;
ret = btrfs_add_new_free_space(cache, cache->start,
cache->start + cache->length, NULL);
@@ -2479,7 +2484,8 @@ static int read_one_block_group(struct btrfs_fs_info *info,
set_avail_alloc_bits(info, cache->flags);
if (btrfs_chunk_writeable(info, cache->start)) {
- if (cache->used == 0) {
+ if (cache->used == 0 && cache->identity_remap_count == 0 &&
+ cache->remap_bytes == 0) {
ASSERT(list_empty(&cache->bg_list));
if (btrfs_test_opt(info, DISCARD_ASYNC) &&
!(cache->flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
@@ -2585,9 +2591,10 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
need_clear = 1;
while (1) {
- struct btrfs_block_group_item bgi;
+ struct btrfs_block_group_item_v2 bgi;
struct extent_buffer *leaf;
int slot;
+ size_t size;
ret = find_first_block_group(info, path, &key);
if (ret > 0)
@@ -2598,8 +2605,16 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
leaf = path->nodes[0];
slot = path->slots[0];
+ if (btrfs_fs_incompat(info, REMAP_TREE)) {
+ size = sizeof(struct btrfs_block_group_item_v2);
+ } else {
+ size = sizeof(struct btrfs_block_group_item);
+ btrfs_set_stack_block_group_v2_remap_bytes(&bgi, 0);
+ btrfs_set_stack_block_group_v2_identity_remap_count(&bgi, 0);
+ }
+
read_extent_buffer(leaf, &bgi, btrfs_item_ptr_offset(leaf, slot),
- sizeof(bgi));
+ size);
btrfs_item_key_to_cpu(leaf, &key, slot);
btrfs_release_path(path);
@@ -2669,25 +2684,38 @@ static int insert_block_group_item(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
- struct btrfs_block_group_item bgi;
+ struct btrfs_block_group_item_v2 bgi;
struct btrfs_root *root = btrfs_block_group_root(fs_info);
struct btrfs_key key;
u64 old_commit_used;
+ size_t size;
int ret;
spin_lock(&block_group->lock);
- btrfs_set_stack_block_group_used(&bgi, block_group->used);
- btrfs_set_stack_block_group_chunk_objectid(&bgi,
- block_group->global_root_id);
- btrfs_set_stack_block_group_flags(&bgi, block_group->flags);
+ btrfs_set_stack_block_group_v2_used(&bgi, block_group->used);
+ btrfs_set_stack_block_group_v2_chunk_objectid(&bgi,
+ block_group->global_root_id);
+ btrfs_set_stack_block_group_v2_flags(&bgi, block_group->flags);
+ btrfs_set_stack_block_group_v2_remap_bytes(&bgi,
+ block_group->remap_bytes);
+ btrfs_set_stack_block_group_v2_identity_remap_count(&bgi,
+ block_group->identity_remap_count);
old_commit_used = block_group->commit_used;
block_group->commit_used = block_group->used;
+ block_group->commit_remap_bytes = block_group->remap_bytes;
+ block_group->commit_identity_remap_count =
+ block_group->identity_remap_count;
key.objectid = block_group->start;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
key.offset = block_group->length;
spin_unlock(&block_group->lock);
- ret = btrfs_insert_item(trans, root, &key, &bgi, sizeof(bgi));
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE))
+ size = sizeof(struct btrfs_block_group_item_v2);
+ else
+ size = sizeof(struct btrfs_block_group_item);
+
+ ret = btrfs_insert_item(trans, root, &key, &bgi, size);
if (ret < 0) {
spin_lock(&block_group->lock);
block_group->commit_used = old_commit_used;
@@ -3142,10 +3170,12 @@ static int update_block_group_item(struct btrfs_trans_handle *trans,
struct btrfs_root *root = btrfs_block_group_root(fs_info);
unsigned long bi;
struct extent_buffer *leaf;
- struct btrfs_block_group_item bgi;
+ struct btrfs_block_group_item_v2 bgi;
struct btrfs_key key;
- u64 old_commit_used;
- u64 used;
+ u64 old_commit_used, old_commit_remap_bytes;
+ u32 old_commit_identity_remap_count;
+ u64 used, remap_bytes;
+ u32 identity_remap_count;
/*
* Block group items update can be triggered out of commit transaction
@@ -3155,13 +3185,21 @@ static int update_block_group_item(struct btrfs_trans_handle *trans,
*/
spin_lock(&cache->lock);
old_commit_used = cache->commit_used;
+ old_commit_remap_bytes = cache->commit_remap_bytes;
+ old_commit_identity_remap_count = cache->commit_identity_remap_count;
used = cache->used;
- /* No change in used bytes, can safely skip it. */
- if (cache->commit_used == used) {
+ remap_bytes = cache->remap_bytes;
+ identity_remap_count = cache->identity_remap_count;
+ /* No change in values, can safely skip it. */
+ if (cache->commit_used == used &&
+ cache->commit_remap_bytes == remap_bytes &&
+ cache->commit_identity_remap_count == identity_remap_count) {
spin_unlock(&cache->lock);
return 0;
}
cache->commit_used = used;
+ cache->commit_remap_bytes = remap_bytes;
+ cache->commit_identity_remap_count = identity_remap_count;
spin_unlock(&cache->lock);
key.objectid = cache->start;
@@ -3177,11 +3215,23 @@ static int update_block_group_item(struct btrfs_trans_handle *trans,
leaf = path->nodes[0];
bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
- btrfs_set_stack_block_group_used(&bgi, used);
- btrfs_set_stack_block_group_chunk_objectid(&bgi,
- cache->global_root_id);
- btrfs_set_stack_block_group_flags(&bgi, cache->flags);
- write_extent_buffer(leaf, &bgi, bi, sizeof(bgi));
+ btrfs_set_stack_block_group_v2_used(&bgi, used);
+ btrfs_set_stack_block_group_v2_chunk_objectid(&bgi,
+ cache->global_root_id);
+ btrfs_set_stack_block_group_v2_flags(&bgi, cache->flags);
+
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
+ btrfs_set_stack_block_group_v2_remap_bytes(&bgi,
+ cache->remap_bytes);
+ btrfs_set_stack_block_group_v2_identity_remap_count(&bgi,
+ cache->identity_remap_count);
+ write_extent_buffer(leaf, &bgi, bi,
+ sizeof(struct btrfs_block_group_item_v2));
+ } else {
+ write_extent_buffer(leaf, &bgi, bi,
+ sizeof(struct btrfs_block_group_item));
+ }
+
fail:
btrfs_release_path(path);
/*
@@ -3196,6 +3246,9 @@ static int update_block_group_item(struct btrfs_trans_handle *trans,
if (ret < 0 && ret != -ENOENT) {
spin_lock(&cache->lock);
cache->commit_used = old_commit_used;
+ cache->commit_remap_bytes = old_commit_remap_bytes;
+ cache->commit_identity_remap_count =
+ old_commit_identity_remap_count;
spin_unlock(&cache->lock);
}
return ret;
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index 9172104a5889..af23fdb3cf4d 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -129,6 +129,8 @@ struct btrfs_block_group {
u64 flags;
u64 cache_generation;
u64 global_root_id;
+ u64 remap_bytes;
+ u32 identity_remap_count;
/*
* The last committed used bytes of this block group, if the above @used
@@ -136,6 +138,15 @@ struct btrfs_block_group {
* group item of this block group.
*/
u64 commit_used;
+ /*
+ * The last committed remap_bytes value of this block group.
+ */
+ u64 commit_remap_bytes;
+ /*
+ * The last commited identity_remap_count value of this block group.
+ */
+ u32 commit_identity_remap_count;
+
/*
* If the free space extent count exceeds this number, convert the block
* group to bitmaps.
@@ -282,7 +293,8 @@ static inline bool btrfs_is_block_group_used(const struct btrfs_block_group *bg)
{
lockdep_assert_held(&bg->lock);
- return (bg->used > 0 || bg->reserved > 0 || bg->pinned > 0);
+ return (bg->used > 0 || bg->reserved > 0 || bg->pinned > 0 ||
+ bg->remap_bytes > 0);
}
static inline bool btrfs_is_block_group_data_only(const struct btrfs_block_group *block_group)
diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
index 1015a4d37fb2..2b7b1e440bc8 100644
--- a/fs/btrfs/discard.c
+++ b/fs/btrfs/discard.c
@@ -373,7 +373,7 @@ void btrfs_discard_queue_work(struct btrfs_discard_ctl *discard_ctl,
if (!block_group || !btrfs_test_opt(block_group->fs_info, DISCARD_ASYNC))
return;
- if (block_group->used == 0)
+ if (block_group->used == 0 && block_group->remap_bytes == 0)
add_to_discard_unused_list(discard_ctl, block_group);
else
add_to_discard_list(discard_ctl, block_group);
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 59b1393e5018..60b554450e91 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -688,6 +688,7 @@ static int check_block_group_item(struct extent_buffer *leaf,
u64 chunk_objectid;
u64 flags;
u64 type;
+ size_t exp_size;
/*
* Here we don't really care about alignment since extent allocator can
@@ -699,10 +700,15 @@ static int check_block_group_item(struct extent_buffer *leaf,
return -EUCLEAN;
}
- if (unlikely(item_size != sizeof(bgi))) {
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE))
+ exp_size = sizeof(struct btrfs_block_group_item_v2);
+ else
+ exp_size = sizeof(struct btrfs_block_group_item);
+
+ if (unlikely(item_size != exp_size)) {
block_group_err(leaf, slot,
"invalid item size, have %u expect %zu",
- item_size, sizeof(bgi));
+ item_size, exp_size);
return -EUCLEAN;
}
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 9a36f0206d90..500e3a7df90b 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -1229,6 +1229,14 @@ struct btrfs_block_group_item {
__le64 flags;
} __attribute__ ((__packed__));
+struct btrfs_block_group_item_v2 {
+ __le64 used;
+ __le64 chunk_objectid;
+ __le64 flags;
+ __le64 remap_bytes;
+ __le32 identity_remap_count;
+} __attribute__ ((__packed__));
+
struct btrfs_free_space_info {
__le32 extent_count;
__le32 flags;
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (5 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 06/17] btrfs: add extended version of struct block_group_item Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-15 3:55 ` Boris Burkov
2025-10-09 11:28 ` [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups Mark Harmstone
` (9 subsequent siblings)
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
If we encounter a filesystem with the remap-tree incompat flag set,
valdiate its compatibility with the other flags, and load the remap tree
using the values that have been added to the superblock.
The remap-tree feature depends on the free space tere, but no-holes and
block-group-tree have been made dependencies to reduce the testing
matrix. Similarly I'm not aware of any reason why mixed-bg and zoned would be
incompatible with remap-tree, but this is blocked for the time being
until it can be fully tested.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/Kconfig | 2 +
fs/btrfs/accessors.h | 6 ++
fs/btrfs/disk-io.c | 101 ++++++++++++++++++++++++++++----
fs/btrfs/extent-tree.c | 2 +
fs/btrfs/fs.h | 4 +-
fs/btrfs/transaction.c | 7 +++
include/uapi/linux/btrfs_tree.h | 5 +-
7 files changed, 113 insertions(+), 14 deletions(-)
diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 4438637c8900..77b5a9f27840 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -117,4 +117,6 @@ config BTRFS_EXPERIMENTAL
- large folio support
+ - remap-tree - logical address remapping tree
+
If unsure, say N.
diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
index 0dd161ee6863..392eaad75e72 100644
--- a/fs/btrfs/accessors.h
+++ b/fs/btrfs/accessors.h
@@ -882,6 +882,12 @@ BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
uuid_tree_generation, 64);
BTRFS_SETGET_STACK_FUNCS(super_nr_global_roots, struct btrfs_super_block,
nr_global_roots, 64);
+BTRFS_SETGET_STACK_FUNCS(super_remap_root, struct btrfs_super_block,
+ remap_root, 64);
+BTRFS_SETGET_STACK_FUNCS(super_remap_root_generation, struct btrfs_super_block,
+ remap_root_generation, 64);
+BTRFS_SETGET_STACK_FUNCS(super_remap_root_level, struct btrfs_super_block,
+ remap_root_level, 8);
/* struct btrfs_file_extent_item */
BTRFS_SETGET_STACK_FUNCS(stack_file_extent_type, struct btrfs_file_extent_item,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 92cb789957b4..60507e971aad 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1180,6 +1180,8 @@ static struct btrfs_root *btrfs_get_global_root(struct btrfs_fs_info *fs_info,
return btrfs_grab_root(btrfs_global_root(fs_info, &key));
case BTRFS_RAID_STRIPE_TREE_OBJECTID:
return btrfs_grab_root(fs_info->stripe_root);
+ case BTRFS_REMAP_TREE_OBJECTID:
+ return btrfs_grab_root(fs_info->remap_root);
default:
return NULL;
}
@@ -1271,6 +1273,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
btrfs_put_root(fs_info->data_reloc_root);
btrfs_put_root(fs_info->block_group_root);
btrfs_put_root(fs_info->stripe_root);
+ btrfs_put_root(fs_info->remap_root);
btrfs_check_leaked_roots(fs_info);
btrfs_extent_buffer_leak_debug_check(fs_info);
kfree(fs_info->super_copy);
@@ -1825,6 +1828,7 @@ static void free_root_pointers(struct btrfs_fs_info *info, bool free_chunk_root)
free_root_extent_buffers(info->data_reloc_root);
free_root_extent_buffers(info->block_group_root);
free_root_extent_buffers(info->stripe_root);
+ free_root_extent_buffers(info->remap_root);
if (free_chunk_root)
free_root_extent_buffers(info->chunk_root);
}
@@ -2256,20 +2260,45 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
if (ret)
goto out;
- /*
- * This tree can share blocks with some other fs tree during relocation
- * and we need a proper setup by btrfs_get_fs_root
- */
- root = btrfs_get_fs_root(tree_root->fs_info,
- BTRFS_DATA_RELOC_TREE_OBJECTID, true);
- if (IS_ERR(root)) {
- if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
- ret = PTR_ERR(root);
- goto out;
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
+ /* remap_root already loaded in load_important_roots() */
+ root = fs_info->remap_root;
+
+ set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
+
+ root->root_key.objectid = BTRFS_REMAP_TREE_OBJECTID;
+ root->root_key.type = BTRFS_ROOT_ITEM_KEY;
+ root->root_key.offset = 0;
+
+ /* Check that data reloc tree doesn't also exist */
+ location.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
+ root = btrfs_read_tree_root(fs_info->tree_root, &location);
+ if (!IS_ERR(root)) {
+ btrfs_err(fs_info,
+ "data reloc tree exists when remap-tree enabled");
+ btrfs_put_root(root);
+ return -EIO;
+ } else if (PTR_ERR(root) != -ENOENT) {
+ btrfs_warn(fs_info,
+ "error %ld when checking for data reloc tree",
+ PTR_ERR(root));
}
} else {
- set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
- fs_info->data_reloc_root = root;
+ /*
+ * This tree can share blocks with some other fs tree during
+ * relocation and we need a proper setup by btrfs_get_fs_root
+ */
+ root = btrfs_get_fs_root(tree_root->fs_info,
+ BTRFS_DATA_RELOC_TREE_OBJECTID, true);
+ if (IS_ERR(root)) {
+ if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
+ ret = PTR_ERR(root);
+ goto out;
+ }
+ } else {
+ set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
+ fs_info->data_reloc_root = root;
+ }
}
location.objectid = BTRFS_QUOTA_TREE_OBJECTID;
@@ -2509,6 +2538,31 @@ int btrfs_validate_super(const struct btrfs_fs_info *fs_info,
ret = -EINVAL;
}
+ /*
+ * Reduce test matrix for remap tree by requiring block-group-tree
+ * and no-holes. Free-space-tree is a hard requirement.
+ */
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+ (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID) ||
+ !btrfs_fs_incompat(fs_info, NO_HOLES) ||
+ !btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE))) {
+ btrfs_err(fs_info,
+"remap-tree feature requires free-space-tree, no-holes, and block-group-tree");
+ ret = -EINVAL;
+ }
+
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+ btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
+ btrfs_err(fs_info, "remap-tree not supported with mixed-bg");
+ ret = -EINVAL;
+ }
+
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+ btrfs_fs_incompat(fs_info, ZONED)) {
+ btrfs_err(fs_info, "remap-tree not supported with zoned devices");
+ ret = -EINVAL;
+ }
+
/*
* Hint to catch really bogus numbers, bitflips or so, more exact checks are
* done later
@@ -2667,6 +2721,18 @@ static int load_important_roots(struct btrfs_fs_info *fs_info)
btrfs_warn(fs_info, "couldn't read tree root");
return ret;
}
+
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
+ bytenr = btrfs_super_remap_root(sb);
+ gen = btrfs_super_remap_root_generation(sb);
+ level = btrfs_super_remap_root_level(sb);
+ ret = load_super_root(fs_info->remap_root, bytenr, gen, level);
+ if (ret) {
+ btrfs_warn(fs_info, "couldn't read remap root");
+ return ret;
+ }
+ }
+
return 0;
}
@@ -3284,6 +3350,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
struct btrfs_fs_info *fs_info = btrfs_sb(sb);
struct btrfs_root *tree_root;
struct btrfs_root *chunk_root;
+ struct btrfs_root *remap_root;
int ret;
int level;
@@ -3417,6 +3484,16 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
if (ret < 0)
goto fail_alloc;
+ if (btrfs_super_incompat_flags(disk_super) & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
+ remap_root = btrfs_alloc_root(fs_info, BTRFS_REMAP_TREE_OBJECTID,
+ GFP_KERNEL);
+ fs_info->remap_root = remap_root;
+ if (!remap_root) {
+ ret = -ENOMEM;
+ goto fail_alloc;
+ }
+ }
+
/*
* At this point our mount options are validated, if we set ->max_inline
* to something non-standard make sure we truncate it to sectorsize.
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index d964147b8097..7805a148bbd8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2589,6 +2589,8 @@ static u64 get_alloc_profile_by_root(struct btrfs_root *root, int data)
flags = BTRFS_BLOCK_GROUP_DATA;
else if (root == fs_info->chunk_root)
flags = BTRFS_BLOCK_GROUP_SYSTEM;
+ else if (root == fs_info->remap_root)
+ flags = BTRFS_BLOCK_GROUP_REMAP;
else
flags = BTRFS_BLOCK_GROUP_METADATA;
diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index c4dba7e7ce5a..c76f4c2701f9 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -291,7 +291,8 @@ enum {
#define BTRFS_FEATURE_INCOMPAT_SUPP \
(BTRFS_FEATURE_INCOMPAT_SUPP_STABLE | \
BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE | \
- BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2)
+ BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2 | \
+ BTRFS_FEATURE_INCOMPAT_REMAP_TREE)
#else
@@ -451,6 +452,7 @@ struct btrfs_fs_info {
struct btrfs_root *data_reloc_root;
struct btrfs_root *block_group_root;
struct btrfs_root *stripe_root;
+ struct btrfs_root *remap_root;
/* The log root tree is a directory of all the other log roots */
struct btrfs_root *log_root_tree;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 89ae0c7a610a..b1c41982e7b2 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1950,6 +1950,13 @@ static void update_super_roots(struct btrfs_fs_info *fs_info)
super->cache_generation = 0;
if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
super->uuid_tree_generation = root_item->generation;
+
+ if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
+ root_item = &fs_info->remap_root->root_item;
+ super->remap_root = root_item->bytenr;
+ super->remap_root_generation = root_item->generation;
+ super->remap_root_level = root_item->level;
+ }
}
int btrfs_transaction_blocked(struct btrfs_fs_info *info)
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 500e3a7df90b..89bcb80081a6 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -721,9 +721,12 @@ struct btrfs_super_block {
__u8 metadata_uuid[BTRFS_FSID_SIZE];
__u64 nr_global_roots;
+ __le64 remap_root;
+ __le64 remap_root_generation;
+ __u8 remap_root_level;
/* Future expansion */
- __le64 reserved[27];
+ __u8 reserved[199];
__u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (6 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-15 4:21 ` Boris Burkov
2025-10-09 11:28 ` [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list() Mark Harmstone
` (8 subsequent siblings)
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Change btrfs_map_block() so that if the block group has the REMAPPED
flag set, we call btrfs_translate_remap() to obtain a new address.
btrfs_translate_remap() searches the remap tree for a range
corresponding to the logical address passed to btrfs_map_block(). If it
is within an identity remap, this part of the block group hasn't yet
been relocated, and so we use the existing address.
If it is within an actual remap, we subtract the start of the remap
range and add the address of its destination, contained in the item's
payload.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/relocation.c | 59 +++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/relocation.h | 2 ++
fs/btrfs/volumes.c | 31 +++++++++++++++++++++++
3 files changed, 92 insertions(+)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 748290758459..4f5d3aaf0f65 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3870,6 +3870,65 @@ static const char *stage_to_string(enum reloc_stage stage)
return "unknown";
}
+int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
+ u64 *length, bool nolock)
+{
+ int ret;
+ struct btrfs_key key, found_key;
+ struct extent_buffer *leaf;
+ struct btrfs_remap *remap;
+ BTRFS_PATH_AUTO_FREE(path);
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ if (nolock) {
+ path->search_commit_root = 1;
+ path->skip_locking = 1;
+ }
+
+ key.objectid = *logical;
+ key.type = (u8)-1;
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(NULL, fs_info->remap_root, &key, path,
+ 0, 0);
+ if (ret < 0)
+ return ret;
+
+ leaf = path->nodes[0];
+
+ if (path->slots[0] == 0)
+ return -ENOENT;
+
+ path->slots[0]--;
+
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+ if (found_key.type != BTRFS_REMAP_KEY &&
+ found_key.type != BTRFS_IDENTITY_REMAP_KEY) {
+ return -ENOENT;
+ }
+
+ if (found_key.objectid > *logical ||
+ found_key.objectid + found_key.offset <= *logical) {
+ return -ENOENT;
+ }
+
+ if (*logical + *length > found_key.objectid + found_key.offset)
+ *length = found_key.objectid + found_key.offset - *logical;
+
+ if (found_key.type == BTRFS_IDENTITY_REMAP_KEY)
+ return 0;
+
+ remap = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_remap);
+
+ *logical += btrfs_remap_address(leaf, remap) - found_key.objectid;
+
+ return 0;
+}
+
/*
* function to relocate all extents in a block group.
*/
diff --git a/fs/btrfs/relocation.h b/fs/btrfs/relocation.h
index 5c36b3f84b57..a653c42a25a3 100644
--- a/fs/btrfs/relocation.h
+++ b/fs/btrfs/relocation.h
@@ -31,5 +31,7 @@ int btrfs_should_cancel_balance(const struct btrfs_fs_info *fs_info);
struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr);
bool btrfs_should_ignore_reloc_root(const struct btrfs_root *root);
u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info);
+int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
+ u64 *length, bool nolock);
#endif
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0abe02a7072f..f2d1203778aa 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6635,6 +6635,37 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
if (IS_ERR(map))
return PTR_ERR(map);
+ if (map->type & BTRFS_BLOCK_GROUP_REMAPPED) {
+ u64 new_logical = logical;
+ bool nolock = !(map->type & BTRFS_BLOCK_GROUP_DATA);
+
+ /*
+ * We use search_commit_root in btrfs_translate_remap for
+ * metadata blocks, to avoid lockdep complaining about
+ * recursive locking.
+ * If we get -ENOENT this means this is a BG that has just had
+ * its REMAPPED flag set, and so nothing has yet been actually
+ * remapped.
+ */
+ ret = btrfs_translate_remap(fs_info, &new_logical, length,
+ nolock);
+ if (ret && (!nolock || ret != -ENOENT))
+ return ret;
+
+ if (ret != -ENOENT && new_logical != logical) {
+ btrfs_free_chunk_map(map);
+
+ map = btrfs_get_chunk_map(fs_info, new_logical,
+ *length);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ logical = new_logical;
+ }
+
+ ret = 0;
+ }
+
num_copies = btrfs_chunk_map_num_copies(map);
if (io_geom.mirror_num > num_copies)
return -EINVAL;
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list()
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (7 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:56 ` Filipe Manana
2025-10-09 11:28 ` [PATCH v3 10/17] btrfs: handle deletions from remapped block group Mark Harmstone
` (7 subsequent siblings)
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Release block_group->lock before calling btrfs_link_bg_list() in
btrfs_delete_unused_bgs(), as this was causing lockdep issues.
This lock isn't held in any other place that we call btrfs_link_bg_list(), as
the block group lists are manipulated while holding fs_info->unused_bgs_lock.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Fixes: 0497dfba98c0 ("btrfs: codify pattern for adding block_group to bg_list")
---
fs/btrfs/block-group.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index d3433a5b169f..a3c984f905fc 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1620,6 +1620,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
if ((space_info->total_bytes - block_group->length < used &&
block_group->zone_unusable < block_group->length) ||
has_unwritten_metadata(block_group)) {
+ spin_unlock(&block_group->lock);
+
/*
* Add a reference for the list, compensate for the ref
* drop under the "next" label for the
@@ -1628,7 +1630,6 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
btrfs_link_bg_list(block_group, &retry_list);
trace_btrfs_skip_unused_block_group(block_group);
- spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
up_write(&space_info->groups_sem);
goto next;
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 10/17] btrfs: handle deletions from remapped block group
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (8 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list() Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 11/17] btrfs: handle setting up relocation of block group with remap-tree Mark Harmstone
` (6 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Handle the case where we free an extent from a block group that has the
REMAPPED flag set. Because the remap tree is orthogonal to the extent
tree, for data this may be within any number of identity remaps or
actual remaps. If we're freeing a metadata node, this will be wholly
inside one or the other.
btrfs_remove_extent_from_remap_tree() searches the remap tree for the
remaps that cover the range in question, then calls
remove_range_from_remap_tree() for each one, to punch a hole in the
remap and adjust the free-space tree.
For an identity remap, remove_range_from_remap_tree() will adjust the
block group's `identity_remap_count` if this changes. If it reaches
zero we call last_identity_remap_gone(), which removes the chunk's
stripes and device extents - it is now fully remapped.
The changes which involve the block group's ro flag are because the
REMAPPED flag itself prevents a block group from having any new
allocations within it, and so we don't need to account for this
separately.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/block-group.c | 108 ++++++---
fs/btrfs/block-group.h | 3 +
fs/btrfs/disk-io.c | 2 +
fs/btrfs/extent-tree.c | 77 ++++++-
fs/btrfs/extent-tree.h | 1 +
fs/btrfs/fs.h | 4 +-
fs/btrfs/relocation.c | 495 +++++++++++++++++++++++++++++++++++++++++
fs/btrfs/relocation.h | 6 +
fs/btrfs/transaction.c | 4 +
fs/btrfs/volumes.c | 56 +++--
fs/btrfs/volumes.h | 6 +
11 files changed, 703 insertions(+), 59 deletions(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index a3c984f905fc..bfb4b8a840c8 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1068,6 +1068,32 @@ static int remove_block_group_item(struct btrfs_trans_handle *trans,
return ret;
}
+void btrfs_remove_bg_from_sinfo(struct btrfs_block_group *block_group)
+{
+ int factor = btrfs_bg_type_to_factor(block_group->flags);
+
+ spin_lock(&block_group->space_info->lock);
+
+ if (btrfs_test_opt(block_group->fs_info, ENOSPC_DEBUG)) {
+ WARN_ON(block_group->space_info->total_bytes
+ < block_group->length);
+ WARN_ON(block_group->space_info->bytes_readonly
+ < block_group->length - block_group->zone_unusable);
+ WARN_ON(block_group->space_info->bytes_zone_unusable
+ < block_group->zone_unusable);
+ WARN_ON(block_group->space_info->disk_total
+ < block_group->length * factor);
+ }
+ block_group->space_info->total_bytes -= block_group->length;
+ block_group->space_info->bytes_readonly -=
+ (block_group->length - block_group->zone_unusable);
+ btrfs_space_info_update_bytes_zone_unusable(block_group->space_info,
+ -block_group->zone_unusable);
+ block_group->space_info->disk_total -= block_group->length * factor;
+
+ spin_unlock(&block_group->space_info->lock);
+}
+
int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
struct btrfs_chunk_map *map)
{
@@ -1079,7 +1105,6 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
struct kobject *kobj = NULL;
int ret;
int index;
- int factor;
struct btrfs_caching_control *caching_ctl = NULL;
bool remove_map;
bool remove_rsv = false;
@@ -1088,7 +1113,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
if (!block_group)
return -ENOENT;
- BUG_ON(!block_group->ro);
+ BUG_ON(!block_group->ro && !(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED));
trace_btrfs_remove_block_group(block_group);
/*
@@ -1100,7 +1125,6 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
block_group->length);
index = btrfs_bg_flags_to_raid_index(block_group->flags);
- factor = btrfs_bg_type_to_factor(block_group->flags);
/* make sure this block group isn't part of an allocation cluster */
cluster = &fs_info->data_alloc_cluster;
@@ -1224,26 +1248,11 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
spin_lock(&block_group->space_info->lock);
list_del_init(&block_group->ro_list);
-
- if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
- WARN_ON(block_group->space_info->total_bytes
- < block_group->length);
- WARN_ON(block_group->space_info->bytes_readonly
- < block_group->length - block_group->zone_unusable);
- WARN_ON(block_group->space_info->bytes_zone_unusable
- < block_group->zone_unusable);
- WARN_ON(block_group->space_info->disk_total
- < block_group->length * factor);
- }
- block_group->space_info->total_bytes -= block_group->length;
- block_group->space_info->bytes_readonly -=
- (block_group->length - block_group->zone_unusable);
- btrfs_space_info_update_bytes_zone_unusable(block_group->space_info,
- -block_group->zone_unusable);
- block_group->space_info->disk_total -= block_group->length * factor;
-
spin_unlock(&block_group->space_info->lock);
+ if (!(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED))
+ btrfs_remove_bg_from_sinfo(block_group);
+
/*
* Remove the free space for the block group from the free space tree
* and the block group's item from the extent tree before marking the
@@ -1539,6 +1548,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
while (!list_empty(&fs_info->unused_bgs)) {
u64 used;
int trimming;
+ bool made_ro = false;
block_group = list_first_entry(&fs_info->unused_bgs,
struct btrfs_block_group,
@@ -1575,7 +1585,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
spin_lock(&space_info->lock);
spin_lock(&block_group->lock);
- if (btrfs_is_block_group_used(block_group) || block_group->ro ||
+ if (btrfs_is_block_group_used(block_group) ||
+ (block_group->ro && !(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED)) ||
list_is_singular(&block_group->list)) {
/*
* We want to bail if we made new allocations or have
@@ -1617,9 +1628,10 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
* needing to allocate extents from the block group.
*/
used = btrfs_space_info_used(space_info, true);
- if ((space_info->total_bytes - block_group->length < used &&
+ if (((space_info->total_bytes - block_group->length < used &&
block_group->zone_unusable < block_group->length) ||
- has_unwritten_metadata(block_group)) {
+ has_unwritten_metadata(block_group)) &&
+ !(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
spin_unlock(&block_group->lock);
/*
@@ -1638,8 +1650,14 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
- /* We don't want to force the issue, only flip if it's ok. */
- ret = inc_block_group_ro(block_group, 0);
+ if (!(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
+ /* We don't want to force the issue, only flip if it's ok. */
+ ret = inc_block_group_ro(block_group, 0);
+ made_ro = true;
+ } else {
+ ret = 0;
+ }
+
up_write(&space_info->groups_sem);
if (ret < 0) {
ret = 0;
@@ -1648,7 +1666,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
ret = btrfs_zone_finish(block_group);
if (ret < 0) {
- btrfs_dec_block_group_ro(block_group);
+ if (made_ro)
+ btrfs_dec_block_group_ro(block_group);
if (ret == -EAGAIN) {
btrfs_link_bg_list(block_group, &retry_list);
ret = 0;
@@ -1663,7 +1682,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
trans = btrfs_start_trans_remove_block_group(fs_info,
block_group->start);
if (IS_ERR(trans)) {
- btrfs_dec_block_group_ro(block_group);
+ if (made_ro)
+ btrfs_dec_block_group_ro(block_group);
ret = PTR_ERR(trans);
goto next;
}
@@ -1673,7 +1693,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
* just delete them, we don't care about them anymore.
*/
if (!clean_pinned_extents(trans, block_group)) {
- btrfs_dec_block_group_ro(block_group);
+ if (made_ro)
+ btrfs_dec_block_group_ro(block_group);
goto end_trans;
}
@@ -1687,7 +1708,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
spin_lock(&fs_info->discard_ctl.lock);
if (!list_empty(&block_group->discard_list)) {
spin_unlock(&fs_info->discard_ctl.lock);
- btrfs_dec_block_group_ro(block_group);
+ if (made_ro)
+ btrfs_dec_block_group_ro(block_group);
btrfs_discard_queue_work(&fs_info->discard_ctl,
block_group);
goto end_trans;
@@ -1781,6 +1803,14 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg)
struct btrfs_fs_info *fs_info = bg->fs_info;
spin_lock(&fs_info->unused_bgs_lock);
+
+ /* Leave fully remapped block groups on the fully_remapped_bgs list. */
+ if (bg->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
+ bg->identity_remap_count == 0) {
+ spin_unlock(&fs_info->unused_bgs_lock);
+ return;
+ }
+
if (list_empty(&bg->bg_list)) {
btrfs_get_block_group(bg);
trace_btrfs_add_unused_block_group(bg);
@@ -4777,3 +4807,21 @@ bool btrfs_block_group_should_use_size_class(const struct btrfs_block_group *bg)
return false;
return true;
}
+
+void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
+ struct btrfs_trans_handle *trans)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+
+ spin_lock(&fs_info->unused_bgs_lock);
+
+ if (!list_empty(&bg->bg_list))
+ list_del(&bg->bg_list);
+ else
+ btrfs_get_block_group(bg);
+
+ list_add_tail(&bg->bg_list, &fs_info->fully_remapped_bgs);
+
+ spin_unlock(&fs_info->unused_bgs_lock);
+
+}
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index af23fdb3cf4d..f0a1462f1d31 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -336,6 +336,7 @@ int btrfs_add_new_free_space(struct btrfs_block_group *block_group,
struct btrfs_trans_handle *btrfs_start_trans_remove_block_group(
struct btrfs_fs_info *fs_info,
const u64 chunk_offset);
+void btrfs_remove_bg_from_sinfo(struct btrfs_block_group *block_group);
int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
struct btrfs_chunk_map *map);
void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info);
@@ -407,5 +408,7 @@ int btrfs_use_block_group_size_class(struct btrfs_block_group *bg,
enum btrfs_block_group_size_class size_class,
bool force_wrong_size_class);
bool btrfs_block_group_should_use_size_class(const struct btrfs_block_group *bg);
+void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
+ struct btrfs_trans_handle *trans);
#endif /* BTRFS_BLOCK_GROUP_H */
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 60507e971aad..4b136addf902 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2869,6 +2869,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
INIT_LIST_HEAD(&fs_info->tree_mod_seq_list);
INIT_LIST_HEAD(&fs_info->unused_bgs);
INIT_LIST_HEAD(&fs_info->reclaim_bgs);
+ INIT_LIST_HEAD(&fs_info->fully_remapped_bgs);
INIT_LIST_HEAD(&fs_info->zone_active_bgs);
#ifdef CONFIG_BTRFS_DEBUG
INIT_LIST_HEAD(&fs_info->allocated_roots);
@@ -2924,6 +2925,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
mutex_init(&fs_info->chunk_mutex);
mutex_init(&fs_info->transaction_kthread_mutex);
mutex_init(&fs_info->cleaner_mutex);
+ mutex_init(&fs_info->remap_mutex);
mutex_init(&fs_info->ro_block_group_mutex);
init_rwsem(&fs_info->commit_root_sem);
init_rwsem(&fs_info->cleanup_work_sem);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 7805a148bbd8..60287aca283d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -40,6 +40,7 @@
#include "orphan.h"
#include "tree-checker.h"
#include "raid-stripe-tree.h"
+#include "relocation.h"
#undef SCRAMBLE_DELAYED_REFS
@@ -2847,6 +2848,52 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
return ret;
}
+int btrfs_handle_fully_remapped_bgs(struct btrfs_trans_handle *trans)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_block_group *block_group, *tmp;
+ struct list_head *fully_remapped_bgs;
+ int ret;
+
+ fully_remapped_bgs = &fs_info->fully_remapped_bgs;
+ list_for_each_entry_safe(block_group, tmp, fully_remapped_bgs, bg_list) {
+ struct btrfs_chunk_map *map;
+
+ map = btrfs_get_chunk_map(fs_info, block_group->start, 1);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ ret = btrfs_last_identity_remap_gone(trans, map, block_group);
+ if (ret) {
+ btrfs_free_chunk_map(map);
+ return ret;
+ }
+
+ /*
+ * Set num_stripes to 0, so that btrfs_remove_dev_extents()
+ * won't run a second time.
+ */
+ map->num_stripes = 0;
+
+ btrfs_free_chunk_map(map);
+
+ if (block_group->used == 0 && block_group->remap_bytes == 0) {
+ spin_lock(&fs_info->unused_bgs_lock);
+ list_move_tail(&block_group->bg_list,
+ &fs_info->unused_bgs);
+ spin_unlock(&fs_info->unused_bgs_lock);
+ } else {
+ spin_lock(&fs_info->unused_bgs_lock);
+ list_del_init(&block_group->bg_list);
+ spin_unlock(&fs_info->unused_bgs_lock);
+
+ btrfs_put_block_group(block_group);
+ }
+ }
+
+ return 0;
+}
+
int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
@@ -2999,11 +3046,23 @@ u64 btrfs_get_extent_owner_root(struct btrfs_fs_info *fs_info,
}
static int do_free_extent_accounting(struct btrfs_trans_handle *trans,
- u64 bytenr, struct btrfs_squota_delta *delta)
+ u64 bytenr, struct btrfs_squota_delta *delta,
+ struct btrfs_path *path)
{
int ret;
+ bool remapped = false;
u64 num_bytes = delta->num_bytes;
+ /* returns 1 on success and 0 on no-op */
+ ret = btrfs_remove_extent_from_remap_tree(trans, path, bytenr,
+ num_bytes);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ } else if (ret == 1) {
+ remapped = true;
+ }
+
if (delta->is_data) {
struct btrfs_root *csum_root;
@@ -3027,10 +3086,16 @@ static int do_free_extent_accounting(struct btrfs_trans_handle *trans,
return ret;
}
- ret = btrfs_add_to_free_space_tree(trans, bytenr, num_bytes);
- if (unlikely(ret)) {
- btrfs_abort_transaction(trans, ret);
- return ret;
+ /*
+ * If remapped, FST has already been taken care of in
+ * remove_range_from_remap_tree().
+ */
+ if (!remapped) {
+ ret = btrfs_add_to_free_space_tree(trans, bytenr, num_bytes);
+ if (unlikely(ret)) {
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
}
ret = btrfs_update_block_group(trans, bytenr, num_bytes, false);
@@ -3396,7 +3461,7 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
}
btrfs_release_path(path);
- ret = do_free_extent_accounting(trans, bytenr, &delta);
+ ret = do_free_extent_accounting(trans, bytenr, &delta, path);
}
btrfs_release_path(path);
diff --git a/fs/btrfs/extent-tree.h b/fs/btrfs/extent-tree.h
index e970ac42a871..6b67a4e528da 100644
--- a/fs/btrfs/extent-tree.h
+++ b/fs/btrfs/extent-tree.h
@@ -164,5 +164,6 @@ void btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info, u64 start, u6
int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
u64 num_bytes, u64 *actual_bytes);
int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range);
+int btrfs_handle_fully_remapped_bgs(struct btrfs_trans_handle *trans);
#endif
diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index c76f4c2701f9..e60fd1841996 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -563,6 +563,7 @@ struct btrfs_fs_info {
struct mutex transaction_kthread_mutex;
struct mutex cleaner_mutex;
struct mutex chunk_mutex;
+ struct mutex remap_mutex;
/*
* This is taken to make sure we don't set block groups ro after the
@@ -817,10 +818,11 @@ struct btrfs_fs_info {
struct list_head reclaim_bgs;
int bg_reclaim_threshold;
- /* Protects the lists unused_bgs and reclaim_bgs. */
+ /* Protects the lists unused_bgs, reclaim_bgs, and fully_remapped_bgs. */
spinlock_t unused_bgs_lock;
/* Protected by unused_bgs_lock. */
struct list_head unused_bgs;
+ struct list_head fully_remapped_bgs;
struct mutex unused_bg_unpin_mutex;
/* Protect block groups that are going to be deleted */
struct mutex reclaim_bgs_lock;
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 4f5d3aaf0f65..d0c1e0533c6e 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -37,6 +37,7 @@
#include "super.h"
#include "tree-checker.h"
#include "raid-stripe-tree.h"
+#include "free-space-tree.h"
/*
* Relocation overview
@@ -3870,6 +3871,137 @@ static const char *stage_to_string(enum reloc_stage stage)
return "unknown";
}
+static void adjust_block_group_remap_bytes(struct btrfs_trans_handle *trans,
+ struct btrfs_block_group *bg,
+ s64 diff)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ bool bg_already_dirty = true;
+
+ bg->remap_bytes += diff;
+
+ if (bg->used == 0 && bg->remap_bytes == 0)
+ btrfs_mark_bg_unused(bg);
+
+ spin_lock(&trans->transaction->dirty_bgs_lock);
+ if (list_empty(&bg->dirty_list)) {
+ list_add_tail(&bg->dirty_list, &trans->transaction->dirty_bgs);
+ bg_already_dirty = false;
+ btrfs_get_block_group(bg);
+ }
+ spin_unlock(&trans->transaction->dirty_bgs_lock);
+
+ /* Modified block groups are accounted for in the delayed_refs_rsv. */
+ if (!bg_already_dirty)
+ btrfs_inc_delayed_refs_rsv_bg_updates(fs_info);
+}
+
+static int remove_chunk_stripes(struct btrfs_trans_handle *trans,
+ struct btrfs_chunk_map *chunk,
+ struct btrfs_path *path)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_key key;
+ struct extent_buffer *leaf;
+ struct btrfs_chunk *c;
+ int ret;
+
+ key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+ key.type = BTRFS_CHUNK_ITEM_KEY;
+ key.offset = chunk->start;
+
+ ret = btrfs_search_slot(trans, fs_info->chunk_root, &key, path,
+ 0, 1);
+ if (ret) {
+ if (ret == 1) {
+ btrfs_release_path(path);
+ ret = -ENOENT;
+ }
+ return ret;
+ }
+
+ leaf = path->nodes[0];
+
+ c = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_chunk);
+ btrfs_set_chunk_num_stripes(leaf, c, 0);
+ btrfs_set_chunk_sub_stripes(leaf, c, 0);
+
+ btrfs_truncate_item(trans, path, offsetof(struct btrfs_chunk, stripe),
+ 1);
+
+ btrfs_mark_buffer_dirty(trans, leaf);
+
+ btrfs_release_path(path);
+
+ return 0;
+}
+
+int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
+ struct btrfs_chunk_map *chunk,
+ struct btrfs_block_group *bg)
+{
+ int ret;
+ BTRFS_PATH_AUTO_FREE(path);
+
+ ret = btrfs_remove_dev_extents(trans, chunk);
+ if (ret)
+ return ret;
+
+ mutex_lock(&trans->fs_info->chunk_mutex);
+
+ for (unsigned int i = 0; i < chunk->num_stripes; i++) {
+ ret = btrfs_update_device(trans, chunk->stripes[i].dev);
+ if (ret) {
+ mutex_unlock(&trans->fs_info->chunk_mutex);
+ return ret;
+ }
+ }
+
+ mutex_unlock(&trans->fs_info->chunk_mutex);
+
+ write_lock(&trans->fs_info->mapping_tree_lock);
+ btrfs_chunk_map_device_clear_bits(chunk, CHUNK_ALLOCATED);
+ write_unlock(&trans->fs_info->mapping_tree_lock);
+
+ btrfs_remove_bg_from_sinfo(bg);
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ ret = remove_chunk_stripes(trans, chunk, path);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static void adjust_identity_remap_count(struct btrfs_trans_handle *trans,
+ struct btrfs_block_group *bg, int delta)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ bool bg_already_dirty = true;
+
+ WARN_ON(delta < 0 && -delta > bg->identity_remap_count);
+
+ bg->identity_remap_count += delta;
+
+ spin_lock(&trans->transaction->dirty_bgs_lock);
+ if (list_empty(&bg->dirty_list)) {
+ list_add_tail(&bg->dirty_list, &trans->transaction->dirty_bgs);
+ bg_already_dirty = false;
+ btrfs_get_block_group(bg);
+ }
+ spin_unlock(&trans->transaction->dirty_bgs_lock);
+
+ /* Modified block groups are accounted for in the delayed_refs_rsv. */
+ if (!bg_already_dirty)
+ btrfs_inc_delayed_refs_rsv_bg_updates(fs_info);
+
+ if (bg->identity_remap_count == 0)
+ btrfs_mark_bg_fully_remapped(bg, trans);
+}
+
int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
u64 *length, bool nolock)
{
@@ -4483,3 +4615,366 @@ u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info)
logical = fs_info->reloc_ctl->block_group->start;
return logical;
}
+
+static int remove_range_from_remap_tree(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ struct btrfs_block_group *bg,
+ u64 bytenr, u64 num_bytes)
+{
+ int ret;
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct extent_buffer *leaf = path->nodes[0];
+ struct btrfs_key key, new_key;
+ struct btrfs_remap *remap_ptr = NULL, remap;
+ struct btrfs_block_group *dest_bg = NULL;
+ u64 end, new_addr = 0, remap_start, remap_length, overlap_length;
+ bool is_identity_remap;
+
+ end = bytenr + num_bytes;
+
+ btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+ is_identity_remap = key.type == BTRFS_IDENTITY_REMAP_KEY;
+
+ remap_start = key.objectid;
+ remap_length = key.offset;
+
+ if (!is_identity_remap) {
+ remap_ptr = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_remap);
+ new_addr = btrfs_remap_address(leaf, remap_ptr);
+
+ dest_bg = btrfs_lookup_block_group(fs_info, new_addr);
+ }
+
+ if (bytenr == remap_start && num_bytes >= remap_length) {
+ /* Remove entirely. */
+
+ ret = btrfs_del_item(trans, fs_info->remap_root, path);
+ if (ret)
+ goto end;
+
+ btrfs_release_path(path);
+
+ overlap_length = remap_length;
+
+ if (!is_identity_remap) {
+ /* Remove backref. */
+
+ key.objectid = new_addr;
+ key.type = BTRFS_REMAP_BACKREF_KEY;
+ key.offset = remap_length;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root,
+ &key, path, -1, 1);
+ if (ret) {
+ if (ret == 1) {
+ btrfs_release_path(path);
+ ret = -ENOENT;
+ }
+ goto end;
+ }
+
+ ret = btrfs_del_item(trans, fs_info->remap_root, path);
+
+ btrfs_release_path(path);
+
+ if (ret)
+ goto end;
+
+ adjust_block_group_remap_bytes(trans, dest_bg,
+ -remap_length);
+ } else {
+ adjust_identity_remap_count(trans, bg, -1);
+ }
+ } else if (bytenr == remap_start) {
+ /* Remove beginning. */
+
+ new_key.objectid = end;
+ new_key.type = key.type;
+ new_key.offset = remap_length + remap_start - end;
+
+ btrfs_set_item_key_safe(trans, path, &new_key);
+ btrfs_mark_buffer_dirty(trans, leaf);
+
+ overlap_length = num_bytes;
+
+ if (!is_identity_remap) {
+ btrfs_set_remap_address(leaf, remap_ptr,
+ new_addr + end - remap_start);
+ btrfs_release_path(path);
+
+ /* Adjust backref. */
+
+ key.objectid = new_addr;
+ key.type = BTRFS_REMAP_BACKREF_KEY;
+ key.offset = remap_length;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root,
+ &key, path, -1, 1);
+ if (ret) {
+ if (ret == 1) {
+ btrfs_release_path(path);
+ ret = -ENOENT;
+ }
+ goto end;
+ }
+
+ leaf = path->nodes[0];
+
+ new_key.objectid = new_addr + end - remap_start;
+ new_key.type = BTRFS_REMAP_BACKREF_KEY;
+ new_key.offset = remap_length + remap_start - end;
+
+ btrfs_set_item_key_safe(trans, path, &new_key);
+
+ remap_ptr = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_remap);
+ btrfs_set_remap_address(leaf, remap_ptr, end);
+
+ btrfs_mark_buffer_dirty(trans, path->nodes[0]);
+
+ btrfs_release_path(path);
+
+ adjust_block_group_remap_bytes(trans, dest_bg,
+ -num_bytes);
+ }
+ } else if (bytenr + num_bytes < remap_start + remap_length) {
+ /* Remove middle. */
+
+ new_key.objectid = remap_start;
+ new_key.type = key.type;
+ new_key.offset = bytenr - remap_start;
+
+ btrfs_set_item_key_safe(trans, path, &new_key);
+ btrfs_mark_buffer_dirty(trans, leaf);
+
+ new_key.objectid = end;
+ new_key.offset = remap_start + remap_length - end;
+
+ btrfs_release_path(path);
+
+ overlap_length = num_bytes;
+
+ if (!is_identity_remap) {
+ /* Add second remap entry. */
+
+ ret = btrfs_insert_empty_item(trans, fs_info->remap_root,
+ path, &new_key,
+ sizeof(struct btrfs_remap));
+ if (ret)
+ goto end;
+
+ btrfs_set_stack_remap_address(&remap,
+ new_addr + end - remap_start);
+
+ write_extent_buffer(path->nodes[0], &remap,
+ btrfs_item_ptr_offset(path->nodes[0], path->slots[0]),
+ sizeof(struct btrfs_remap));
+
+ btrfs_release_path(path);
+
+ /* Shorten backref entry. */
+
+ key.objectid = new_addr;
+ key.type = BTRFS_REMAP_BACKREF_KEY;
+ key.offset = remap_length;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root,
+ &key, path, -1, 1);
+ if (ret) {
+ if (ret == 1) {
+ btrfs_release_path(path);
+ ret = -ENOENT;
+ }
+ goto end;
+ }
+
+ new_key.objectid = new_addr;
+ new_key.type = BTRFS_REMAP_BACKREF_KEY;
+ new_key.offset = bytenr - remap_start;
+
+ btrfs_set_item_key_safe(trans, path, &new_key);
+ btrfs_mark_buffer_dirty(trans, path->nodes[0]);
+
+ btrfs_release_path(path);
+
+ /* Add second backref entry. */
+
+ new_key.objectid = new_addr + end - remap_start;
+ new_key.type = BTRFS_REMAP_BACKREF_KEY;
+ new_key.offset = remap_start + remap_length - end;
+
+ ret = btrfs_insert_empty_item(trans, fs_info->remap_root,
+ path, &new_key,
+ sizeof(struct btrfs_remap));
+ if (ret)
+ goto end;
+
+ btrfs_set_stack_remap_address(&remap, end);
+
+ write_extent_buffer(path->nodes[0], &remap,
+ btrfs_item_ptr_offset(path->nodes[0], path->slots[0]),
+ sizeof(struct btrfs_remap));
+
+ btrfs_release_path(path);
+
+ adjust_block_group_remap_bytes(trans, dest_bg,
+ -num_bytes);
+ } else {
+ /* Add second identity remap entry. */
+
+ ret = btrfs_insert_empty_item(trans, fs_info->remap_root,
+ path, &new_key, 0);
+ if (ret)
+ goto end;
+
+ btrfs_release_path(path);
+
+ adjust_identity_remap_count(trans, bg, 1);
+ }
+ } else {
+ /* Remove end. */
+
+ new_key.objectid = remap_start;
+ new_key.type = key.type;
+ new_key.offset = bytenr - remap_start;
+
+ btrfs_set_item_key_safe(trans, path, &new_key);
+ btrfs_mark_buffer_dirty(trans, leaf);
+
+ btrfs_release_path(path);
+
+ overlap_length = remap_start + remap_length - bytenr;
+
+ if (!is_identity_remap) {
+ /* Shorten backref entry. */
+
+ key.objectid = new_addr;
+ key.type = BTRFS_REMAP_BACKREF_KEY;
+ key.offset = remap_length;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root,
+ &key, path, -1, 1);
+ if (ret) {
+ if (ret == 1) {
+ btrfs_release_path(path);
+ ret = -ENOENT;
+ }
+ goto end;
+ }
+
+ new_key.objectid = new_addr;
+ new_key.type = BTRFS_REMAP_BACKREF_KEY;
+ new_key.offset = bytenr - remap_start;
+
+ btrfs_set_item_key_safe(trans, path, &new_key);
+ btrfs_mark_buffer_dirty(trans, path->nodes[0]);
+
+ btrfs_release_path(path);
+
+ adjust_block_group_remap_bytes(trans, dest_bg,
+ bytenr - remap_start - remap_length);
+ }
+ }
+
+ if (!is_identity_remap) {
+ ret = btrfs_add_to_free_space_tree(trans,
+ bytenr - remap_start + new_addr,
+ overlap_length);
+ if (ret)
+ goto end;
+ }
+
+ ret = overlap_length;
+
+end:
+ if (dest_bg)
+ btrfs_put_block_group(dest_bg);
+
+ return ret;
+}
+
+/*
+ * Returns 1 if remove_range_from_remap_tree() has been called successfully,
+ * 0 if block group wasn't remapped, and a negative number on error.
+ */
+int btrfs_remove_extent_from_remap_tree(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ u64 bytenr, u64 num_bytes)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_key key, found_key;
+ struct extent_buffer *leaf;
+ struct btrfs_block_group *bg;
+ int ret, length;
+
+ if (!(btrfs_super_incompat_flags(fs_info->super_copy) &
+ BTRFS_FEATURE_INCOMPAT_REMAP_TREE))
+ return 0;
+
+ bg = btrfs_lookup_block_group(fs_info, bytenr);
+ if (!bg)
+ return 0;
+
+ mutex_lock(&fs_info->remap_mutex);
+
+ if (!(bg->flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
+ mutex_unlock(&fs_info->remap_mutex);
+ btrfs_put_block_group(bg);
+ return 0;
+ }
+
+ do {
+ key.objectid = bytenr;
+ key.type = (u8)-1;
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root, &key, path,
+ -1, 1);
+ if (ret < 0)
+ goto end;
+
+ leaf = path->nodes[0];
+
+ if (path->slots[0] == 0) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ path->slots[0]--;
+
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+ if (found_key.type != BTRFS_IDENTITY_REMAP_KEY &&
+ found_key.type != BTRFS_REMAP_KEY) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ if (bytenr < found_key.objectid ||
+ bytenr >= found_key.objectid + found_key.offset) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ length = remove_range_from_remap_tree(trans, path, bg, bytenr,
+ num_bytes);
+ if (length < 0) {
+ ret = length;
+ goto end;
+ }
+
+ bytenr += length;
+ num_bytes -= length;
+ } while (num_bytes > 0);
+
+ ret = 1;
+
+end:
+ mutex_unlock(&fs_info->remap_mutex);
+
+ btrfs_put_block_group(bg);
+ btrfs_release_path(path);
+ return ret;
+}
diff --git a/fs/btrfs/relocation.h b/fs/btrfs/relocation.h
index a653c42a25a3..a272ebaa621f 100644
--- a/fs/btrfs/relocation.h
+++ b/fs/btrfs/relocation.h
@@ -33,5 +33,11 @@ bool btrfs_should_ignore_reloc_root(const struct btrfs_root *root);
u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info);
int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
u64 *length, bool nolock);
+int btrfs_remove_extent_from_remap_tree(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ u64 bytenr, u64 num_bytes);
+int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
+ struct btrfs_chunk_map *chunk,
+ struct btrfs_block_group *bg);
#endif
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index b1c41982e7b2..6ce91397afe6 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -2438,6 +2438,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
if (ret)
goto unlock_reloc;
+ ret = btrfs_handle_fully_remapped_bgs(trans);
+ if (ret)
+ goto unlock_reloc;
+
/*
* make sure none of the code above managed to slip in a
* delayed item
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f2d1203778aa..8078d2fa4df6 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2946,8 +2946,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
return ret;
}
-static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
- struct btrfs_device *device)
+int btrfs_update_device(struct btrfs_trans_handle *trans,
+ struct btrfs_device *device)
{
int ret;
struct btrfs_path *path;
@@ -3251,25 +3251,13 @@ static int remove_chunk_item(struct btrfs_trans_handle *trans,
return btrfs_free_chunk(trans, chunk_offset);
}
-int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
+int btrfs_remove_dev_extents(struct btrfs_trans_handle *trans,
+ struct btrfs_chunk_map *map)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
- struct btrfs_chunk_map *map;
+ struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
u64 dev_extent_len = 0;
int i, ret = 0;
- struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
-
- map = btrfs_get_chunk_map(fs_info, chunk_offset, 1);
- if (IS_ERR(map)) {
- /*
- * This is a logic error, but we don't want to just rely on the
- * user having built with ASSERT enabled, so if ASSERT doesn't
- * do anything we still error out.
- */
- DEBUG_WARN("errr %ld reading chunk map at offset %llu",
- PTR_ERR(map), chunk_offset);
- return PTR_ERR(map);
- }
/*
* First delete the device extent items from the devices btree.
@@ -3290,7 +3278,7 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
if (unlikely(ret)) {
mutex_unlock(&fs_devices->device_list_mutex);
btrfs_abort_transaction(trans, ret);
- goto out;
+ return ret;
}
if (device->bytes_used > 0) {
@@ -3310,6 +3298,30 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
}
mutex_unlock(&fs_devices->device_list_mutex);
+ return 0;
+}
+
+int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_chunk_map *map;
+ int ret;
+
+ map = btrfs_get_chunk_map(fs_info, chunk_offset, 1);
+ if (IS_ERR(map)) {
+ /*
+ * This is a logic error, but we don't want to just rely on the
+ * user having built with ASSERT enabled, so if ASSERT doesn't
+ * do anything we still error out.
+ */
+ ASSERT(0);
+ return PTR_ERR(map);
+ }
+
+ ret = btrfs_remove_dev_extents(trans, map);
+ if (ret)
+ goto out;
+
/*
* We acquire fs_info->chunk_mutex for 2 reasons:
*
@@ -5453,7 +5465,7 @@ static void chunk_map_device_set_bits(struct btrfs_chunk_map *map, unsigned int
}
}
-static void chunk_map_device_clear_bits(struct btrfs_chunk_map *map, unsigned int bits)
+void btrfs_chunk_map_device_clear_bits(struct btrfs_chunk_map *map, unsigned int bits)
{
for (int i = 0; i < map->num_stripes; i++) {
struct btrfs_io_stripe *stripe = &map->stripes[i];
@@ -5470,7 +5482,7 @@ void btrfs_remove_chunk_map(struct btrfs_fs_info *fs_info, struct btrfs_chunk_ma
write_lock(&fs_info->mapping_tree_lock);
rb_erase_cached(&map->rb_node, &fs_info->mapping_tree);
RB_CLEAR_NODE(&map->rb_node);
- chunk_map_device_clear_bits(map, CHUNK_ALLOCATED);
+ btrfs_chunk_map_device_clear_bits(map, CHUNK_ALLOCATED);
write_unlock(&fs_info->mapping_tree_lock);
/* Once for the tree reference. */
@@ -5506,7 +5518,7 @@ int btrfs_add_chunk_map(struct btrfs_fs_info *fs_info, struct btrfs_chunk_map *m
return -EEXIST;
}
chunk_map_device_set_bits(map, CHUNK_ALLOCATED);
- chunk_map_device_clear_bits(map, CHUNK_TRIMMED);
+ btrfs_chunk_map_device_clear_bits(map, CHUNK_TRIMMED);
write_unlock(&fs_info->mapping_tree_lock);
return 0;
@@ -5871,7 +5883,7 @@ void btrfs_mapping_tree_free(struct btrfs_fs_info *fs_info)
map = rb_entry(node, struct btrfs_chunk_map, rb_node);
rb_erase_cached(&map->rb_node, &fs_info->mapping_tree);
RB_CLEAR_NODE(&map->rb_node);
- chunk_map_device_clear_bits(map, CHUNK_ALLOCATED);
+ btrfs_chunk_map_device_clear_bits(map, CHUNK_ALLOCATED);
/* Once for the tree ref. */
btrfs_free_chunk_map(map);
cond_resched_rwlock_write(&fs_info->mapping_tree_lock);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index b0fa8eb38060..05a3e6922f78 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -789,6 +789,8 @@ u64 btrfs_calc_stripe_length(const struct btrfs_chunk_map *map);
int btrfs_nr_parity_stripes(u64 type);
int btrfs_chunk_alloc_add_chunk_item(struct btrfs_trans_handle *trans,
struct btrfs_block_group *bg);
+int btrfs_remove_dev_extents(struct btrfs_trans_handle *trans,
+ struct btrfs_chunk_map *map);
int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset);
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
@@ -900,6 +902,10 @@ bool btrfs_repair_one_zone(struct btrfs_fs_info *fs_info, u64 logical);
bool btrfs_pinned_by_swapfile(struct btrfs_fs_info *fs_info, void *ptr);
const u8 *btrfs_sb_fsid_ptr(const struct btrfs_super_block *sb);
+int btrfs_update_device(struct btrfs_trans_handle *trans,
+ struct btrfs_device *device);
+void btrfs_chunk_map_device_clear_bits(struct btrfs_chunk_map *map,
+ unsigned int bits);
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_info,
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 11/17] btrfs: handle setting up relocation of block group with remap-tree
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (9 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 10/17] btrfs: handle deletions from remapped block group Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 12/17] btrfs: move existing remaps before relocating block group Mark Harmstone
` (5 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Handle the preliminary work for relocating a block group in a filesystem
with the remap-tree flag set.
If the block group is SYSTEM btrfs_relocate_block_group() proceeds as it
does already, as bootstrapping issues mean that these block groups have
to be processed the existing way. Similarly with REMAP blocks, which are
dealt with in a later patch.
Otherwise we walk the free-space tree for the block group in question,
recording any holes. These get converted into identity remaps and placed
in the remap tree, and the block group's REMAPPED flag is set. From now
on no new allocations are possible within this block group, and any I/O
to it will be funnelled through btrfs_translate_remap(). We store the
number of identity remaps in `identity_remap_count`, so that we know
when we've removed the last one and the block group is fully remapped.
The change in btrfs_read_roots() is because data relocations no longer
rely on the data reloc tree as a hidden subvolume in which to do
snapshots.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/block-group.c | 6 +-
fs/btrfs/block-group.h | 4 +
fs/btrfs/free-space-tree.c | 4 +-
fs/btrfs/free-space-tree.h | 5 +-
fs/btrfs/relocation.c | 419 ++++++++++++++++++++++++++++++++++++-
fs/btrfs/relocation.h | 2 +-
fs/btrfs/space-info.c | 9 +-
fs/btrfs/volumes.c | 15 +-
8 files changed, 443 insertions(+), 21 deletions(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index bfb4b8a840c8..3f7c45d17415 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -2424,6 +2424,7 @@ static int read_one_block_group(struct btrfs_fs_info *info,
cache->used = btrfs_stack_block_group_v2_used(bgi);
cache->commit_used = cache->used;
cache->flags = btrfs_stack_block_group_v2_flags(bgi);
+ cache->commit_flags = cache->flags;
cache->global_root_id = btrfs_stack_block_group_v2_chunk_objectid(bgi);
cache->space_info = btrfs_find_space_info(info, cache->flags);
cache->remap_bytes = btrfs_stack_block_group_v2_remap_bytes(bgi);
@@ -2736,6 +2737,7 @@ static int insert_block_group_item(struct btrfs_trans_handle *trans,
block_group->commit_remap_bytes = block_group->remap_bytes;
block_group->commit_identity_remap_count =
block_group->identity_remap_count;
+ block_group->commit_flags = block_group->flags;
key.objectid = block_group->start;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
key.offset = block_group->length;
@@ -3224,13 +3226,15 @@ static int update_block_group_item(struct btrfs_trans_handle *trans,
/* No change in values, can safely skip it. */
if (cache->commit_used == used &&
cache->commit_remap_bytes == remap_bytes &&
- cache->commit_identity_remap_count == identity_remap_count) {
+ cache->commit_identity_remap_count == identity_remap_count &&
+ cache->commit_flags == cache->flags) {
spin_unlock(&cache->lock);
return 0;
}
cache->commit_used = used;
cache->commit_remap_bytes = remap_bytes;
cache->commit_identity_remap_count = identity_remap_count;
+ cache->commit_flags = cache->flags;
spin_unlock(&cache->lock);
key.objectid = cache->start;
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index f0a1462f1d31..c6866a57ea24 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -146,6 +146,10 @@ struct btrfs_block_group {
* The last commited identity_remap_count value of this block group.
*/
u32 commit_identity_remap_count;
+ /*
+ * The last committed flags value for this block group.
+ */
+ u64 commit_flags;
/*
* If the free space extent count exceeds this number, convert the block
diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
index 26eae347739f..e46b1fa86f80 100644
--- a/fs/btrfs/free-space-tree.c
+++ b/fs/btrfs/free-space-tree.c
@@ -21,8 +21,7 @@ static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group,
struct btrfs_path *path);
-static struct btrfs_root *btrfs_free_space_root(
- struct btrfs_block_group *block_group)
+struct btrfs_root *btrfs_free_space_root(struct btrfs_block_group *block_group)
{
struct btrfs_key key = {
.objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
@@ -93,7 +92,6 @@ static int add_new_free_space_info(struct btrfs_trans_handle *trans,
return 0;
}
-EXPORT_FOR_TESTS
struct btrfs_free_space_info *btrfs_search_free_space_info(
struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group,
diff --git a/fs/btrfs/free-space-tree.h b/fs/btrfs/free-space-tree.h
index 3d9a5d4477fc..89d2ff7e5c18 100644
--- a/fs/btrfs/free-space-tree.h
+++ b/fs/btrfs/free-space-tree.h
@@ -35,12 +35,13 @@ int btrfs_add_to_free_space_tree(struct btrfs_trans_handle *trans,
u64 start, u64 size);
int btrfs_remove_from_free_space_tree(struct btrfs_trans_handle *trans,
u64 start, u64 size);
-
-#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
struct btrfs_free_space_info *
btrfs_search_free_space_info(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group,
struct btrfs_path *path, int cow);
+struct btrfs_root *btrfs_free_space_root(struct btrfs_block_group *block_group);
+
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
int __btrfs_add_to_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group,
struct btrfs_path *path, u64 start, u64 size);
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index d0c1e0533c6e..44614e149016 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3627,7 +3627,7 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
btrfs_btree_balance_dirty(fs_info);
}
- if (!err) {
+ if (!err && !btrfs_fs_incompat(fs_info, REMAP_TREE)) {
ret = relocate_file_extent_cluster(rc);
if (ret < 0)
err = ret;
@@ -3871,6 +3871,90 @@ static const char *stage_to_string(enum reloc_stage stage)
return "unknown";
}
+static int add_remap_tree_entries(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ struct btrfs_key *entries,
+ unsigned int num_entries)
+{
+ int ret;
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_item_batch batch;
+ u32 *data_sizes;
+ u32 max_items;
+
+ max_items = BTRFS_LEAF_DATA_SIZE(trans->fs_info) / sizeof(struct btrfs_item);
+
+ data_sizes = kzalloc(sizeof(u32) * min_t(u32, num_entries, max_items),
+ GFP_NOFS);
+ if (!data_sizes)
+ return -ENOMEM;
+
+ while (true) {
+ batch.keys = entries;
+ batch.data_sizes = data_sizes;
+ batch.total_data_size = 0;
+ batch.nr = min_t(u32, num_entries, max_items);
+
+ ret = btrfs_insert_empty_items(trans, fs_info->remap_root, path,
+ &batch);
+ btrfs_release_path(path);
+
+ if (num_entries <= max_items)
+ break;
+
+ num_entries -= max_items;
+ entries += max_items;
+ }
+
+ kfree(data_sizes);
+
+ return ret;
+}
+
+struct space_run {
+ u64 start;
+ u64 end;
+};
+
+static void parse_bitmap(u64 block_size, const unsigned long *bitmap,
+ unsigned long size, u64 address,
+ struct space_run *space_runs,
+ unsigned int *num_space_runs)
+{
+ unsigned long pos, end;
+ u64 run_start, run_length;
+
+ pos = find_first_bit(bitmap, size);
+
+ if (pos == size)
+ return;
+
+ while (true) {
+ end = find_next_zero_bit(bitmap, size, pos);
+
+ run_start = address + (pos * block_size);
+ run_length = (end - pos) * block_size;
+
+ if (*num_space_runs != 0 &&
+ space_runs[*num_space_runs - 1].end == run_start) {
+ space_runs[*num_space_runs - 1].end += run_length;
+ } else {
+ space_runs[*num_space_runs].start = run_start;
+ space_runs[*num_space_runs].end = run_start + run_length;
+
+ (*num_space_runs)++;
+ }
+
+ if (end == size)
+ break;
+
+ pos = find_next_bit(bitmap, size, end + 1);
+
+ if (pos == size)
+ break;
+ }
+}
+
static void adjust_block_group_remap_bytes(struct btrfs_trans_handle *trans,
struct btrfs_block_group *bg,
s64 diff)
@@ -3896,6 +3980,184 @@ static void adjust_block_group_remap_bytes(struct btrfs_trans_handle *trans,
btrfs_inc_delayed_refs_rsv_bg_updates(fs_info);
}
+static int create_remap_tree_entries(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ struct btrfs_block_group *bg)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_free_space_info *fsi;
+ struct btrfs_key key, found_key;
+ struct extent_buffer *leaf;
+ struct btrfs_root *space_root;
+ u32 extent_count;
+ struct space_run *space_runs = NULL;
+ unsigned int num_space_runs = 0;
+ struct btrfs_key *entries = NULL;
+ unsigned int max_entries, num_entries;
+ int ret;
+
+ mutex_lock(&bg->free_space_lock);
+
+ if (test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &bg->runtime_flags)) {
+ mutex_unlock(&bg->free_space_lock);
+
+ ret = btrfs_add_block_group_free_space(trans, bg);
+ if (ret)
+ return ret;
+
+ mutex_lock(&bg->free_space_lock);
+ }
+
+ fsi = btrfs_search_free_space_info(trans, bg, path, 0);
+ if (IS_ERR(fsi)) {
+ mutex_unlock(&bg->free_space_lock);
+ return PTR_ERR(fsi);
+ }
+
+ extent_count = btrfs_free_space_extent_count(path->nodes[0], fsi);
+
+ btrfs_release_path(path);
+
+ space_runs = kmalloc(sizeof(*space_runs) * extent_count, GFP_NOFS);
+ if (!space_runs) {
+ mutex_unlock(&bg->free_space_lock);
+ return -ENOMEM;
+ }
+
+ key.objectid = bg->start;
+ key.type = 0;
+ key.offset = 0;
+
+ space_root = btrfs_free_space_root(bg);
+
+ ret = btrfs_search_slot(trans, space_root, &key, path, 0, 0);
+ if (ret < 0) {
+ mutex_unlock(&bg->free_space_lock);
+ goto out;
+ }
+
+ ret = 0;
+
+ while (true) {
+ leaf = path->nodes[0];
+
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+ if (found_key.objectid >= bg->start + bg->length)
+ break;
+
+ if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
+ if (num_space_runs != 0 &&
+ space_runs[num_space_runs - 1].end == found_key.objectid) {
+ space_runs[num_space_runs - 1].end =
+ found_key.objectid + found_key.offset;
+ } else {
+ BUG_ON(num_space_runs >= extent_count);
+
+ space_runs[num_space_runs].start = found_key.objectid;
+ space_runs[num_space_runs].end =
+ found_key.objectid + found_key.offset;
+
+ num_space_runs++;
+ }
+ } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
+ void *bitmap;
+ unsigned long offset;
+ u32 data_size;
+
+ offset = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ data_size = btrfs_item_size(leaf, path->slots[0]);
+
+ if (data_size != 0) {
+ bitmap = kmalloc(data_size, GFP_NOFS);
+ if (!bitmap) {
+ mutex_unlock(&bg->free_space_lock);
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ read_extent_buffer(leaf, bitmap, offset,
+ data_size);
+
+ parse_bitmap(fs_info->sectorsize, bitmap,
+ data_size * BITS_PER_BYTE,
+ found_key.objectid, space_runs,
+ &num_space_runs);
+
+ BUG_ON(num_space_runs > extent_count);
+
+ kfree(bitmap);
+ }
+ }
+
+ path->slots[0]++;
+
+ if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+ ret = btrfs_next_leaf(space_root, path);
+ if (ret != 0) {
+ if (ret == 1)
+ ret = 0;
+ break;
+ }
+ leaf = path->nodes[0];
+ }
+ }
+
+ btrfs_release_path(path);
+
+ mutex_unlock(&bg->free_space_lock);
+
+ max_entries = extent_count + 2;
+ entries = kmalloc(sizeof(*entries) * max_entries, GFP_NOFS);
+ if (!entries) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ num_entries = 0;
+
+ if (num_space_runs > 0 && space_runs[0].start > bg->start) {
+ entries[num_entries].objectid = bg->start;
+ entries[num_entries].type = BTRFS_IDENTITY_REMAP_KEY;
+ entries[num_entries].offset = space_runs[0].start - bg->start;
+ num_entries++;
+ }
+
+ for (unsigned int i = 1; i < num_space_runs; i++) {
+ entries[num_entries].objectid = space_runs[i - 1].end;
+ entries[num_entries].type = BTRFS_IDENTITY_REMAP_KEY;
+ entries[num_entries].offset =
+ space_runs[i].start - space_runs[i - 1].end;
+ num_entries++;
+ }
+
+ if (num_space_runs == 0) {
+ entries[num_entries].objectid = bg->start;
+ entries[num_entries].type = BTRFS_IDENTITY_REMAP_KEY;
+ entries[num_entries].offset = bg->length;
+ num_entries++;
+ } else if (space_runs[num_space_runs - 1].end < bg->start + bg->length) {
+ entries[num_entries].objectid = space_runs[num_space_runs - 1].end;
+ entries[num_entries].type = BTRFS_IDENTITY_REMAP_KEY;
+ entries[num_entries].offset =
+ bg->start + bg->length - space_runs[num_space_runs - 1].end;
+ num_entries++;
+ }
+
+ if (num_entries == 0)
+ goto out;
+
+ bg->identity_remap_count = num_entries;
+
+ ret = add_remap_tree_entries(trans, path, entries, num_entries);
+
+out:
+ kfree(entries);
+ kfree(space_runs);
+
+ return ret;
+}
+
static int remove_chunk_stripes(struct btrfs_trans_handle *trans,
struct btrfs_chunk_map *chunk,
struct btrfs_path *path)
@@ -4002,6 +4264,55 @@ static void adjust_identity_remap_count(struct btrfs_trans_handle *trans,
btrfs_mark_bg_fully_remapped(bg, trans);
}
+static int mark_chunk_remapped(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path, uint64_t start)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_chunk_map *chunk;
+ struct btrfs_key key;
+ u64 type;
+ int ret;
+ struct extent_buffer *leaf;
+ struct btrfs_chunk *c;
+
+ read_lock(&fs_info->mapping_tree_lock);
+
+ chunk = btrfs_find_chunk_map_nolock(fs_info, start, 1);
+ if (!chunk) {
+ read_unlock(&fs_info->mapping_tree_lock);
+ return -ENOENT;
+ }
+
+ chunk->type |= BTRFS_BLOCK_GROUP_REMAPPED;
+ type = chunk->type;
+
+ read_unlock(&fs_info->mapping_tree_lock);
+
+ key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+ key.type = BTRFS_CHUNK_ITEM_KEY;
+ key.offset = start;
+
+ ret = btrfs_search_slot(trans, fs_info->chunk_root, &key, path,
+ 0, 1);
+ if (ret == 1) {
+ ret = -ENOENT;
+ goto end;
+ } else if (ret < 0)
+ goto end;
+
+ leaf = path->nodes[0];
+
+ c = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_chunk);
+ btrfs_set_chunk_type(leaf, c, type);
+ btrfs_mark_buffer_dirty(trans, leaf);
+
+ ret = 0;
+end:
+ btrfs_free_chunk_map(chunk);
+ btrfs_release_path(path);
+ return ret;
+}
+
int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
u64 *length, bool nolock)
{
@@ -4061,17 +4372,90 @@ int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
return 0;
}
+static int start_block_group_remapping(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path,
+ struct btrfs_block_group *bg)
+{
+ struct btrfs_trans_handle *trans;
+ bool bg_already_dirty = true;
+ int ret, ret2;
+
+ ret = btrfs_cache_block_group(bg, true);
+ if (ret)
+ return ret;
+
+ trans = btrfs_start_transaction(fs_info->remap_root, 0);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ /* We need to run delayed refs, to make sure FST is up to date. */
+ ret = btrfs_run_delayed_refs(trans, U64_MAX);
+ if (ret) {
+ btrfs_end_transaction(trans);
+ return ret;
+ }
+
+ mutex_lock(&fs_info->remap_mutex);
+
+ if (bg->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
+ ret = 0;
+ goto end;
+ }
+
+ ret = create_remap_tree_entries(trans, path, bg);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ goto end;
+ }
+
+ spin_lock(&bg->lock);
+ bg->flags |= BTRFS_BLOCK_GROUP_REMAPPED;
+ spin_unlock(&bg->lock);
+
+ spin_lock(&trans->transaction->dirty_bgs_lock);
+ if (list_empty(&bg->dirty_list)) {
+ list_add_tail(&bg->dirty_list,
+ &trans->transaction->dirty_bgs);
+ bg_already_dirty = false;
+ btrfs_get_block_group(bg);
+ }
+ spin_unlock(&trans->transaction->dirty_bgs_lock);
+
+ /* Modified block groups are accounted for in the delayed_refs_rsv. */
+ if (!bg_already_dirty)
+ btrfs_inc_delayed_refs_rsv_bg_updates(fs_info);
+
+ ret = mark_chunk_remapped(trans, path, bg->start);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ goto end;
+ }
+
+ ret = btrfs_remove_block_group_free_space(trans, bg);
+ if (ret)
+ btrfs_abort_transaction(trans, ret);
+
+end:
+ mutex_unlock(&fs_info->remap_mutex);
+
+ ret2 = btrfs_end_transaction(trans);
+ if (!ret)
+ ret = ret2;
+
+ return ret;
+}
+
/*
* function to relocate all extents in a block group.
*/
int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
- bool verbose)
+ bool verbose, bool *using_remap_tree)
{
struct btrfs_block_group *bg;
struct btrfs_root *extent_root = btrfs_extent_root(fs_info, group_start);
struct reloc_control *rc;
struct inode *inode;
- struct btrfs_path *path;
+ struct btrfs_path *path = NULL;
int ret;
bool bg_is_ro = false;
@@ -4133,7 +4517,7 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
}
inode = lookup_free_space_inode(rc->block_group, path);
- btrfs_free_path(path);
+ btrfs_release_path(path);
if (!IS_ERR(inode))
ret = delete_block_group_cache(rc->block_group, inode, 0);
@@ -4143,11 +4527,17 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
if (ret && ret != -ENOENT)
goto out;
- rc->data_inode = create_reloc_inode(rc->block_group);
- if (IS_ERR(rc->data_inode)) {
- ret = PTR_ERR(rc->data_inode);
- rc->data_inode = NULL;
- goto out;
+ *using_remap_tree = btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+ !(bg->flags & BTRFS_BLOCK_GROUP_SYSTEM) &&
+ !(bg->flags & BTRFS_BLOCK_GROUP_REMAP);
+
+ if (!btrfs_fs_incompat(fs_info, REMAP_TREE)) {
+ rc->data_inode = create_reloc_inode(rc->block_group);
+ if (IS_ERR(rc->data_inode)) {
+ ret = PTR_ERR(rc->data_inode);
+ rc->data_inode = NULL;
+ goto out;
+ }
}
if (verbose)
@@ -4160,6 +4550,11 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
ret = btrfs_zone_finish(rc->block_group);
WARN_ON(ret && ret != -EAGAIN);
+ if (*using_remap_tree) {
+ ret = start_block_group_remapping(fs_info, path, bg);
+ goto out;
+ }
+
while (1) {
enum reloc_stage finishes_stage;
@@ -4207,7 +4602,9 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
out:
if (ret && bg_is_ro)
btrfs_dec_block_group_ro(rc->block_group);
- iput(rc->data_inode);
+ if (!btrfs_fs_incompat(fs_info, REMAP_TREE))
+ iput(rc->data_inode);
+ btrfs_free_path(path);
reloc_chunk_end(fs_info);
out_put_bg:
btrfs_put_block_group(bg);
@@ -4401,7 +4798,7 @@ int btrfs_recover_relocation(struct btrfs_fs_info *fs_info)
btrfs_free_path(path);
- if (ret == 0) {
+ if (ret == 0 && !btrfs_fs_incompat(fs_info, REMAP_TREE)) {
/* cleanup orphan inode in data relocation tree */
fs_root = btrfs_grab_root(fs_info->data_reloc_root);
ASSERT(fs_root);
diff --git a/fs/btrfs/relocation.h b/fs/btrfs/relocation.h
index a272ebaa621f..95fdf369835a 100644
--- a/fs/btrfs/relocation.h
+++ b/fs/btrfs/relocation.h
@@ -13,7 +13,7 @@ struct btrfs_ordered_extent;
struct btrfs_pending_snapshot;
int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
- bool verbose);
+ bool verbose, bool *using_remap_tree);
int btrfs_init_reloc_root(struct btrfs_trans_handle *trans, struct btrfs_root *root);
int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 22bc95f33a6f..bde746944bd5 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -375,8 +375,13 @@ void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info,
factor = btrfs_bg_type_to_factor(block_group->flags);
spin_lock(&space_info->lock);
- space_info->total_bytes += block_group->length;
- space_info->disk_total += block_group->length * factor;
+
+ if (!(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) ||
+ block_group->identity_remap_count != 0) {
+ space_info->total_bytes += block_group->length;
+ space_info->disk_total += block_group->length * factor;
+ }
+
space_info->bytes_used += block_group->used;
space_info->disk_used += block_group->used * factor;
space_info->bytes_readonly += block_group->bytes_super;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8078d2fa4df6..efe4eefec5c4 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3441,6 +3441,7 @@ int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset,
struct btrfs_block_group *block_group;
u64 length;
int ret;
+ bool using_remap_tree;
if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
btrfs_err(fs_info,
@@ -3464,7 +3465,8 @@ int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset,
/* step one, relocate all the extents inside this chunk */
btrfs_scrub_pause(fs_info);
- ret = btrfs_relocate_block_group(fs_info, chunk_offset, true);
+ ret = btrfs_relocate_block_group(fs_info, chunk_offset, true,
+ &using_remap_tree);
btrfs_scrub_continue(fs_info);
if (ret) {
/*
@@ -3476,6 +3478,9 @@ int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset,
return ret;
}
+ if (using_remap_tree)
+ return 0;
+
block_group = btrfs_lookup_block_group(fs_info, chunk_offset);
if (!block_group)
return -ENOENT;
@@ -4182,6 +4187,14 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
chunk_type = btrfs_chunk_type(leaf, chunk);
+ /* Check if chunk has already been fully relocated. */
+ if (chunk_type & BTRFS_BLOCK_GROUP_REMAPPED &&
+ btrfs_chunk_num_stripes(leaf, chunk) == 0) {
+ btrfs_release_path(path);
+ mutex_unlock(&fs_info->reclaim_bgs_lock);
+ goto loop;
+ }
+
if (!counting) {
spin_lock(&fs_info->balance_lock);
bctl->stat.considered++;
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 12/17] btrfs: move existing remaps before relocating block group
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (10 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 11/17] btrfs: handle setting up relocation of block group with remap-tree Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 13/17] btrfs: replace identity maps with actual remaps when doing relocations Mark Harmstone
` (4 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
If when relocating a block group we find that `remap_bytes` > 0 in its
block group item, that means that it has been the destination block
group for another that has been remapped.
We need to seach the remap tree for any remap backrefs within this
range, and move the data to a third block group. This is because
otherwise btrfs_translate_remap() could end up following an unbounded
chain of remaps, which would only get worse over time.
We only relocate one block group at a time, so `remap_bytes` will only
ever go down while we are doing this. Once we're finished we set the
REMAPPED flag on the block group, which will permanently prevent any
other data from being moved to within it.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/extent-tree.c | 6 +-
fs/btrfs/relocation.c | 481 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 485 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 60287aca283d..469b083f11ea 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4545,7 +4545,8 @@ static noinline int find_free_extent(struct btrfs_root *root,
block_group->cached != BTRFS_CACHE_NO) {
down_read(&space_info->groups_sem);
if (list_empty(&block_group->list) ||
- block_group->ro) {
+ block_group->ro ||
+ block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
/*
* someone is removing this block group,
* we can't jump into the have_block_group
@@ -4579,7 +4580,8 @@ static noinline int find_free_extent(struct btrfs_root *root,
ffe_ctl->hinted = false;
/* If the block group is read-only, we can skip it entirely. */
- if (unlikely(block_group->ro)) {
+ if (unlikely(block_group->ro) ||
+ block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
if (ffe_ctl->for_treelog)
btrfs_clear_treelog_bg(block_group);
if (ffe_ctl->for_data_reloc)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 44614e149016..307d68d93259 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3980,6 +3980,481 @@ static void adjust_block_group_remap_bytes(struct btrfs_trans_handle *trans,
btrfs_inc_delayed_refs_rsv_bg_updates(fs_info);
}
+struct reloc_io_private {
+ struct completion done;
+ refcount_t pending_refs;
+ blk_status_t status;
+};
+
+static void reloc_endio(struct btrfs_bio *bbio)
+{
+ struct reloc_io_private *priv = bbio->private;
+
+ if (bbio->bio.bi_status)
+ WRITE_ONCE(priv->status, bbio->bio.bi_status);
+
+ if (refcount_dec_and_test(&priv->pending_refs))
+ complete(&priv->done);
+
+ bio_put(&bbio->bio);
+}
+
+static int copy_remapped_data_io(struct btrfs_fs_info *fs_info,
+ struct reloc_io_private *priv,
+ struct page **pages, u64 addr, u64 length,
+ bool do_write)
+{
+ struct btrfs_bio *bbio;
+ unsigned long i = 0;
+ blk_opf_t op = do_write ? REQ_OP_WRITE : REQ_OP_READ;
+
+ init_completion(&priv->done);
+ refcount_set(&priv->pending_refs, 1);
+ priv->status = 0;
+
+ bbio = btrfs_bio_alloc(BIO_MAX_VECS, op, fs_info, reloc_endio,
+ priv);
+ bbio->bio.bi_iter.bi_sector = addr >> SECTOR_SHIFT;
+
+ do {
+ size_t bytes = min_t(u64, length, PAGE_SIZE);
+
+ if (bio_add_page(&bbio->bio, pages[i], bytes, 0) < bytes) {
+ refcount_inc(&priv->pending_refs);
+ btrfs_submit_bbio(bbio, 0);
+
+ bbio = btrfs_bio_alloc(BIO_MAX_VECS, op, fs_info,
+ reloc_endio, priv);
+ bbio->bio.bi_iter.bi_sector = addr >> SECTOR_SHIFT;
+ continue;
+ }
+
+ i++;
+ addr += bytes;
+ length -= bytes;
+ } while (length);
+
+ refcount_inc(&priv->pending_refs);
+ btrfs_submit_bbio(bbio, 0);
+
+ if (!refcount_dec_and_test(&priv->pending_refs))
+ wait_for_completion_io(&priv->done);
+
+ return blk_status_to_errno(READ_ONCE(priv->status));
+}
+
+static int copy_remapped_data(struct btrfs_fs_info *fs_info, u64 old_addr,
+ u64 new_addr, u64 length)
+{
+ int ret;
+ struct page **pages;
+ unsigned int nr_pages;
+ struct reloc_io_private priv;
+
+ nr_pages = DIV_ROUND_UP(length, PAGE_SIZE);
+ pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
+ if (!pages)
+ return -ENOMEM;
+ ret = btrfs_alloc_page_array(nr_pages, pages, 0);
+ if (ret) {
+ ret = -ENOMEM;
+ goto end;
+ }
+
+ ret = copy_remapped_data_io(fs_info, &priv, pages, old_addr, length,
+ false);
+ if (ret)
+ goto end;
+
+ ret = copy_remapped_data_io(fs_info, &priv, pages, new_addr, length,
+ true);
+
+end:
+ for (unsigned int i = 0; i < nr_pages; i++) {
+ if (pages[i])
+ __free_page(pages[i]);
+ }
+ kfree(pages);
+
+ return ret;
+}
+
+static int do_copy(struct btrfs_fs_info *fs_info, u64 old_addr, u64 new_addr,
+ u64 length)
+{
+ int ret;
+
+ /* Copy 1MB at a time, to avoid using too much memory. */
+
+ do {
+ u64 to_copy = min_t(u64, length, SZ_1M);
+
+ ret = copy_remapped_data(fs_info, old_addr, new_addr,
+ to_copy);
+ if (ret)
+ return ret;
+
+ if (to_copy == length)
+ break;
+
+ old_addr += to_copy;
+ new_addr += to_copy;
+ length -= to_copy;
+ } while (true);
+
+ return 0;
+}
+
+static int add_remap_item(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path, u64 new_addr, u64 length,
+ u64 old_addr)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_remap remap;
+ struct btrfs_key key;
+ struct extent_buffer *leaf;
+ int ret;
+
+ key.objectid = old_addr;
+ key.type = BTRFS_REMAP_KEY;
+ key.offset = length;
+
+ ret = btrfs_insert_empty_item(trans, fs_info->remap_root, path,
+ &key, sizeof(struct btrfs_remap));
+ if (ret)
+ return ret;
+
+ leaf = path->nodes[0];
+
+ btrfs_set_stack_remap_address(&remap, new_addr);
+
+ write_extent_buffer(leaf, &remap,
+ btrfs_item_ptr_offset(leaf, path->slots[0]),
+ sizeof(struct btrfs_remap));
+
+ btrfs_release_path(path);
+
+ return 0;
+}
+
+static int add_remap_backref_item(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path, u64 new_addr,
+ u64 length, u64 old_addr)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_remap remap;
+ struct btrfs_key key;
+ struct extent_buffer *leaf;
+ int ret;
+
+ key.objectid = new_addr;
+ key.type = BTRFS_REMAP_BACKREF_KEY;
+ key.offset = length;
+
+ ret = btrfs_insert_empty_item(trans, fs_info->remap_root,
+ path, &key, sizeof(struct btrfs_remap));
+ if (ret)
+ return ret;
+
+ leaf = path->nodes[0];
+
+ btrfs_set_stack_remap_address(&remap, old_addr);
+
+ write_extent_buffer(leaf, &remap,
+ btrfs_item_ptr_offset(leaf, path->slots[0]),
+ sizeof(struct btrfs_remap));
+
+ btrfs_release_path(path);
+
+ return 0;
+}
+
+static int move_existing_remap(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path,
+ struct btrfs_block_group *bg, u64 new_addr,
+ u64 length, u64 old_addr)
+{
+ struct btrfs_trans_handle *trans;
+ struct extent_buffer *leaf;
+ struct btrfs_remap *remap_ptr, remap;
+ struct btrfs_key key, ins;
+ u64 dest_addr, dest_length, min_size;
+ struct btrfs_block_group *dest_bg;
+ int ret;
+ bool is_data = bg->flags & BTRFS_BLOCK_GROUP_DATA;
+ struct btrfs_space_info *sinfo = bg->space_info;
+ bool mutex_taken = false, bg_needs_free_space;
+
+ spin_lock(&sinfo->lock);
+ btrfs_space_info_update_bytes_may_use(sinfo, length);
+ spin_unlock(&sinfo->lock);
+
+ if (is_data)
+ min_size = fs_info->sectorsize;
+ else
+ min_size = fs_info->nodesize;
+
+ ret = btrfs_reserve_extent(fs_info->fs_root, length, length, min_size,
+ 0, 0, &ins, is_data, false);
+ if (ret) {
+ spin_lock(&sinfo->lock);
+ btrfs_space_info_update_bytes_may_use(sinfo, -length);
+ spin_unlock(&sinfo->lock);
+ return ret;
+ }
+
+ dest_addr = ins.objectid;
+ dest_length = ins.offset;
+
+ if (!is_data && !IS_ALIGNED(dest_length, fs_info->nodesize)) {
+ u64 new_length = ALIGN_DOWN(dest_length, fs_info->nodesize);
+
+ btrfs_free_reserved_extent(fs_info, dest_addr + new_length,
+ dest_length - new_length, 0);
+
+ dest_length = new_length;
+ }
+
+ trans = btrfs_join_transaction(fs_info->remap_root);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ trans = NULL;
+ goto end;
+ }
+
+ mutex_lock(&fs_info->remap_mutex);
+ mutex_taken = true;
+
+ /* Find old remap entry. */
+
+ key.objectid = old_addr;
+ key.type = BTRFS_REMAP_KEY;
+ key.offset = length;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root, &key,
+ path, 0, 1);
+ if (ret == 1) {
+ /*
+ * Not a problem if the remap entry wasn't found: that means
+ * that another transaction has deallocated the data.
+ * move_existing_remaps() loops until the BG contains no
+ * remaps, so we can just return 0 in this case.
+ */
+ btrfs_release_path(path);
+ ret = 0;
+ goto end;
+ } else if (ret) {
+ goto end;
+ }
+
+ ret = do_copy(fs_info, new_addr, dest_addr, dest_length);
+ if (ret)
+ goto end;
+
+ /* Change data of old remap entry. */
+
+ leaf = path->nodes[0];
+
+ remap_ptr = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_remap);
+ btrfs_set_remap_address(leaf, remap_ptr, dest_addr);
+
+ btrfs_mark_buffer_dirty(trans, leaf);
+
+ if (dest_length != length) {
+ key.offset = dest_length;
+ btrfs_set_item_key_safe(trans, path, &key);
+ }
+
+ btrfs_release_path(path);
+
+ if (dest_length != length) {
+ /* Add remap item for remainder. */
+
+ ret = add_remap_item(trans, path, new_addr + dest_length,
+ length - dest_length,
+ old_addr + dest_length);
+ if (ret)
+ goto end;
+ }
+
+ /* Change or remove old backref. */
+
+ key.objectid = new_addr;
+ key.type = BTRFS_REMAP_BACKREF_KEY;
+ key.offset = length;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root, &key,
+ path, -1, 1);
+ if (ret) {
+ if (ret == 1) {
+ btrfs_release_path(path);
+ ret = -ENOENT;
+ }
+ goto end;
+ }
+
+ leaf = path->nodes[0];
+
+ if (dest_length == length) {
+ ret = btrfs_del_item(trans, fs_info->remap_root, path);
+ if (ret) {
+ btrfs_release_path(path);
+ goto end;
+ }
+ } else {
+ key.objectid += dest_length;
+ key.offset -= dest_length;
+ btrfs_set_item_key_safe(trans, path, &key);
+
+ btrfs_set_stack_remap_address(&remap, old_addr + dest_length);
+
+ write_extent_buffer(leaf, &remap,
+ btrfs_item_ptr_offset(leaf, path->slots[0]),
+ sizeof(struct btrfs_remap));
+ }
+
+ btrfs_release_path(path);
+
+ /* Add new backref. */
+
+ ret = add_remap_backref_item(trans, path, dest_addr, dest_length,
+ old_addr);
+ if (ret)
+ goto end;
+
+ adjust_block_group_remap_bytes(trans, bg, -dest_length);
+
+ ret = btrfs_add_to_free_space_tree(trans, new_addr, dest_length);
+ if (ret)
+ goto end;
+
+ dest_bg = btrfs_lookup_block_group(fs_info, dest_addr);
+
+ adjust_block_group_remap_bytes(trans, dest_bg, dest_length);
+
+ mutex_lock(&dest_bg->free_space_lock);
+ bg_needs_free_space = test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE,
+ &dest_bg->runtime_flags);
+ mutex_unlock(&dest_bg->free_space_lock);
+ btrfs_put_block_group(dest_bg);
+
+ if (bg_needs_free_space) {
+ ret = btrfs_add_block_group_free_space(trans, dest_bg);
+ if (ret)
+ goto end;
+ }
+
+ ret = btrfs_remove_from_free_space_tree(trans, dest_addr, dest_length);
+ if (ret) {
+ btrfs_remove_from_free_space_tree(trans, new_addr,
+ dest_length);
+ goto end;
+ }
+
+ ret = 0;
+
+end:
+ if (mutex_taken)
+ mutex_unlock(&fs_info->remap_mutex);
+
+ btrfs_dec_block_group_reservations(fs_info, dest_addr);
+
+ if (ret) {
+ btrfs_free_reserved_extent(fs_info, dest_addr, dest_length, 0);
+
+ if (trans) {
+ btrfs_abort_transaction(trans, ret);
+ btrfs_end_transaction(trans);
+ }
+ } else {
+ dest_bg = btrfs_lookup_block_group(fs_info, dest_addr);
+ btrfs_free_reserved_bytes(dest_bg, dest_length, 0);
+ btrfs_put_block_group(dest_bg);
+
+ ret = btrfs_commit_transaction(trans);
+ }
+
+ return ret;
+}
+
+static int move_existing_remaps(struct btrfs_fs_info *fs_info,
+ struct btrfs_block_group *bg,
+ struct btrfs_path *path)
+{
+ int ret;
+ struct btrfs_key key;
+ struct extent_buffer *leaf;
+ struct btrfs_remap *remap;
+ u64 old_addr;
+
+ /* Look for backrefs in remap tree. */
+
+ while (bg->remap_bytes > 0) {
+ key.objectid = bg->start;
+ key.type = BTRFS_REMAP_BACKREF_KEY;
+ key.offset = 0;
+
+ ret = btrfs_search_slot(NULL, fs_info->remap_root, &key, path,
+ 0, 0);
+ if (ret < 0)
+ return ret;
+
+ leaf = path->nodes[0];
+
+ if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+ ret = btrfs_next_leaf(fs_info->remap_root, path);
+ if (ret < 0) {
+ btrfs_release_path(path);
+ return ret;
+ }
+
+ if (ret) {
+ btrfs_release_path(path);
+ break;
+ }
+
+ leaf = path->nodes[0];
+ }
+
+ btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+ if (key.type != BTRFS_REMAP_BACKREF_KEY) {
+ path->slots[0]++;
+
+ if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+ ret = btrfs_next_leaf(fs_info->remap_root, path);
+ if (ret < 0) {
+ btrfs_release_path(path);
+ return ret;
+ }
+
+ if (ret) {
+ btrfs_release_path(path);
+ break;
+ }
+
+ leaf = path->nodes[0];
+ }
+ }
+
+ remap = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_remap);
+
+ old_addr = btrfs_remap_address(leaf, remap);
+
+ btrfs_release_path(path);
+
+ ret = move_existing_remap(fs_info, path, bg, key.objectid,
+ key.offset, old_addr);
+ if (ret)
+ return ret;
+ }
+
+ BUG_ON(bg->remap_bytes > 0);
+
+ return 0;
+}
+
static int create_remap_tree_entries(struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct btrfs_block_group *bg)
@@ -4551,6 +5026,12 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
WARN_ON(ret && ret != -EAGAIN);
if (*using_remap_tree) {
+ if (bg->remap_bytes != 0) {
+ ret = move_existing_remaps(fs_info, bg, path);
+ if (ret)
+ goto out;
+ }
+
ret = start_block_group_remapping(fs_info, path, bg);
goto out;
}
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 13/17] btrfs: replace identity maps with actual remaps when doing relocations
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (11 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 12/17] btrfs: move existing remaps before relocating block group Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 14/17] btrfs: add do_remap param to btrfs_discard_extent() Mark Harmstone
` (3 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Add a function do_remap_tree_reloc(), which does the actual work of
doing a relocation using the remap tree.
In a loop we call do_remap_tree_reloc_trans(), which searches for the
first identity remap for the block group. We call btrfs_reserve_extent()
to find space elsewhere for it, and read the data into memory and write
it to the new location. We then carve out the identity remap and replace
it with an actual remap, which points to the new location in which to
look.
Once the last identity remap has been removed we call
last_identity_remap_gone(), which, as with deletions, removes the
chunk's stripes and device extents.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/relocation.c | 317 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 317 insertions(+)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 307d68d93259..7bad8d65d145 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4633,6 +4633,61 @@ static int create_remap_tree_entries(struct btrfs_trans_handle *trans,
return ret;
}
+static int find_next_identity_remap(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path, u64 bg_end,
+ u64 last_start, u64 *start,
+ u64 *length)
+{
+ int ret;
+ struct btrfs_key key, found_key;
+ struct btrfs_root *remap_root = trans->fs_info->remap_root;
+ struct extent_buffer *leaf;
+
+ key.objectid = last_start;
+ key.type = BTRFS_IDENTITY_REMAP_KEY;
+ key.offset = 0;
+
+ ret = btrfs_search_slot(trans, remap_root, &key, path, 0, 0);
+ if (ret < 0)
+ goto out;
+
+ leaf = path->nodes[0];
+ while (true) {
+ if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+ ret = btrfs_next_leaf(remap_root, path);
+
+ if (ret != 0) {
+ if (ret == 1)
+ ret = -ENOENT;
+ goto out;
+ }
+
+ leaf = path->nodes[0];
+ }
+
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+ if (found_key.objectid >= bg_end) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ if (found_key.type == BTRFS_IDENTITY_REMAP_KEY) {
+ *start = found_key.objectid;
+ *length = found_key.offset;
+ ret = 0;
+ goto out;
+ }
+
+ path->slots[0]++;
+ }
+
+out:
+ btrfs_release_path(path);
+
+ return ret;
+}
+
static int remove_chunk_stripes(struct btrfs_trans_handle *trans,
struct btrfs_chunk_map *chunk,
struct btrfs_path *path)
@@ -4739,6 +4794,96 @@ static void adjust_identity_remap_count(struct btrfs_trans_handle *trans,
btrfs_mark_bg_fully_remapped(bg, trans);
}
+static int add_remap_entry(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ struct btrfs_block_group *src_bg, u64 old_addr,
+ u64 new_addr, u64 length)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_key key, new_key;
+ int ret;
+ int identity_count_delta = 0;
+
+ key.objectid = old_addr;
+ key.type = (u8)-1;
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root, &key, path, -1, 1);
+ if (ret < 0)
+ goto end;
+
+ if (path->slots[0] == 0) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ path->slots[0]--;
+
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+
+ if (key.type != BTRFS_IDENTITY_REMAP_KEY ||
+ key.objectid > old_addr ||
+ key.objectid + key.offset <= old_addr) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ /* Shorten or delete identity mapping entry. */
+
+ if (key.objectid == old_addr) {
+ ret = btrfs_del_item(trans, fs_info->remap_root, path);
+ if (ret)
+ goto end;
+
+ identity_count_delta--;
+ } else {
+ new_key.objectid = key.objectid;
+ new_key.type = BTRFS_IDENTITY_REMAP_KEY;
+ new_key.offset = old_addr - key.objectid;
+
+ btrfs_set_item_key_safe(trans, path, &new_key);
+ }
+
+ btrfs_release_path(path);
+
+ /* Create new remap entry. */
+
+ ret = add_remap_item(trans, path, new_addr, length, old_addr);
+ if (ret)
+ goto end;
+
+ /* Add entry for remainder of identity mapping, if necessary. */
+
+ if (key.objectid + key.offset != old_addr + length) {
+ new_key.objectid = old_addr + length;
+ new_key.type = BTRFS_IDENTITY_REMAP_KEY;
+ new_key.offset = key.objectid + key.offset - old_addr - length;
+
+ ret = btrfs_insert_empty_item(trans, fs_info->remap_root,
+ path, &new_key, 0);
+ if (ret)
+ goto end;
+
+ btrfs_release_path(path);
+
+ identity_count_delta++;
+ }
+
+ /* Add backref. */
+
+ ret = add_remap_backref_item(trans, path, new_addr, length, old_addr);
+ if (ret)
+ goto end;
+
+ if (identity_count_delta != 0)
+ adjust_identity_remap_count(trans, src_bg, identity_count_delta);
+
+end:
+ btrfs_release_path(path);
+
+ return ret;
+}
+
static int mark_chunk_remapped(struct btrfs_trans_handle *trans,
struct btrfs_path *path, uint64_t start)
{
@@ -4788,6 +4933,169 @@ static int mark_chunk_remapped(struct btrfs_trans_handle *trans,
return ret;
}
+static int do_remap_tree_reloc_trans(struct btrfs_fs_info *fs_info,
+ struct btrfs_block_group *src_bg,
+ struct btrfs_path *path, u64 *last_start)
+{
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *extent_root;
+ struct btrfs_key ins;
+ struct btrfs_block_group *dest_bg = NULL;
+ u64 start, remap_length, length, new_addr, min_size;
+ int ret;
+ bool no_more = false;
+ bool is_data = src_bg->flags & BTRFS_BLOCK_GROUP_DATA;
+ bool made_reservation = false, bg_needs_free_space;
+ struct btrfs_space_info *sinfo = src_bg->space_info;
+
+ extent_root = btrfs_extent_root(fs_info, src_bg->start);
+
+ trans = btrfs_start_transaction(extent_root, 0);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ mutex_lock(&fs_info->remap_mutex);
+
+ ret = find_next_identity_remap(trans, path, src_bg->start + src_bg->length,
+ *last_start, &start, &remap_length);
+ if (ret == -ENOENT) {
+ no_more = true;
+ goto next;
+ } else if (ret) {
+ mutex_unlock(&fs_info->remap_mutex);
+ btrfs_end_transaction(trans);
+ return ret;
+ }
+
+ /* Try to reserve enough space for block. */
+
+ spin_lock(&sinfo->lock);
+ btrfs_space_info_update_bytes_may_use(sinfo, remap_length);
+ spin_unlock(&sinfo->lock);
+
+ if (is_data)
+ min_size = fs_info->sectorsize;
+ else
+ min_size = fs_info->nodesize;
+
+ ret = btrfs_reserve_extent(fs_info->fs_root, remap_length,
+ remap_length, min_size,
+ 0, 0, &ins, is_data, false);
+ if (ret) {
+ spin_lock(&sinfo->lock);
+ btrfs_space_info_update_bytes_may_use(sinfo, -remap_length);
+ spin_unlock(&sinfo->lock);
+
+ mutex_unlock(&fs_info->remap_mutex);
+ btrfs_end_transaction(trans);
+ return ret;
+ }
+
+ made_reservation = true;
+
+ new_addr = ins.objectid;
+ length = ins.offset;
+
+ if (!is_data && !IS_ALIGNED(length, fs_info->nodesize)) {
+ u64 new_length = ALIGN_DOWN(length, fs_info->nodesize);
+
+ btrfs_free_reserved_extent(fs_info, new_addr + new_length,
+ length - new_length, 0);
+
+ length = new_length;
+ }
+
+ dest_bg = btrfs_lookup_block_group(fs_info, new_addr);
+
+ mutex_lock(&dest_bg->free_space_lock);
+ bg_needs_free_space = test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE,
+ &dest_bg->runtime_flags);
+ mutex_unlock(&dest_bg->free_space_lock);
+
+ if (bg_needs_free_space) {
+ ret = btrfs_add_block_group_free_space(trans, dest_bg);
+ if (ret)
+ goto fail;
+ }
+
+ ret = do_copy(fs_info, start, new_addr, length);
+ if (ret)
+ goto fail;
+
+ ret = btrfs_remove_from_free_space_tree(trans, new_addr, length);
+ if (ret)
+ goto fail;
+
+ ret = add_remap_entry(trans, path, src_bg, start, new_addr, length);
+ if (ret) {
+ btrfs_add_to_free_space_tree(trans, new_addr, length);
+ goto fail;
+ }
+
+ adjust_block_group_remap_bytes(trans, dest_bg, length);
+ btrfs_free_reserved_bytes(dest_bg, length, 0);
+
+ spin_lock(&sinfo->lock);
+ sinfo->bytes_readonly += length;
+ spin_unlock(&sinfo->lock);
+
+next:
+ if (dest_bg)
+ btrfs_put_block_group(dest_bg);
+
+ if (made_reservation)
+ btrfs_dec_block_group_reservations(fs_info, new_addr);
+
+ if (src_bg->used == 0 && src_bg->remap_bytes == 0)
+ btrfs_mark_bg_fully_remapped(src_bg, trans);
+
+ mutex_unlock(&fs_info->remap_mutex);
+
+ ret = btrfs_end_transaction(trans);
+ if (ret)
+ return ret;
+
+ if (no_more)
+ return 1;
+
+ *last_start = start;
+
+ return 0;
+
+fail:
+ if (dest_bg)
+ btrfs_put_block_group(dest_bg);
+
+ btrfs_free_reserved_extent(fs_info, new_addr, length, 0);
+
+ mutex_unlock(&fs_info->remap_mutex);
+ btrfs_end_transaction(trans);
+
+ return ret;
+}
+
+static int do_remap_tree_reloc(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path,
+ struct btrfs_block_group *bg)
+{
+ u64 last_start;
+ int ret;
+
+ last_start = bg->start;
+
+ while (true) {
+ ret = do_remap_tree_reloc_trans(fs_info, bg, path,
+ &last_start);
+ if (ret) {
+ if (ret == 1)
+ ret = 0;
+ break;
+ }
+ }
+
+ return ret;
+}
+
int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
u64 *length, bool nolock)
{
@@ -5033,6 +5341,15 @@ int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start,
}
ret = start_block_group_remapping(fs_info, path, bg);
+ if (ret)
+ goto out;
+
+ ret = do_remap_tree_reloc(fs_info, path, rc->block_group);
+ if (ret)
+ goto out;
+
+ btrfs_delete_unused_bgs(fs_info);
+
goto out;
}
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 14/17] btrfs: add do_remap param to btrfs_discard_extent()
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (12 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 13/17] btrfs: replace identity maps with actual remaps when doing relocations Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 15/17] btrfs: allow balancing remap tree Mark Harmstone
` (2 subsequent siblings)
16 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
btrfs_discard_extent() can be called either when an extent is removed
or from walking the free-space tree. With a remapped block group these
two things are no longer equivalent: the extent's addresses are
remapped, while the free-space tree exclusively uses underlying
addresses.
Add a do_remap parameter to btrfs_discard_extent() and
btrfs_map_discard(), saying whether or not the address needs to be run
through the remap tree first.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/extent-tree.c | 11 +++++++----
fs/btrfs/extent-tree.h | 2 +-
fs/btrfs/free-space-cache.c | 2 +-
fs/btrfs/inode.c | 2 +-
fs/btrfs/volumes.c | 25 +++++++++++++++++++++++--
fs/btrfs/volumes.h | 2 +-
6 files changed, 34 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 469b083f11ea..2e3074612f39 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1380,7 +1380,7 @@ static int do_discard_extent(struct btrfs_discard_stripe *stripe, u64 *bytes)
}
int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
- u64 num_bytes, u64 *actual_bytes)
+ u64 num_bytes, u64 *actual_bytes, bool do_remap)
{
int ret = 0;
u64 discarded_bytes = 0;
@@ -1398,7 +1398,8 @@ int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
int i;
num_bytes = end - cur;
- stripes = btrfs_map_discard(fs_info, cur, &num_bytes, &num_stripes);
+ stripes = btrfs_map_discard(fs_info, cur, &num_bytes,
+ &num_stripes, do_remap);
if (IS_ERR(stripes)) {
ret = PTR_ERR(stripes);
if (ret == -EOPNOTSUPP)
@@ -2914,7 +2915,8 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
if (btrfs_test_opt(fs_info, DISCARD_SYNC))
ret = btrfs_discard_extent(fs_info, start,
- end + 1 - start, NULL);
+ end + 1 - start, NULL,
+ true);
next_state = btrfs_next_extent_state(unpin, cached_state);
btrfs_clear_extent_dirty(unpin, start, end, &cached_state);
@@ -2972,7 +2974,8 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
ret = -EROFS;
if (!TRANS_ABORTED(trans))
ret = btrfs_discard_extent(fs_info, block_group->start,
- block_group->length, NULL);
+ block_group->length, NULL,
+ true);
/*
* Not strictly necessary to lock, as the block_group should be
diff --git a/fs/btrfs/extent-tree.h b/fs/btrfs/extent-tree.h
index 6b67a4e528da..721b03d682b4 100644
--- a/fs/btrfs/extent-tree.h
+++ b/fs/btrfs/extent-tree.h
@@ -162,7 +162,7 @@ int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
struct extent_buffer *parent);
void btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info, u64 start, u64 end);
int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
- u64 num_bytes, u64 *actual_bytes);
+ u64 num_bytes, u64 *actual_bytes, bool do_remap);
int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range);
int btrfs_handle_fully_remapped_bgs(struct btrfs_trans_handle *trans);
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index ab873bd67192..6387f8d1c3a1 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3672,7 +3672,7 @@ static int do_trimming(struct btrfs_block_group *block_group,
spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
- ret = btrfs_discard_extent(fs_info, start, bytes, &trimmed);
+ ret = btrfs_discard_extent(fs_info, start, bytes, &trimmed, false);
if (!ret) {
*total_trimmed += trimmed;
trim_state = BTRFS_TRIM_STATE_TRIMMED;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ac2fd589697d..c43715a1f337 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3293,7 +3293,7 @@ int btrfs_finish_one_ordered(struct btrfs_ordered_extent *ordered_extent)
btrfs_discard_extent(fs_info,
ordered_extent->disk_bytenr,
ordered_extent->disk_num_bytes,
- NULL);
+ NULL, true);
btrfs_free_reserved_extent(fs_info,
ordered_extent->disk_bytenr,
ordered_extent->disk_num_bytes, true);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index efe4eefec5c4..1ce06c343918 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3495,7 +3495,8 @@ int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset,
* filesystem's point of view.
*/
if (btrfs_is_zoned(fs_info)) {
- ret = btrfs_discard_extent(fs_info, chunk_offset, length, NULL);
+ ret = btrfs_discard_extent(fs_info, chunk_offset, length, NULL,
+ true);
if (ret)
btrfs_info(fs_info,
"failed to reset zone %llu after relocation",
@@ -6143,7 +6144,7 @@ void btrfs_put_bioc(struct btrfs_io_context *bioc)
*/
struct btrfs_discard_stripe *btrfs_map_discard(struct btrfs_fs_info *fs_info,
u64 logical, u64 *length_ret,
- u32 *num_stripes)
+ u32 *num_stripes, bool do_remap)
{
struct btrfs_chunk_map *map;
struct btrfs_discard_stripe *stripes;
@@ -6167,6 +6168,26 @@ struct btrfs_discard_stripe *btrfs_map_discard(struct btrfs_fs_info *fs_info,
if (IS_ERR(map))
return ERR_CAST(map);
+ if (do_remap && map->type & BTRFS_BLOCK_GROUP_REMAPPED) {
+ u64 new_logical = logical;
+
+ ret = btrfs_translate_remap(fs_info, &new_logical, &length,
+ false);
+ if (ret)
+ goto out_free_map;
+
+ if (new_logical != logical) {
+ btrfs_free_chunk_map(map);
+
+ map = btrfs_get_chunk_map(fs_info, new_logical,
+ length);
+ if (IS_ERR(map))
+ return ERR_CAST(map);
+
+ logical = new_logical;
+ }
+ }
+
/* we don't discard raid56 yet */
if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
ret = -EOPNOTSUPP;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 05a3e6922f78..7644e9cee148 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -727,7 +727,7 @@ int btrfs_map_repair_block(struct btrfs_fs_info *fs_info,
u32 length, int mirror_num);
struct btrfs_discard_stripe *btrfs_map_discard(struct btrfs_fs_info *fs_info,
u64 logical, u64 *length_ret,
- u32 *num_stripes);
+ u32 *num_stripes, bool do_remap);
int btrfs_read_sys_array(struct btrfs_fs_info *fs_info);
int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info);
struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans,
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 15/17] btrfs: allow balancing remap tree
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (13 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 14/17] btrfs: add do_remap param to btrfs_discard_extent() Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-15 4:24 ` Boris Burkov
2025-10-09 11:28 ` [PATCH v3 16/17] btrfs: handle discarding fully-remapped block groups Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 17/17] btrfs: add stripe removal pending flag Mark Harmstone
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Balancing the REMAP chunk, i.e. the chunk in which the remap tree lives,
is a special case.
We can't use the remap tree itself for this, as then we'd have no way to
boostrap it on mount. And we can't use the pre-remap tree code for this
as it relies on walking the extent tree, and we're not creating backrefs
for REMAP chunks.
So instead, if a balance would relocate any REMAP block groups, mark
those block groups as readonly and COW every leaf of the remap tree.
There's more sophisticated ways of doing this, such as only COWing nodes
within a block group that's to be relocated, but they're fiddly and with
lots of edge cases. Plus it's not anticipated that a) the number of
REMAP chunks is going to be particularly large, or b) that users will
want to only relocate some of these chunks - the main use case here is
to unbreak RAID conversion and device removal.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/volumes.c | 159 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 155 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1ce06c343918..a4dcafe2d565 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4016,8 +4016,11 @@ static bool should_balance_chunk(struct extent_buffer *leaf, struct btrfs_chunk
struct btrfs_balance_args *bargs = NULL;
u64 chunk_type = btrfs_chunk_type(leaf, chunk);
- if (chunk_type & BTRFS_BLOCK_GROUP_REMAP)
- return false;
+ /* treat REMAP chunks as METADATA */
+ if (chunk_type & BTRFS_BLOCK_GROUP_REMAP) {
+ chunk_type &= ~BTRFS_BLOCK_GROUP_REMAP;
+ chunk_type |= BTRFS_BLOCK_GROUP_METADATA;
+ }
/* type filter */
if (!((chunk_type & BTRFS_BLOCK_GROUP_TYPE_MASK) &
@@ -4100,6 +4103,113 @@ static bool should_balance_chunk(struct extent_buffer *leaf, struct btrfs_chunk
return true;
}
+struct remap_chunk_info {
+ struct list_head list;
+ u64 offset;
+ struct btrfs_block_group *bg;
+ bool made_ro;
+};
+
+static int cow_remap_tree(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_key key = { 0 };
+ int ret;
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root, &key, path, 0, 1);
+ if (ret < 0)
+ return ret;
+
+ while (true) {
+ ret = btrfs_next_leaf(fs_info->remap_root, path);
+ if (ret < 0) {
+ return ret;
+ } else if (ret > 0) {
+ ret = 0;
+ break;
+ }
+
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+
+ btrfs_release_path(path);
+
+ ret = btrfs_search_slot(trans, fs_info->remap_root, &key, path,
+ 0, 1);
+ if (ret < 0)
+ break;
+ }
+
+ return ret;
+}
+
+static int balance_remap_chunks(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path,
+ struct list_head *chunks)
+{
+ struct remap_chunk_info *rci, *tmp;
+ struct btrfs_trans_handle *trans;
+ int ret;
+
+ list_for_each_entry_safe(rci, tmp, chunks, list) {
+ rci->bg = btrfs_lookup_block_group(fs_info, rci->offset);
+ if (!rci->bg) {
+ list_del(&rci->list);
+ kfree(rci);
+ continue;
+ }
+
+ ret = btrfs_inc_block_group_ro(rci->bg, false);
+ if (ret)
+ goto end;
+
+ rci->made_ro = true;
+ }
+
+ if (list_empty(chunks))
+ return 0;
+
+ trans = btrfs_start_transaction(fs_info->remap_root, 0);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto end;
+ }
+
+ mutex_lock(&fs_info->remap_mutex);
+
+ ret = cow_remap_tree(trans, path);
+
+ btrfs_release_path(path);
+
+ mutex_unlock(&fs_info->remap_mutex);
+
+ btrfs_commit_transaction(trans);
+
+end:
+ while (!list_empty(chunks)) {
+ bool unused;
+
+ rci = list_first_entry(chunks, struct remap_chunk_info, list);
+
+ spin_lock(&rci->bg->lock);
+ unused = !btrfs_is_block_group_used(rci->bg);
+ spin_unlock(&rci->bg->lock);
+
+ if (unused)
+ btrfs_mark_bg_unused(rci->bg);
+
+ if (rci->made_ro)
+ btrfs_dec_block_group_ro(rci->bg);
+
+ btrfs_put_block_group(rci->bg);
+
+ list_del(&rci->list);
+ kfree(rci);
+ }
+
+ return ret;
+}
+
static int __btrfs_balance(struct btrfs_fs_info *fs_info)
{
struct btrfs_balance_control *bctl = fs_info->balance_ctl;
@@ -4122,6 +4232,9 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
u32 count_meta = 0;
u32 count_sys = 0;
int chunk_reserved = 0;
+ struct remap_chunk_info *rci;
+ unsigned int num_remap_chunks = 0;
+ LIST_HEAD(remap_chunks);
path = btrfs_alloc_path();
if (!path) {
@@ -4220,7 +4333,8 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
count_data++;
else if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM)
count_sys++;
- else if (chunk_type & BTRFS_BLOCK_GROUP_METADATA)
+ else if (chunk_type & (BTRFS_BLOCK_GROUP_METADATA |
+ BTRFS_BLOCK_GROUP_REMAP))
count_meta++;
goto loop;
@@ -4240,6 +4354,30 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
goto loop;
}
+ /*
+ * Balancing REMAP chunks takes place separately - add the
+ * details to a list so it can be processed later.
+ */
+ if (chunk_type & BTRFS_BLOCK_GROUP_REMAP) {
+ mutex_unlock(&fs_info->reclaim_bgs_lock);
+
+ rci = kmalloc(sizeof(struct remap_chunk_info),
+ GFP_NOFS);
+ if (!rci) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ rci->offset = found_key.offset;
+ rci->bg = NULL;
+ rci->made_ro = false;
+ list_add_tail(&rci->list, &remap_chunks);
+
+ num_remap_chunks++;
+
+ goto loop;
+ }
+
if (!chunk_reserved) {
/*
* We may be relocating the only data chunk we have,
@@ -4279,11 +4417,24 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
key.offset = found_key.offset - 1;
}
+ btrfs_release_path(path);
+
if (counting) {
- btrfs_release_path(path);
counting = false;
goto again;
}
+
+ if (!list_empty(&remap_chunks)) {
+ ret = balance_remap_chunks(fs_info, path, &remap_chunks);
+ if (ret == -ENOSPC)
+ enospc_errors++;
+
+ if (!ret) {
+ spin_lock(&fs_info->balance_lock);
+ bctl->stat.completed += num_remap_chunks;
+ spin_unlock(&fs_info->balance_lock);
+ }
+ }
error:
btrfs_free_path(path);
if (enospc_errors) {
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 16/17] btrfs: handle discarding fully-remapped block groups
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (14 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 15/17] btrfs: allow balancing remap tree Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-15 4:54 ` Boris Burkov
2025-10-09 11:28 ` [PATCH v3 17/17] btrfs: add stripe removal pending flag Mark Harmstone
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Discard normally works by iterating over the free-space entries of a
block group. This doesn't work for fully-remapped block groups, as we
removed their free-space entries when we started relocation.
For sync discard, call btrfs_discard_extent() when we commit the
transaction in which the last identity remap was removed.
For async discard, add a new function btrfs_trim_fully_remapped_block_group()
to be called by the discard worker, which iterates over the block
group's range using the normal async discard rules. Once we reach the
end, remove the chunk's stripes and device extents to get back its free
space.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/block-group.c | 2 +
fs/btrfs/block-group.h | 1 +
fs/btrfs/discard.c | 61 +++++++++++++++++++++++++----
fs/btrfs/extent-tree.c | 4 ++
fs/btrfs/free-space-cache.c | 77 +++++++++++++++++++++++++++++++++++++
fs/btrfs/free-space-cache.h | 1 +
fs/btrfs/transaction.c | 8 ++--
7 files changed, 144 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 3f7c45d17415..a7dfa6c95223 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -4828,4 +4828,6 @@ void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
spin_unlock(&fs_info->unused_bgs_lock);
+ if (btrfs_test_opt(fs_info, DISCARD_ASYNC))
+ btrfs_discard_queue_work(&fs_info->discard_ctl, bg);
}
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index c6866a57ea24..3c086fbb0a7c 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -49,6 +49,7 @@ enum btrfs_discard_state {
BTRFS_DISCARD_EXTENTS,
BTRFS_DISCARD_BITMAPS,
BTRFS_DISCARD_RESET_CURSOR,
+ BTRFS_DISCARD_FULLY_REMAPPED,
};
/*
diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
index 2b7b1e440bc8..421f48a6603a 100644
--- a/fs/btrfs/discard.c
+++ b/fs/btrfs/discard.c
@@ -241,8 +241,17 @@ static struct btrfs_block_group *peek_discard_list(
block_group = find_next_block_group(discard_ctl, now);
if (block_group && now >= block_group->discard_eligible_time) {
+ bool unused;
+
+ if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
+ unused = block_group->remap_bytes == 0 &&
+ block_group->identity_remap_count == 0;
+ } else {
+ unused = block_group->used == 0;
+ }
+
if (block_group->discard_index == BTRFS_DISCARD_INDEX_UNUSED &&
- block_group->used != 0) {
+ !unused) {
if (btrfs_is_block_group_data_only(block_group)) {
__add_to_discard_list(discard_ctl, block_group);
/*
@@ -267,7 +276,15 @@ static struct btrfs_block_group *peek_discard_list(
}
if (block_group->discard_state == BTRFS_DISCARD_RESET_CURSOR) {
block_group->discard_cursor = block_group->start;
- block_group->discard_state = BTRFS_DISCARD_EXTENTS;
+
+ if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
+ unused) {
+ block_group->discard_state =
+ BTRFS_DISCARD_FULLY_REMAPPED;
+ } else {
+ block_group->discard_state =
+ BTRFS_DISCARD_EXTENTS;
+ }
}
}
if (block_group) {
@@ -370,10 +387,19 @@ void btrfs_discard_cancel_work(struct btrfs_discard_ctl *discard_ctl,
void btrfs_discard_queue_work(struct btrfs_discard_ctl *discard_ctl,
struct btrfs_block_group *block_group)
{
+ bool unused;
+
if (!block_group || !btrfs_test_opt(block_group->fs_info, DISCARD_ASYNC))
return;
- if (block_group->used == 0 && block_group->remap_bytes == 0)
+ if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
+ unused = block_group->remap_bytes == 0 &&
+ block_group->identity_remap_count == 0;
+ } else {
+ unused = block_group->used == 0;
+ }
+
+ if (unused)
add_to_discard_unused_list(discard_ctl, block_group);
else
add_to_discard_list(discard_ctl, block_group);
@@ -468,9 +494,18 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl,
static void btrfs_finish_discard_pass(struct btrfs_discard_ctl *discard_ctl,
struct btrfs_block_group *block_group)
{
+ bool unused;
+
remove_from_discard_list(discard_ctl, block_group);
- if (block_group->used == 0) {
+ if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
+ unused = block_group->remap_bytes == 0 &&
+ block_group->identity_remap_count == 0;
+ } else {
+ unused = block_group->used == 0;
+ }
+
+ if (unused) {
if (btrfs_is_free_space_trimmed(block_group))
btrfs_mark_bg_unused(block_group);
else
@@ -524,7 +559,8 @@ static void btrfs_discard_workfn(struct work_struct *work)
/* Perform discarding */
minlen = discard_minlen[discard_index];
- if (discard_state == BTRFS_DISCARD_BITMAPS) {
+ switch (discard_state) {
+ case BTRFS_DISCARD_BITMAPS: {
u64 maxlen = 0;
/*
@@ -541,17 +577,28 @@ static void btrfs_discard_workfn(struct work_struct *work)
btrfs_block_group_end(block_group),
minlen, maxlen, true);
discard_ctl->discard_bitmap_bytes += trimmed;
- } else {
+
+ break;
+ }
+
+ case BTRFS_DISCARD_FULLY_REMAPPED:
+ btrfs_trim_fully_remapped_block_group(block_group);
+ break;
+
+ default:
btrfs_trim_block_group_extents(block_group, &trimmed,
block_group->discard_cursor,
btrfs_block_group_end(block_group),
minlen, true);
discard_ctl->discard_extent_bytes += trimmed;
+
+ break;
}
/* Determine next steps for a block_group */
if (block_group->discard_cursor >= btrfs_block_group_end(block_group)) {
- if (discard_state == BTRFS_DISCARD_BITMAPS) {
+ if (discard_state == BTRFS_DISCARD_BITMAPS ||
+ discard_state == BTRFS_DISCARD_FULLY_REMAPPED) {
btrfs_finish_discard_pass(discard_ctl, block_group);
} else {
block_group->discard_cursor = block_group->start;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 2e3074612f39..03674d171ec0 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2870,6 +2870,10 @@ int btrfs_handle_fully_remapped_bgs(struct btrfs_trans_handle *trans)
return ret;
}
+ if (!TRANS_ABORTED(trans))
+ btrfs_discard_extent(fs_info, block_group->start,
+ block_group->length, NULL, false);
+
/*
* Set num_stripes to 0, so that btrfs_remove_dev_extents()
* won't run a second time.
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 6387f8d1c3a1..56f27487b632 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -29,6 +29,7 @@
#include "file-item.h"
#include "file.h"
#include "super.h"
+#include "relocation.h"
#define BITS_PER_BITMAP (PAGE_SIZE * 8UL)
#define MAX_CACHE_BYTES_PER_GIG SZ_64K
@@ -3063,6 +3064,12 @@ bool btrfs_is_free_space_trimmed(struct btrfs_block_group *block_group)
struct rb_node *node;
bool ret = true;
+ if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
+ block_group->remap_bytes == 0 &&
+ block_group->identity_remap_count == 0) {
+ return true;
+ }
+
spin_lock(&ctl->tree_lock);
node = rb_first(&ctl->free_space_offset);
@@ -3827,6 +3834,76 @@ static int trim_no_bitmap(struct btrfs_block_group *block_group,
return ret;
}
+void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
+{
+ struct btrfs_fs_info *fs_info = bg->fs_info;
+ struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl;
+ int ret = 0;
+ u64 bytes;
+ const u64 max_discard_size = READ_ONCE(discard_ctl->max_discard_size);
+ u64 end = btrfs_block_group_end(bg);
+ struct btrfs_trans_handle *trans;
+ struct btrfs_chunk_map *map;
+
+ while (bg->discard_cursor < end) {
+ u64 trimmed;
+
+ bytes = end - bg->discard_cursor;
+
+ if (max_discard_size &&
+ bytes >= (max_discard_size +
+ BTRFS_ASYNC_DISCARD_MIN_FILTER)) {
+ bytes = max_discard_size;
+ }
+
+ ret = btrfs_discard_extent(fs_info, bg->discard_cursor, bytes,
+ &trimmed, false);
+ if (ret || trimmed == 0)
+ return;
+
+ bg->discard_cursor += trimmed;
+
+ if (btrfs_trim_interrupted())
+ return;
+
+ cond_resched();
+ }
+
+ trans = btrfs_start_transaction(fs_info->tree_root, 0);
+ if (IS_ERR(trans))
+ return;
+
+ map = btrfs_get_chunk_map(fs_info, bg->start, 1);
+ if (IS_ERR(map)) {
+ ret = PTR_ERR(map);
+ btrfs_abort_transaction(trans, ret);
+ return;
+ }
+
+ ret = btrfs_last_identity_remap_gone(trans, map, bg);
+ if (ret) {
+ btrfs_free_chunk_map(map);
+ btrfs_abort_transaction(trans, ret);
+ return;
+ }
+
+ btrfs_end_transaction(trans);
+
+ /*
+ * Set num_stripes to 0, so that btrfs_remove_dev_extents()
+ * won't run a second time.
+ */
+ map->num_stripes = 0;
+
+ btrfs_free_chunk_map(map);
+
+ if (bg->used == 0) {
+ spin_lock(&fs_info->unused_bgs_lock);
+ list_move_tail(&bg->bg_list, &fs_info->unused_bgs);
+ spin_unlock(&fs_info->unused_bgs_lock);
+ }
+}
+
/*
* If we break out of trimming a bitmap prematurely, we should reset the
* trimming bit. In a rather contrived case, it's possible to race here so
diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
index 9f1dbfdee8ca..33fc3b245648 100644
--- a/fs/btrfs/free-space-cache.h
+++ b/fs/btrfs/free-space-cache.h
@@ -166,6 +166,7 @@ int btrfs_trim_block_group_extents(struct btrfs_block_group *block_group,
int btrfs_trim_block_group_bitmaps(struct btrfs_block_group *block_group,
u64 *trimmed, u64 start, u64 end, u64 minlen,
u64 maxlen, bool async);
+void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg);
bool btrfs_free_space_cache_v1_active(struct btrfs_fs_info *fs_info);
int btrfs_set_free_space_cache_v1_active(struct btrfs_fs_info *fs_info, bool active);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 6ce91397afe6..b0a5254ba214 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -2438,9 +2438,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
if (ret)
goto unlock_reloc;
- ret = btrfs_handle_fully_remapped_bgs(trans);
- if (ret)
- goto unlock_reloc;
+ if (!btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
+ ret = btrfs_handle_fully_remapped_bgs(trans);
+ if (ret)
+ goto unlock_reloc;
+ }
/*
* make sure none of the code above managed to slip in a
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* [PATCH v3 17/17] btrfs: add stripe removal pending flag
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
` (15 preceding siblings ...)
2025-10-09 11:28 ` [PATCH v3 16/17] btrfs: handle discarding fully-remapped block groups Mark Harmstone
@ 2025-10-09 11:28 ` Mark Harmstone
2025-10-15 5:05 ` Boris Burkov
16 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 11:28 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
If the filesystem is unmounted while the async discard of a fully remapped
block group is in progress, its unused device extents will never be freed.
To counter this, add a new flag BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING
to say that this has been interrupted. Set it in the transaction in which
the last identity remap has been removed, clear it when we remove the
device extents, and if we encounter it on mount queue that block group
up for discard.
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/block-group.c | 35 ++++++++++++++++++++++++++++++++-
fs/btrfs/free-space-cache.c | 5 +++++
fs/btrfs/relocation.c | 18 +++++++++++++++++
include/uapi/linux/btrfs_tree.h | 1 +
4 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index a7dfa6c95223..851d76ce8ec9 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -2530,6 +2530,16 @@ static int read_one_block_group(struct btrfs_fs_info *info,
inc_block_group_ro(cache, 1);
}
+ if (cache->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING) {
+ btrfs_get_block_group(cache);
+ spin_lock(&info->unused_bgs_lock);
+ list_add_tail(&cache->bg_list, &info->fully_remapped_bgs);
+ spin_unlock(&info->unused_bgs_lock);
+
+ if (btrfs_test_opt(info, DISCARD_ASYNC))
+ btrfs_discard_queue_work(&info->discard_ctl, cache);
+ }
+
return 0;
error:
btrfs_put_block_group(cache);
@@ -4828,6 +4838,29 @@ void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
spin_unlock(&fs_info->unused_bgs_lock);
- if (btrfs_test_opt(fs_info, DISCARD_ASYNC))
+ if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
+ bool bg_already_dirty = true;
+
+ spin_lock(&bg->lock);
+ bg->flags |= BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING;
+ spin_unlock(&bg->lock);
+
+ spin_lock(&trans->transaction->dirty_bgs_lock);
+ if (list_empty(&bg->dirty_list)) {
+ list_add_tail(&bg->dirty_list,
+ &trans->transaction->dirty_bgs);
+ bg_already_dirty = false;
+ btrfs_get_block_group(bg);
+ }
+ spin_unlock(&trans->transaction->dirty_bgs_lock);
+
+ /*
+ * Modified block groups are accounted for in
+ * the delayed_refs_rsv.
+ */
+ if (!bg_already_dirty)
+ btrfs_inc_delayed_refs_rsv_bg_updates(trans->fs_info);
+
btrfs_discard_queue_work(&fs_info->discard_ctl, bg);
+ }
}
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 56f27487b632..813b82294341 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3065,6 +3065,7 @@ bool btrfs_is_free_space_trimmed(struct btrfs_block_group *block_group)
bool ret = true;
if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
+ !(block_group->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING) &&
block_group->remap_bytes == 0 &&
block_group->identity_remap_count == 0) {
return true;
@@ -3845,6 +3846,9 @@ void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
struct btrfs_trans_handle *trans;
struct btrfs_chunk_map *map;
+ if (!(bg->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING))
+ goto skip_discard;
+
while (bg->discard_cursor < end) {
u64 trimmed;
@@ -3897,6 +3901,7 @@ void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
btrfs_free_chunk_map(map);
+skip_discard:
if (bg->used == 0) {
spin_lock(&fs_info->unused_bgs_lock);
list_move_tail(&bg->bg_list, &fs_info->unused_bgs);
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 7bad8d65d145..a179e4a8e960 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4733,6 +4733,7 @@ int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
struct btrfs_block_group *bg)
{
int ret;
+ bool bg_already_dirty = true;
BTRFS_PATH_AUTO_FREE(path);
ret = btrfs_remove_dev_extents(trans, chunk);
@@ -4757,6 +4758,23 @@ int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
btrfs_remove_bg_from_sinfo(bg);
+ spin_lock(&bg->lock);
+ bg->flags &= ~BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING;
+ spin_unlock(&bg->lock);
+
+ spin_lock(&trans->transaction->dirty_bgs_lock);
+ if (list_empty(&bg->dirty_list)) {
+ list_add_tail(&bg->dirty_list,
+ &trans->transaction->dirty_bgs);
+ bg_already_dirty = false;
+ btrfs_get_block_group(bg);
+ }
+ spin_unlock(&trans->transaction->dirty_bgs_lock);
+
+ /* Modified block groups are accounted for in the delayed_refs_rsv. */
+ if (!bg_already_dirty)
+ btrfs_inc_delayed_refs_rsv_bg_updates(trans->fs_info);
+
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 89bcb80081a6..36a7d1a3cbe3 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -1173,6 +1173,7 @@ struct btrfs_dev_replace_item {
#define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
#define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
#define BTRFS_BLOCK_GROUP_REMAP (1ULL << 12)
+#define BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING (1ULL << 13)
#define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
BTRFS_SPACE_INFO_GLOBAL_RSV)
--
2.49.1
^ permalink raw reply related [flat|nested] 38+ messages in thread
* Re: [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list()
2025-10-09 11:28 ` [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list() Mark Harmstone
@ 2025-10-09 11:56 ` Filipe Manana
2025-10-09 14:58 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Filipe Manana @ 2025-10-09 11:56 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 9, 2025 at 12:29 PM Mark Harmstone <mark@harmstone.com> wrote:
>
> Release block_group->lock before calling btrfs_link_bg_list() in
> btrfs_delete_unused_bgs(), as this was causing lockdep issues.
I believe this was asked before:
What issues?
Do we have for example any other place where we have a different
locking order and can cause a deadlock?
Can you please paste the lockdep splat?
>
> This lock isn't held in any other place that we call btrfs_link_bg_list(), as
> the block group lists are manipulated while holding fs_info->unused_bgs_lock.
>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> Fixes: 0497dfba98c0 ("btrfs: codify pattern for adding block_group to bg_list")
Also as told before, this doesn't seem related to the rest of the
patchset (the new remap tree feature).
So instead of dragging this along in every new version of the
patchset, can you please make it a standalone patch and remove it from
future versions of the patchset?
Thanks.
> ---
> fs/btrfs/block-group.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index d3433a5b169f..a3c984f905fc 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -1620,6 +1620,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
> if ((space_info->total_bytes - block_group->length < used &&
> block_group->zone_unusable < block_group->length) ||
> has_unwritten_metadata(block_group)) {
> + spin_unlock(&block_group->lock);
> +
> /*
> * Add a reference for the list, compensate for the ref
> * drop under the "next" label for the
> @@ -1628,7 +1630,6 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
> btrfs_link_bg_list(block_group, &retry_list);
>
> trace_btrfs_skip_unused_block_group(block_group);
> - spin_unlock(&block_group->lock);
> spin_unlock(&space_info->lock);
> up_write(&space_info->groups_sem);
> goto next;
> --
> 2.49.1
>
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list()
2025-10-09 11:56 ` Filipe Manana
@ 2025-10-09 14:58 ` Mark Harmstone
2025-10-09 15:16 ` Filipe Manana
0 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 14:58 UTC (permalink / raw)
To: Filipe Manana; +Cc: linux-btrfs
On 09/10/2025 12.56 pm, Filipe Manana wrote:
> On Thu, Oct 9, 2025 at 12:29 PM Mark Harmstone <mark@harmstone.com> wrote:
>>
>> Release block_group->lock before calling btrfs_link_bg_list() in
>> btrfs_delete_unused_bgs(), as this was causing lockdep issues.
>
> I believe this was asked before:
>
> What issues?
> Do we have for example any other place where we have a different
> locking order and can cause a deadlock?
>
> Can you please paste the lockdep splat?
I didn't take a copy the first time, and I've not been able to replicate it
since.
But you can see the issue in patch 4, "btrfs: remove remapped block groups
from the free-space tree". In btrfs_discard_punt_unused_bgs_list() we acquire
unused_bgs_lock to loop through the unused_bgs list, then take the individual
BG lock so we can check its flags.
In btrfs_delete_unused_bgs() we're acquiring the unused_bgs lock through
btrfs_link_bg_list(), while still unnecessarily holding the BG lock.
The reason it's in this patchset is that a minor existing bug (holding a
spinlock longer than we strictly need to) becomes a potential deadlock because
of patch 4.
>
>>
>> This lock isn't held in any other place that we call btrfs_link_bg_list(), as
>> the block group lists are manipulated while holding fs_info->unused_bgs_lock.
>>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>> Fixes: 0497dfba98c0 ("btrfs: codify pattern for adding block_group to bg_list")
>
> Also as told before, this doesn't seem related to the rest of the
> patchset (the new remap tree feature).
> So instead of dragging this along in every new version of the
> patchset, can you please make it a standalone patch and remove it from
> future versions of the patchset?
>
> Thanks.
>
>> ---
>> fs/btrfs/block-group.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
>> index d3433a5b169f..a3c984f905fc 100644
>> --- a/fs/btrfs/block-group.c
>> +++ b/fs/btrfs/block-group.c
>> @@ -1620,6 +1620,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
>> if ((space_info->total_bytes - block_group->length < used &&
>> block_group->zone_unusable < block_group->length) ||
>> has_unwritten_metadata(block_group)) {
>> + spin_unlock(&block_group->lock);
>> +
>> /*
>> * Add a reference for the list, compensate for the ref
>> * drop under the "next" label for the
>> @@ -1628,7 +1630,6 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
>> btrfs_link_bg_list(block_group, &retry_list);
>>
>> trace_btrfs_skip_unused_block_group(block_group);
>> - spin_unlock(&block_group->lock);
>> spin_unlock(&space_info->lock);
>> up_write(&space_info->groups_sem);
>> goto next;
>> --
>> 2.49.1
>>
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list()
2025-10-09 14:58 ` Mark Harmstone
@ 2025-10-09 15:16 ` Filipe Manana
2025-10-09 16:30 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Filipe Manana @ 2025-10-09 15:16 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 9, 2025 at 3:58 PM Mark Harmstone <mark@harmstone.com> wrote:
>
> On 09/10/2025 12.56 pm, Filipe Manana wrote:
> > On Thu, Oct 9, 2025 at 12:29 PM Mark Harmstone <mark@harmstone.com> wrote:
> >>
> >> Release block_group->lock before calling btrfs_link_bg_list() in
> >> btrfs_delete_unused_bgs(), as this was causing lockdep issues.
> >
> > I believe this was asked before:
> >
> > What issues?
> > Do we have for example any other place where we have a different
> > locking order and can cause a deadlock?
> >
> > Can you please paste the lockdep splat?
>
> I didn't take a copy the first time, and I've not been able to replicate it
> since.
>
> But you can see the issue in patch 4, "btrfs: remove remapped block groups
> from the free-space tree". In btrfs_discard_punt_unused_bgs_list() we acquire
> unused_bgs_lock to loop through the unused_bgs list, then take the individual
> BG lock so we can check its flags.
So then the problem is caused by patch 4, a potential ABBA deadlock.
In that case this change should be squashed into that patch or at
least come before and say it's preparation work to avoid a lockdep
splat and potential deadlock, without the Fixes tag since, as far as I
can see, we currently don't have any code where we take the locks in a
different order.
>
> In btrfs_delete_unused_bgs() we're acquiring the unused_bgs lock through
> btrfs_link_bg_list(), while still unnecessarily holding the BG lock.
>
> The reason it's in this patchset is that a minor existing bug (holding a
> spinlock longer than we strictly need to) becomes a potential deadlock because
> of patch 4.
I don't think we can call that an existing bug...
If before patch 4 of this patchset it didn't cause any problems as
mentioned before.
>
> >
> >>
> >> This lock isn't held in any other place that we call btrfs_link_bg_list(), as
> >> the block group lists are manipulated while holding fs_info->unused_bgs_lock.
> >>
> >> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> >> Fixes: 0497dfba98c0 ("btrfs: codify pattern for adding block_group to bg_list")
> >
> > Also as told before, this doesn't seem related to the rest of the
> > patchset (the new remap tree feature).
> > So instead of dragging this along in every new version of the
> > patchset, can you please make it a standalone patch and remove it from
> > future versions of the patchset?
> >
> > Thanks.
> >
> >> ---
> >> fs/btrfs/block-group.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> >> index d3433a5b169f..a3c984f905fc 100644
> >> --- a/fs/btrfs/block-group.c
> >> +++ b/fs/btrfs/block-group.c
> >> @@ -1620,6 +1620,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
> >> if ((space_info->total_bytes - block_group->length < used &&
> >> block_group->zone_unusable < block_group->length) ||
> >> has_unwritten_metadata(block_group)) {
> >> + spin_unlock(&block_group->lock);
> >> +
> >> /*
> >> * Add a reference for the list, compensate for the ref
> >> * drop under the "next" label for the
> >> @@ -1628,7 +1630,6 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
> >> btrfs_link_bg_list(block_group, &retry_list);
> >>
> >> trace_btrfs_skip_unused_block_group(block_group);
> >> - spin_unlock(&block_group->lock);
> >> spin_unlock(&space_info->lock);
> >> up_write(&space_info->groups_sem);
> >> goto next;
> >> --
> >> 2.49.1
> >>
> >>
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list()
2025-10-09 15:16 ` Filipe Manana
@ 2025-10-09 16:30 ` Mark Harmstone
0 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-09 16:30 UTC (permalink / raw)
To: Filipe Manana; +Cc: linux-btrfs
On 09/10/2025 4.16 pm, Filipe Manana wrote:
> On Thu, Oct 9, 2025 at 3:58 PM Mark Harmstone <mark@harmstone.com> wrote:
>>
>> On 09/10/2025 12.56 pm, Filipe Manana wrote:
>>> On Thu, Oct 9, 2025 at 12:29 PM Mark Harmstone <mark@harmstone.com> wrote:
>>>>
>>>> Release block_group->lock before calling btrfs_link_bg_list() in
>>>> btrfs_delete_unused_bgs(), as this was causing lockdep issues.
>>>
>>> I believe this was asked before:
>>>
>>> What issues?
>>> Do we have for example any other place where we have a different
>>> locking order and can cause a deadlock?
>>>
>>> Can you please paste the lockdep splat?
>>
>> I didn't take a copy the first time, and I've not been able to replicate it
>> since.
>>
>> But you can see the issue in patch 4, "btrfs: remove remapped block groups
>> from the free-space tree". In btrfs_discard_punt_unused_bgs_list() we acquire
>> unused_bgs_lock to loop through the unused_bgs list, then take the individual
>> BG lock so we can check its flags.
>
> So then the problem is caused by patch 4, a potential ABBA deadlock.
>
> In that case this change should be squashed into that patch or at
> least come before and say it's preparation work to avoid a lockdep
> splat and potential deadlock, without the Fixes tag since, as far as I
> can see, we currently don't have any code where we take the locks in a
> different order.
That's fine. If there's a version 4 of the patchset I'll resend it like that,
otherwise I'll squash patch 9 into patch 4 when I push it.
>> In btrfs_delete_unused_bgs() we're acquiring the unused_bgs lock through
>> btrfs_link_bg_list(), while still unnecessarily holding the BG lock.
>>
>> The reason it's in this patchset is that a minor existing bug (holding a
>> spinlock longer than we strictly need to) becomes a potential deadlock because
>> of patch 4.
>
> I don't think we can call that an existing bug...
> If before patch 4 of this patchset it didn't cause any problems as
> mentioned before.
>
>>
>>>
>>>>
>>>> This lock isn't held in any other place that we call btrfs_link_bg_list(), as
>>>> the block group lists are manipulated while holding fs_info->unused_bgs_lock.
>>>>
>>>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>>>> Fixes: 0497dfba98c0 ("btrfs: codify pattern for adding block_group to bg_list")
>>>
>>> Also as told before, this doesn't seem related to the rest of the
>>> patchset (the new remap tree feature).
>>> So instead of dragging this along in every new version of the
>>> patchset, can you please make it a standalone patch and remove it from
>>> future versions of the patchset?
>>>
>>> Thanks.
>>>
>>>> ---
>>>> fs/btrfs/block-group.c | 3 ++-
>>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
>>>> index d3433a5b169f..a3c984f905fc 100644
>>>> --- a/fs/btrfs/block-group.c
>>>> +++ b/fs/btrfs/block-group.c
>>>> @@ -1620,6 +1620,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
>>>> if ((space_info->total_bytes - block_group->length < used &&
>>>> block_group->zone_unusable < block_group->length) ||
>>>> has_unwritten_metadata(block_group)) {
>>>> + spin_unlock(&block_group->lock);
>>>> +
>>>> /*
>>>> * Add a reference for the list, compensate for the ref
>>>> * drop under the "next" label for the
>>>> @@ -1628,7 +1630,6 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
>>>> btrfs_link_bg_list(block_group, &retry_list);
>>>>
>>>> trace_btrfs_skip_unused_block_group(block_group);
>>>> - spin_unlock(&block_group->lock);
>>>> spin_unlock(&space_info->lock);
>>>> up_write(&space_info->groups_sem);
>>>> goto next;
>>>> --
>>>> 2.49.1
>>>>
>>>>
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 02/17] btrfs: add REMAP chunk type
2025-10-09 11:27 ` [PATCH v3 02/17] btrfs: add REMAP chunk type Mark Harmstone
@ 2025-10-15 3:37 ` Boris Burkov
2025-10-20 9:58 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Boris Burkov @ 2025-10-15 3:37 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 09, 2025 at 12:27:57PM +0100, Mark Harmstone wrote:
> Add a new REMAP chunk type, which is a metadata chunk that holds the
> remap tree.
>
> This is needed for bootstrapping purposes: the remap tree can't itself
> be remapped, and must be relocated the existing way, by COWing every
> leaf. The remap tree can't go in the SYSTEM chunk as space there is
> limited, because a copy of the chunk item gets placed in the superblock.
>
> The changes in fs/btrfs/volumes.h are because we're adding a new block
> group type bit after the profile bits, and so can no longer rely on the
> const_ilog2 trick.
>
> The sizing to 32MB per chunk, matching the SYSTEM chunk, is an estimate
> here, we can adjust it later if it proves to be too big or too small.
> This works out to be ~500,000 remap items, which for a 4KB block size
> covers ~2GB of remapped data in the worst case and ~500TB in the best case.
>
Asked a relatively inconsequential question about static asserts in
volumes.h. Otherwise,
Reviewed-by: Boris Burkov <boris@bur.io>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> ---
> fs/btrfs/block-rsv.c | 8 ++++++++
> fs/btrfs/block-rsv.h | 1 +
> fs/btrfs/disk-io.c | 1 +
> fs/btrfs/fs.h | 2 ++
> fs/btrfs/space-info.c | 13 ++++++++++++-
> fs/btrfs/sysfs.c | 2 ++
> fs/btrfs/tree-checker.c | 13 +++++++++++--
> fs/btrfs/volumes.c | 3 +++
> fs/btrfs/volumes.h | 11 +++++++++--
> include/uapi/linux/btrfs_tree.h | 4 +++-
> 10 files changed, 52 insertions(+), 6 deletions(-)
>
> diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
> index 5ad6de738aee..2678cd3bed29 100644
> --- a/fs/btrfs/block-rsv.c
> +++ b/fs/btrfs/block-rsv.c
> @@ -421,6 +421,9 @@ void btrfs_init_root_block_rsv(struct btrfs_root *root)
> case BTRFS_TREE_LOG_OBJECTID:
> root->block_rsv = &fs_info->treelog_rsv;
> break;
> + case BTRFS_REMAP_TREE_OBJECTID:
> + root->block_rsv = &fs_info->remap_block_rsv;
> + break;
> default:
> root->block_rsv = NULL;
> break;
> @@ -434,6 +437,9 @@ void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
> space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
> fs_info->chunk_block_rsv.space_info = space_info;
>
> + space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_REMAP);
> + fs_info->remap_block_rsv.space_info = space_info;
> +
> space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
> fs_info->global_block_rsv.space_info = space_info;
> fs_info->trans_block_rsv.space_info = space_info;
> @@ -460,6 +466,8 @@ void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
> WARN_ON(fs_info->trans_block_rsv.reserved > 0);
> WARN_ON(fs_info->chunk_block_rsv.size > 0);
> WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
> + WARN_ON(fs_info->remap_block_rsv.size > 0);
> + WARN_ON(fs_info->remap_block_rsv.reserved > 0);
> WARN_ON(fs_info->delayed_block_rsv.size > 0);
> WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
> WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
> diff --git a/fs/btrfs/block-rsv.h b/fs/btrfs/block-rsv.h
> index 79ae9d05cd91..8359fb96bc3c 100644
> --- a/fs/btrfs/block-rsv.h
> +++ b/fs/btrfs/block-rsv.h
> @@ -22,6 +22,7 @@ enum btrfs_rsv_type {
> BTRFS_BLOCK_RSV_DELALLOC,
> BTRFS_BLOCK_RSV_TRANS,
> BTRFS_BLOCK_RSV_CHUNK,
> + BTRFS_BLOCK_RSV_REMAP,
> BTRFS_BLOCK_RSV_DELOPS,
> BTRFS_BLOCK_RSV_DELREFS,
> BTRFS_BLOCK_RSV_TREELOG,
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index f475fb2272ac..102e5e0ad10c 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2815,6 +2815,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
> BTRFS_BLOCK_RSV_GLOBAL);
> btrfs_init_block_rsv(&fs_info->trans_block_rsv, BTRFS_BLOCK_RSV_TRANS);
> btrfs_init_block_rsv(&fs_info->chunk_block_rsv, BTRFS_BLOCK_RSV_CHUNK);
> + btrfs_init_block_rsv(&fs_info->remap_block_rsv, BTRFS_BLOCK_RSV_REMAP);
> btrfs_init_block_rsv(&fs_info->treelog_rsv, BTRFS_BLOCK_RSV_TREELOG);
> btrfs_init_block_rsv(&fs_info->empty_block_rsv, BTRFS_BLOCK_RSV_EMPTY);
> btrfs_init_block_rsv(&fs_info->delayed_block_rsv,
> diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
> index 814bbc9417d2..c4dba7e7ce5a 100644
> --- a/fs/btrfs/fs.h
> +++ b/fs/btrfs/fs.h
> @@ -485,6 +485,8 @@ struct btrfs_fs_info {
> struct btrfs_block_rsv trans_block_rsv;
> /* Block reservation for chunk tree */
> struct btrfs_block_rsv chunk_block_rsv;
> + /* Block reservation for remap tree */
> + struct btrfs_block_rsv remap_block_rsv;
> /* Block reservation for delayed operations */
> struct btrfs_block_rsv delayed_block_rsv;
> /* Block reservation for delayed refs */
> diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
> index 04a07d6f8537..22bc95f33a6f 100644
> --- a/fs/btrfs/space-info.c
> +++ b/fs/btrfs/space-info.c
> @@ -215,7 +215,7 @@ static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
>
> if (flags & BTRFS_BLOCK_GROUP_DATA)
> return BTRFS_MAX_DATA_CHUNK_SIZE;
> - else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
> + else if (flags & (BTRFS_BLOCK_GROUP_SYSTEM | BTRFS_BLOCK_GROUP_REMAP))
> return SZ_32M;
>
> /* Handle BTRFS_BLOCK_GROUP_METADATA */
> @@ -343,6 +343,8 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
> if (mixed) {
> flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
> ret = create_space_info(fs_info, flags);
> + if (ret)
> + goto out;
> } else {
> flags = BTRFS_BLOCK_GROUP_METADATA;
> ret = create_space_info(fs_info, flags);
> @@ -351,7 +353,15 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
>
> flags = BTRFS_BLOCK_GROUP_DATA;
> ret = create_space_info(fs_info, flags);
> + if (ret)
> + goto out;
> + }
> +
> + if (features & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
> + flags = BTRFS_BLOCK_GROUP_REMAP;
> + ret = create_space_info(fs_info, flags);
> }
> +
> out:
> return ret;
> }
> @@ -590,6 +600,7 @@ static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
> DUMP_BLOCK_RSV(fs_info, global_block_rsv);
> DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
> DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
> + DUMP_BLOCK_RSV(fs_info, remap_block_rsv);
> DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
> DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
> }
> diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
> index 857d2772db1c..f942fde1d936 100644
> --- a/fs/btrfs/sysfs.c
> +++ b/fs/btrfs/sysfs.c
> @@ -1973,6 +1973,8 @@ static const char *alloc_name(struct btrfs_space_info *space_info)
> case BTRFS_BLOCK_GROUP_SYSTEM:
> ASSERT(space_info->subgroup_id == BTRFS_SUB_GROUP_PRIMARY);
> return "system";
> + case BTRFS_BLOCK_GROUP_REMAP:
> + return "remap";
> default:
> WARN_ON(1);
> return "invalid-combination";
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index 9c03aeb6f2c7..62f35338a555 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -748,17 +748,26 @@ static int check_block_group_item(struct extent_buffer *leaf,
> return -EUCLEAN;
> }
>
> + if (flags & BTRFS_BLOCK_GROUP_REMAP &&
> + !btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> + block_group_err(leaf, slot,
> +"invalid flags, have 0x%llx (REMAP flag set) but no remap-tree incompat flag",
> + flags);
> + return -EUCLEAN;
> + }
> +
> type = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
> if (unlikely(type != BTRFS_BLOCK_GROUP_DATA &&
> type != BTRFS_BLOCK_GROUP_METADATA &&
> type != BTRFS_BLOCK_GROUP_SYSTEM &&
> + type != BTRFS_BLOCK_GROUP_REMAP &&
> type != (BTRFS_BLOCK_GROUP_METADATA |
> BTRFS_BLOCK_GROUP_DATA))) {
> block_group_err(leaf, slot,
> -"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx or 0x%llx",
> +"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx, 0x%llx or 0x%llx",
> type, hweight64(type),
> BTRFS_BLOCK_GROUP_DATA, BTRFS_BLOCK_GROUP_METADATA,
> - BTRFS_BLOCK_GROUP_SYSTEM,
> + BTRFS_BLOCK_GROUP_SYSTEM, BTRFS_BLOCK_GROUP_REMAP,
> BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
> return -EUCLEAN;
> }
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 2e144ebd56ac..e14b86e2996b 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -231,6 +231,9 @@ void btrfs_describe_block_groups(u64 bg_flags, char *buf, u32 size_buf)
> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_DATA, "data");
> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_SYSTEM, "system");
> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_METADATA, "metadata");
> + /* block groups containing the remap tree */
> + DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAP, "remap");
> + /* block group that has been remapped */
> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAPPED, "remapped");
>
> DESCRIBE_FLAG(BTRFS_AVAIL_ALLOC_BIT_SINGLE, "single");
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 2cbf8080eade..b0fa8eb38060 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -58,8 +58,6 @@ static_assert(const_ilog2(BTRFS_STRIPE_LEN) == BTRFS_STRIPE_LEN_SHIFT);
> */
> static_assert(const_ffs(BTRFS_BLOCK_GROUP_RAID0) <
> const_ffs(BTRFS_BLOCK_GROUP_PROFILE_MASK & ~BTRFS_BLOCK_GROUP_RAID0));
> -static_assert(const_ilog2(BTRFS_BLOCK_GROUP_RAID0) >
> - ilog2(BTRFS_BLOCK_GROUP_TYPE_MASK));
>
> /* ilog2() can handle both constants and variables */
> #define BTRFS_BG_FLAG_TO_INDEX(profile) \
> @@ -81,6 +79,15 @@ enum btrfs_raid_types {
> BTRFS_NR_RAID_TYPES
> };
>
> +static_assert(BTRFS_RAID_RAID0 == 1);
> +static_assert(BTRFS_RAID_RAID1 == 2);
> +static_assert(BTRFS_RAID_DUP == 3);
> +static_assert(BTRFS_RAID_RAID10 == 4);
> +static_assert(BTRFS_RAID_RAID5 == 5);
> +static_assert(BTRFS_RAID_RAID6 == 6);
> +static_assert(BTRFS_RAID_RAID1C3 == 7);
> +static_assert(BTRFS_RAID_RAID1C4 == 8);
> +
What is the significance of these static_assert changes?
> /*
> * Use sequence counter to get consistent device stat data on
> * 32-bit processors.
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> index 4439d77a7252..9a36f0206d90 100644
> --- a/include/uapi/linux/btrfs_tree.h
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -1169,12 +1169,14 @@ struct btrfs_dev_replace_item {
> #define BTRFS_BLOCK_GROUP_RAID1C3 (1ULL << 9)
> #define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
> #define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
> +#define BTRFS_BLOCK_GROUP_REMAP (1ULL << 12)
> #define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
> BTRFS_SPACE_INFO_GLOBAL_RSV)
>
> #define BTRFS_BLOCK_GROUP_TYPE_MASK (BTRFS_BLOCK_GROUP_DATA | \
> BTRFS_BLOCK_GROUP_SYSTEM | \
> - BTRFS_BLOCK_GROUP_METADATA)
> + BTRFS_BLOCK_GROUP_METADATA | \
> + BTRFS_BLOCK_GROUP_REMAP)
>
> #define BTRFS_BLOCK_GROUP_PROFILE_MASK (BTRFS_BLOCK_GROUP_RAID0 | \
> BTRFS_BLOCK_GROUP_RAID1 | \
> --
> 2.49.1
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 03/17] btrfs: allow remapped chunks to have zero stripes
2025-10-09 11:27 ` [PATCH v3 03/17] btrfs: allow remapped chunks to have zero stripes Mark Harmstone
@ 2025-10-15 3:47 ` Boris Burkov
2025-10-20 12:15 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Boris Burkov @ 2025-10-15 3:47 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 09, 2025 at 12:27:58PM +0100, Mark Harmstone wrote:
> When a chunk has been fully remapped, we are going to set its
> num_stripes to 0, as it will no longer represent a physical location on
> disk.
>
> Change tree-checker to allow for this, and fix a couple of
> divide-by-zeroes seen elsewhere.
>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
This one feels close to me but I still have a few reservations. Happy to
discuss the details a bit more, of course.
> ---
> fs/btrfs/tree-checker.c | 65 ++++++++++++++++++++++++++++-------------
> fs/btrfs/volumes.c | 13 ++++++++-
> 2 files changed, 57 insertions(+), 21 deletions(-)
>
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index 62f35338a555..59b1393e5018 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -816,6 +816,41 @@ static void chunk_err(const struct btrfs_fs_info *fs_info,
> va_end(args);
> }
>
> +static bool valid_stripe_count(u64 profile, u16 num_stripes,
> + u16 sub_stripes)
> +{
> + switch (profile) {
> + case BTRFS_BLOCK_GROUP_RAID0:
> + return true;
> + case BTRFS_BLOCK_GROUP_RAID10:
> + return sub_stripes ==
> + btrfs_raid_array[BTRFS_RAID_RAID10].sub_stripes;
> + case BTRFS_BLOCK_GROUP_RAID1:
> + return num_stripes ==
> + btrfs_raid_array[BTRFS_RAID_RAID1].devs_min;
> + case BTRFS_BLOCK_GROUP_RAID1C3:
> + return num_stripes ==
> + btrfs_raid_array[BTRFS_RAID_RAID1C3].devs_min;
> + case BTRFS_BLOCK_GROUP_RAID1C4:
> + return num_stripes ==
> + btrfs_raid_array[BTRFS_RAID_RAID1C4].devs_min;
> + case BTRFS_BLOCK_GROUP_RAID5:
> + return num_stripes >=
> + btrfs_raid_array[BTRFS_RAID_RAID5].devs_min;
> + case BTRFS_BLOCK_GROUP_RAID6:
> + return num_stripes >=
> + btrfs_raid_array[BTRFS_RAID_RAID6].devs_min;
> + case BTRFS_BLOCK_GROUP_DUP:
> + return num_stripes ==
> + btrfs_raid_array[BTRFS_RAID_DUP].dev_stripes;
> + case 0: /* SINGLE */
> + return num_stripes ==
> + btrfs_raid_array[BTRFS_RAID_SINGLE].dev_stripes;
> + default:
> + BUG();
> + }
> +}
> +
> /*
> * The common chunk check which could also work on super block sys chunk array.
> *
> @@ -839,6 +874,7 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
> u64 features;
> u32 chunk_sector_size;
> bool mixed = false;
> + bool remapped;
> int raid_index;
> int nparity;
> int ncopies;
> @@ -862,12 +898,14 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
> ncopies = btrfs_raid_array[raid_index].ncopies;
> nparity = btrfs_raid_array[raid_index].nparity;
>
> - if (unlikely(!num_stripes)) {
> + remapped = type & BTRFS_BLOCK_GROUP_REMAPPED;
> +
> + if (unlikely(!remapped && !num_stripes)) {
> chunk_err(fs_info, leaf, chunk, logical,
> "invalid chunk num_stripes, have %u", num_stripes);
> return -EUCLEAN;
> }
> - if (unlikely(num_stripes < ncopies)) {
> + if (unlikely(num_stripes != 0 && num_stripes < ncopies)) {
> chunk_err(fs_info, leaf, chunk, logical,
> "invalid chunk num_stripes < ncopies, have %u < %d",
> num_stripes, ncopies);
> @@ -965,22 +1003,9 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
> }
> }
>
> - if (unlikely((type & BTRFS_BLOCK_GROUP_RAID10 &&
> - sub_stripes != btrfs_raid_array[BTRFS_RAID_RAID10].sub_stripes) ||
> - (type & BTRFS_BLOCK_GROUP_RAID1 &&
> - num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1].devs_min) ||
> - (type & BTRFS_BLOCK_GROUP_RAID1C3 &&
> - num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1C3].devs_min) ||
> - (type & BTRFS_BLOCK_GROUP_RAID1C4 &&
> - num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1C4].devs_min) ||
> - (type & BTRFS_BLOCK_GROUP_RAID5 &&
> - num_stripes < btrfs_raid_array[BTRFS_RAID_RAID5].devs_min) ||
> - (type & BTRFS_BLOCK_GROUP_RAID6 &&
> - num_stripes < btrfs_raid_array[BTRFS_RAID_RAID6].devs_min) ||
> - (type & BTRFS_BLOCK_GROUP_DUP &&
> - num_stripes != btrfs_raid_array[BTRFS_RAID_DUP].dev_stripes) ||
> - ((type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 &&
> - num_stripes != btrfs_raid_array[BTRFS_RAID_SINGLE].dev_stripes))) {
> + if (!remapped &&
> + !valid_stripe_count(type & BTRFS_BLOCK_GROUP_PROFILE_MASK,
> + num_stripes, sub_stripes)) {
Is num_stripes == 0 valid for raid 0 aside from remapped?
> chunk_err(fs_info, leaf, chunk, logical,
> "invalid num_stripes:sub_stripes %u:%u for profile %llu",
> num_stripes, sub_stripes,
> @@ -1004,11 +1029,11 @@ static int check_leaf_chunk_item(struct extent_buffer *leaf,
> struct btrfs_fs_info *fs_info = leaf->fs_info;
> int num_stripes;
>
> - if (unlikely(btrfs_item_size(leaf, slot) < sizeof(struct btrfs_chunk))) {
> + if (unlikely(btrfs_item_size(leaf, slot) < offsetof(struct btrfs_chunk, stripe))) {
Does this need a remapped parameter as part of the check too?
> chunk_err(fs_info, leaf, chunk, key->offset,
> "invalid chunk item size: have %u expect [%zu, %u)",
> btrfs_item_size(leaf, slot),
> - sizeof(struct btrfs_chunk),
> + offsetof(struct btrfs_chunk, stripe),
> BTRFS_LEAF_DATA_SIZE(fs_info));
> return -EUCLEAN;
> }
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index e14b86e2996b..6750f6f0af59 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -6145,6 +6145,12 @@ struct btrfs_discard_stripe *btrfs_map_discard(struct btrfs_fs_info *fs_info,
> goto out_free_map;
> }
>
> + /* avoid divide by zero on fully-remapped chunks */
> + if (map->num_stripes == 0) {
> + ret = -EOPNOTSUPP;
> + goto out_free_map;
> + }
> +
I'll reconsider this when I read the discard stuff more closely, but
aren't you intending to discard fully remapped chunks? So this seems
counter-intuitive at best. Since you tested it, I assume it must work,
just saying since it stuck out to me..
> offset = logical - map->start;
> length = min_t(u64, map->start + map->chunk_len - logical, length);
> *length_ret = length;
> @@ -7088,7 +7094,12 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
> */
> map->sub_stripes = btrfs_raid_array[index].sub_stripes;
> map->verified_stripes = 0;
> - map->stripe_size = btrfs_calc_stripe_length(map);
> +
> + if (num_stripes > 0)
> + map->stripe_size = btrfs_calc_stripe_length(map);
> + else
> + map->stripe_size = 0;
> +
> for (i = 0; i < num_stripes; i++) {
> map->stripes[i].physical =
> btrfs_stripe_offset_nr(leaf, chunk, i);
> --
> 2.49.1
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag
2025-10-09 11:28 ` [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag Mark Harmstone
@ 2025-10-15 3:55 ` Boris Burkov
2025-10-20 11:32 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Boris Burkov @ 2025-10-15 3:55 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 09, 2025 at 12:28:02PM +0100, Mark Harmstone wrote:
> If we encounter a filesystem with the remap-tree incompat flag set,
> valdiate its compatibility with the other flags, and load the remap tree
> using the values that have been added to the superblock.
>
> The remap-tree feature depends on the free space tere, but no-holes and
> block-group-tree have been made dependencies to reduce the testing
> matrix. Similarly I'm not aware of any reason why mixed-bg and zoned would be
> incompatible with remap-tree, but this is blocked for the time being
> until it can be fully tested.
>
Bonus points on offer for moving the open ctree bit as late as humanly
possible for that good "partial ordering" self documentation. (Or
explaining why it is already so).
Thanks.
Reviewed-by: Boris Burkov <boris@bur.io>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> ---
> fs/btrfs/Kconfig | 2 +
> fs/btrfs/accessors.h | 6 ++
> fs/btrfs/disk-io.c | 101 ++++++++++++++++++++++++++++----
> fs/btrfs/extent-tree.c | 2 +
> fs/btrfs/fs.h | 4 +-
> fs/btrfs/transaction.c | 7 +++
> include/uapi/linux/btrfs_tree.h | 5 +-
> 7 files changed, 113 insertions(+), 14 deletions(-)
>
> diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
> index 4438637c8900..77b5a9f27840 100644
> --- a/fs/btrfs/Kconfig
> +++ b/fs/btrfs/Kconfig
> @@ -117,4 +117,6 @@ config BTRFS_EXPERIMENTAL
>
> - large folio support
>
> + - remap-tree - logical address remapping tree
> +
> If unsure, say N.
> diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
> index 0dd161ee6863..392eaad75e72 100644
> --- a/fs/btrfs/accessors.h
> +++ b/fs/btrfs/accessors.h
> @@ -882,6 +882,12 @@ BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
> uuid_tree_generation, 64);
> BTRFS_SETGET_STACK_FUNCS(super_nr_global_roots, struct btrfs_super_block,
> nr_global_roots, 64);
> +BTRFS_SETGET_STACK_FUNCS(super_remap_root, struct btrfs_super_block,
> + remap_root, 64);
> +BTRFS_SETGET_STACK_FUNCS(super_remap_root_generation, struct btrfs_super_block,
> + remap_root_generation, 64);
> +BTRFS_SETGET_STACK_FUNCS(super_remap_root_level, struct btrfs_super_block,
> + remap_root_level, 8);
>
> /* struct btrfs_file_extent_item */
> BTRFS_SETGET_STACK_FUNCS(stack_file_extent_type, struct btrfs_file_extent_item,
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 92cb789957b4..60507e971aad 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -1180,6 +1180,8 @@ static struct btrfs_root *btrfs_get_global_root(struct btrfs_fs_info *fs_info,
> return btrfs_grab_root(btrfs_global_root(fs_info, &key));
> case BTRFS_RAID_STRIPE_TREE_OBJECTID:
> return btrfs_grab_root(fs_info->stripe_root);
> + case BTRFS_REMAP_TREE_OBJECTID:
> + return btrfs_grab_root(fs_info->remap_root);
> default:
> return NULL;
> }
> @@ -1271,6 +1273,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
> btrfs_put_root(fs_info->data_reloc_root);
> btrfs_put_root(fs_info->block_group_root);
> btrfs_put_root(fs_info->stripe_root);
> + btrfs_put_root(fs_info->remap_root);
> btrfs_check_leaked_roots(fs_info);
> btrfs_extent_buffer_leak_debug_check(fs_info);
> kfree(fs_info->super_copy);
> @@ -1825,6 +1828,7 @@ static void free_root_pointers(struct btrfs_fs_info *info, bool free_chunk_root)
> free_root_extent_buffers(info->data_reloc_root);
> free_root_extent_buffers(info->block_group_root);
> free_root_extent_buffers(info->stripe_root);
> + free_root_extent_buffers(info->remap_root);
> if (free_chunk_root)
> free_root_extent_buffers(info->chunk_root);
> }
> @@ -2256,20 +2260,45 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
> if (ret)
> goto out;
>
> - /*
> - * This tree can share blocks with some other fs tree during relocation
> - * and we need a proper setup by btrfs_get_fs_root
> - */
> - root = btrfs_get_fs_root(tree_root->fs_info,
> - BTRFS_DATA_RELOC_TREE_OBJECTID, true);
> - if (IS_ERR(root)) {
> - if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
> - ret = PTR_ERR(root);
> - goto out;
> + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> + /* remap_root already loaded in load_important_roots() */
> + root = fs_info->remap_root;
> +
> + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> +
> + root->root_key.objectid = BTRFS_REMAP_TREE_OBJECTID;
> + root->root_key.type = BTRFS_ROOT_ITEM_KEY;
> + root->root_key.offset = 0;
> +
> + /* Check that data reloc tree doesn't also exist */
> + location.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
> + root = btrfs_read_tree_root(fs_info->tree_root, &location);
> + if (!IS_ERR(root)) {
> + btrfs_err(fs_info,
> + "data reloc tree exists when remap-tree enabled");
> + btrfs_put_root(root);
> + return -EIO;
> + } else if (PTR_ERR(root) != -ENOENT) {
> + btrfs_warn(fs_info,
> + "error %ld when checking for data reloc tree",
> + PTR_ERR(root));
> }
> } else {
> - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> - fs_info->data_reloc_root = root;
> + /*
> + * This tree can share blocks with some other fs tree during
> + * relocation and we need a proper setup by btrfs_get_fs_root
> + */
> + root = btrfs_get_fs_root(tree_root->fs_info,
> + BTRFS_DATA_RELOC_TREE_OBJECTID, true);
> + if (IS_ERR(root)) {
> + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
> + ret = PTR_ERR(root);
> + goto out;
> + }
> + } else {
> + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> + fs_info->data_reloc_root = root;
> + }
> }
>
> location.objectid = BTRFS_QUOTA_TREE_OBJECTID;
> @@ -2509,6 +2538,31 @@ int btrfs_validate_super(const struct btrfs_fs_info *fs_info,
> ret = -EINVAL;
> }
>
> + /*
> + * Reduce test matrix for remap tree by requiring block-group-tree
> + * and no-holes. Free-space-tree is a hard requirement.
> + */
> + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> + (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID) ||
> + !btrfs_fs_incompat(fs_info, NO_HOLES) ||
> + !btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE))) {
> + btrfs_err(fs_info,
> +"remap-tree feature requires free-space-tree, no-holes, and block-group-tree");
> + ret = -EINVAL;
> + }
> +
> + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> + btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
> + btrfs_err(fs_info, "remap-tree not supported with mixed-bg");
> + ret = -EINVAL;
> + }
> +
> + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> + btrfs_fs_incompat(fs_info, ZONED)) {
> + btrfs_err(fs_info, "remap-tree not supported with zoned devices");
> + ret = -EINVAL;
> + }
> +
> /*
> * Hint to catch really bogus numbers, bitflips or so, more exact checks are
> * done later
> @@ -2667,6 +2721,18 @@ static int load_important_roots(struct btrfs_fs_info *fs_info)
> btrfs_warn(fs_info, "couldn't read tree root");
> return ret;
> }
> +
> + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> + bytenr = btrfs_super_remap_root(sb);
> + gen = btrfs_super_remap_root_generation(sb);
> + level = btrfs_super_remap_root_level(sb);
> + ret = load_super_root(fs_info->remap_root, bytenr, gen, level);
> + if (ret) {
> + btrfs_warn(fs_info, "couldn't read remap root");
> + return ret;
> + }
> + }
> +
> return 0;
> }
>
> @@ -3284,6 +3350,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
> struct btrfs_fs_info *fs_info = btrfs_sb(sb);
> struct btrfs_root *tree_root;
> struct btrfs_root *chunk_root;
> + struct btrfs_root *remap_root;
> int ret;
> int level;
>
> @@ -3417,6 +3484,16 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
> if (ret < 0)
> goto fail_alloc;
>
> + if (btrfs_super_incompat_flags(disk_super) & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
> + remap_root = btrfs_alloc_root(fs_info, BTRFS_REMAP_TREE_OBJECTID,
> + GFP_KERNEL);
> + fs_info->remap_root = remap_root;
> + if (!remap_root) {
> + ret = -ENOMEM;
> + goto fail_alloc;
> + }
> + }
> +
Thanks for scooting it down. Does this need to be before reading the sys
array / chunk tree? I would guess no, as we can't remap that, but
perhaps I have misunderstood.
> /*
> * At this point our mount options are validated, if we set ->max_inline
> * to something non-standard make sure we truncate it to sectorsize.
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index d964147b8097..7805a148bbd8 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -2589,6 +2589,8 @@ static u64 get_alloc_profile_by_root(struct btrfs_root *root, int data)
> flags = BTRFS_BLOCK_GROUP_DATA;
> else if (root == fs_info->chunk_root)
> flags = BTRFS_BLOCK_GROUP_SYSTEM;
> + else if (root == fs_info->remap_root)
> + flags = BTRFS_BLOCK_GROUP_REMAP;
> else
> flags = BTRFS_BLOCK_GROUP_METADATA;
>
> diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
> index c4dba7e7ce5a..c76f4c2701f9 100644
> --- a/fs/btrfs/fs.h
> +++ b/fs/btrfs/fs.h
> @@ -291,7 +291,8 @@ enum {
> #define BTRFS_FEATURE_INCOMPAT_SUPP \
> (BTRFS_FEATURE_INCOMPAT_SUPP_STABLE | \
> BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE | \
> - BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2)
> + BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2 | \
> + BTRFS_FEATURE_INCOMPAT_REMAP_TREE)
>
> #else
>
> @@ -451,6 +452,7 @@ struct btrfs_fs_info {
> struct btrfs_root *data_reloc_root;
> struct btrfs_root *block_group_root;
> struct btrfs_root *stripe_root;
> + struct btrfs_root *remap_root;
>
> /* The log root tree is a directory of all the other log roots */
> struct btrfs_root *log_root_tree;
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index 89ae0c7a610a..b1c41982e7b2 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -1950,6 +1950,13 @@ static void update_super_roots(struct btrfs_fs_info *fs_info)
> super->cache_generation = 0;
> if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
> super->uuid_tree_generation = root_item->generation;
> +
> + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> + root_item = &fs_info->remap_root->root_item;
> + super->remap_root = root_item->bytenr;
> + super->remap_root_generation = root_item->generation;
> + super->remap_root_level = root_item->level;
> + }
> }
>
> int btrfs_transaction_blocked(struct btrfs_fs_info *info)
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> index 500e3a7df90b..89bcb80081a6 100644
> --- a/include/uapi/linux/btrfs_tree.h
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -721,9 +721,12 @@ struct btrfs_super_block {
> __u8 metadata_uuid[BTRFS_FSID_SIZE];
>
> __u64 nr_global_roots;
> + __le64 remap_root;
> + __le64 remap_root_generation;
> + __u8 remap_root_level;
>
> /* Future expansion */
> - __le64 reserved[27];
> + __u8 reserved[199];
> __u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
> struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
>
> --
> 2.49.1
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups
2025-10-09 11:28 ` [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups Mark Harmstone
@ 2025-10-15 4:21 ` Boris Burkov
2025-10-20 14:31 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Boris Burkov @ 2025-10-15 4:21 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 09, 2025 at 12:28:03PM +0100, Mark Harmstone wrote:
> Change btrfs_map_block() so that if the block group has the REMAPPED
> flag set, we call btrfs_translate_remap() to obtain a new address.
>
> btrfs_translate_remap() searches the remap tree for a range
> corresponding to the logical address passed to btrfs_map_block(). If it
> is within an identity remap, this part of the block group hasn't yet
> been relocated, and so we use the existing address.
>
> If it is within an actual remap, we subtract the start of the remap
> range and add the address of its destination, contained in the item's
> payload.
>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> ---
> fs/btrfs/relocation.c | 59 +++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/relocation.h | 2 ++
> fs/btrfs/volumes.c | 31 +++++++++++++++++++++++
> 3 files changed, 92 insertions(+)
>
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 748290758459..4f5d3aaf0f65 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -3870,6 +3870,65 @@ static const char *stage_to_string(enum reloc_stage stage)
> return "unknown";
> }
>
> +int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
> + u64 *length, bool nolock)
> +{
> + int ret;
> + struct btrfs_key key, found_key;
> + struct extent_buffer *leaf;
> + struct btrfs_remap *remap;
> + BTRFS_PATH_AUTO_FREE(path);
> +
> + path = btrfs_alloc_path();
> + if (!path)
> + return -ENOMEM;
> +
> + if (nolock) {
> + path->search_commit_root = 1;
> + path->skip_locking = 1;
> + }
> +
> + key.objectid = *logical;
> + key.type = (u8)-1;
> + key.offset = (u64)-1;
> +
> + ret = btrfs_search_slot(NULL, fs_info->remap_root, &key, path,
> + 0, 0);
> + if (ret < 0)
> + return ret;
> +
> + leaf = path->nodes[0];
> +
> + if (path->slots[0] == 0)
> + return -ENOENT;
> +
> + path->slots[0]--;
> +
> + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
> +
> + if (found_key.type != BTRFS_REMAP_KEY &&
> + found_key.type != BTRFS_IDENTITY_REMAP_KEY) {
> + return -ENOENT;
> + }
> +
> + if (found_key.objectid > *logical ||
> + found_key.objectid + found_key.offset <= *logical) {
> + return -ENOENT;
> + }
> +
> + if (*logical + *length > found_key.objectid + found_key.offset)
> + *length = found_key.objectid + found_key.offset - *logical;
> +
> + if (found_key.type == BTRFS_IDENTITY_REMAP_KEY)
> + return 0;
> +
> + remap = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_remap);
> +
> + *logical += btrfs_remap_address(leaf, remap) - found_key.objectid;
> +
> + return 0;
> +}
> +
> /*
> * function to relocate all extents in a block group.
> */
> diff --git a/fs/btrfs/relocation.h b/fs/btrfs/relocation.h
> index 5c36b3f84b57..a653c42a25a3 100644
> --- a/fs/btrfs/relocation.h
> +++ b/fs/btrfs/relocation.h
> @@ -31,5 +31,7 @@ int btrfs_should_cancel_balance(const struct btrfs_fs_info *fs_info);
> struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr);
> bool btrfs_should_ignore_reloc_root(const struct btrfs_root *root);
> u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info);
> +int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
> + u64 *length, bool nolock);
>
> #endif
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 0abe02a7072f..f2d1203778aa 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -6635,6 +6635,37 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
> if (IS_ERR(map))
> return PTR_ERR(map);
>
> + if (map->type & BTRFS_BLOCK_GROUP_REMAPPED) {
> + u64 new_logical = logical;
> + bool nolock = !(map->type & BTRFS_BLOCK_GROUP_DATA);
Why not data?
> +
> + /*
> + * We use search_commit_root in btrfs_translate_remap for
> + * metadata blocks, to avoid lockdep complaining about
> + * recursive locking.
> + * If we get -ENOENT this means this is a BG that has just had
> + * its REMAPPED flag set, and so nothing has yet been actually
> + * remapped.
> + */
I'm actually kind of worried about this now. What is preventing the
following racy interleaving:
T1 T2
start_block_group_remapping() // in TXN-K set REMAPPED
btrfs_map_block()
btrfs_translate_remap()
ENOENT // searched in commit root
do_remap_tree_reloc() // in TXN-K do all remaps
// fully remapped, removed, discarded
// TXN-K committed
// not remapped! but the original chunk map is gone gone
num_copies = ...
> + ret = btrfs_translate_remap(fs_info, &new_logical, length,
> + nolock);
> + if (ret && (!nolock || ret != -ENOENT))
> + return ret;
> +
> + if (ret != -ENOENT && new_logical != logical) {
> + btrfs_free_chunk_map(map);
> +
> + map = btrfs_get_chunk_map(fs_info, new_logical,
> + *length);
> + if (IS_ERR(map))
> + return PTR_ERR(map);
> +
> + logical = new_logical;
> + }
> +
> + ret = 0;
> + }
> +
> num_copies = btrfs_chunk_map_num_copies(map);
> if (io_geom.mirror_num > num_copies)
> return -EINVAL;
> --
> 2.49.1
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 15/17] btrfs: allow balancing remap tree
2025-10-09 11:28 ` [PATCH v3 15/17] btrfs: allow balancing remap tree Mark Harmstone
@ 2025-10-15 4:24 ` Boris Burkov
0 siblings, 0 replies; 38+ messages in thread
From: Boris Burkov @ 2025-10-15 4:24 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 09, 2025 at 12:28:10PM +0100, Mark Harmstone wrote:
> Balancing the REMAP chunk, i.e. the chunk in which the remap tree lives,
> is a special case.
>
> We can't use the remap tree itself for this, as then we'd have no way to
> boostrap it on mount. And we can't use the pre-remap tree code for this
> as it relies on walking the extent tree, and we're not creating backrefs
> for REMAP chunks.
>
> So instead, if a balance would relocate any REMAP block groups, mark
> those block groups as readonly and COW every leaf of the remap tree.
>
> There's more sophisticated ways of doing this, such as only COWing nodes
> within a block group that's to be relocated, but they're fiddly and with
> lots of edge cases. Plus it's not anticipated that a) the number of
> REMAP chunks is going to be particularly large, or b) that users will
> want to only relocate some of these chunks - the main use case here is
> to unbreak RAID conversion and device removal.
>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: Boris Burkov <boris@bur.io>
> ---
> fs/btrfs/volumes.c | 159 +++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 155 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 1ce06c343918..a4dcafe2d565 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -4016,8 +4016,11 @@ static bool should_balance_chunk(struct extent_buffer *leaf, struct btrfs_chunk
> struct btrfs_balance_args *bargs = NULL;
> u64 chunk_type = btrfs_chunk_type(leaf, chunk);
>
> - if (chunk_type & BTRFS_BLOCK_GROUP_REMAP)
> - return false;
> + /* treat REMAP chunks as METADATA */
> + if (chunk_type & BTRFS_BLOCK_GROUP_REMAP) {
> + chunk_type &= ~BTRFS_BLOCK_GROUP_REMAP;
> + chunk_type |= BTRFS_BLOCK_GROUP_METADATA;
> + }
>
> /* type filter */
> if (!((chunk_type & BTRFS_BLOCK_GROUP_TYPE_MASK) &
> @@ -4100,6 +4103,113 @@ static bool should_balance_chunk(struct extent_buffer *leaf, struct btrfs_chunk
> return true;
> }
>
> +struct remap_chunk_info {
> + struct list_head list;
> + u64 offset;
> + struct btrfs_block_group *bg;
> + bool made_ro;
> +};
> +
> +static int cow_remap_tree(struct btrfs_trans_handle *trans,
> + struct btrfs_path *path)
> +{
> + struct btrfs_fs_info *fs_info = trans->fs_info;
> + struct btrfs_key key = { 0 };
> + int ret;
> +
> + ret = btrfs_search_slot(trans, fs_info->remap_root, &key, path, 0, 1);
> + if (ret < 0)
> + return ret;
> +
> + while (true) {
> + ret = btrfs_next_leaf(fs_info->remap_root, path);
> + if (ret < 0) {
> + return ret;
> + } else if (ret > 0) {
> + ret = 0;
> + break;
> + }
> +
> + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
> +
> + btrfs_release_path(path);
> +
> + ret = btrfs_search_slot(trans, fs_info->remap_root, &key, path,
> + 0, 1);
> + if (ret < 0)
> + break;
> + }
> +
> + return ret;
> +}
> +
> +static int balance_remap_chunks(struct btrfs_fs_info *fs_info,
> + struct btrfs_path *path,
> + struct list_head *chunks)
> +{
> + struct remap_chunk_info *rci, *tmp;
> + struct btrfs_trans_handle *trans;
> + int ret;
> +
> + list_for_each_entry_safe(rci, tmp, chunks, list) {
> + rci->bg = btrfs_lookup_block_group(fs_info, rci->offset);
> + if (!rci->bg) {
> + list_del(&rci->list);
> + kfree(rci);
> + continue;
> + }
> +
> + ret = btrfs_inc_block_group_ro(rci->bg, false);
> + if (ret)
> + goto end;
> +
> + rci->made_ro = true;
> + }
> +
> + if (list_empty(chunks))
> + return 0;
> +
> + trans = btrfs_start_transaction(fs_info->remap_root, 0);
> + if (IS_ERR(trans)) {
> + ret = PTR_ERR(trans);
> + goto end;
> + }
> +
> + mutex_lock(&fs_info->remap_mutex);
> +
> + ret = cow_remap_tree(trans, path);
> +
> + btrfs_release_path(path);
> +
> + mutex_unlock(&fs_info->remap_mutex);
> +
> + btrfs_commit_transaction(trans);
> +
> +end:
> + while (!list_empty(chunks)) {
> + bool unused;
> +
> + rci = list_first_entry(chunks, struct remap_chunk_info, list);
> +
> + spin_lock(&rci->bg->lock);
> + unused = !btrfs_is_block_group_used(rci->bg);
> + spin_unlock(&rci->bg->lock);
> +
> + if (unused)
> + btrfs_mark_bg_unused(rci->bg);
> +
> + if (rci->made_ro)
> + btrfs_dec_block_group_ro(rci->bg);
> +
> + btrfs_put_block_group(rci->bg);
> +
> + list_del(&rci->list);
> + kfree(rci);
> + }
> +
> + return ret;
> +}
> +
> static int __btrfs_balance(struct btrfs_fs_info *fs_info)
> {
> struct btrfs_balance_control *bctl = fs_info->balance_ctl;
> @@ -4122,6 +4232,9 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
> u32 count_meta = 0;
> u32 count_sys = 0;
> int chunk_reserved = 0;
> + struct remap_chunk_info *rci;
> + unsigned int num_remap_chunks = 0;
> + LIST_HEAD(remap_chunks);
>
> path = btrfs_alloc_path();
> if (!path) {
> @@ -4220,7 +4333,8 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
> count_data++;
> else if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM)
> count_sys++;
> - else if (chunk_type & BTRFS_BLOCK_GROUP_METADATA)
> + else if (chunk_type & (BTRFS_BLOCK_GROUP_METADATA |
> + BTRFS_BLOCK_GROUP_REMAP))
> count_meta++;
>
> goto loop;
> @@ -4240,6 +4354,30 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
> goto loop;
> }
>
> + /*
> + * Balancing REMAP chunks takes place separately - add the
> + * details to a list so it can be processed later.
> + */
> + if (chunk_type & BTRFS_BLOCK_GROUP_REMAP) {
> + mutex_unlock(&fs_info->reclaim_bgs_lock);
> +
> + rci = kmalloc(sizeof(struct remap_chunk_info),
> + GFP_NOFS);
> + if (!rci) {
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> + rci->offset = found_key.offset;
> + rci->bg = NULL;
> + rci->made_ro = false;
> + list_add_tail(&rci->list, &remap_chunks);
> +
> + num_remap_chunks++;
> +
> + goto loop;
> + }
> +
> if (!chunk_reserved) {
> /*
> * We may be relocating the only data chunk we have,
> @@ -4279,11 +4417,24 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
> key.offset = found_key.offset - 1;
> }
>
> + btrfs_release_path(path);
> +
> if (counting) {
> - btrfs_release_path(path);
> counting = false;
> goto again;
> }
> +
> + if (!list_empty(&remap_chunks)) {
> + ret = balance_remap_chunks(fs_info, path, &remap_chunks);
> + if (ret == -ENOSPC)
> + enospc_errors++;
> +
> + if (!ret) {
> + spin_lock(&fs_info->balance_lock);
> + bctl->stat.completed += num_remap_chunks;
> + spin_unlock(&fs_info->balance_lock);
> + }
> + }
> error:
> btrfs_free_path(path);
> if (enospc_errors) {
> --
> 2.49.1
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 16/17] btrfs: handle discarding fully-remapped block groups
2025-10-09 11:28 ` [PATCH v3 16/17] btrfs: handle discarding fully-remapped block groups Mark Harmstone
@ 2025-10-15 4:54 ` Boris Burkov
2025-10-23 17:35 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Boris Burkov @ 2025-10-15 4:54 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 09, 2025 at 12:28:11PM +0100, Mark Harmstone wrote:
> Discard normally works by iterating over the free-space entries of a
> block group. This doesn't work for fully-remapped block groups, as we
> removed their free-space entries when we started relocation.
>
> For sync discard, call btrfs_discard_extent() when we commit the
> transaction in which the last identity remap was removed.
>
> For async discard, add a new function btrfs_trim_fully_remapped_block_group()
> to be called by the discard worker, which iterates over the block
> group's range using the normal async discard rules. Once we reach the
> end, remove the chunk's stripes and device extents to get back its free
> space.
>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> ---
> fs/btrfs/block-group.c | 2 +
> fs/btrfs/block-group.h | 1 +
> fs/btrfs/discard.c | 61 +++++++++++++++++++++++++----
> fs/btrfs/extent-tree.c | 4 ++
> fs/btrfs/free-space-cache.c | 77 +++++++++++++++++++++++++++++++++++++
> fs/btrfs/free-space-cache.h | 1 +
> fs/btrfs/transaction.c | 8 ++--
> 7 files changed, 144 insertions(+), 10 deletions(-)
>
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index 3f7c45d17415..a7dfa6c95223 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -4828,4 +4828,6 @@ void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
>
> spin_unlock(&fs_info->unused_bgs_lock);
>
> + if (btrfs_test_opt(fs_info, DISCARD_ASYNC))
> + btrfs_discard_queue_work(&fs_info->discard_ctl, bg);
> }
> diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
> index c6866a57ea24..3c086fbb0a7c 100644
> --- a/fs/btrfs/block-group.h
> +++ b/fs/btrfs/block-group.h
> @@ -49,6 +49,7 @@ enum btrfs_discard_state {
> BTRFS_DISCARD_EXTENTS,
> BTRFS_DISCARD_BITMAPS,
> BTRFS_DISCARD_RESET_CURSOR,
> + BTRFS_DISCARD_FULLY_REMAPPED,
> };
>
> /*
> diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
> index 2b7b1e440bc8..421f48a6603a 100644
> --- a/fs/btrfs/discard.c
> +++ b/fs/btrfs/discard.c
> @@ -241,8 +241,17 @@ static struct btrfs_block_group *peek_discard_list(
> block_group = find_next_block_group(discard_ctl, now);
>
> if (block_group && now >= block_group->discard_eligible_time) {
> + bool unused;
> +
> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
> + unused = block_group->remap_bytes == 0 &&
> + block_group->identity_remap_count == 0;
> + } else {
> + unused = block_group->used == 0;
> + }
> +
This pattern for computing unused gets repeated enough times in this file
that I think a static helper is merited.
> if (block_group->discard_index == BTRFS_DISCARD_INDEX_UNUSED &&
> - block_group->used != 0) {
> + !unused) {
> if (btrfs_is_block_group_data_only(block_group)) {
> __add_to_discard_list(discard_ctl, block_group);
> /*
> @@ -267,7 +276,15 @@ static struct btrfs_block_group *peek_discard_list(
> }
> if (block_group->discard_state == BTRFS_DISCARD_RESET_CURSOR) {
> block_group->discard_cursor = block_group->start;
> - block_group->discard_state = BTRFS_DISCARD_EXTENTS;
> +
> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
> + unused) {
> + block_group->discard_state =
> + BTRFS_DISCARD_FULLY_REMAPPED;
> + } else {
> + block_group->discard_state =
> + BTRFS_DISCARD_EXTENTS;
> + }
> }
> }
> if (block_group) {
> @@ -370,10 +387,19 @@ void btrfs_discard_cancel_work(struct btrfs_discard_ctl *discard_ctl,
> void btrfs_discard_queue_work(struct btrfs_discard_ctl *discard_ctl,
> struct btrfs_block_group *block_group)
> {
> + bool unused;
> +
> if (!block_group || !btrfs_test_opt(block_group->fs_info, DISCARD_ASYNC))
> return;
>
> - if (block_group->used == 0 && block_group->remap_bytes == 0)
> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
> + unused = block_group->remap_bytes == 0 &&
> + block_group->identity_remap_count == 0;
> + } else {
> + unused = block_group->used == 0;
> + }
> +
> + if (unused)
> add_to_discard_unused_list(discard_ctl, block_group);
> else
> add_to_discard_list(discard_ctl, block_group);
> @@ -468,9 +494,18 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl,
> static void btrfs_finish_discard_pass(struct btrfs_discard_ctl *discard_ctl,
> struct btrfs_block_group *block_group)
> {
> + bool unused;
> +
> remove_from_discard_list(discard_ctl, block_group);
>
> - if (block_group->used == 0) {
> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
> + unused = block_group->remap_bytes == 0 &&
> + block_group->identity_remap_count == 0;
> + } else {
> + unused = block_group->used == 0;
> + }
> +
> + if (unused) {
> if (btrfs_is_free_space_trimmed(block_group))
> btrfs_mark_bg_unused(block_group);
> else
> @@ -524,7 +559,8 @@ static void btrfs_discard_workfn(struct work_struct *work)
> /* Perform discarding */
> minlen = discard_minlen[discard_index];
>
> - if (discard_state == BTRFS_DISCARD_BITMAPS) {
> + switch (discard_state) {
> + case BTRFS_DISCARD_BITMAPS: {
> u64 maxlen = 0;
>
> /*
> @@ -541,17 +577,28 @@ static void btrfs_discard_workfn(struct work_struct *work)
> btrfs_block_group_end(block_group),
> minlen, maxlen, true);
> discard_ctl->discard_bitmap_bytes += trimmed;
> - } else {
> +
> + break;
> + }
> +
> + case BTRFS_DISCARD_FULLY_REMAPPED:
> + btrfs_trim_fully_remapped_block_group(block_group);
> + break;
> +
> + default:
> btrfs_trim_block_group_extents(block_group, &trimmed,
> block_group->discard_cursor,
> btrfs_block_group_end(block_group),
> minlen, true);
> discard_ctl->discard_extent_bytes += trimmed;
> +
> + break;
> }
>
> /* Determine next steps for a block_group */
> if (block_group->discard_cursor >= btrfs_block_group_end(block_group)) {
> - if (discard_state == BTRFS_DISCARD_BITMAPS) {
> + if (discard_state == BTRFS_DISCARD_BITMAPS ||
> + discard_state == BTRFS_DISCARD_FULLY_REMAPPED) {
> btrfs_finish_discard_pass(discard_ctl, block_group);
> } else {
> block_group->discard_cursor = block_group->start;
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 2e3074612f39..03674d171ec0 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -2870,6 +2870,10 @@ int btrfs_handle_fully_remapped_bgs(struct btrfs_trans_handle *trans)
> return ret;
> }
>
> + if (!TRANS_ABORTED(trans))
> + btrfs_discard_extent(fs_info, block_group->start,
> + block_group->length, NULL, false);
> +
> /*
> * Set num_stripes to 0, so that btrfs_remove_dev_extents()
> * won't run a second time.
> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
> index 6387f8d1c3a1..56f27487b632 100644
> --- a/fs/btrfs/free-space-cache.c
> +++ b/fs/btrfs/free-space-cache.c
> @@ -29,6 +29,7 @@
> #include "file-item.h"
> #include "file.h"
> #include "super.h"
> +#include "relocation.h"
>
> #define BITS_PER_BITMAP (PAGE_SIZE * 8UL)
> #define MAX_CACHE_BYTES_PER_GIG SZ_64K
> @@ -3063,6 +3064,12 @@ bool btrfs_is_free_space_trimmed(struct btrfs_block_group *block_group)
> struct rb_node *node;
> bool ret = true;
>
> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
> + block_group->remap_bytes == 0 &&
> + block_group->identity_remap_count == 0) {
> + return true;
> + }
> +
> spin_lock(&ctl->tree_lock);
> node = rb_first(&ctl->free_space_offset);
>
> @@ -3827,6 +3834,76 @@ static int trim_no_bitmap(struct btrfs_block_group *block_group,
> return ret;
> }
>
> +void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
> +{
> + struct btrfs_fs_info *fs_info = bg->fs_info;
> + struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl;
> + int ret = 0;
> + u64 bytes;
> + const u64 max_discard_size = READ_ONCE(discard_ctl->max_discard_size);
> + u64 end = btrfs_block_group_end(bg);
> + struct btrfs_trans_handle *trans;
> + struct btrfs_chunk_map *map;
> +
> + while (bg->discard_cursor < end) {
> + u64 trimmed;
> +
> + bytes = end - bg->discard_cursor;
> +
> + if (max_discard_size &&
> + bytes >= (max_discard_size +
> + BTRFS_ASYNC_DISCARD_MIN_FILTER)) {
> + bytes = max_discard_size;
> + }
> +
> + ret = btrfs_discard_extent(fs_info, bg->discard_cursor, bytes,
> + &trimmed, false);
> + if (ret || trimmed == 0)
> + return;
As opposed to btrfs_trim_block_group_extents() / trim_no_bitmap() this will
always do all the discarding in a tight loop without sending control
back up to the delayed work queue. As a result, the rate limiting is
unable to do its job; this will simply rip through the whole bg in steps
of max_discard_size.
Check out the `async` parameter to trim_no_bitamp() and how it breaks
the loop, which then lets the higher level metering operate properly.
> +
> + bg->discard_cursor += trimmed;
> +
> + if (btrfs_trim_interrupted())
> + return;
> +
> + cond_resched();
> + }
> +
> + trans = btrfs_start_transaction(fs_info->tree_root, 0);
> + if (IS_ERR(trans))
> + return;
> +
> + map = btrfs_get_chunk_map(fs_info, bg->start, 1);
> + if (IS_ERR(map)) {
> + ret = PTR_ERR(map);
> + btrfs_abort_transaction(trans, ret);
> + return;
> + }
> +
> + ret = btrfs_last_identity_remap_gone(trans, map, bg);
> + if (ret) {
> + btrfs_free_chunk_map(map);
> + btrfs_abort_transaction(trans, ret);
> + return;
> + }
> +
> + btrfs_end_transaction(trans);
> +
> + /*
> + * Set num_stripes to 0, so that btrfs_remove_dev_extents()
> + * won't run a second time.
> + */
> + map->num_stripes = 0;
> +
> + btrfs_free_chunk_map(map);
> +
> + if (bg->used == 0) {
> + spin_lock(&fs_info->unused_bgs_lock);
> + list_move_tail(&bg->bg_list, &fs_info->unused_bgs);
> + spin_unlock(&fs_info->unused_bgs_lock);
> + }
> +}
> +
> /*
> * If we break out of trimming a bitmap prematurely, we should reset the
> * trimming bit. In a rather contrived case, it's possible to race here so
> diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
> index 9f1dbfdee8ca..33fc3b245648 100644
> --- a/fs/btrfs/free-space-cache.h
> +++ b/fs/btrfs/free-space-cache.h
> @@ -166,6 +166,7 @@ int btrfs_trim_block_group_extents(struct btrfs_block_group *block_group,
> int btrfs_trim_block_group_bitmaps(struct btrfs_block_group *block_group,
> u64 *trimmed, u64 start, u64 end, u64 minlen,
> u64 maxlen, bool async);
> +void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg);
>
> bool btrfs_free_space_cache_v1_active(struct btrfs_fs_info *fs_info);
> int btrfs_set_free_space_cache_v1_active(struct btrfs_fs_info *fs_info, bool active);
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index 6ce91397afe6..b0a5254ba214 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -2438,9 +2438,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
> if (ret)
> goto unlock_reloc;
>
> - ret = btrfs_handle_fully_remapped_bgs(trans);
> - if (ret)
> - goto unlock_reloc;
> + if (!btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
> + ret = btrfs_handle_fully_remapped_bgs(trans);
> + if (ret)
> + goto unlock_reloc;
> + }
>
> /*
> * make sure none of the code above managed to slip in a
> --
> 2.49.1
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 17/17] btrfs: add stripe removal pending flag
2025-10-09 11:28 ` [PATCH v3 17/17] btrfs: add stripe removal pending flag Mark Harmstone
@ 2025-10-15 5:05 ` Boris Burkov
2025-10-20 14:52 ` Mark Harmstone
0 siblings, 1 reply; 38+ messages in thread
From: Boris Burkov @ 2025-10-15 5:05 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Thu, Oct 09, 2025 at 12:28:12PM +0100, Mark Harmstone wrote:
> If the filesystem is unmounted while the async discard of a fully remapped
> block group is in progress, its unused device extents will never be freed.
>
> To counter this, add a new flag BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING
> to say that this has been interrupted. Set it in the transaction in which
> the last identity remap has been removed, clear it when we remove the
> device extents, and if we encounter it on mount queue that block group
> up for discard.
I don't see how this is special for remapped block groups.
in read_one_block_group() for empty block groups we queue them for async
discard unconditionally. There is a comment to this effect in discard.c
about crashes and mounts behaving the same.
And either way, if we go down at any point before we remove the bg, then
we will be re-discarding everything we already discarded (possibly the
whole thing) so this is optimistic anyway, right?
I don't think the benefit of this is worth the special case compared to
normal unused bgs, and I don't think it makes sense to "take advantage"
of this format change opportunity to also add the persisted "needs
discard" bit for all discard.
A persisted "discard state" on the extents would actually be
interesting, I think, but I don't think that is in scope or even
necessarily a good idea.
Thanks,
Boris
>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> ---
> fs/btrfs/block-group.c | 35 ++++++++++++++++++++++++++++++++-
> fs/btrfs/free-space-cache.c | 5 +++++
> fs/btrfs/relocation.c | 18 +++++++++++++++++
> include/uapi/linux/btrfs_tree.h | 1 +
> 4 files changed, 58 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index a7dfa6c95223..851d76ce8ec9 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -2530,6 +2530,16 @@ static int read_one_block_group(struct btrfs_fs_info *info,
> inc_block_group_ro(cache, 1);
> }
>
> + if (cache->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING) {
> + btrfs_get_block_group(cache);
> + spin_lock(&info->unused_bgs_lock);
> + list_add_tail(&cache->bg_list, &info->fully_remapped_bgs);
> + spin_unlock(&info->unused_bgs_lock);
> +
> + if (btrfs_test_opt(info, DISCARD_ASYNC))
> + btrfs_discard_queue_work(&info->discard_ctl, cache);
> + }
> +
> return 0;
> error:
> btrfs_put_block_group(cache);
> @@ -4828,6 +4838,29 @@ void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
>
> spin_unlock(&fs_info->unused_bgs_lock);
>
> - if (btrfs_test_opt(fs_info, DISCARD_ASYNC))
> + if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
> + bool bg_already_dirty = true;
> +
> + spin_lock(&bg->lock);
> + bg->flags |= BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING;
> + spin_unlock(&bg->lock);
> +
> + spin_lock(&trans->transaction->dirty_bgs_lock);
> + if (list_empty(&bg->dirty_list)) {
> + list_add_tail(&bg->dirty_list,
> + &trans->transaction->dirty_bgs);
> + bg_already_dirty = false;
> + btrfs_get_block_group(bg);
> + }
> + spin_unlock(&trans->transaction->dirty_bgs_lock);
> +
> + /*
> + * Modified block groups are accounted for in
> + * the delayed_refs_rsv.
> + */
> + if (!bg_already_dirty)
> + btrfs_inc_delayed_refs_rsv_bg_updates(trans->fs_info);
> +
> btrfs_discard_queue_work(&fs_info->discard_ctl, bg);
> + }
> }
> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
> index 56f27487b632..813b82294341 100644
> --- a/fs/btrfs/free-space-cache.c
> +++ b/fs/btrfs/free-space-cache.c
> @@ -3065,6 +3065,7 @@ bool btrfs_is_free_space_trimmed(struct btrfs_block_group *block_group)
> bool ret = true;
>
> if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
> + !(block_group->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING) &&
> block_group->remap_bytes == 0 &&
> block_group->identity_remap_count == 0) {
> return true;
> @@ -3845,6 +3846,9 @@ void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
> struct btrfs_trans_handle *trans;
> struct btrfs_chunk_map *map;
>
> + if (!(bg->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING))
> + goto skip_discard;
> +
> while (bg->discard_cursor < end) {
> u64 trimmed;
>
> @@ -3897,6 +3901,7 @@ void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
>
> btrfs_free_chunk_map(map);
>
> +skip_discard:
> if (bg->used == 0) {
> spin_lock(&fs_info->unused_bgs_lock);
> list_move_tail(&bg->bg_list, &fs_info->unused_bgs);
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 7bad8d65d145..a179e4a8e960 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -4733,6 +4733,7 @@ int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
> struct btrfs_block_group *bg)
> {
> int ret;
> + bool bg_already_dirty = true;
> BTRFS_PATH_AUTO_FREE(path);
>
> ret = btrfs_remove_dev_extents(trans, chunk);
> @@ -4757,6 +4758,23 @@ int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
>
> btrfs_remove_bg_from_sinfo(bg);
>
> + spin_lock(&bg->lock);
> + bg->flags &= ~BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING;
> + spin_unlock(&bg->lock);
> +
> + spin_lock(&trans->transaction->dirty_bgs_lock);
> + if (list_empty(&bg->dirty_list)) {
> + list_add_tail(&bg->dirty_list,
> + &trans->transaction->dirty_bgs);
> + bg_already_dirty = false;
> + btrfs_get_block_group(bg);
> + }
> + spin_unlock(&trans->transaction->dirty_bgs_lock);
> +
> + /* Modified block groups are accounted for in the delayed_refs_rsv. */
> + if (!bg_already_dirty)
> + btrfs_inc_delayed_refs_rsv_bg_updates(trans->fs_info);
> +
> path = btrfs_alloc_path();
> if (!path)
> return -ENOMEM;
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> index 89bcb80081a6..36a7d1a3cbe3 100644
> --- a/include/uapi/linux/btrfs_tree.h
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -1173,6 +1173,7 @@ struct btrfs_dev_replace_item {
> #define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
> #define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
> #define BTRFS_BLOCK_GROUP_REMAP (1ULL << 12)
> +#define BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING (1ULL << 13)
> #define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
> BTRFS_SPACE_INFO_GLOBAL_RSV)
>
> --
> 2.49.1
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 02/17] btrfs: add REMAP chunk type
2025-10-15 3:37 ` Boris Burkov
@ 2025-10-20 9:58 ` Mark Harmstone
2025-10-20 17:35 ` Boris Burkov
0 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-20 9:58 UTC (permalink / raw)
To: Boris Burkov; +Cc: linux-btrfs
Thanks Boris. Have a look at the third paragraph of the commit message, I
explain the volumes.h changes there.
On 15/10/2025 4.37 am, Boris Burkov wrote:
> On Thu, Oct 09, 2025 at 12:27:57PM +0100, Mark Harmstone wrote:
>> Add a new REMAP chunk type, which is a metadata chunk that holds the
>> remap tree.
>>
>> This is needed for bootstrapping purposes: the remap tree can't itself
>> be remapped, and must be relocated the existing way, by COWing every
>> leaf. The remap tree can't go in the SYSTEM chunk as space there is
>> limited, because a copy of the chunk item gets placed in the superblock.
>>
>> The changes in fs/btrfs/volumes.h are because we're adding a new block
>> group type bit after the profile bits, and so can no longer rely on the
>> const_ilog2 trick.
>>
>> The sizing to 32MB per chunk, matching the SYSTEM chunk, is an estimate
>> here, we can adjust it later if it proves to be too big or too small.
>> This works out to be ~500,000 remap items, which for a 4KB block size
>> covers ~2GB of remapped data in the worst case and ~500TB in the best case.
>>
>
> Asked a relatively inconsequential question about static asserts in
> volumes.h. Otherwise,
>
> Reviewed-by: Boris Burkov <boris@bur.io>
>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>> ---
>> fs/btrfs/block-rsv.c | 8 ++++++++
>> fs/btrfs/block-rsv.h | 1 +
>> fs/btrfs/disk-io.c | 1 +
>> fs/btrfs/fs.h | 2 ++
>> fs/btrfs/space-info.c | 13 ++++++++++++-
>> fs/btrfs/sysfs.c | 2 ++
>> fs/btrfs/tree-checker.c | 13 +++++++++++--
>> fs/btrfs/volumes.c | 3 +++
>> fs/btrfs/volumes.h | 11 +++++++++--
>> include/uapi/linux/btrfs_tree.h | 4 +++-
>> 10 files changed, 52 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
>> index 5ad6de738aee..2678cd3bed29 100644
>> --- a/fs/btrfs/block-rsv.c
>> +++ b/fs/btrfs/block-rsv.c
>> @@ -421,6 +421,9 @@ void btrfs_init_root_block_rsv(struct btrfs_root *root)
>> case BTRFS_TREE_LOG_OBJECTID:
>> root->block_rsv = &fs_info->treelog_rsv;
>> break;
>> + case BTRFS_REMAP_TREE_OBJECTID:
>> + root->block_rsv = &fs_info->remap_block_rsv;
>> + break;
>> default:
>> root->block_rsv = NULL;
>> break;
>> @@ -434,6 +437,9 @@ void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
>> space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
>> fs_info->chunk_block_rsv.space_info = space_info;
>>
>> + space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_REMAP);
>> + fs_info->remap_block_rsv.space_info = space_info;
>> +
>> space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
>> fs_info->global_block_rsv.space_info = space_info;
>> fs_info->trans_block_rsv.space_info = space_info;
>> @@ -460,6 +466,8 @@ void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
>> WARN_ON(fs_info->trans_block_rsv.reserved > 0);
>> WARN_ON(fs_info->chunk_block_rsv.size > 0);
>> WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
>> + WARN_ON(fs_info->remap_block_rsv.size > 0);
>> + WARN_ON(fs_info->remap_block_rsv.reserved > 0);
>> WARN_ON(fs_info->delayed_block_rsv.size > 0);
>> WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
>> WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
>> diff --git a/fs/btrfs/block-rsv.h b/fs/btrfs/block-rsv.h
>> index 79ae9d05cd91..8359fb96bc3c 100644
>> --- a/fs/btrfs/block-rsv.h
>> +++ b/fs/btrfs/block-rsv.h
>> @@ -22,6 +22,7 @@ enum btrfs_rsv_type {
>> BTRFS_BLOCK_RSV_DELALLOC,
>> BTRFS_BLOCK_RSV_TRANS,
>> BTRFS_BLOCK_RSV_CHUNK,
>> + BTRFS_BLOCK_RSV_REMAP,
>> BTRFS_BLOCK_RSV_DELOPS,
>> BTRFS_BLOCK_RSV_DELREFS,
>> BTRFS_BLOCK_RSV_TREELOG,
>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>> index f475fb2272ac..102e5e0ad10c 100644
>> --- a/fs/btrfs/disk-io.c
>> +++ b/fs/btrfs/disk-io.c
>> @@ -2815,6 +2815,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
>> BTRFS_BLOCK_RSV_GLOBAL);
>> btrfs_init_block_rsv(&fs_info->trans_block_rsv, BTRFS_BLOCK_RSV_TRANS);
>> btrfs_init_block_rsv(&fs_info->chunk_block_rsv, BTRFS_BLOCK_RSV_CHUNK);
>> + btrfs_init_block_rsv(&fs_info->remap_block_rsv, BTRFS_BLOCK_RSV_REMAP);
>> btrfs_init_block_rsv(&fs_info->treelog_rsv, BTRFS_BLOCK_RSV_TREELOG);
>> btrfs_init_block_rsv(&fs_info->empty_block_rsv, BTRFS_BLOCK_RSV_EMPTY);
>> btrfs_init_block_rsv(&fs_info->delayed_block_rsv,
>> diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
>> index 814bbc9417d2..c4dba7e7ce5a 100644
>> --- a/fs/btrfs/fs.h
>> +++ b/fs/btrfs/fs.h
>> @@ -485,6 +485,8 @@ struct btrfs_fs_info {
>> struct btrfs_block_rsv trans_block_rsv;
>> /* Block reservation for chunk tree */
>> struct btrfs_block_rsv chunk_block_rsv;
>> + /* Block reservation for remap tree */
>> + struct btrfs_block_rsv remap_block_rsv;
>> /* Block reservation for delayed operations */
>> struct btrfs_block_rsv delayed_block_rsv;
>> /* Block reservation for delayed refs */
>> diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
>> index 04a07d6f8537..22bc95f33a6f 100644
>> --- a/fs/btrfs/space-info.c
>> +++ b/fs/btrfs/space-info.c
>> @@ -215,7 +215,7 @@ static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
>>
>> if (flags & BTRFS_BLOCK_GROUP_DATA)
>> return BTRFS_MAX_DATA_CHUNK_SIZE;
>> - else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
>> + else if (flags & (BTRFS_BLOCK_GROUP_SYSTEM | BTRFS_BLOCK_GROUP_REMAP))
>> return SZ_32M;
>>
>> /* Handle BTRFS_BLOCK_GROUP_METADATA */
>> @@ -343,6 +343,8 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
>> if (mixed) {
>> flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
>> ret = create_space_info(fs_info, flags);
>> + if (ret)
>> + goto out;
>> } else {
>> flags = BTRFS_BLOCK_GROUP_METADATA;
>> ret = create_space_info(fs_info, flags);
>> @@ -351,7 +353,15 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
>>
>> flags = BTRFS_BLOCK_GROUP_DATA;
>> ret = create_space_info(fs_info, flags);
>> + if (ret)
>> + goto out;
>> + }
>> +
>> + if (features & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
>> + flags = BTRFS_BLOCK_GROUP_REMAP;
>> + ret = create_space_info(fs_info, flags);
>> }
>> +
>> out:
>> return ret;
>> }
>> @@ -590,6 +600,7 @@ static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
>> DUMP_BLOCK_RSV(fs_info, global_block_rsv);
>> DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
>> DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
>> + DUMP_BLOCK_RSV(fs_info, remap_block_rsv);
>> DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
>> DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
>> }
>> diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
>> index 857d2772db1c..f942fde1d936 100644
>> --- a/fs/btrfs/sysfs.c
>> +++ b/fs/btrfs/sysfs.c
>> @@ -1973,6 +1973,8 @@ static const char *alloc_name(struct btrfs_space_info *space_info)
>> case BTRFS_BLOCK_GROUP_SYSTEM:
>> ASSERT(space_info->subgroup_id == BTRFS_SUB_GROUP_PRIMARY);
>> return "system";
>> + case BTRFS_BLOCK_GROUP_REMAP:
>> + return "remap";
>> default:
>> WARN_ON(1);
>> return "invalid-combination";
>> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
>> index 9c03aeb6f2c7..62f35338a555 100644
>> --- a/fs/btrfs/tree-checker.c
>> +++ b/fs/btrfs/tree-checker.c
>> @@ -748,17 +748,26 @@ static int check_block_group_item(struct extent_buffer *leaf,
>> return -EUCLEAN;
>> }
>>
>> + if (flags & BTRFS_BLOCK_GROUP_REMAP &&
>> + !btrfs_fs_incompat(fs_info, REMAP_TREE)) {
>> + block_group_err(leaf, slot,
>> +"invalid flags, have 0x%llx (REMAP flag set) but no remap-tree incompat flag",
>> + flags);
>> + return -EUCLEAN;
>> + }
>> +
>> type = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
>> if (unlikely(type != BTRFS_BLOCK_GROUP_DATA &&
>> type != BTRFS_BLOCK_GROUP_METADATA &&
>> type != BTRFS_BLOCK_GROUP_SYSTEM &&
>> + type != BTRFS_BLOCK_GROUP_REMAP &&
>> type != (BTRFS_BLOCK_GROUP_METADATA |
>> BTRFS_BLOCK_GROUP_DATA))) {
>> block_group_err(leaf, slot,
>> -"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx or 0x%llx",
>> +"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx, 0x%llx or 0x%llx",
>> type, hweight64(type),
>> BTRFS_BLOCK_GROUP_DATA, BTRFS_BLOCK_GROUP_METADATA,
>> - BTRFS_BLOCK_GROUP_SYSTEM,
>> + BTRFS_BLOCK_GROUP_SYSTEM, BTRFS_BLOCK_GROUP_REMAP,
>> BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
>> return -EUCLEAN;
>> }
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index 2e144ebd56ac..e14b86e2996b 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -231,6 +231,9 @@ void btrfs_describe_block_groups(u64 bg_flags, char *buf, u32 size_buf)
>> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_DATA, "data");
>> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_SYSTEM, "system");
>> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_METADATA, "metadata");
>> + /* block groups containing the remap tree */
>> + DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAP, "remap");
>> + /* block group that has been remapped */
>> DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAPPED, "remapped");
>>
>> DESCRIBE_FLAG(BTRFS_AVAIL_ALLOC_BIT_SINGLE, "single");
>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>> index 2cbf8080eade..b0fa8eb38060 100644
>> --- a/fs/btrfs/volumes.h
>> +++ b/fs/btrfs/volumes.h
>> @@ -58,8 +58,6 @@ static_assert(const_ilog2(BTRFS_STRIPE_LEN) == BTRFS_STRIPE_LEN_SHIFT);
>> */
>> static_assert(const_ffs(BTRFS_BLOCK_GROUP_RAID0) <
>> const_ffs(BTRFS_BLOCK_GROUP_PROFILE_MASK & ~BTRFS_BLOCK_GROUP_RAID0));
>> -static_assert(const_ilog2(BTRFS_BLOCK_GROUP_RAID0) >
>> - ilog2(BTRFS_BLOCK_GROUP_TYPE_MASK));
>>
>> /* ilog2() can handle both constants and variables */
>> #define BTRFS_BG_FLAG_TO_INDEX(profile) \
>> @@ -81,6 +79,15 @@ enum btrfs_raid_types {
>> BTRFS_NR_RAID_TYPES
>> };
>>
>> +static_assert(BTRFS_RAID_RAID0 == 1);
>> +static_assert(BTRFS_RAID_RAID1 == 2);
>> +static_assert(BTRFS_RAID_DUP == 3);
>> +static_assert(BTRFS_RAID_RAID10 == 4);
>> +static_assert(BTRFS_RAID_RAID5 == 5);
>> +static_assert(BTRFS_RAID_RAID6 == 6);
>> +static_assert(BTRFS_RAID_RAID1C3 == 7);
>> +static_assert(BTRFS_RAID_RAID1C4 == 8);
>> +
>
> What is the significance of these static_assert changes?
>
>> /*
>> * Use sequence counter to get consistent device stat data on
>> * 32-bit processors.
>> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
>> index 4439d77a7252..9a36f0206d90 100644
>> --- a/include/uapi/linux/btrfs_tree.h
>> +++ b/include/uapi/linux/btrfs_tree.h
>> @@ -1169,12 +1169,14 @@ struct btrfs_dev_replace_item {
>> #define BTRFS_BLOCK_GROUP_RAID1C3 (1ULL << 9)
>> #define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
>> #define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
>> +#define BTRFS_BLOCK_GROUP_REMAP (1ULL << 12)
>> #define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
>> BTRFS_SPACE_INFO_GLOBAL_RSV)
>>
>> #define BTRFS_BLOCK_GROUP_TYPE_MASK (BTRFS_BLOCK_GROUP_DATA | \
>> BTRFS_BLOCK_GROUP_SYSTEM | \
>> - BTRFS_BLOCK_GROUP_METADATA)
>> + BTRFS_BLOCK_GROUP_METADATA | \
>> + BTRFS_BLOCK_GROUP_REMAP)
>>
>> #define BTRFS_BLOCK_GROUP_PROFILE_MASK (BTRFS_BLOCK_GROUP_RAID0 | \
>> BTRFS_BLOCK_GROUP_RAID1 | \
>> --
>> 2.49.1
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag
2025-10-15 3:55 ` Boris Burkov
@ 2025-10-20 11:32 ` Mark Harmstone
2025-10-20 17:44 ` Boris Burkov
0 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-20 11:32 UTC (permalink / raw)
To: Boris Burkov; +Cc: linux-btrfs
On 15/10/2025 4.55 am, Boris Burkov wrote:
> On Thu, Oct 09, 2025 at 12:28:02PM +0100, Mark Harmstone wrote:
>> If we encounter a filesystem with the remap-tree incompat flag set,
>> valdiate its compatibility with the other flags, and load the remap tree
>> using the values that have been added to the superblock.
>>
>> The remap-tree feature depends on the free space tere, but no-holes and
>> block-group-tree have been made dependencies to reduce the testing
>> matrix. Similarly I'm not aware of any reason why mixed-bg and zoned would be
>> incompatible with remap-tree, but this is blocked for the time being
>> until it can be fully tested.
>>
>
> Bonus points on offer for moving the open ctree bit as late as humanly
> possible for that good "partial ordering" self documentation. (Or
> explaining why it is already so).
>
> Thanks.
>
> Reviewed-by: Boris Burkov <boris@bur.io>
>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>> ---
>> fs/btrfs/Kconfig | 2 +
>> fs/btrfs/accessors.h | 6 ++
>> fs/btrfs/disk-io.c | 101 ++++++++++++++++++++++++++++----
>> fs/btrfs/extent-tree.c | 2 +
>> fs/btrfs/fs.h | 4 +-
>> fs/btrfs/transaction.c | 7 +++
>> include/uapi/linux/btrfs_tree.h | 5 +-
>> 7 files changed, 113 insertions(+), 14 deletions(-)
>>
>> diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
>> index 4438637c8900..77b5a9f27840 100644
>> --- a/fs/btrfs/Kconfig
>> +++ b/fs/btrfs/Kconfig
>> @@ -117,4 +117,6 @@ config BTRFS_EXPERIMENTAL
>>
>> - large folio support
>>
>> + - remap-tree - logical address remapping tree
>> +
>> If unsure, say N.
>> diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
>> index 0dd161ee6863..392eaad75e72 100644
>> --- a/fs/btrfs/accessors.h
>> +++ b/fs/btrfs/accessors.h
>> @@ -882,6 +882,12 @@ BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
>> uuid_tree_generation, 64);
>> BTRFS_SETGET_STACK_FUNCS(super_nr_global_roots, struct btrfs_super_block,
>> nr_global_roots, 64);
>> +BTRFS_SETGET_STACK_FUNCS(super_remap_root, struct btrfs_super_block,
>> + remap_root, 64);
>> +BTRFS_SETGET_STACK_FUNCS(super_remap_root_generation, struct btrfs_super_block,
>> + remap_root_generation, 64);
>> +BTRFS_SETGET_STACK_FUNCS(super_remap_root_level, struct btrfs_super_block,
>> + remap_root_level, 8);
>>
>> /* struct btrfs_file_extent_item */
>> BTRFS_SETGET_STACK_FUNCS(stack_file_extent_type, struct btrfs_file_extent_item,
>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>> index 92cb789957b4..60507e971aad 100644
>> --- a/fs/btrfs/disk-io.c
>> +++ b/fs/btrfs/disk-io.c
>> @@ -1180,6 +1180,8 @@ static struct btrfs_root *btrfs_get_global_root(struct btrfs_fs_info *fs_info,
>> return btrfs_grab_root(btrfs_global_root(fs_info, &key));
>> case BTRFS_RAID_STRIPE_TREE_OBJECTID:
>> return btrfs_grab_root(fs_info->stripe_root);
>> + case BTRFS_REMAP_TREE_OBJECTID:
>> + return btrfs_grab_root(fs_info->remap_root);
>> default:
>> return NULL;
>> }
>> @@ -1271,6 +1273,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
>> btrfs_put_root(fs_info->data_reloc_root);
>> btrfs_put_root(fs_info->block_group_root);
>> btrfs_put_root(fs_info->stripe_root);
>> + btrfs_put_root(fs_info->remap_root);
>> btrfs_check_leaked_roots(fs_info);
>> btrfs_extent_buffer_leak_debug_check(fs_info);
>> kfree(fs_info->super_copy);
>> @@ -1825,6 +1828,7 @@ static void free_root_pointers(struct btrfs_fs_info *info, bool free_chunk_root)
>> free_root_extent_buffers(info->data_reloc_root);
>> free_root_extent_buffers(info->block_group_root);
>> free_root_extent_buffers(info->stripe_root);
>> + free_root_extent_buffers(info->remap_root);
>> if (free_chunk_root)
>> free_root_extent_buffers(info->chunk_root);
>> }
>> @@ -2256,20 +2260,45 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
>> if (ret)
>> goto out;
>>
>> - /*
>> - * This tree can share blocks with some other fs tree during relocation
>> - * and we need a proper setup by btrfs_get_fs_root
>> - */
>> - root = btrfs_get_fs_root(tree_root->fs_info,
>> - BTRFS_DATA_RELOC_TREE_OBJECTID, true);
>> - if (IS_ERR(root)) {
>> - if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
>> - ret = PTR_ERR(root);
>> - goto out;
>> + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
>> + /* remap_root already loaded in load_important_roots() */
>> + root = fs_info->remap_root;
>> +
>> + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
>> +
>> + root->root_key.objectid = BTRFS_REMAP_TREE_OBJECTID;
>> + root->root_key.type = BTRFS_ROOT_ITEM_KEY;
>> + root->root_key.offset = 0;
>> +
>> + /* Check that data reloc tree doesn't also exist */
>> + location.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
>> + root = btrfs_read_tree_root(fs_info->tree_root, &location);
>> + if (!IS_ERR(root)) {
>> + btrfs_err(fs_info,
>> + "data reloc tree exists when remap-tree enabled");
>> + btrfs_put_root(root);
>> + return -EIO;
>> + } else if (PTR_ERR(root) != -ENOENT) {
>> + btrfs_warn(fs_info,
>> + "error %ld when checking for data reloc tree",
>> + PTR_ERR(root));
>> }
>> } else {
>> - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
>> - fs_info->data_reloc_root = root;
>> + /*
>> + * This tree can share blocks with some other fs tree during
>> + * relocation and we need a proper setup by btrfs_get_fs_root
>> + */
>> + root = btrfs_get_fs_root(tree_root->fs_info,
>> + BTRFS_DATA_RELOC_TREE_OBJECTID, true);
>> + if (IS_ERR(root)) {
>> + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
>> + ret = PTR_ERR(root);
>> + goto out;
>> + }
>> + } else {
>> + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
>> + fs_info->data_reloc_root = root;
>> + }
>> }
>>
>> location.objectid = BTRFS_QUOTA_TREE_OBJECTID;
>> @@ -2509,6 +2538,31 @@ int btrfs_validate_super(const struct btrfs_fs_info *fs_info,
>> ret = -EINVAL;
>> }
>>
>> + /*
>> + * Reduce test matrix for remap tree by requiring block-group-tree
>> + * and no-holes. Free-space-tree is a hard requirement.
>> + */
>> + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
>> + (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID) ||
>> + !btrfs_fs_incompat(fs_info, NO_HOLES) ||
>> + !btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE))) {
>> + btrfs_err(fs_info,
>> +"remap-tree feature requires free-space-tree, no-holes, and block-group-tree");
>> + ret = -EINVAL;
>> + }
>> +
>> + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
>> + btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
>> + btrfs_err(fs_info, "remap-tree not supported with mixed-bg");
>> + ret = -EINVAL;
>> + }
>> +
>> + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
>> + btrfs_fs_incompat(fs_info, ZONED)) {
>> + btrfs_err(fs_info, "remap-tree not supported with zoned devices");
>> + ret = -EINVAL;
>> + }
>> +
>> /*
>> * Hint to catch really bogus numbers, bitflips or so, more exact checks are
>> * done later
>> @@ -2667,6 +2721,18 @@ static int load_important_roots(struct btrfs_fs_info *fs_info)
>> btrfs_warn(fs_info, "couldn't read tree root");
>> return ret;
>> }
>> +
>> + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
>> + bytenr = btrfs_super_remap_root(sb);
>> + gen = btrfs_super_remap_root_generation(sb);
>> + level = btrfs_super_remap_root_level(sb);
>> + ret = load_super_root(fs_info->remap_root, bytenr, gen, level);
>> + if (ret) {
>> + btrfs_warn(fs_info, "couldn't read remap root");
>> + return ret;
>> + }
>> + }
>> +
>> return 0;
>> }
>>
>> @@ -3284,6 +3350,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
>> struct btrfs_fs_info *fs_info = btrfs_sb(sb);
>> struct btrfs_root *tree_root;
>> struct btrfs_root *chunk_root;
>> + struct btrfs_root *remap_root;
>> int ret;
>> int level;
>>
>> @@ -3417,6 +3484,16 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
>> if (ret < 0)
>> goto fail_alloc;
>>
>> + if (btrfs_super_incompat_flags(disk_super) & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
>> + remap_root = btrfs_alloc_root(fs_info, BTRFS_REMAP_TREE_OBJECTID,
>> + GFP_KERNEL);
>> + fs_info->remap_root = remap_root;
>> + if (!remap_root) {
>> + ret = -ENOMEM;
>> + goto fail_alloc;
>> + }
>> + }
>> +
>
> Thanks for scooting it down. Does this need to be before reading the sys
> array / chunk tree? I would guess no, as we can't remap that, but
> perhaps I have misunderstood.
Yes, that's right. The dependency ordering when loading is:
1. System chunks (contained in superblock)
2. Chunk tree (located in system chunks)
3. Remap tree (needs chunk tree to map logicals to physicals, logical address is in superblock)
4. Root tree (may be remapped)
5. All other trees (found in root tree)
>> /*
>> * At this point our mount options are validated, if we set ->max_inline
>> * to something non-standard make sure we truncate it to sectorsize.
>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>> index d964147b8097..7805a148bbd8 100644
>> --- a/fs/btrfs/extent-tree.c
>> +++ b/fs/btrfs/extent-tree.c
>> @@ -2589,6 +2589,8 @@ static u64 get_alloc_profile_by_root(struct btrfs_root *root, int data)
>> flags = BTRFS_BLOCK_GROUP_DATA;
>> else if (root == fs_info->chunk_root)
>> flags = BTRFS_BLOCK_GROUP_SYSTEM;
>> + else if (root == fs_info->remap_root)
>> + flags = BTRFS_BLOCK_GROUP_REMAP;
>> else
>> flags = BTRFS_BLOCK_GROUP_METADATA;
>>
>> diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
>> index c4dba7e7ce5a..c76f4c2701f9 100644
>> --- a/fs/btrfs/fs.h
>> +++ b/fs/btrfs/fs.h
>> @@ -291,7 +291,8 @@ enum {
>> #define BTRFS_FEATURE_INCOMPAT_SUPP \
>> (BTRFS_FEATURE_INCOMPAT_SUPP_STABLE | \
>> BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE | \
>> - BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2)
>> + BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2 | \
>> + BTRFS_FEATURE_INCOMPAT_REMAP_TREE)
>>
>> #else
>>
>> @@ -451,6 +452,7 @@ struct btrfs_fs_info {
>> struct btrfs_root *data_reloc_root;
>> struct btrfs_root *block_group_root;
>> struct btrfs_root *stripe_root;
>> + struct btrfs_root *remap_root;
>>
>> /* The log root tree is a directory of all the other log roots */
>> struct btrfs_root *log_root_tree;
>> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
>> index 89ae0c7a610a..b1c41982e7b2 100644
>> --- a/fs/btrfs/transaction.c
>> +++ b/fs/btrfs/transaction.c
>> @@ -1950,6 +1950,13 @@ static void update_super_roots(struct btrfs_fs_info *fs_info)
>> super->cache_generation = 0;
>> if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
>> super->uuid_tree_generation = root_item->generation;
>> +
>> + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
>> + root_item = &fs_info->remap_root->root_item;
>> + super->remap_root = root_item->bytenr;
>> + super->remap_root_generation = root_item->generation;
>> + super->remap_root_level = root_item->level;
>> + }
>> }
>>
>> int btrfs_transaction_blocked(struct btrfs_fs_info *info)
>> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
>> index 500e3a7df90b..89bcb80081a6 100644
>> --- a/include/uapi/linux/btrfs_tree.h
>> +++ b/include/uapi/linux/btrfs_tree.h
>> @@ -721,9 +721,12 @@ struct btrfs_super_block {
>> __u8 metadata_uuid[BTRFS_FSID_SIZE];
>>
>> __u64 nr_global_roots;
>> + __le64 remap_root;
>> + __le64 remap_root_generation;
>> + __u8 remap_root_level;
>>
>> /* Future expansion */
>> - __le64 reserved[27];
>> + __u8 reserved[199];
>> __u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
>> struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
>>
>> --
>> 2.49.1
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 03/17] btrfs: allow remapped chunks to have zero stripes
2025-10-15 3:47 ` Boris Burkov
@ 2025-10-20 12:15 ` Mark Harmstone
0 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-20 12:15 UTC (permalink / raw)
To: Boris Burkov; +Cc: linux-btrfs
On 15/10/2025 4.47 am, Boris Burkov wrote:
> On Thu, Oct 09, 2025 at 12:27:58PM +0100, Mark Harmstone wrote:
>> When a chunk has been fully remapped, we are going to set its
>> num_stripes to 0, as it will no longer represent a physical location on
>> disk.
>>
>> Change tree-checker to allow for this, and fix a couple of
>> divide-by-zeroes seen elsewhere.
>>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>
> This one feels close to me but I still have a few reservations. Happy to
> discuss the details a bit more, of course.
>
>> ---
>> fs/btrfs/tree-checker.c | 65 ++++++++++++++++++++++++++++-------------
>> fs/btrfs/volumes.c | 13 ++++++++-
>> 2 files changed, 57 insertions(+), 21 deletions(-)
>>
>> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
>> index 62f35338a555..59b1393e5018 100644
>> --- a/fs/btrfs/tree-checker.c
>> +++ b/fs/btrfs/tree-checker.c
>> @@ -816,6 +816,41 @@ static void chunk_err(const struct btrfs_fs_info *fs_info,
>> va_end(args);
>> }
>>
>> +static bool valid_stripe_count(u64 profile, u16 num_stripes,
>> + u16 sub_stripes)
>> +{
>> + switch (profile) {
>> + case BTRFS_BLOCK_GROUP_RAID0:
>> + return true;
>> + case BTRFS_BLOCK_GROUP_RAID10:
>> + return sub_stripes ==
>> + btrfs_raid_array[BTRFS_RAID_RAID10].sub_stripes;
>> + case BTRFS_BLOCK_GROUP_RAID1:
>> + return num_stripes ==
>> + btrfs_raid_array[BTRFS_RAID_RAID1].devs_min;
>> + case BTRFS_BLOCK_GROUP_RAID1C3:
>> + return num_stripes ==
>> + btrfs_raid_array[BTRFS_RAID_RAID1C3].devs_min;
>> + case BTRFS_BLOCK_GROUP_RAID1C4:
>> + return num_stripes ==
>> + btrfs_raid_array[BTRFS_RAID_RAID1C4].devs_min;
>> + case BTRFS_BLOCK_GROUP_RAID5:
>> + return num_stripes >=
>> + btrfs_raid_array[BTRFS_RAID_RAID5].devs_min;
>> + case BTRFS_BLOCK_GROUP_RAID6:
>> + return num_stripes >=
>> + btrfs_raid_array[BTRFS_RAID_RAID6].devs_min;
>> + case BTRFS_BLOCK_GROUP_DUP:
>> + return num_stripes ==
>> + btrfs_raid_array[BTRFS_RAID_DUP].dev_stripes;
>> + case 0: /* SINGLE */
>> + return num_stripes ==
>> + btrfs_raid_array[BTRFS_RAID_SINGLE].dev_stripes;
>> + default:
>> + BUG();
>> + }
>> +}
>> +
>> /*
>> * The common chunk check which could also work on super block sys chunk array.
>> *
>> @@ -839,6 +874,7 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
>> u64 features;
>> u32 chunk_sector_size;
>> bool mixed = false;
>> + bool remapped;
>> int raid_index;
>> int nparity;
>> int ncopies;
>> @@ -862,12 +898,14 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
>> ncopies = btrfs_raid_array[raid_index].ncopies;
>> nparity = btrfs_raid_array[raid_index].nparity;
>>
>> - if (unlikely(!num_stripes)) {
>> + remapped = type & BTRFS_BLOCK_GROUP_REMAPPED;
>> +
>> + if (unlikely(!remapped && !num_stripes)) {
>> chunk_err(fs_info, leaf, chunk, logical,
>> "invalid chunk num_stripes, have %u", num_stripes);
>> return -EUCLEAN;
>> }
>> - if (unlikely(num_stripes < ncopies)) {
>> + if (unlikely(num_stripes != 0 && num_stripes < ncopies)) {
>> chunk_err(fs_info, leaf, chunk, logical,
>> "invalid chunk num_stripes < ncopies, have %u < %d",
>> num_stripes, ncopies);
>> @@ -965,22 +1003,9 @@ int btrfs_check_chunk_valid(const struct btrfs_fs_info *fs_info,
>> }
>> }
>>
>> - if (unlikely((type & BTRFS_BLOCK_GROUP_RAID10 &&
>> - sub_stripes != btrfs_raid_array[BTRFS_RAID_RAID10].sub_stripes) ||
>> - (type & BTRFS_BLOCK_GROUP_RAID1 &&
>> - num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1].devs_min) ||
>> - (type & BTRFS_BLOCK_GROUP_RAID1C3 &&
>> - num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1C3].devs_min) ||
>> - (type & BTRFS_BLOCK_GROUP_RAID1C4 &&
>> - num_stripes != btrfs_raid_array[BTRFS_RAID_RAID1C4].devs_min) ||
>> - (type & BTRFS_BLOCK_GROUP_RAID5 &&
>> - num_stripes < btrfs_raid_array[BTRFS_RAID_RAID5].devs_min) ||
>> - (type & BTRFS_BLOCK_GROUP_RAID6 &&
>> - num_stripes < btrfs_raid_array[BTRFS_RAID_RAID6].devs_min) ||
>> - (type & BTRFS_BLOCK_GROUP_DUP &&
>> - num_stripes != btrfs_raid_array[BTRFS_RAID_DUP].dev_stripes) ||
>> - ((type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 &&
>> - num_stripes != btrfs_raid_array[BTRFS_RAID_SINGLE].dev_stripes))) {
>> + if (!remapped &&
>> + !valid_stripe_count(type & BTRFS_BLOCK_GROUP_PROFILE_MASK,
>> + num_stripes, sub_stripes)) {
>
> Is num_stripes == 0 valid for raid 0 aside from remapped?
It's not, but this is caught earlier in the function.
In an earlier version of this patchset I didn't notice that RAID0 wasn't accounted for
in the big if, which led to a BUG() that the robot caught.
valid_stripe_count() is replicating the functionality of the big if. From the looks of
things it's valid for RAID0 to have a single stripe, which is surprising.
>> chunk_err(fs_info, leaf, chunk, logical,
>> "invalid num_stripes:sub_stripes %u:%u for profile %llu",
>> num_stripes, sub_stripes,
>> @@ -1004,11 +1029,11 @@ static int check_leaf_chunk_item(struct extent_buffer *leaf,
>> struct btrfs_fs_info *fs_info = leaf->fs_info;
>> int num_stripes;
>>
>> - if (unlikely(btrfs_item_size(leaf, slot) < sizeof(struct btrfs_chunk))) {
>> + if (unlikely(btrfs_item_size(leaf, slot) < offsetof(struct btrfs_chunk, stripe))) {
>
> Does this need a remapped parameter as part of the check too?
Probably not. It's checking that the chunk item is long enough that the num_stripes we
read won't be nonsense, and then later on in the function checks the size again taking
this into account.
>
>> chunk_err(fs_info, leaf, chunk, key->offset,
>> "invalid chunk item size: have %u expect [%zu, %u)",
>> btrfs_item_size(leaf, slot),
>> - sizeof(struct btrfs_chunk),
>> + offsetof(struct btrfs_chunk, stripe),
>> BTRFS_LEAF_DATA_SIZE(fs_info));
>> return -EUCLEAN;
>> }
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index e14b86e2996b..6750f6f0af59 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -6145,6 +6145,12 @@ struct btrfs_discard_stripe *btrfs_map_discard(struct btrfs_fs_info *fs_info,
>> goto out_free_map;
>> }
>>
>> + /* avoid divide by zero on fully-remapped chunks */
>> + if (map->num_stripes == 0) {
>> + ret = -EOPNOTSUPP;
>> + goto out_free_map;
>> + }
>> +
>
> I'll reconsider this when I read the discard stuff more closely, but
> aren't you intending to discard fully remapped chunks? So this seems
> counter-intuitive at best. Since you tested it, I assume it must work,
> just saying since it stuck out to me..
This only kicks in when the do_remap parameter is false. Quite possibly this check isn't
necessary anymore, I wrote it before I did the async discard stuff. Let me check.
>
>> offset = logical - map->start;
>> length = min_t(u64, map->start + map->chunk_len - logical, length);
>> *length_ret = length;
>> @@ -7088,7 +7094,12 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
>> */
>> map->sub_stripes = btrfs_raid_array[index].sub_stripes;
>> map->verified_stripes = 0;
>> - map->stripe_size = btrfs_calc_stripe_length(map);
>> +
>> + if (num_stripes > 0)
>> + map->stripe_size = btrfs_calc_stripe_length(map);
>> + else
>> + map->stripe_size = 0;
>> +
>> for (i = 0; i < num_stripes; i++) {
>> map->stripes[i].physical =
>> btrfs_stripe_offset_nr(leaf, chunk, i);
>> --
>> 2.49.1
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups
2025-10-15 4:21 ` Boris Burkov
@ 2025-10-20 14:31 ` Mark Harmstone
2025-10-20 17:44 ` Boris Burkov
0 siblings, 1 reply; 38+ messages in thread
From: Mark Harmstone @ 2025-10-20 14:31 UTC (permalink / raw)
To: Boris Burkov; +Cc: linux-btrfs
On 15/10/2025 5.21 am, Boris Burkov wrote:
> On Thu, Oct 09, 2025 at 12:28:03PM +0100, Mark Harmstone wrote:
>> Change btrfs_map_block() so that if the block group has the REMAPPED
>> flag set, we call btrfs_translate_remap() to obtain a new address.
>>
>> btrfs_translate_remap() searches the remap tree for a range
>> corresponding to the logical address passed to btrfs_map_block(). If it
>> is within an identity remap, this part of the block group hasn't yet
>> been relocated, and so we use the existing address.
>>
>> If it is within an actual remap, we subtract the start of the remap
>> range and add the address of its destination, contained in the item's
>> payload.
>>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>> ---
>> fs/btrfs/relocation.c | 59 +++++++++++++++++++++++++++++++++++++++++++
>> fs/btrfs/relocation.h | 2 ++
>> fs/btrfs/volumes.c | 31 +++++++++++++++++++++++
>> 3 files changed, 92 insertions(+)
>>
>> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
>> index 748290758459..4f5d3aaf0f65 100644
>> --- a/fs/btrfs/relocation.c
>> +++ b/fs/btrfs/relocation.c
>> @@ -3870,6 +3870,65 @@ static const char *stage_to_string(enum reloc_stage stage)
>> return "unknown";
>> }
>>
>> +int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
>> + u64 *length, bool nolock)
>> +{
>> + int ret;
>> + struct btrfs_key key, found_key;
>> + struct extent_buffer *leaf;
>> + struct btrfs_remap *remap;
>> + BTRFS_PATH_AUTO_FREE(path);
>> +
>> + path = btrfs_alloc_path();
>> + if (!path)
>> + return -ENOMEM;
>> +
>> + if (nolock) {
>> + path->search_commit_root = 1;
>> + path->skip_locking = 1;
>> + }
>> +
>> + key.objectid = *logical;
>> + key.type = (u8)-1;
>> + key.offset = (u64)-1;
>> +
>> + ret = btrfs_search_slot(NULL, fs_info->remap_root, &key, path,
>> + 0, 0);
>> + if (ret < 0)
>> + return ret;
>> +
>> + leaf = path->nodes[0];
>> +
>> + if (path->slots[0] == 0)
>> + return -ENOENT;
>> +
>> + path->slots[0]--;
>> +
>> + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
>> +
>> + if (found_key.type != BTRFS_REMAP_KEY &&
>> + found_key.type != BTRFS_IDENTITY_REMAP_KEY) {
>> + return -ENOENT;
>> + }
>> +
>> + if (found_key.objectid > *logical ||
>> + found_key.objectid + found_key.offset <= *logical) {
>> + return -ENOENT;
>> + }
>> +
>> + if (*logical + *length > found_key.objectid + found_key.offset)
>> + *length = found_key.objectid + found_key.offset - *logical;
>> +
>> + if (found_key.type == BTRFS_IDENTITY_REMAP_KEY)
>> + return 0;
>> +
>> + remap = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_remap);
>> +
>> + *logical += btrfs_remap_address(leaf, remap) - found_key.objectid;
>> +
>> + return 0;
>> +}
>> +
>> /*
>> * function to relocate all extents in a block group.
>> */
>> diff --git a/fs/btrfs/relocation.h b/fs/btrfs/relocation.h
>> index 5c36b3f84b57..a653c42a25a3 100644
>> --- a/fs/btrfs/relocation.h
>> +++ b/fs/btrfs/relocation.h
>> @@ -31,5 +31,7 @@ int btrfs_should_cancel_balance(const struct btrfs_fs_info *fs_info);
>> struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr);
>> bool btrfs_should_ignore_reloc_root(const struct btrfs_root *root);
>> u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info);
>> +int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
>> + u64 *length, bool nolock);
>>
>> #endif
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index 0abe02a7072f..f2d1203778aa 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -6635,6 +6635,37 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
>> if (IS_ERR(map))
>> return PTR_ERR(map);
>>
>> + if (map->type & BTRFS_BLOCK_GROUP_REMAPPED) {
>> + u64 new_logical = logical;
>> + bool nolock = !(map->type & BTRFS_BLOCK_GROUP_DATA);
>
> Why not data?
Because I thought we'd maxed out our lockdep classes so this was the only way to
prevent lockdep from complaining about metadata reads - not yet knowing about
the btrfs_lockdep_keysets array.
I think I'm going to remove the search_commit_root stuff from this patchset, and
leave it for a future optimization. As you know it's full of gotchas.
>> +
>> + /*
>> + * We use search_commit_root in btrfs_translate_remap for
>> + * metadata blocks, to avoid lockdep complaining about
>> + * recursive locking.
>> + * If we get -ENOENT this means this is a BG that has just had
>> + * its REMAPPED flag set, and so nothing has yet been actually
>> + * remapped.
>> + */
>
> I'm actually kind of worried about this now. What is preventing the
> following racy interleaving:
>
> T1 T2
> start_block_group_remapping() // in TXN-K set REMAPPED
> btrfs_map_block()
> btrfs_translate_remap()
> ENOENT // searched in commit root
> do_remap_tree_reloc() // in TXN-K do all remaps
> // fully remapped, removed, discarded
> // TXN-K committed
> // not remapped! but the original chunk map is gone gone
> num_copies = ...
The bits on the right will be separate transactions, I thought that would save
us - does it not? I'm guessing this means that search_commit_root means to
search the last transaction that was flushed to disk, rather than the last
in-memory transaction.
Yes, I'm definitely saving this bit until later.
>> + ret = btrfs_translate_remap(fs_info, &new_logical, length,
>> + nolock);
>> + if (ret && (!nolock || ret != -ENOENT))
>> + return ret;
>> +
>> + if (ret != -ENOENT && new_logical != logical) {
>> + btrfs_free_chunk_map(map);
>> +
>> + map = btrfs_get_chunk_map(fs_info, new_logical,
>> + *length);
>> + if (IS_ERR(map))
>> + return PTR_ERR(map);
>> +
>> + logical = new_logical;
>> + }
>> +
>> + ret = 0;
>> + }
>> +
>> num_copies = btrfs_chunk_map_num_copies(map);
>> if (io_geom.mirror_num > num_copies)
>> return -EINVAL;
>> --
>> 2.49.1
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 17/17] btrfs: add stripe removal pending flag
2025-10-15 5:05 ` Boris Burkov
@ 2025-10-20 14:52 ` Mark Harmstone
0 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-20 14:52 UTC (permalink / raw)
To: Boris Burkov; +Cc: linux-btrfs
On 15/10/2025 6.05 am, Boris Burkov wrote:
> On Thu, Oct 09, 2025 at 12:28:12PM +0100, Mark Harmstone wrote:
>> If the filesystem is unmounted while the async discard of a fully remapped
>> block group is in progress, its unused device extents will never be freed.
>>
>> To counter this, add a new flag BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING
>> to say that this has been interrupted. Set it in the transaction in which
>> the last identity remap has been removed, clear it when we remove the
>> device extents, and if we encounter it on mount queue that block group
>> up for discard.
>
> I don't see how this is special for remapped block groups.
>
> in read_one_block_group() for empty block groups we queue them for async
> discard unconditionally. There is a comment to this effect in discard.c
> about crashes and mounts behaving the same.
>
> And either way, if we go down at any point before we remove the bg, then
> we will be re-discarding everything we already discarded (possibly the
> whole thing) so this is optimistic anyway, right?
>
> I don't think the benefit of this is worth the special case compared to
> normal unused bgs, and I don't think it makes sense to "take advantage"
> of this format change opportunity to also add the persisted "needs
> discard" bit for all discard.
>
> A persisted "discard state" on the extents would actually be
> interesting, I think, but I don't think that is in scope or even
> necessarily a good idea.
>
> Thanks,
> Boris
So here we need to find block groups that:
* have the REMAPPED flag set
* have identity_remap_count == 0 (i.e. are fully remapped)
* have a corresponding chunk item where num_stripes != 0
They aren't empty in the same way as empty BGs are now: their used value
might be non-zero, meaning that there's extents that are nominally within
the range. The device extents don't get freed until discard has run, so
it's pretty important that this gets done.
The problem is that num_stripes is on the chunk item rather than the BG
item, so you would need to do a lookup in the other tree on mount for
every single fully-remapped BG, on the off chance that one of them hasn't
had its stripes removed. The flag's there to prevent us having to do the
lookup, as we know in advance which BG they will be.
Probably in an ideal world we'd have a merged BG and chunk tree, but we
are where we are.
>>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>> ---
>> fs/btrfs/block-group.c | 35 ++++++++++++++++++++++++++++++++-
>> fs/btrfs/free-space-cache.c | 5 +++++
>> fs/btrfs/relocation.c | 18 +++++++++++++++++
>> include/uapi/linux/btrfs_tree.h | 1 +
>> 4 files changed, 58 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
>> index a7dfa6c95223..851d76ce8ec9 100644
>> --- a/fs/btrfs/block-group.c
>> +++ b/fs/btrfs/block-group.c
>> @@ -2530,6 +2530,16 @@ static int read_one_block_group(struct btrfs_fs_info *info,
>> inc_block_group_ro(cache, 1);
>> }
>>
>> + if (cache->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING) {
>> + btrfs_get_block_group(cache);
>> + spin_lock(&info->unused_bgs_lock);
>> + list_add_tail(&cache->bg_list, &info->fully_remapped_bgs);
>> + spin_unlock(&info->unused_bgs_lock);
>> +
>> + if (btrfs_test_opt(info, DISCARD_ASYNC))
>> + btrfs_discard_queue_work(&info->discard_ctl, cache);
>> + }
>> +
>> return 0;
>> error:
>> btrfs_put_block_group(cache);
>> @@ -4828,6 +4838,29 @@ void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
>>
>> spin_unlock(&fs_info->unused_bgs_lock);
>>
>> - if (btrfs_test_opt(fs_info, DISCARD_ASYNC))
>> + if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
>> + bool bg_already_dirty = true;
>> +
>> + spin_lock(&bg->lock);
>> + bg->flags |= BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING;
>> + spin_unlock(&bg->lock);
>> +
>> + spin_lock(&trans->transaction->dirty_bgs_lock);
>> + if (list_empty(&bg->dirty_list)) {
>> + list_add_tail(&bg->dirty_list,
>> + &trans->transaction->dirty_bgs);
>> + bg_already_dirty = false;
>> + btrfs_get_block_group(bg);
>> + }
>> + spin_unlock(&trans->transaction->dirty_bgs_lock);
>> +
>> + /*
>> + * Modified block groups are accounted for in
>> + * the delayed_refs_rsv.
>> + */
>> + if (!bg_already_dirty)
>> + btrfs_inc_delayed_refs_rsv_bg_updates(trans->fs_info);
>> +
>> btrfs_discard_queue_work(&fs_info->discard_ctl, bg);
>> + }
>> }
>> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
>> index 56f27487b632..813b82294341 100644
>> --- a/fs/btrfs/free-space-cache.c
>> +++ b/fs/btrfs/free-space-cache.c
>> @@ -3065,6 +3065,7 @@ bool btrfs_is_free_space_trimmed(struct btrfs_block_group *block_group)
>> bool ret = true;
>>
>> if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
>> + !(block_group->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING) &&
>> block_group->remap_bytes == 0 &&
>> block_group->identity_remap_count == 0) {
>> return true;
>> @@ -3845,6 +3846,9 @@ void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
>> struct btrfs_trans_handle *trans;
>> struct btrfs_chunk_map *map;
>>
>> + if (!(bg->flags & BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING))
>> + goto skip_discard;
>> +
>> while (bg->discard_cursor < end) {
>> u64 trimmed;
>>
>> @@ -3897,6 +3901,7 @@ void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
>>
>> btrfs_free_chunk_map(map);
>>
>> +skip_discard:
>> if (bg->used == 0) {
>> spin_lock(&fs_info->unused_bgs_lock);
>> list_move_tail(&bg->bg_list, &fs_info->unused_bgs);
>> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
>> index 7bad8d65d145..a179e4a8e960 100644
>> --- a/fs/btrfs/relocation.c
>> +++ b/fs/btrfs/relocation.c
>> @@ -4733,6 +4733,7 @@ int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
>> struct btrfs_block_group *bg)
>> {
>> int ret;
>> + bool bg_already_dirty = true;
>> BTRFS_PATH_AUTO_FREE(path);
>>
>> ret = btrfs_remove_dev_extents(trans, chunk);
>> @@ -4757,6 +4758,23 @@ int btrfs_last_identity_remap_gone(struct btrfs_trans_handle *trans,
>>
>> btrfs_remove_bg_from_sinfo(bg);
>>
>> + spin_lock(&bg->lock);
>> + bg->flags &= ~BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING;
>> + spin_unlock(&bg->lock);
>> +
>> + spin_lock(&trans->transaction->dirty_bgs_lock);
>> + if (list_empty(&bg->dirty_list)) {
>> + list_add_tail(&bg->dirty_list,
>> + &trans->transaction->dirty_bgs);
>> + bg_already_dirty = false;
>> + btrfs_get_block_group(bg);
>> + }
>> + spin_unlock(&trans->transaction->dirty_bgs_lock);
>> +
>> + /* Modified block groups are accounted for in the delayed_refs_rsv. */
>> + if (!bg_already_dirty)
>> + btrfs_inc_delayed_refs_rsv_bg_updates(trans->fs_info);
>> +
>> path = btrfs_alloc_path();
>> if (!path)
>> return -ENOMEM;
>> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
>> index 89bcb80081a6..36a7d1a3cbe3 100644
>> --- a/include/uapi/linux/btrfs_tree.h
>> +++ b/include/uapi/linux/btrfs_tree.h
>> @@ -1173,6 +1173,7 @@ struct btrfs_dev_replace_item {
>> #define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
>> #define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
>> #define BTRFS_BLOCK_GROUP_REMAP (1ULL << 12)
>> +#define BTRFS_BLOCK_GROUP_STRIPE_REMOVAL_PENDING (1ULL << 13)
>> #define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
>> BTRFS_SPACE_INFO_GLOBAL_RSV)
>>
>> --
>> 2.49.1
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 02/17] btrfs: add REMAP chunk type
2025-10-20 9:58 ` Mark Harmstone
@ 2025-10-20 17:35 ` Boris Burkov
0 siblings, 0 replies; 38+ messages in thread
From: Boris Burkov @ 2025-10-20 17:35 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Mon, Oct 20, 2025 at 10:58:55AM +0100, Mark Harmstone wrote:
> Thanks Boris. Have a look at the third paragraph of the commit message, I
> explain the volumes.h changes there.
>
Well, great job reading by me. *facepalm*
Sorry about that..
> On 15/10/2025 4.37 am, Boris Burkov wrote:
> > On Thu, Oct 09, 2025 at 12:27:57PM +0100, Mark Harmstone wrote:
> > > Add a new REMAP chunk type, which is a metadata chunk that holds the
> > > remap tree.
> > >
> > > This is needed for bootstrapping purposes: the remap tree can't itself
> > > be remapped, and must be relocated the existing way, by COWing every
> > > leaf. The remap tree can't go in the SYSTEM chunk as space there is
> > > limited, because a copy of the chunk item gets placed in the superblock.
> > >
> > > The changes in fs/btrfs/volumes.h are because we're adding a new block
> > > group type bit after the profile bits, and so can no longer rely on the
> > > const_ilog2 trick.
> > >
> > > The sizing to 32MB per chunk, matching the SYSTEM chunk, is an estimate
> > > here, we can adjust it later if it proves to be too big or too small.
> > > This works out to be ~500,000 remap items, which for a 4KB block size
> > > covers ~2GB of remapped data in the worst case and ~500TB in the best case.
> > >
> >
> > Asked a relatively inconsequential question about static asserts in
> > volumes.h. Otherwise,
> >
> > Reviewed-by: Boris Burkov <boris@bur.io>
> >
> > > Signed-off-by: Mark Harmstone <mark@harmstone.com>
> > > ---
> > > fs/btrfs/block-rsv.c | 8 ++++++++
> > > fs/btrfs/block-rsv.h | 1 +
> > > fs/btrfs/disk-io.c | 1 +
> > > fs/btrfs/fs.h | 2 ++
> > > fs/btrfs/space-info.c | 13 ++++++++++++-
> > > fs/btrfs/sysfs.c | 2 ++
> > > fs/btrfs/tree-checker.c | 13 +++++++++++--
> > > fs/btrfs/volumes.c | 3 +++
> > > fs/btrfs/volumes.h | 11 +++++++++--
> > > include/uapi/linux/btrfs_tree.h | 4 +++-
> > > 10 files changed, 52 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
> > > index 5ad6de738aee..2678cd3bed29 100644
> > > --- a/fs/btrfs/block-rsv.c
> > > +++ b/fs/btrfs/block-rsv.c
> > > @@ -421,6 +421,9 @@ void btrfs_init_root_block_rsv(struct btrfs_root *root)
> > > case BTRFS_TREE_LOG_OBJECTID:
> > > root->block_rsv = &fs_info->treelog_rsv;
> > > break;
> > > + case BTRFS_REMAP_TREE_OBJECTID:
> > > + root->block_rsv = &fs_info->remap_block_rsv;
> > > + break;
> > > default:
> > > root->block_rsv = NULL;
> > > break;
> > > @@ -434,6 +437,9 @@ void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
> > > space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
> > > fs_info->chunk_block_rsv.space_info = space_info;
> > > + space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_REMAP);
> > > + fs_info->remap_block_rsv.space_info = space_info;
> > > +
> > > space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
> > > fs_info->global_block_rsv.space_info = space_info;
> > > fs_info->trans_block_rsv.space_info = space_info;
> > > @@ -460,6 +466,8 @@ void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
> > > WARN_ON(fs_info->trans_block_rsv.reserved > 0);
> > > WARN_ON(fs_info->chunk_block_rsv.size > 0);
> > > WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
> > > + WARN_ON(fs_info->remap_block_rsv.size > 0);
> > > + WARN_ON(fs_info->remap_block_rsv.reserved > 0);
> > > WARN_ON(fs_info->delayed_block_rsv.size > 0);
> > > WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
> > > WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
> > > diff --git a/fs/btrfs/block-rsv.h b/fs/btrfs/block-rsv.h
> > > index 79ae9d05cd91..8359fb96bc3c 100644
> > > --- a/fs/btrfs/block-rsv.h
> > > +++ b/fs/btrfs/block-rsv.h
> > > @@ -22,6 +22,7 @@ enum btrfs_rsv_type {
> > > BTRFS_BLOCK_RSV_DELALLOC,
> > > BTRFS_BLOCK_RSV_TRANS,
> > > BTRFS_BLOCK_RSV_CHUNK,
> > > + BTRFS_BLOCK_RSV_REMAP,
> > > BTRFS_BLOCK_RSV_DELOPS,
> > > BTRFS_BLOCK_RSV_DELREFS,
> > > BTRFS_BLOCK_RSV_TREELOG,
> > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> > > index f475fb2272ac..102e5e0ad10c 100644
> > > --- a/fs/btrfs/disk-io.c
> > > +++ b/fs/btrfs/disk-io.c
> > > @@ -2815,6 +2815,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
> > > BTRFS_BLOCK_RSV_GLOBAL);
> > > btrfs_init_block_rsv(&fs_info->trans_block_rsv, BTRFS_BLOCK_RSV_TRANS);
> > > btrfs_init_block_rsv(&fs_info->chunk_block_rsv, BTRFS_BLOCK_RSV_CHUNK);
> > > + btrfs_init_block_rsv(&fs_info->remap_block_rsv, BTRFS_BLOCK_RSV_REMAP);
> > > btrfs_init_block_rsv(&fs_info->treelog_rsv, BTRFS_BLOCK_RSV_TREELOG);
> > > btrfs_init_block_rsv(&fs_info->empty_block_rsv, BTRFS_BLOCK_RSV_EMPTY);
> > > btrfs_init_block_rsv(&fs_info->delayed_block_rsv,
> > > diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
> > > index 814bbc9417d2..c4dba7e7ce5a 100644
> > > --- a/fs/btrfs/fs.h
> > > +++ b/fs/btrfs/fs.h
> > > @@ -485,6 +485,8 @@ struct btrfs_fs_info {
> > > struct btrfs_block_rsv trans_block_rsv;
> > > /* Block reservation for chunk tree */
> > > struct btrfs_block_rsv chunk_block_rsv;
> > > + /* Block reservation for remap tree */
> > > + struct btrfs_block_rsv remap_block_rsv;
> > > /* Block reservation for delayed operations */
> > > struct btrfs_block_rsv delayed_block_rsv;
> > > /* Block reservation for delayed refs */
> > > diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
> > > index 04a07d6f8537..22bc95f33a6f 100644
> > > --- a/fs/btrfs/space-info.c
> > > +++ b/fs/btrfs/space-info.c
> > > @@ -215,7 +215,7 @@ static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
> > > if (flags & BTRFS_BLOCK_GROUP_DATA)
> > > return BTRFS_MAX_DATA_CHUNK_SIZE;
> > > - else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
> > > + else if (flags & (BTRFS_BLOCK_GROUP_SYSTEM | BTRFS_BLOCK_GROUP_REMAP))
> > > return SZ_32M;
> > > /* Handle BTRFS_BLOCK_GROUP_METADATA */
> > > @@ -343,6 +343,8 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
> > > if (mixed) {
> > > flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
> > > ret = create_space_info(fs_info, flags);
> > > + if (ret)
> > > + goto out;
> > > } else {
> > > flags = BTRFS_BLOCK_GROUP_METADATA;
> > > ret = create_space_info(fs_info, flags);
> > > @@ -351,7 +353,15 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
> > > flags = BTRFS_BLOCK_GROUP_DATA;
> > > ret = create_space_info(fs_info, flags);
> > > + if (ret)
> > > + goto out;
> > > + }
> > > +
> > > + if (features & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
> > > + flags = BTRFS_BLOCK_GROUP_REMAP;
> > > + ret = create_space_info(fs_info, flags);
> > > }
> > > +
> > > out:
> > > return ret;
> > > }
> > > @@ -590,6 +600,7 @@ static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
> > > DUMP_BLOCK_RSV(fs_info, global_block_rsv);
> > > DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
> > > DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
> > > + DUMP_BLOCK_RSV(fs_info, remap_block_rsv);
> > > DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
> > > DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
> > > }
> > > diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
> > > index 857d2772db1c..f942fde1d936 100644
> > > --- a/fs/btrfs/sysfs.c
> > > +++ b/fs/btrfs/sysfs.c
> > > @@ -1973,6 +1973,8 @@ static const char *alloc_name(struct btrfs_space_info *space_info)
> > > case BTRFS_BLOCK_GROUP_SYSTEM:
> > > ASSERT(space_info->subgroup_id == BTRFS_SUB_GROUP_PRIMARY);
> > > return "system";
> > > + case BTRFS_BLOCK_GROUP_REMAP:
> > > + return "remap";
> > > default:
> > > WARN_ON(1);
> > > return "invalid-combination";
> > > diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> > > index 9c03aeb6f2c7..62f35338a555 100644
> > > --- a/fs/btrfs/tree-checker.c
> > > +++ b/fs/btrfs/tree-checker.c
> > > @@ -748,17 +748,26 @@ static int check_block_group_item(struct extent_buffer *leaf,
> > > return -EUCLEAN;
> > > }
> > > + if (flags & BTRFS_BLOCK_GROUP_REMAP &&
> > > + !btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> > > + block_group_err(leaf, slot,
> > > +"invalid flags, have 0x%llx (REMAP flag set) but no remap-tree incompat flag",
> > > + flags);
> > > + return -EUCLEAN;
> > > + }
> > > +
> > > type = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
> > > if (unlikely(type != BTRFS_BLOCK_GROUP_DATA &&
> > > type != BTRFS_BLOCK_GROUP_METADATA &&
> > > type != BTRFS_BLOCK_GROUP_SYSTEM &&
> > > + type != BTRFS_BLOCK_GROUP_REMAP &&
> > > type != (BTRFS_BLOCK_GROUP_METADATA |
> > > BTRFS_BLOCK_GROUP_DATA))) {
> > > block_group_err(leaf, slot,
> > > -"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx or 0x%llx",
> > > +"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx, 0x%llx or 0x%llx",
> > > type, hweight64(type),
> > > BTRFS_BLOCK_GROUP_DATA, BTRFS_BLOCK_GROUP_METADATA,
> > > - BTRFS_BLOCK_GROUP_SYSTEM,
> > > + BTRFS_BLOCK_GROUP_SYSTEM, BTRFS_BLOCK_GROUP_REMAP,
> > > BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
> > > return -EUCLEAN;
> > > }
> > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> > > index 2e144ebd56ac..e14b86e2996b 100644
> > > --- a/fs/btrfs/volumes.c
> > > +++ b/fs/btrfs/volumes.c
> > > @@ -231,6 +231,9 @@ void btrfs_describe_block_groups(u64 bg_flags, char *buf, u32 size_buf)
> > > DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_DATA, "data");
> > > DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_SYSTEM, "system");
> > > DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_METADATA, "metadata");
> > > + /* block groups containing the remap tree */
> > > + DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAP, "remap");
> > > + /* block group that has been remapped */
> > > DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAPPED, "remapped");
> > > DESCRIBE_FLAG(BTRFS_AVAIL_ALLOC_BIT_SINGLE, "single");
> > > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> > > index 2cbf8080eade..b0fa8eb38060 100644
> > > --- a/fs/btrfs/volumes.h
> > > +++ b/fs/btrfs/volumes.h
> > > @@ -58,8 +58,6 @@ static_assert(const_ilog2(BTRFS_STRIPE_LEN) == BTRFS_STRIPE_LEN_SHIFT);
> > > */
> > > static_assert(const_ffs(BTRFS_BLOCK_GROUP_RAID0) <
> > > const_ffs(BTRFS_BLOCK_GROUP_PROFILE_MASK & ~BTRFS_BLOCK_GROUP_RAID0));
> > > -static_assert(const_ilog2(BTRFS_BLOCK_GROUP_RAID0) >
> > > - ilog2(BTRFS_BLOCK_GROUP_TYPE_MASK));
> > > /* ilog2() can handle both constants and variables */
> > > #define BTRFS_BG_FLAG_TO_INDEX(profile) \
> > > @@ -81,6 +79,15 @@ enum btrfs_raid_types {
> > > BTRFS_NR_RAID_TYPES
> > > };
> > > +static_assert(BTRFS_RAID_RAID0 == 1);
> > > +static_assert(BTRFS_RAID_RAID1 == 2);
> > > +static_assert(BTRFS_RAID_DUP == 3);
> > > +static_assert(BTRFS_RAID_RAID10 == 4);
> > > +static_assert(BTRFS_RAID_RAID5 == 5);
> > > +static_assert(BTRFS_RAID_RAID6 == 6);
> > > +static_assert(BTRFS_RAID_RAID1C3 == 7);
> > > +static_assert(BTRFS_RAID_RAID1C4 == 8);
> > > +
> >
> > What is the significance of these static_assert changes?
> >
> > > /*
> > > * Use sequence counter to get consistent device stat data on
> > > * 32-bit processors.
> > > diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> > > index 4439d77a7252..9a36f0206d90 100644
> > > --- a/include/uapi/linux/btrfs_tree.h
> > > +++ b/include/uapi/linux/btrfs_tree.h
> > > @@ -1169,12 +1169,14 @@ struct btrfs_dev_replace_item {
> > > #define BTRFS_BLOCK_GROUP_RAID1C3 (1ULL << 9)
> > > #define BTRFS_BLOCK_GROUP_RAID1C4 (1ULL << 10)
> > > #define BTRFS_BLOCK_GROUP_REMAPPED (1ULL << 11)
> > > +#define BTRFS_BLOCK_GROUP_REMAP (1ULL << 12)
> > > #define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
> > > BTRFS_SPACE_INFO_GLOBAL_RSV)
> > > #define BTRFS_BLOCK_GROUP_TYPE_MASK (BTRFS_BLOCK_GROUP_DATA | \
> > > BTRFS_BLOCK_GROUP_SYSTEM | \
> > > - BTRFS_BLOCK_GROUP_METADATA)
> > > + BTRFS_BLOCK_GROUP_METADATA | \
> > > + BTRFS_BLOCK_GROUP_REMAP)
> > > #define BTRFS_BLOCK_GROUP_PROFILE_MASK (BTRFS_BLOCK_GROUP_RAID0 | \
> > > BTRFS_BLOCK_GROUP_RAID1 | \
> > > --
> > > 2.49.1
> > >
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag
2025-10-20 11:32 ` Mark Harmstone
@ 2025-10-20 17:44 ` Boris Burkov
0 siblings, 0 replies; 38+ messages in thread
From: Boris Burkov @ 2025-10-20 17:44 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Mon, Oct 20, 2025 at 12:32:57PM +0100, Mark Harmstone wrote:
> On 15/10/2025 4.55 am, Boris Burkov wrote:
> > On Thu, Oct 09, 2025 at 12:28:02PM +0100, Mark Harmstone wrote:
> > > If we encounter a filesystem with the remap-tree incompat flag set,
> > > valdiate its compatibility with the other flags, and load the remap tree
> > > using the values that have been added to the superblock.
> > >
> > > The remap-tree feature depends on the free space tere, but no-holes and
> > > block-group-tree have been made dependencies to reduce the testing
> > > matrix. Similarly I'm not aware of any reason why mixed-bg and zoned would be
> > > incompatible with remap-tree, but this is blocked for the time being
> > > until it can be fully tested.
> > >
> >
> > Bonus points on offer for moving the open ctree bit as late as humanly
> > possible for that good "partial ordering" self documentation. (Or
> > explaining why it is already so).
> >
> > Thanks.
> >
> > Reviewed-by: Boris Burkov <boris@bur.io>
> >
> > > Signed-off-by: Mark Harmstone <mark@harmstone.com>
> > > ---
> > > fs/btrfs/Kconfig | 2 +
> > > fs/btrfs/accessors.h | 6 ++
> > > fs/btrfs/disk-io.c | 101 ++++++++++++++++++++++++++++----
> > > fs/btrfs/extent-tree.c | 2 +
> > > fs/btrfs/fs.h | 4 +-
> > > fs/btrfs/transaction.c | 7 +++
> > > include/uapi/linux/btrfs_tree.h | 5 +-
> > > 7 files changed, 113 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
> > > index 4438637c8900..77b5a9f27840 100644
> > > --- a/fs/btrfs/Kconfig
> > > +++ b/fs/btrfs/Kconfig
> > > @@ -117,4 +117,6 @@ config BTRFS_EXPERIMENTAL
> > > - large folio support
> > > + - remap-tree - logical address remapping tree
> > > +
> > > If unsure, say N.
> > > diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
> > > index 0dd161ee6863..392eaad75e72 100644
> > > --- a/fs/btrfs/accessors.h
> > > +++ b/fs/btrfs/accessors.h
> > > @@ -882,6 +882,12 @@ BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
> > > uuid_tree_generation, 64);
> > > BTRFS_SETGET_STACK_FUNCS(super_nr_global_roots, struct btrfs_super_block,
> > > nr_global_roots, 64);
> > > +BTRFS_SETGET_STACK_FUNCS(super_remap_root, struct btrfs_super_block,
> > > + remap_root, 64);
> > > +BTRFS_SETGET_STACK_FUNCS(super_remap_root_generation, struct btrfs_super_block,
> > > + remap_root_generation, 64);
> > > +BTRFS_SETGET_STACK_FUNCS(super_remap_root_level, struct btrfs_super_block,
> > > + remap_root_level, 8);
> > > /* struct btrfs_file_extent_item */
> > > BTRFS_SETGET_STACK_FUNCS(stack_file_extent_type, struct btrfs_file_extent_item,
> > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> > > index 92cb789957b4..60507e971aad 100644
> > > --- a/fs/btrfs/disk-io.c
> > > +++ b/fs/btrfs/disk-io.c
> > > @@ -1180,6 +1180,8 @@ static struct btrfs_root *btrfs_get_global_root(struct btrfs_fs_info *fs_info,
> > > return btrfs_grab_root(btrfs_global_root(fs_info, &key));
> > > case BTRFS_RAID_STRIPE_TREE_OBJECTID:
> > > return btrfs_grab_root(fs_info->stripe_root);
> > > + case BTRFS_REMAP_TREE_OBJECTID:
> > > + return btrfs_grab_root(fs_info->remap_root);
> > > default:
> > > return NULL;
> > > }
> > > @@ -1271,6 +1273,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
> > > btrfs_put_root(fs_info->data_reloc_root);
> > > btrfs_put_root(fs_info->block_group_root);
> > > btrfs_put_root(fs_info->stripe_root);
> > > + btrfs_put_root(fs_info->remap_root);
> > > btrfs_check_leaked_roots(fs_info);
> > > btrfs_extent_buffer_leak_debug_check(fs_info);
> > > kfree(fs_info->super_copy);
> > > @@ -1825,6 +1828,7 @@ static void free_root_pointers(struct btrfs_fs_info *info, bool free_chunk_root)
> > > free_root_extent_buffers(info->data_reloc_root);
> > > free_root_extent_buffers(info->block_group_root);
> > > free_root_extent_buffers(info->stripe_root);
> > > + free_root_extent_buffers(info->remap_root);
> > > if (free_chunk_root)
> > > free_root_extent_buffers(info->chunk_root);
> > > }
> > > @@ -2256,20 +2260,45 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
> > > if (ret)
> > > goto out;
> > > - /*
> > > - * This tree can share blocks with some other fs tree during relocation
> > > - * and we need a proper setup by btrfs_get_fs_root
> > > - */
> > > - root = btrfs_get_fs_root(tree_root->fs_info,
> > > - BTRFS_DATA_RELOC_TREE_OBJECTID, true);
> > > - if (IS_ERR(root)) {
> > > - if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
> > > - ret = PTR_ERR(root);
> > > - goto out;
> > > + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> > > + /* remap_root already loaded in load_important_roots() */
> > > + root = fs_info->remap_root;
> > > +
> > > + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> > > +
> > > + root->root_key.objectid = BTRFS_REMAP_TREE_OBJECTID;
> > > + root->root_key.type = BTRFS_ROOT_ITEM_KEY;
> > > + root->root_key.offset = 0;
> > > +
> > > + /* Check that data reloc tree doesn't also exist */
> > > + location.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
> > > + root = btrfs_read_tree_root(fs_info->tree_root, &location);
> > > + if (!IS_ERR(root)) {
> > > + btrfs_err(fs_info,
> > > + "data reloc tree exists when remap-tree enabled");
> > > + btrfs_put_root(root);
> > > + return -EIO;
> > > + } else if (PTR_ERR(root) != -ENOENT) {
> > > + btrfs_warn(fs_info,
> > > + "error %ld when checking for data reloc tree",
> > > + PTR_ERR(root));
> > > }
> > > } else {
> > > - set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> > > - fs_info->data_reloc_root = root;
> > > + /*
> > > + * This tree can share blocks with some other fs tree during
> > > + * relocation and we need a proper setup by btrfs_get_fs_root
> > > + */
> > > + root = btrfs_get_fs_root(tree_root->fs_info,
> > > + BTRFS_DATA_RELOC_TREE_OBJECTID, true);
> > > + if (IS_ERR(root)) {
> > > + if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
> > > + ret = PTR_ERR(root);
> > > + goto out;
> > > + }
> > > + } else {
> > > + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> > > + fs_info->data_reloc_root = root;
> > > + }
> > > }
> > > location.objectid = BTRFS_QUOTA_TREE_OBJECTID;
> > > @@ -2509,6 +2538,31 @@ int btrfs_validate_super(const struct btrfs_fs_info *fs_info,
> > > ret = -EINVAL;
> > > }
> > > + /*
> > > + * Reduce test matrix for remap tree by requiring block-group-tree
> > > + * and no-holes. Free-space-tree is a hard requirement.
> > > + */
> > > + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> > > + (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID) ||
> > > + !btrfs_fs_incompat(fs_info, NO_HOLES) ||
> > > + !btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE))) {
> > > + btrfs_err(fs_info,
> > > +"remap-tree feature requires free-space-tree, no-holes, and block-group-tree");
> > > + ret = -EINVAL;
> > > + }
> > > +
> > > + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> > > + btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
> > > + btrfs_err(fs_info, "remap-tree not supported with mixed-bg");
> > > + ret = -EINVAL;
> > > + }
> > > +
> > > + if (btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> > > + btrfs_fs_incompat(fs_info, ZONED)) {
> > > + btrfs_err(fs_info, "remap-tree not supported with zoned devices");
> > > + ret = -EINVAL;
> > > + }
> > > +
> > > /*
> > > * Hint to catch really bogus numbers, bitflips or so, more exact checks are
> > > * done later
> > > @@ -2667,6 +2721,18 @@ static int load_important_roots(struct btrfs_fs_info *fs_info)
> > > btrfs_warn(fs_info, "couldn't read tree root");
> > > return ret;
> > > }
> > > +
> > > + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> > > + bytenr = btrfs_super_remap_root(sb);
> > > + gen = btrfs_super_remap_root_generation(sb);
> > > + level = btrfs_super_remap_root_level(sb);
> > > + ret = load_super_root(fs_info->remap_root, bytenr, gen, level);
> > > + if (ret) {
> > > + btrfs_warn(fs_info, "couldn't read remap root");
> > > + return ret;
> > > + }
> > > + }
> > > +
> > > return 0;
> > > }
> > > @@ -3284,6 +3350,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
> > > struct btrfs_fs_info *fs_info = btrfs_sb(sb);
> > > struct btrfs_root *tree_root;
> > > struct btrfs_root *chunk_root;
> > > + struct btrfs_root *remap_root;
> > > int ret;
> > > int level;
> > > @@ -3417,6 +3484,16 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
> > > if (ret < 0)
> > > goto fail_alloc;
> > > + if (btrfs_super_incompat_flags(disk_super) & BTRFS_FEATURE_INCOMPAT_REMAP_TREE) {
> > > + remap_root = btrfs_alloc_root(fs_info, BTRFS_REMAP_TREE_OBJECTID,
> > > + GFP_KERNEL);
> > > + fs_info->remap_root = remap_root;
> > > + if (!remap_root) {
> > > + ret = -ENOMEM;
> > > + goto fail_alloc;
> > > + }
> > > + }
> > > +
> >
> > Thanks for scooting it down. Does this need to be before reading the sys
> > array / chunk tree? I would guess no, as we can't remap that, but
> > perhaps I have misunderstood.
>
> Yes, that's right. The dependency ordering when loading is:
>
> 1. System chunks (contained in superblock)
> 2. Chunk tree (located in system chunks)
> 3. Remap tree (needs chunk tree to map logicals to physicals, logical address is in superblock)
> 4. Root tree (may be remapped)
> 5. All other trees (found in root tree)
I mixed up allocating the root and filling it out in
load_important_roots.. This all makes sense to me know, thanks for the
extra explanation on the dependencies. That would be good to document in
some bootstrapping document, by the way :)
> > > /*
> > > * At this point our mount options are validated, if we set ->max_inline
> > > * to something non-standard make sure we truncate it to sectorsize.
> > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> > > index d964147b8097..7805a148bbd8 100644
> > > --- a/fs/btrfs/extent-tree.c
> > > +++ b/fs/btrfs/extent-tree.c
> > > @@ -2589,6 +2589,8 @@ static u64 get_alloc_profile_by_root(struct btrfs_root *root, int data)
> > > flags = BTRFS_BLOCK_GROUP_DATA;
> > > else if (root == fs_info->chunk_root)
> > > flags = BTRFS_BLOCK_GROUP_SYSTEM;
> > > + else if (root == fs_info->remap_root)
> > > + flags = BTRFS_BLOCK_GROUP_REMAP;
> > > else
> > > flags = BTRFS_BLOCK_GROUP_METADATA;
> > > diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
> > > index c4dba7e7ce5a..c76f4c2701f9 100644
> > > --- a/fs/btrfs/fs.h
> > > +++ b/fs/btrfs/fs.h
> > > @@ -291,7 +291,8 @@ enum {
> > > #define BTRFS_FEATURE_INCOMPAT_SUPP \
> > > (BTRFS_FEATURE_INCOMPAT_SUPP_STABLE | \
> > > BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE | \
> > > - BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2)
> > > + BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2 | \
> > > + BTRFS_FEATURE_INCOMPAT_REMAP_TREE)
> > > #else
> > > @@ -451,6 +452,7 @@ struct btrfs_fs_info {
> > > struct btrfs_root *data_reloc_root;
> > > struct btrfs_root *block_group_root;
> > > struct btrfs_root *stripe_root;
> > > + struct btrfs_root *remap_root;
> > > /* The log root tree is a directory of all the other log roots */
> > > struct btrfs_root *log_root_tree;
> > > diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> > > index 89ae0c7a610a..b1c41982e7b2 100644
> > > --- a/fs/btrfs/transaction.c
> > > +++ b/fs/btrfs/transaction.c
> > > @@ -1950,6 +1950,13 @@ static void update_super_roots(struct btrfs_fs_info *fs_info)
> > > super->cache_generation = 0;
> > > if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
> > > super->uuid_tree_generation = root_item->generation;
> > > +
> > > + if (btrfs_fs_incompat(fs_info, REMAP_TREE)) {
> > > + root_item = &fs_info->remap_root->root_item;
> > > + super->remap_root = root_item->bytenr;
> > > + super->remap_root_generation = root_item->generation;
> > > + super->remap_root_level = root_item->level;
> > > + }
> > > }
> > > int btrfs_transaction_blocked(struct btrfs_fs_info *info)
> > > diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> > > index 500e3a7df90b..89bcb80081a6 100644
> > > --- a/include/uapi/linux/btrfs_tree.h
> > > +++ b/include/uapi/linux/btrfs_tree.h
> > > @@ -721,9 +721,12 @@ struct btrfs_super_block {
> > > __u8 metadata_uuid[BTRFS_FSID_SIZE];
> > > __u64 nr_global_roots;
> > > + __le64 remap_root;
> > > + __le64 remap_root_generation;
> > > + __u8 remap_root_level;
> > > /* Future expansion */
> > > - __le64 reserved[27];
> > > + __u8 reserved[199];
> > > __u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
> > > struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
> > > --
> > > 2.49.1
> > >
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups
2025-10-20 14:31 ` Mark Harmstone
@ 2025-10-20 17:44 ` Boris Burkov
0 siblings, 0 replies; 38+ messages in thread
From: Boris Burkov @ 2025-10-20 17:44 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Mon, Oct 20, 2025 at 03:31:39PM +0100, Mark Harmstone wrote:
> On 15/10/2025 5.21 am, Boris Burkov wrote:
> > On Thu, Oct 09, 2025 at 12:28:03PM +0100, Mark Harmstone wrote:
> > > Change btrfs_map_block() so that if the block group has the REMAPPED
> > > flag set, we call btrfs_translate_remap() to obtain a new address.
> > >
> > > btrfs_translate_remap() searches the remap tree for a range
> > > corresponding to the logical address passed to btrfs_map_block(). If it
> > > is within an identity remap, this part of the block group hasn't yet
> > > been relocated, and so we use the existing address.
> > >
> > > If it is within an actual remap, we subtract the start of the remap
> > > range and add the address of its destination, contained in the item's
> > > payload.
> > >
> > > Signed-off-by: Mark Harmstone <mark@harmstone.com>
> > > ---
> > > fs/btrfs/relocation.c | 59 +++++++++++++++++++++++++++++++++++++++++++
> > > fs/btrfs/relocation.h | 2 ++
> > > fs/btrfs/volumes.c | 31 +++++++++++++++++++++++
> > > 3 files changed, 92 insertions(+)
> > >
> > > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> > > index 748290758459..4f5d3aaf0f65 100644
> > > --- a/fs/btrfs/relocation.c
> > > +++ b/fs/btrfs/relocation.c
> > > @@ -3870,6 +3870,65 @@ static const char *stage_to_string(enum reloc_stage stage)
> > > return "unknown";
> > > }
> > > +int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
> > > + u64 *length, bool nolock)
> > > +{
> > > + int ret;
> > > + struct btrfs_key key, found_key;
> > > + struct extent_buffer *leaf;
> > > + struct btrfs_remap *remap;
> > > + BTRFS_PATH_AUTO_FREE(path);
> > > +
> > > + path = btrfs_alloc_path();
> > > + if (!path)
> > > + return -ENOMEM;
> > > +
> > > + if (nolock) {
> > > + path->search_commit_root = 1;
> > > + path->skip_locking = 1;
> > > + }
> > > +
> > > + key.objectid = *logical;
> > > + key.type = (u8)-1;
> > > + key.offset = (u64)-1;
> > > +
> > > + ret = btrfs_search_slot(NULL, fs_info->remap_root, &key, path,
> > > + 0, 0);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + leaf = path->nodes[0];
> > > +
> > > + if (path->slots[0] == 0)
> > > + return -ENOENT;
> > > +
> > > + path->slots[0]--;
> > > +
> > > + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
> > > +
> > > + if (found_key.type != BTRFS_REMAP_KEY &&
> > > + found_key.type != BTRFS_IDENTITY_REMAP_KEY) {
> > > + return -ENOENT;
> > > + }
> > > +
> > > + if (found_key.objectid > *logical ||
> > > + found_key.objectid + found_key.offset <= *logical) {
> > > + return -ENOENT;
> > > + }
> > > +
> > > + if (*logical + *length > found_key.objectid + found_key.offset)
> > > + *length = found_key.objectid + found_key.offset - *logical;
> > > +
> > > + if (found_key.type == BTRFS_IDENTITY_REMAP_KEY)
> > > + return 0;
> > > +
> > > + remap = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_remap);
> > > +
> > > + *logical += btrfs_remap_address(leaf, remap) - found_key.objectid;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > /*
> > > * function to relocate all extents in a block group.
> > > */
> > > diff --git a/fs/btrfs/relocation.h b/fs/btrfs/relocation.h
> > > index 5c36b3f84b57..a653c42a25a3 100644
> > > --- a/fs/btrfs/relocation.h
> > > +++ b/fs/btrfs/relocation.h
> > > @@ -31,5 +31,7 @@ int btrfs_should_cancel_balance(const struct btrfs_fs_info *fs_info);
> > > struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr);
> > > bool btrfs_should_ignore_reloc_root(const struct btrfs_root *root);
> > > u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info);
> > > +int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical,
> > > + u64 *length, bool nolock);
> > > #endif
> > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> > > index 0abe02a7072f..f2d1203778aa 100644
> > > --- a/fs/btrfs/volumes.c
> > > +++ b/fs/btrfs/volumes.c
> > > @@ -6635,6 +6635,37 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
> > > if (IS_ERR(map))
> > > return PTR_ERR(map);
> > > + if (map->type & BTRFS_BLOCK_GROUP_REMAPPED) {
> > > + u64 new_logical = logical;
> > > + bool nolock = !(map->type & BTRFS_BLOCK_GROUP_DATA);
> >
> > Why not data?
>
> Because I thought we'd maxed out our lockdep classes so this was the only way to
> prevent lockdep from complaining about metadata reads - not yet knowing about
> the btrfs_lockdep_keysets array.
>
> I think I'm going to remove the search_commit_root stuff from this patchset, and
> leave it for a future optimization. As you know it's full of gotchas.
>
> > > +
> > > + /*
> > > + * We use search_commit_root in btrfs_translate_remap for
> > > + * metadata blocks, to avoid lockdep complaining about
> > > + * recursive locking.
> > > + * If we get -ENOENT this means this is a BG that has just had
> > > + * its REMAPPED flag set, and so nothing has yet been actually
> > > + * remapped.
> > > + */
> >
> > I'm actually kind of worried about this now. What is preventing the
> > following racy interleaving:
> >
> > T1 T2
> > start_block_group_remapping() // in TXN-K set REMAPPED
> > btrfs_map_block()
> > btrfs_translate_remap()
> > ENOENT // searched in commit root
> > do_remap_tree_reloc() // in TXN-K do all remaps
> > // fully remapped, removed, discarded
> > // TXN-K committed
> > // not remapped! but the original chunk map is gone gone
> > num_copies = ...
>
> The bits on the right will be separate transactions, I thought that would save
> us - does it not? I'm guessing this means that search_commit_root means to
> search the last transaction that was flushed to disk, rather than the last
> in-memory transaction.
>
> Yes, I'm definitely saving this bit until later.
>
I think that's a good idea.
> > > + ret = btrfs_translate_remap(fs_info, &new_logical, length,
> > > + nolock);
> > > + if (ret && (!nolock || ret != -ENOENT))
> > > + return ret;
> > > +
> > > + if (ret != -ENOENT && new_logical != logical) {
> > > + btrfs_free_chunk_map(map);
> > > +
> > > + map = btrfs_get_chunk_map(fs_info, new_logical,
> > > + *length);
> > > + if (IS_ERR(map))
> > > + return PTR_ERR(map);
> > > +
> > > + logical = new_logical;
> > > + }
> > > +
> > > + ret = 0;
> > > + }
> > > +
> > > num_copies = btrfs_chunk_map_num_copies(map);
> > > if (io_geom.mirror_num > num_copies)
> > > return -EINVAL;
> > > --
> > > 2.49.1
> > >
>
^ permalink raw reply [flat|nested] 38+ messages in thread
* Re: [PATCH v3 16/17] btrfs: handle discarding fully-remapped block groups
2025-10-15 4:54 ` Boris Burkov
@ 2025-10-23 17:35 ` Mark Harmstone
0 siblings, 0 replies; 38+ messages in thread
From: Mark Harmstone @ 2025-10-23 17:35 UTC (permalink / raw)
To: Boris Burkov; +Cc: linux-btrfs
On 15/10/2025 5.54 am, Boris Burkov wrote:
> On Thu, Oct 09, 2025 at 12:28:11PM +0100, Mark Harmstone wrote:
>> Discard normally works by iterating over the free-space entries of a
>> block group. This doesn't work for fully-remapped block groups, as we
>> removed their free-space entries when we started relocation.
>>
>> For sync discard, call btrfs_discard_extent() when we commit the
>> transaction in which the last identity remap was removed.
>>
>> For async discard, add a new function btrfs_trim_fully_remapped_block_group()
>> to be called by the discard worker, which iterates over the block
>> group's range using the normal async discard rules. Once we reach the
>> end, remove the chunk's stripes and device extents to get back its free
>> space.
>>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>> ---
>> fs/btrfs/block-group.c | 2 +
>> fs/btrfs/block-group.h | 1 +
>> fs/btrfs/discard.c | 61 +++++++++++++++++++++++++----
>> fs/btrfs/extent-tree.c | 4 ++
>> fs/btrfs/free-space-cache.c | 77 +++++++++++++++++++++++++++++++++++++
>> fs/btrfs/free-space-cache.h | 1 +
>> fs/btrfs/transaction.c | 8 ++--
>> 7 files changed, 144 insertions(+), 10 deletions(-)
>>
>> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
>> index 3f7c45d17415..a7dfa6c95223 100644
>> --- a/fs/btrfs/block-group.c
>> +++ b/fs/btrfs/block-group.c
>> @@ -4828,4 +4828,6 @@ void btrfs_mark_bg_fully_remapped(struct btrfs_block_group *bg,
>>
>> spin_unlock(&fs_info->unused_bgs_lock);
>>
>> + if (btrfs_test_opt(fs_info, DISCARD_ASYNC))
>> + btrfs_discard_queue_work(&fs_info->discard_ctl, bg);
>> }
>> diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
>> index c6866a57ea24..3c086fbb0a7c 100644
>> --- a/fs/btrfs/block-group.h
>> +++ b/fs/btrfs/block-group.h
>> @@ -49,6 +49,7 @@ enum btrfs_discard_state {
>> BTRFS_DISCARD_EXTENTS,
>> BTRFS_DISCARD_BITMAPS,
>> BTRFS_DISCARD_RESET_CURSOR,
>> + BTRFS_DISCARD_FULLY_REMAPPED,
>> };
>>
>> /*
>> diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
>> index 2b7b1e440bc8..421f48a6603a 100644
>> --- a/fs/btrfs/discard.c
>> +++ b/fs/btrfs/discard.c
>> @@ -241,8 +241,17 @@ static struct btrfs_block_group *peek_discard_list(
>> block_group = find_next_block_group(discard_ctl, now);
>>
>> if (block_group && now >= block_group->discard_eligible_time) {
>> + bool unused;
>> +
>> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
>> + unused = block_group->remap_bytes == 0 &&
>> + block_group->identity_remap_count == 0;
>> + } else {
>> + unused = block_group->used == 0;
>> + }
>> +
>
> This pattern for computing unused gets repeated enough times in this file
> that I think a static helper is merited.
That makes sense. Probably "unused" needs a better name here as well, as it
means that the BG doesn't contain any data within its chunk stripes. In
btrfs_mark_bg_unused() "unused" means that no extents are within the BG's
nominal range, which is something different.
The check for remap_bytes == 0 is redundant here as well, as the REMAPPED
flag can only get set when all the remaps have already been moved out.
>> if (block_group->discard_index == BTRFS_DISCARD_INDEX_UNUSED &&
>> - block_group->used != 0) {
>> + !unused) {
>> if (btrfs_is_block_group_data_only(block_group)) {
>> __add_to_discard_list(discard_ctl, block_group);
>> /*
>> @@ -267,7 +276,15 @@ static struct btrfs_block_group *peek_discard_list(
>> }
>> if (block_group->discard_state == BTRFS_DISCARD_RESET_CURSOR) {
>> block_group->discard_cursor = block_group->start;
>> - block_group->discard_state = BTRFS_DISCARD_EXTENTS;
>> +
>> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
>> + unused) {
>> + block_group->discard_state =
>> + BTRFS_DISCARD_FULLY_REMAPPED;
>> + } else {
>> + block_group->discard_state =
>> + BTRFS_DISCARD_EXTENTS;
>> + }
>> }
>> }
>> if (block_group) {
>> @@ -370,10 +387,19 @@ void btrfs_discard_cancel_work(struct btrfs_discard_ctl *discard_ctl,
>> void btrfs_discard_queue_work(struct btrfs_discard_ctl *discard_ctl,
>> struct btrfs_block_group *block_group)
>> {
>> + bool unused;
>> +
>> if (!block_group || !btrfs_test_opt(block_group->fs_info, DISCARD_ASYNC))
>> return;
>>
>> - if (block_group->used == 0 && block_group->remap_bytes == 0)
>> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
>> + unused = block_group->remap_bytes == 0 &&
>> + block_group->identity_remap_count == 0;
>> + } else {
>> + unused = block_group->used == 0;
>> + }
>> +
>> + if (unused)
>> add_to_discard_unused_list(discard_ctl, block_group);
>> else
>> add_to_discard_list(discard_ctl, block_group);
>> @@ -468,9 +494,18 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl,
>> static void btrfs_finish_discard_pass(struct btrfs_discard_ctl *discard_ctl,
>> struct btrfs_block_group *block_group)
>> {
>> + bool unused;
>> +
>> remove_from_discard_list(discard_ctl, block_group);
>>
>> - if (block_group->used == 0) {
>> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED) {
>> + unused = block_group->remap_bytes == 0 &&
>> + block_group->identity_remap_count == 0;
>> + } else {
>> + unused = block_group->used == 0;
>> + }
>> +
>> + if (unused) {
>> if (btrfs_is_free_space_trimmed(block_group))
>> btrfs_mark_bg_unused(block_group);
>> else
>> @@ -524,7 +559,8 @@ static void btrfs_discard_workfn(struct work_struct *work)
>> /* Perform discarding */
>> minlen = discard_minlen[discard_index];
>>
>> - if (discard_state == BTRFS_DISCARD_BITMAPS) {
>> + switch (discard_state) {
>> + case BTRFS_DISCARD_BITMAPS: {
>> u64 maxlen = 0;
>>
>> /*
>> @@ -541,17 +577,28 @@ static void btrfs_discard_workfn(struct work_struct *work)
>> btrfs_block_group_end(block_group),
>> minlen, maxlen, true);
>> discard_ctl->discard_bitmap_bytes += trimmed;
>> - } else {
>> +
>> + break;
>> + }
>> +
>> + case BTRFS_DISCARD_FULLY_REMAPPED:
>> + btrfs_trim_fully_remapped_block_group(block_group);
>> + break;
>> +
>> + default:
>> btrfs_trim_block_group_extents(block_group, &trimmed,
>> block_group->discard_cursor,
>> btrfs_block_group_end(block_group),
>> minlen, true);
>> discard_ctl->discard_extent_bytes += trimmed;
>> +
>> + break;
>> }
>>
>> /* Determine next steps for a block_group */
>> if (block_group->discard_cursor >= btrfs_block_group_end(block_group)) {
>> - if (discard_state == BTRFS_DISCARD_BITMAPS) {
>> + if (discard_state == BTRFS_DISCARD_BITMAPS ||
>> + discard_state == BTRFS_DISCARD_FULLY_REMAPPED) {
>> btrfs_finish_discard_pass(discard_ctl, block_group);
>> } else {
>> block_group->discard_cursor = block_group->start;
>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>> index 2e3074612f39..03674d171ec0 100644
>> --- a/fs/btrfs/extent-tree.c
>> +++ b/fs/btrfs/extent-tree.c
>> @@ -2870,6 +2870,10 @@ int btrfs_handle_fully_remapped_bgs(struct btrfs_trans_handle *trans)
>> return ret;
>> }
>>
>> + if (!TRANS_ABORTED(trans))
>> + btrfs_discard_extent(fs_info, block_group->start,
>> + block_group->length, NULL, false);
>> +
>> /*
>> * Set num_stripes to 0, so that btrfs_remove_dev_extents()
>> * won't run a second time.
>> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
>> index 6387f8d1c3a1..56f27487b632 100644
>> --- a/fs/btrfs/free-space-cache.c
>> +++ b/fs/btrfs/free-space-cache.c
>> @@ -29,6 +29,7 @@
>> #include "file-item.h"
>> #include "file.h"
>> #include "super.h"
>> +#include "relocation.h"
>>
>> #define BITS_PER_BITMAP (PAGE_SIZE * 8UL)
>> #define MAX_CACHE_BYTES_PER_GIG SZ_64K
>> @@ -3063,6 +3064,12 @@ bool btrfs_is_free_space_trimmed(struct btrfs_block_group *block_group)
>> struct rb_node *node;
>> bool ret = true;
>>
>> + if (block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED &&
>> + block_group->remap_bytes == 0 &&
>> + block_group->identity_remap_count == 0) {
>> + return true;
>> + }
>> +
>> spin_lock(&ctl->tree_lock);
>> node = rb_first(&ctl->free_space_offset);
>>
>> @@ -3827,6 +3834,76 @@ static int trim_no_bitmap(struct btrfs_block_group *block_group,
>> return ret;
>> }
>>
>> +void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg)
>> +{
>> + struct btrfs_fs_info *fs_info = bg->fs_info;
>> + struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl;
>> + int ret = 0;
>> + u64 bytes;
>> + const u64 max_discard_size = READ_ONCE(discard_ctl->max_discard_size);
>> + u64 end = btrfs_block_group_end(bg);
>> + struct btrfs_trans_handle *trans;
>> + struct btrfs_chunk_map *map;
>> +
>> + while (bg->discard_cursor < end) {
>> + u64 trimmed;
>> +
>> + bytes = end - bg->discard_cursor;
>> +
>> + if (max_discard_size &&
>> + bytes >= (max_discard_size +
>> + BTRFS_ASYNC_DISCARD_MIN_FILTER)) {
>> + bytes = max_discard_size;
>> + }
>> +
>> + ret = btrfs_discard_extent(fs_info, bg->discard_cursor, bytes,
>> + &trimmed, false);
>> + if (ret || trimmed == 0)
>> + return;
>
> As opposed to btrfs_trim_block_group_extents() / trim_no_bitmap() this will
> always do all the discarding in a tight loop without sending control
> back up to the delayed work queue. As a result, the rate limiting is
> unable to do its job; this will simply rip through the whole bg in steps
> of max_discard_size.
>
> Check out the `async` parameter to trim_no_bitamp() and how it breaks
> the loop, which then lets the higher level metering operate properly.
This makes sense - trim_no_bitmap() was tricking me with its loop. We don't
need a loop here at all, as the function gets called repeatedly.
>> +
>> + bg->discard_cursor += trimmed;
>> +
>> + if (btrfs_trim_interrupted())
>> + return;
>> +
>> + cond_resched();
>> + }
>> +
>> + trans = btrfs_start_transaction(fs_info->tree_root, 0);
>> + if (IS_ERR(trans))
>> + return;
>> +
>> + map = btrfs_get_chunk_map(fs_info, bg->start, 1);
>> + if (IS_ERR(map)) {
>> + ret = PTR_ERR(map);
>> + btrfs_abort_transaction(trans, ret);
>> + return;
>> + }
>> +
>> + ret = btrfs_last_identity_remap_gone(trans, map, bg);
>> + if (ret) {
>> + btrfs_free_chunk_map(map);
>> + btrfs_abort_transaction(trans, ret);
>> + return;
>> + }
>> +
>> + btrfs_end_transaction(trans);
>> +
>> + /*
>> + * Set num_stripes to 0, so that btrfs_remove_dev_extents()
>> + * won't run a second time.
>> + */
>> + map->num_stripes = 0;
>> +
>> + btrfs_free_chunk_map(map);
>> +
>> + if (bg->used == 0) {
>> + spin_lock(&fs_info->unused_bgs_lock);
>> + list_move_tail(&bg->bg_list, &fs_info->unused_bgs);
>> + spin_unlock(&fs_info->unused_bgs_lock);
>> + }
>> +}
>> +
>> /*
>> * If we break out of trimming a bitmap prematurely, we should reset the
>> * trimming bit. In a rather contrived case, it's possible to race here so
>> diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
>> index 9f1dbfdee8ca..33fc3b245648 100644
>> --- a/fs/btrfs/free-space-cache.h
>> +++ b/fs/btrfs/free-space-cache.h
>> @@ -166,6 +166,7 @@ int btrfs_trim_block_group_extents(struct btrfs_block_group *block_group,
>> int btrfs_trim_block_group_bitmaps(struct btrfs_block_group *block_group,
>> u64 *trimmed, u64 start, u64 end, u64 minlen,
>> u64 maxlen, bool async);
>> +void btrfs_trim_fully_remapped_block_group(struct btrfs_block_group *bg);
>>
>> bool btrfs_free_space_cache_v1_active(struct btrfs_fs_info *fs_info);
>> int btrfs_set_free_space_cache_v1_active(struct btrfs_fs_info *fs_info, bool active);
>> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
>> index 6ce91397afe6..b0a5254ba214 100644
>> --- a/fs/btrfs/transaction.c
>> +++ b/fs/btrfs/transaction.c
>> @@ -2438,9 +2438,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
>> if (ret)
>> goto unlock_reloc;
>>
>> - ret = btrfs_handle_fully_remapped_bgs(trans);
>> - if (ret)
>> - goto unlock_reloc;
>> + if (!btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
>> + ret = btrfs_handle_fully_remapped_bgs(trans);
>> + if (ret)
>> + goto unlock_reloc;
>> + }
>>
>> /*
>> * make sure none of the code above managed to slip in a
>> --
>> 2.49.1
>>
^ permalink raw reply [flat|nested] 38+ messages in thread
end of thread, other threads:[~2025-10-23 17:44 UTC | newest]
Thread overview: 38+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-10-09 11:27 [PATCH v3 00/17] Remap tree Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 01/17] btrfs: add definitions and constants for remap-tree Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 02/17] btrfs: add REMAP chunk type Mark Harmstone
2025-10-15 3:37 ` Boris Burkov
2025-10-20 9:58 ` Mark Harmstone
2025-10-20 17:35 ` Boris Burkov
2025-10-09 11:27 ` [PATCH v3 03/17] btrfs: allow remapped chunks to have zero stripes Mark Harmstone
2025-10-15 3:47 ` Boris Burkov
2025-10-20 12:15 ` Mark Harmstone
2025-10-09 11:27 ` [PATCH v3 04/17] btrfs: remove remapped block groups from the free-space tree Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 05/17] btrfs: don't add metadata items for the remap tree to the extent tree Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 06/17] btrfs: add extended version of struct block_group_item Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 07/17] btrfs: allow mounting filesystems with remap-tree incompat flag Mark Harmstone
2025-10-15 3:55 ` Boris Burkov
2025-10-20 11:32 ` Mark Harmstone
2025-10-20 17:44 ` Boris Burkov
2025-10-09 11:28 ` [PATCH v3 08/17] btrfs: redirect I/O for remapped block groups Mark Harmstone
2025-10-15 4:21 ` Boris Burkov
2025-10-20 14:31 ` Mark Harmstone
2025-10-20 17:44 ` Boris Burkov
2025-10-09 11:28 ` [PATCH v3 09/17] btrfs: release BG lock before calling btrfs_link_bg_list() Mark Harmstone
2025-10-09 11:56 ` Filipe Manana
2025-10-09 14:58 ` Mark Harmstone
2025-10-09 15:16 ` Filipe Manana
2025-10-09 16:30 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 10/17] btrfs: handle deletions from remapped block group Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 11/17] btrfs: handle setting up relocation of block group with remap-tree Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 12/17] btrfs: move existing remaps before relocating block group Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 13/17] btrfs: replace identity maps with actual remaps when doing relocations Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 14/17] btrfs: add do_remap param to btrfs_discard_extent() Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 15/17] btrfs: allow balancing remap tree Mark Harmstone
2025-10-15 4:24 ` Boris Burkov
2025-10-09 11:28 ` [PATCH v3 16/17] btrfs: handle discarding fully-remapped block groups Mark Harmstone
2025-10-15 4:54 ` Boris Burkov
2025-10-23 17:35 ` Mark Harmstone
2025-10-09 11:28 ` [PATCH v3 17/17] btrfs: add stripe removal pending flag Mark Harmstone
2025-10-15 5:05 ` Boris Burkov
2025-10-20 14:52 ` Mark Harmstone
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