* [PATCH AUTOSEL 6.10 21/27] btrfs: do not clear page dirty inside extent_write_locked_range()
[not found] <20240728005329.1723272-1-sashal@kernel.org>
@ 2024-07-28 0:53 ` Sasha Levin
2024-07-28 0:53 ` [PATCH AUTOSEL 6.10 22/27] btrfs: do not BUG_ON() when freeing tree block after error Sasha Levin
` (3 subsequent siblings)
4 siblings, 0 replies; 5+ messages in thread
From: Sasha Levin @ 2024-07-28 0:53 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Qu Wenruo, Johannes Thumshirn, David Sterba, Sasha Levin, clm,
josef, linux-btrfs
From: Qu Wenruo <wqu@suse.com>
[ Upstream commit 97713b1a2ced1e4a2a6c40045903797ebd44d7e0 ]
[BUG]
For subpage + zoned case, the following workload can lead to rsv data
leak at unmount time:
# mkfs.btrfs -f -s 4k $dev
# mount $dev $mnt
# fsstress -w -n 8 -d $mnt -s 1709539240
0/0: fiemap - no filename
0/1: copyrange read - no filename
0/2: write - no filename
0/3: rename - no source filename
0/4: creat f0 x:0 0 0
0/4: creat add id=0,parent=-1
0/5: writev f0[259 1 0 0 0 0] [778052,113,965] 0
0/6: ioctl(FIEMAP) f0[259 1 0 0 224 887097] [1294220,2291618343991484791,0x10000] -1
0/7: dwrite - xfsctl(XFS_IOC_DIOINFO) f0[259 1 0 0 224 887097] return 25, fallback to stat()
0/7: dwrite f0[259 1 0 0 224 887097] [696320,102400] 0
# umount $mnt
The dmesg includes the following rsv leak detection warning (all call
trace skipped):
------------[ cut here ]------------
WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8653 btrfs_destroy_inode+0x1e0/0x200 [btrfs]
---[ end trace 0000000000000000 ]---
------------[ cut here ]------------
WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8654 btrfs_destroy_inode+0x1a8/0x200 [btrfs]
---[ end trace 0000000000000000 ]---
------------[ cut here ]------------
WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8660 btrfs_destroy_inode+0x1a0/0x200 [btrfs]
---[ end trace 0000000000000000 ]---
BTRFS info (device sda): last unmount of filesystem 1b4abba9-de34-4f07-9e7f-157cf12a18d6
------------[ cut here ]------------
WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs]
---[ end trace 0000000000000000 ]---
BTRFS info (device sda): space_info DATA has 268218368 free, is not full
BTRFS info (device sda): space_info total=268435456, used=204800, pinned=0, reserved=0, may_use=12288, readonly=0 zone_unusable=0
BTRFS info (device sda): global_block_rsv: size 0 reserved 0
BTRFS info (device sda): trans_block_rsv: size 0 reserved 0
BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0
BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0
BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0
------------[ cut here ]------------
WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs]
---[ end trace 0000000000000000 ]---
BTRFS info (device sda): space_info METADATA has 267796480 free, is not full
BTRFS info (device sda): space_info total=268435456, used=131072, pinned=0, reserved=0, may_use=262144, readonly=0 zone_unusable=245760
BTRFS info (device sda): global_block_rsv: size 0 reserved 0
BTRFS info (device sda): trans_block_rsv: size 0 reserved 0
BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0
BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0
BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0
Above $dev is a tcmu-runner emulated zoned HDD, which has a max zone
append size of 64K, and the system has 64K page size.
[CAUSE]
I have added several trace_printk() to show the events (header skipped):
> btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688
> btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288
> btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536
> btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864
The above lines show our buffered write has dirtied 3 pages of inode
259 of root 5:
704K 768K 832K 896K
I |////I/////////////////I///////////| I
756K 868K
|///| is the dirtied range using subpage bitmaps. and 'I' is the page
boundary.
Meanwhile all three pages (704K, 768K, 832K) have their PageDirty
flag set.
> btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400
Then direct IO write starts, since the range [680K, 780K) covers the
beginning part of the above dirty range, we need to writeback the
two pages at 704K and 768K.
> cow_file_range: r/i=5/259 add ordered extent filepos=774144 len=65536
> extent_write_locked_range: r/i=5/259 locked page=720896 start=774144 len=65536
Now the above 2 lines show that we're writing back for dirty range
[756K, 756K + 64K).
We only writeback 64K because the zoned device has max zone append size
as 64K.
> extent_write_locked_range: r/i=5/259 clear dirty for page=786432
!!! The above line shows the root cause. !!!
We're calling clear_page_dirty_for_io() inside extent_write_locked_range(),
for the page 768K.
This is because extent_write_locked_range() can go beyond the current
locked page, here we hit the page at 768K and clear its page dirt.
In fact this would lead to the desync between subpage dirty and page
dirty flags. We have the page dirty flag cleared, but the subpage range
[820K, 832K) is still dirty.
After the writeback of range [756K, 820K), the dirty flags look like
this, as page 768K no longer has dirty flag set.
704K 768K 832K 896K
I I | I/////////////| I
820K 868K
This means we will no longer writeback range [820K, 832K), thus the
reserved data/metadata space would never be properly released.
> extent_write_cache_pages: r/i=5/259 skip non-dirty folio=786432
Now even though we try to start writeback for page 768K, since the
page is not dirty, we completely skip it at extent_write_cache_pages()
time.
> btrfs_direct_write: r/i=5/259 dio done filepos=696320 len=0
Now the direct IO finished.
> cow_file_range: r/i=5/259 add ordered extent filepos=851968 len=36864
> extent_write_locked_range: r/i=5/259 locked page=851968 start=851968 len=36864
Now we writeback the remaining dirty range, which is [832K, 868K).
Causing the range [820K, 832K) never to be submitted, thus leaking the
reserved space.
This bug only affects subpage and zoned case. For non-subpage and zoned
case, we have exactly one sector for each page, thus no such partial dirty
cases.
For subpage and non-zoned case, we never go into run_delalloc_cow(), and
normally all the dirty subpage ranges would be properly submitted inside
__extent_writepage_io().
[FIX]
Just do not clear the page dirty at all inside extent_write_locked_range().
As __extent_writepage_io() would do a more accurate, subpage compatible
clear for page and subpage dirty flags anyway.
Now the correct trace would look like this:
> btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688
> btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288
> btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536
> btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864
The page dirty part is still the same 3 pages.
> btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400
> cow_file_range: r/i=5/259 add ordered extent filepos=774144 len=65536
> extent_write_locked_range: r/i=5/259 locked page=720896 start=774144 len=65536
And the writeback for the first 64K is still correct.
> cow_file_range: r/i=5/259 add ordered extent filepos=839680 len=49152
> extent_write_locked_range: r/i=5/259 locked page=786432 start=839680 len=49152
Now with the fix, we can properly writeback the range [820K, 832K), and
properly release the reserved data/metadata space.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/extent_io.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 958155cc43a81..0486b1f911248 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2246,10 +2246,8 @@ void extent_write_locked_range(struct inode *inode, struct page *locked_page,
page = find_get_page(mapping, cur >> PAGE_SHIFT);
ASSERT(PageLocked(page));
- if (pages_dirty && page != locked_page) {
+ if (pages_dirty && page != locked_page)
ASSERT(PageDirty(page));
- clear_page_dirty_for_io(page);
- }
ret = __extent_writepage_io(BTRFS_I(inode), page, &bio_ctrl,
i_size, &nr);
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH AUTOSEL 6.10 22/27] btrfs: do not BUG_ON() when freeing tree block after error
[not found] <20240728005329.1723272-1-sashal@kernel.org>
2024-07-28 0:53 ` [PATCH AUTOSEL 6.10 21/27] btrfs: do not clear page dirty inside extent_write_locked_range() Sasha Levin
@ 2024-07-28 0:53 ` Sasha Levin
2024-07-28 0:53 ` [PATCH AUTOSEL 6.10 23/27] btrfs: reduce nesting for extent processing at btrfs_lookup_extent_info() Sasha Levin
` (2 subsequent siblings)
4 siblings, 0 replies; 5+ messages in thread
From: Sasha Levin @ 2024-07-28 0:53 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Filipe Manana, syzbot+a306f914b4d01b3958fe, Qu Wenruo,
David Sterba, Sasha Levin, clm, josef, linux-btrfs
From: Filipe Manana <fdmanana@suse.com>
[ Upstream commit bb3868033a4cccff7be57e9145f2117cbdc91c11 ]
When freeing a tree block, at btrfs_free_tree_block(), if we fail to
create a delayed reference we don't deal with the error and just do a
BUG_ON(). The error most likely to happen is -ENOMEM, and we have a
comment mentioning that only -ENOMEM can happen, but that is not true,
because in case qgroups are enabled any error returned from
btrfs_qgroup_trace_extent_post() (can be -EUCLEAN or anything returned
from btrfs_search_slot() for example) can be propagated back to
btrfs_free_tree_block().
So stop doing a BUG_ON() and return the error to the callers and make
them abort the transaction to prevent leaking space. Syzbot was
triggering this, likely due to memory allocation failure injection.
Reported-by: syzbot+a306f914b4d01b3958fe@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/000000000000fcba1e05e998263c@google.com/
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/ctree.c | 53 ++++++++++++++++++++++++++++++--------
fs/btrfs/extent-tree.c | 24 ++++++++++-------
fs/btrfs/extent-tree.h | 8 +++---
fs/btrfs/free-space-tree.c | 10 ++++---
fs/btrfs/ioctl.c | 6 ++++-
fs/btrfs/qgroup.c | 6 +++--
6 files changed, 76 insertions(+), 31 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 1a49b92329908..ca372068226d5 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -620,10 +620,16 @@ int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
atomic_inc(&cow->refs);
rcu_assign_pointer(root->node, cow);
- btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
- parent_start, last_ref);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
+ parent_start, last_ref);
free_extent_buffer(buf);
add_root_to_dirty_list(root);
+ if (ret < 0) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
} else {
WARN_ON(trans->transid != btrfs_header_generation(parent));
ret = btrfs_tree_mod_log_insert_key(parent, parent_slot,
@@ -648,8 +654,14 @@ int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
return ret;
}
}
- btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
- parent_start, last_ref);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
+ parent_start, last_ref);
+ if (ret < 0) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
}
if (unlock_orig)
btrfs_tree_unlock(buf);
@@ -983,9 +995,13 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
free_extent_buffer(mid);
root_sub_used_bytes(root);
- btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
/* once for the root ptr */
free_extent_buffer_stale(mid);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
return 0;
}
if (btrfs_header_nritems(mid) >
@@ -1053,10 +1069,14 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
goto out;
}
root_sub_used_bytes(root);
- btrfs_free_tree_block(trans, btrfs_root_id(root), right,
- 0, 1);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(root),
+ right, 0, 1);
free_extent_buffer_stale(right);
right = NULL;
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
} else {
struct btrfs_disk_key right_key;
btrfs_node_key(right, &right_key, 0);
@@ -1111,9 +1131,13 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
goto out;
}
root_sub_used_bytes(root);
- btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
free_extent_buffer_stale(mid);
mid = NULL;
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
} else {
/* update the parent key to reflect our changes */
struct btrfs_disk_key mid_key;
@@ -2883,7 +2907,11 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
old = root->node;
ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
if (ret < 0) {
- btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
+ int ret2;
+
+ ret2 = btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
+ if (ret2 < 0)
+ btrfs_abort_transaction(trans, ret2);
btrfs_tree_unlock(c);
free_extent_buffer(c);
return ret;
@@ -4452,9 +4480,12 @@ static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
root_sub_used_bytes(root);
atomic_inc(&leaf->refs);
- btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
free_extent_buffer_stale(leaf);
- return 0;
+ if (ret < 0)
+ btrfs_abort_transaction(trans, ret);
+
+ return ret;
}
/*
* delete the item at the leaf level in path. If that empties
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3774c191e36dc..41db538e4959e 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3419,10 +3419,10 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
return 0;
}
-void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
- u64 root_id,
- struct extent_buffer *buf,
- u64 parent, int last_ref)
+int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
+ u64 root_id,
+ struct extent_buffer *buf,
+ u64 parent, int last_ref)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *bg;
@@ -3449,11 +3449,12 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
btrfs_init_tree_ref(&generic_ref, btrfs_header_level(buf), 0, false);
btrfs_ref_tree_mod(fs_info, &generic_ref);
ret = btrfs_add_delayed_tree_ref(trans, &generic_ref, NULL);
- BUG_ON(ret); /* -ENOMEM */
+ if (ret < 0)
+ return ret;
}
if (!last_ref)
- return;
+ return 0;
if (btrfs_header_generation(buf) != trans->transid)
goto out;
@@ -3510,6 +3511,7 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
* matter anymore.
*/
clear_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags);
+ return 0;
}
/* Can return -ENOMEM */
@@ -5643,7 +5645,7 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
struct walk_control *wc)
{
struct btrfs_fs_info *fs_info = root->fs_info;
- int ret;
+ int ret = 0;
int level = wc->level;
struct extent_buffer *eb = path->nodes[level];
u64 parent = 0;
@@ -5730,12 +5732,14 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
goto owner_mismatch;
}
- btrfs_free_tree_block(trans, btrfs_root_id(root), eb, parent,
- wc->refs[level] == 1);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(root), eb, parent,
+ wc->refs[level] == 1);
+ if (ret < 0)
+ btrfs_abort_transaction(trans, ret);
out:
wc->refs[level] = 0;
wc->flags[level] = 0;
- return 0;
+ return ret;
owner_mismatch:
btrfs_err_rl(fs_info, "unexpected tree owner, have %llu expect %llu",
diff --git a/fs/btrfs/extent-tree.h b/fs/btrfs/extent-tree.h
index af9f8800d5aca..2ad51130c037e 100644
--- a/fs/btrfs/extent-tree.h
+++ b/fs/btrfs/extent-tree.h
@@ -127,10 +127,10 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
u64 empty_size,
u64 reloc_src_root,
enum btrfs_lock_nesting nest);
-void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
- u64 root_id,
- struct extent_buffer *buf,
- u64 parent, int last_ref);
+int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
+ u64 root_id,
+ struct extent_buffer *buf,
+ u64 parent, int last_ref);
int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 owner,
u64 offset, u64 ram_bytes,
diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
index 90f2938bd743d..7ba50e133921a 100644
--- a/fs/btrfs/free-space-tree.c
+++ b/fs/btrfs/free-space-tree.c
@@ -1300,10 +1300,14 @@ int btrfs_delete_free_space_tree(struct btrfs_fs_info *fs_info)
btrfs_tree_lock(free_space_root->node);
btrfs_clear_buffer_dirty(trans, free_space_root->node);
btrfs_tree_unlock(free_space_root->node);
- btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
- free_space_root->node, 0, 1);
-
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
+ free_space_root->node, 0, 1);
btrfs_put_root(free_space_root);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ btrfs_end_transaction(trans);
+ return ret;
+ }
return btrfs_commit_transaction(trans);
}
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index efd5d6e9589e0..c1b0556e40368 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -719,6 +719,8 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
ret = btrfs_insert_root(trans, fs_info->tree_root, &key,
root_item);
if (ret) {
+ int ret2;
+
/*
* Since we don't abort the transaction in this case, free the
* tree block so that we don't leak space and leave the
@@ -729,7 +731,9 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
btrfs_tree_lock(leaf);
btrfs_clear_buffer_dirty(trans, leaf);
btrfs_tree_unlock(leaf);
- btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
+ ret2 = btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
+ if (ret2 < 0)
+ btrfs_abort_transaction(trans, ret2);
free_extent_buffer(leaf);
goto out;
}
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 39a15cca58ca9..29d6ca3b874ec 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1446,9 +1446,11 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
btrfs_tree_lock(quota_root->node);
btrfs_clear_buffer_dirty(trans, quota_root->node);
btrfs_tree_unlock(quota_root->node);
- btrfs_free_tree_block(trans, btrfs_root_id(quota_root),
- quota_root->node, 0, 1);
+ ret = btrfs_free_tree_block(trans, btrfs_root_id(quota_root),
+ quota_root->node, 0, 1);
+ if (ret < 0)
+ btrfs_abort_transaction(trans, ret);
out:
btrfs_put_root(quota_root);
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH AUTOSEL 6.10 24/27] btrfs: fix data race when accessing the last_trans field of a root
[not found] <20240728005329.1723272-1-sashal@kernel.org>
` (2 preceding siblings ...)
2024-07-28 0:53 ` [PATCH AUTOSEL 6.10 23/27] btrfs: reduce nesting for extent processing at btrfs_lookup_extent_info() Sasha Levin
@ 2024-07-28 0:53 ` Sasha Levin
2024-07-28 0:53 ` [PATCH AUTOSEL 6.10 25/27] btrfs: fix bitmap leak when loading free space cache on duplicate entry Sasha Levin
4 siblings, 0 replies; 5+ messages in thread
From: Sasha Levin @ 2024-07-28 0:53 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Filipe Manana, Josef Bacik, David Sterba, Sasha Levin, clm,
linux-btrfs
From: Filipe Manana <fdmanana@suse.com>
[ Upstream commit ca84529a842f3a15a5f17beac6252aa11955923f ]
KCSAN complains about a data race when accessing the last_trans field of a
root:
[ 199.553628] BUG: KCSAN: data-race in btrfs_record_root_in_trans [btrfs] / record_root_in_trans [btrfs]
[ 199.555186] read to 0x000000008801e308 of 8 bytes by task 2812 on cpu 1:
[ 199.555210] btrfs_record_root_in_trans+0x9a/0x128 [btrfs]
[ 199.555999] start_transaction+0x154/0xcd8 [btrfs]
[ 199.556780] btrfs_join_transaction+0x44/0x60 [btrfs]
[ 199.557559] btrfs_dirty_inode+0x9c/0x140 [btrfs]
[ 199.558339] btrfs_update_time+0x8c/0xb0 [btrfs]
[ 199.559123] touch_atime+0x16c/0x1e0
[ 199.559151] pipe_read+0x6a8/0x7d0
[ 199.559179] vfs_read+0x466/0x498
[ 199.559204] ksys_read+0x108/0x150
[ 199.559230] __s390x_sys_read+0x68/0x88
[ 199.559257] do_syscall+0x1c6/0x210
[ 199.559286] __do_syscall+0xc8/0xf0
[ 199.559318] system_call+0x70/0x98
[ 199.559431] write to 0x000000008801e308 of 8 bytes by task 2808 on cpu 0:
[ 199.559464] record_root_in_trans+0x196/0x228 [btrfs]
[ 199.560236] btrfs_record_root_in_trans+0xfe/0x128 [btrfs]
[ 199.561097] start_transaction+0x154/0xcd8 [btrfs]
[ 199.561927] btrfs_join_transaction+0x44/0x60 [btrfs]
[ 199.562700] btrfs_dirty_inode+0x9c/0x140 [btrfs]
[ 199.563493] btrfs_update_time+0x8c/0xb0 [btrfs]
[ 199.564277] file_update_time+0xb8/0xf0
[ 199.564301] pipe_write+0x8ac/0xab8
[ 199.564326] vfs_write+0x33c/0x588
[ 199.564349] ksys_write+0x108/0x150
[ 199.564372] __s390x_sys_write+0x68/0x88
[ 199.564397] do_syscall+0x1c6/0x210
[ 199.564424] __do_syscall+0xc8/0xf0
[ 199.564452] system_call+0x70/0x98
This is because we update and read last_trans concurrently without any
type of synchronization. This should be generally harmless and in the
worst case it can make us do extra locking (btrfs_record_root_in_trans())
trigger some warnings at ctree.c or do extra work during relocation - this
would probably only happen in case of load or store tearing.
So fix this by always reading and updating the field using READ_ONCE()
and WRITE_ONCE(), this silences KCSAN and prevents load and store tearing.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/ctree.c | 4 ++--
fs/btrfs/ctree.h | 10 ++++++++++
fs/btrfs/defrag.c | 2 +-
fs/btrfs/disk-io.c | 4 ++--
fs/btrfs/relocation.c | 8 ++++----
fs/btrfs/transaction.c | 8 ++++----
6 files changed, 23 insertions(+), 13 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ca372068226d5..8a791b648ac53 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -321,7 +321,7 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
trans->transid != fs_info->running_transaction->transid);
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
- trans->transid != root->last_trans);
+ trans->transid != btrfs_get_root_last_trans(root));
level = btrfs_header_level(buf);
if (level == 0)
@@ -551,7 +551,7 @@ int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
trans->transid != fs_info->running_transaction->transid);
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
- trans->transid != root->last_trans);
+ trans->transid != btrfs_get_root_last_trans(root));
level = btrfs_header_level(buf);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index c03c58246033b..b2e4b30b8fae9 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -354,6 +354,16 @@ static inline void btrfs_set_root_last_log_commit(struct btrfs_root *root, int c
WRITE_ONCE(root->last_log_commit, commit_id);
}
+static inline u64 btrfs_get_root_last_trans(const struct btrfs_root *root)
+{
+ return READ_ONCE(root->last_trans);
+}
+
+static inline void btrfs_set_root_last_trans(struct btrfs_root *root, u64 transid)
+{
+ WRITE_ONCE(root->last_trans, transid);
+}
+
/*
* Structure that conveys information about an extent that is going to replace
* all the extents in a file range.
diff --git a/fs/btrfs/defrag.c b/fs/btrfs/defrag.c
index 407ccec3e57ed..f664678c71d15 100644
--- a/fs/btrfs/defrag.c
+++ b/fs/btrfs/defrag.c
@@ -139,7 +139,7 @@ int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
if (trans)
transid = trans->transid;
else
- transid = inode->root->last_trans;
+ transid = btrfs_get_root_last_trans(root);
defrag = kmem_cache_zalloc(btrfs_inode_defrag_cachep, GFP_NOFS);
if (!defrag)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index cabb558dbdaa8..3791813dc7b62 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -658,7 +658,7 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
root->state = 0;
RB_CLEAR_NODE(&root->rb_node);
- root->last_trans = 0;
+ btrfs_set_root_last_trans(root, 0);
root->free_objectid = 0;
root->nr_delalloc_inodes = 0;
root->nr_ordered_extents = 0;
@@ -1010,7 +1010,7 @@ int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
return ret;
}
- log_root->last_trans = trans->transid;
+ btrfs_set_root_last_trans(log_root, trans->transid);
log_root->root_key.offset = btrfs_root_id(root);
inode_item = &log_root->root_item.inode;
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 8b24bb5a0aa18..f2935252b981a 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -817,7 +817,7 @@ static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
goto abort;
}
set_bit(BTRFS_ROOT_SHAREABLE, &reloc_root->state);
- reloc_root->last_trans = trans->transid;
+ btrfs_set_root_last_trans(reloc_root, trans->transid);
return reloc_root;
fail:
kfree(root_item);
@@ -864,7 +864,7 @@ int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
*/
if (root->reloc_root) {
reloc_root = root->reloc_root;
- reloc_root->last_trans = trans->transid;
+ btrfs_set_root_last_trans(reloc_root, trans->transid);
return 0;
}
@@ -1739,7 +1739,7 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
* btrfs_update_reloc_root() and update our root item
* appropriately.
*/
- reloc_root->last_trans = trans->transid;
+ btrfs_set_root_last_trans(reloc_root, trans->transid);
trans->block_rsv = rc->block_rsv;
replaced = 0;
@@ -2082,7 +2082,7 @@ static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
struct btrfs_root *root;
int ret;
- if (reloc_root->last_trans == trans->transid)
+ if (btrfs_get_root_last_trans(reloc_root) == trans->transid)
return 0;
root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset, false);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 3388c836b9a56..76117bb2c726c 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -405,7 +405,7 @@ static int record_root_in_trans(struct btrfs_trans_handle *trans,
int ret = 0;
if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
- root->last_trans < trans->transid) || force) {
+ btrfs_get_root_last_trans(root) < trans->transid) || force) {
WARN_ON(!force && root->commit_root != root->node);
/*
@@ -421,7 +421,7 @@ static int record_root_in_trans(struct btrfs_trans_handle *trans,
smp_wmb();
spin_lock(&fs_info->fs_roots_radix_lock);
- if (root->last_trans == trans->transid && !force) {
+ if (btrfs_get_root_last_trans(root) == trans->transid && !force) {
spin_unlock(&fs_info->fs_roots_radix_lock);
return 0;
}
@@ -429,7 +429,7 @@ static int record_root_in_trans(struct btrfs_trans_handle *trans,
(unsigned long)btrfs_root_id(root),
BTRFS_ROOT_TRANS_TAG);
spin_unlock(&fs_info->fs_roots_radix_lock);
- root->last_trans = trans->transid;
+ btrfs_set_root_last_trans(root, trans->transid);
/* this is pretty tricky. We don't want to
* take the relocation lock in btrfs_record_root_in_trans
@@ -491,7 +491,7 @@ int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
* and barriers
*/
smp_rmb();
- if (root->last_trans == trans->transid &&
+ if (btrfs_get_root_last_trans(root) == trans->transid &&
!test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
return 0;
--
2.43.0
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