Re: [PATCH 1/3] btrfs: rst: remove encoding field from stripe_extent

Qu Wenruo
2024-06-17T06:27:43Z

在 2024/6/10 18:10, Johannes Thumshirn 写道:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
>
> Remove the encoding field from 'struct btrfs_stripe_extent'. It was
> originally intended to encode the RAID type as well as if we're a data
> or a parity stripe.
>
> But the RAID type can be inferred form the block-group and the data vs.
> parity differentiation can be done easier with adding a new key type
> for parity stripes in the RAID stripe tree.

Talking about adding new key type or even new members, I'm wondering can
we also utilizing the higher 8/16/32 bits of key.offset?

Currently the RST entry uses key.offset for the length of the entry,
which is at most the length of the max zone append size.

If the vendor (WDC) is determined to go with zone size smaller than 4G
(32bits) or 256T (48bits), we definitely have 32 or 16 bits for other
usages, without expanding the entry item size.

The 4G (32bits) looks a little unreliable but 256T (48bits) is
definitely worthy considering.

Thanks,
Qu
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
> fs/btrfs/accessors.h | 3 ---
> fs/btrfs/print-tree.c | 5 -----
> fs/btrfs/raid-stripe-tree.c | 13 -------------
> fs/btrfs/raid-stripe-tree.h | 3 +--
> fs/btrfs/tree-checker.c | 19 -------------------
> include/uapi/linux/btrfs_tree.h | 14 +-------------
> 6 files changed, 2 insertions(+), 55 deletions(-)
>
> diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
> index 6c3deaa3e878..b2eb9cde2c5d 100644
> --- a/fs/btrfs/accessors.h
> +++ b/fs/btrfs/accessors.h
> @@ -315,11 +315,8 @@ BTRFS_SETGET_FUNCS(timespec_nsec, struct btrfs_timespec, nsec, 32);
> BTRFS_SETGET_STACK_FUNCS(stack_timespec_sec, struct btrfs_timespec, sec, 64);
> BTRFS_SETGET_STACK_FUNCS(stack_timespec_nsec, struct btrfs_timespec, nsec, 32);
>
> -BTRFS_SETGET_FUNCS(stripe_extent_encoding, struct btrfs_stripe_extent, encoding, 8);
> BTRFS_SETGET_FUNCS(raid_stride_devid, struct btrfs_raid_stride, devid, 64);
> BTRFS_SETGET_FUNCS(raid_stride_physical, struct btrfs_raid_stride, physical, 64);
> -BTRFS_SETGET_STACK_FUNCS(stack_stripe_extent_encoding,
> - struct btrfs_stripe_extent, encoding, 8);
> BTRFS_SETGET_STACK_FUNCS(stack_raid_stride_devid, struct btrfs_raid_stride, devid, 64);
> BTRFS_SETGET_STACK_FUNCS(stack_raid_stride_physical, struct btrfs_raid_stride, physical, 64);
>
> diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
> index 7e46aa8a0444..9f1e5e11bf71 100644
> --- a/fs/btrfs/print-tree.c
> +++ b/fs/btrfs/print-tree.c
> @@ -208,11 +208,6 @@ static void print_raid_stripe_key(const struct extent_buffer *eb, u32 item_size,
> struct btrfs_stripe_extent *stripe)
> {
> const int num_stripes = btrfs_num_raid_stripes(item_size);
> - const u8 encoding = btrfs_stripe_extent_encoding(eb, stripe);
> -
> - pr_info("\t\t\tencoding: %s\n",
> - (encoding && encoding < BTRFS_NR_RAID_TYPES) ?
> - btrfs_raid_array[encoding].raid_name : "unknown");
>
> for (int i = 0; i < num_stripes; i++)
> pr_info("\t\t\tstride %d devid %llu physical %llu\n",
> diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
> index 6af6b4b9a32e..e6f7a234b8f6 100644
> --- a/fs/btrfs/raid-stripe-tree.c
> +++ b/fs/btrfs/raid-stripe-tree.c
> @@ -80,7 +80,6 @@ static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
> struct btrfs_key stripe_key;
> struct btrfs_root *stripe_root = fs_info->stripe_root;
> const int num_stripes = btrfs_bg_type_to_factor(bioc->map_type);
> - u8 encoding = btrfs_bg_flags_to_raid_index(bioc->map_type);
> struct btrfs_stripe_extent *stripe_extent;
> const size_t item_size = struct_size(stripe_extent, strides, num_stripes);
> int ret;
> @@ -94,7 +93,6 @@ static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
>
> trace_btrfs_insert_one_raid_extent(fs_info, bioc->logical, bioc->size,
> num_stripes);
> - btrfs_set_stack_stripe_extent_encoding(stripe_extent, encoding);
> for (int i = 0; i < num_stripes; i++) {
> u64 devid = bioc->stripes[i].dev->devid;
> u64 physical = bioc->stripes[i].physical;
> @@ -159,7 +157,6 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
> struct extent_buffer *leaf;
> const u64 end = logical + *length;
> int num_stripes;
> - u8 encoding;
> u64 offset;
> u64 found_logical;
> u64 found_length;
> @@ -222,16 +219,6 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
>
> num_stripes = btrfs_num_raid_stripes(btrfs_item_size(leaf, slot));
> stripe_extent = btrfs_item_ptr(leaf, slot, struct btrfs_stripe_extent);
> - encoding = btrfs_stripe_extent_encoding(leaf, stripe_extent);
> -
> - if (encoding != btrfs_bg_flags_to_raid_index(map_type)) {
> - ret = -EUCLEAN;
> - btrfs_handle_fs_error(fs_info, ret,
> - "on-disk stripe encoding %d doesn't match RAID index %d",
> - encoding,
> - btrfs_bg_flags_to_raid_index(map_type));
> - goto out;
> - }
>
> for (int i = 0; i < num_stripes; i++) {
> struct btrfs_raid_stride *stride = &stripe_extent->strides[i];
> diff --git a/fs/btrfs/raid-stripe-tree.h b/fs/btrfs/raid-stripe-tree.h
> index c9c258f84903..1ac1c21aac2f 100644
> --- a/fs/btrfs/raid-stripe-tree.h
> +++ b/fs/btrfs/raid-stripe-tree.h
> @@ -48,8 +48,7 @@ static inline bool btrfs_need_stripe_tree_update(struct btrfs_fs_info *fs_info,
>
> static inline int btrfs_num_raid_stripes(u32 item_size)
> {
> - return (item_size - offsetof(struct btrfs_stripe_extent, strides)) /
> - sizeof(struct btrfs_raid_stride);
> + return item_size / sizeof(struct btrfs_raid_stride);
> }
>
> #endif
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index a2c3651a3d8f..1e140f6dabc6 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -1682,9 +1682,6 @@ static int check_inode_ref(struct extent_buffer *leaf,
> static int check_raid_stripe_extent(const struct extent_buffer *leaf,
> const struct btrfs_key *key, int slot)
> {
> - struct btrfs_stripe_extent *stripe_extent =
> - btrfs_item_ptr(leaf, slot, struct btrfs_stripe_extent);
> -
> if (unlikely(!IS_ALIGNED(key->objectid, leaf->fs_info->sectorsize))) {
> generic_err(leaf, slot,
> "invalid key objectid for raid stripe extent, have %llu expect aligned to %u",
> @@ -1698,22 +1695,6 @@ static int check_raid_stripe_extent(const struct extent_buffer *leaf,
> return -EUCLEAN;
> }
>
> - switch (btrfs_stripe_extent_encoding(leaf, stripe_extent)) {
> - case BTRFS_STRIPE_RAID0:
> - case BTRFS_STRIPE_RAID1:
> - case BTRFS_STRIPE_DUP:
> - case BTRFS_STRIPE_RAID10:
> - case BTRFS_STRIPE_RAID5:
> - case BTRFS_STRIPE_RAID6:
> - case BTRFS_STRIPE_RAID1C3:
> - case BTRFS_STRIPE_RAID1C4:
> - break;
> - default:
> - generic_err(leaf, slot, "invalid raid stripe encoding %u",
> - btrfs_stripe_extent_encoding(leaf, stripe_extent));
> - return -EUCLEAN;
> - }
> -
> return 0;
> }
>
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> index d24e8e121507..cb103c76d398 100644
> --- a/include/uapi/linux/btrfs_tree.h
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -747,21 +747,9 @@ struct btrfs_raid_stride {
> __le64 physical;
> } __attribute__ ((__packed__));
>
> -/* The stripe_extent::encoding, 1:1 mapping of enum btrfs_raid_types. */
> -#define BTRFS_STRIPE_RAID0 1
> -#define BTRFS_STRIPE_RAID1 2
> -#define BTRFS_STRIPE_DUP 3
> -#define BTRFS_STRIPE_RAID10 4
> -#define BTRFS_STRIPE_RAID5 5
> -#define BTRFS_STRIPE_RAID6 6
> -#define BTRFS_STRIPE_RAID1C3 7
> -#define BTRFS_STRIPE_RAID1C4 8
> -
> struct btrfs_stripe_extent {
> - __u8 encoding;
> - __u8 reserved[7];
> /* An array of raid strides this stripe is composed of. */
> - struct btrfs_raid_stride strides[];
> + __DECLARE_FLEX_ARRAY(struct btrfs_raid_stride, strides);
> } __attribute__ ((__packed__));
>
> #define BTRFS_HEADER_FLAG_WRITTEN (1ULL << 0)
>