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btrfs: add METADATA_REMAP chunk type

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Add a new METADATA_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.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Mark Harmstone 2026-01-07 14:09:02 +00:00 • committed by David Sterba
parent ef6a31d035
commit 0b4d29fa98
10 changed files with 52 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

8
fs/btrfs/block-rsv.c
View file

@ -419,6 +419,9 @@ 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;
@ -432,6 +435,9 @@ 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_METADATA_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;
@ -458,6 +464,8 @@ 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);

1
fs/btrfs/block-rsv.h
View file

@ -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,

1
fs/btrfs/disk-io.c
View file

@ -2751,6 +2751,7 @@ 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,

2
fs/btrfs/fs.h
View file

@ -509,6 +509,8 @@ 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 */

13
fs/btrfs/space-info.c
View file

@ -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_METADATA_REMAP))
return SZ_32M;
/* Handle BTRFS_BLOCK_GROUP_METADATA */
@ -348,6 +348,8 @@ 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);
@ -356,7 +358,15 @@ 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_METADATA_REMAP;
ret = create_space_info(fs_info, flags);
}
out:
return ret;
}
@ -611,6 +621,7 @@ 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);
}

2
fs/btrfs/sysfs.c
View file

@ -1929,6 +1929,8 @@ 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_METADATA_REMAP:
return "metadata-remap";
default:
WARN_ON(1);
return "invalid-combination";

13
fs/btrfs/tree-checker.c
View file

@ -748,17 +748,26 @@ static int check_block_group_item(struct extent_buffer *leaf,
return -EUCLEAN;
}
if (unlikely(flags & BTRFS_BLOCK_GROUP_METADATA_REMAP &&
!btrfs_fs_incompat(fs_info, REMAP_TREE))) {
block_group_err(leaf, slot,
"invalid flags, have 0x%llx (METADATA_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_METADATA_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_METADATA_REMAP,
BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
return -EUCLEAN;
}

3
fs/btrfs/volumes.c
View file

@ -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_METADATA_REMAP, "metadata-remap");
/* Block group that has been remapped. */
DESCRIBE_FLAG(BTRFS_BLOCK_GROUP_REMAPPED, "remapped");
DESCRIBE_FLAG(BTRFS_AVAIL_ALLOC_BIT_SINGLE, "single");

10
fs/btrfs/volumes.h
View file

@ -58,7 +58,6 @@ static_assert(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(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) \
@ -80,6 +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.

4
include/uapi/linux/btrfs_tree.h
View file

@ -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_METADATA_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_METADATA_REMAP)
#define BTRFS_BLOCK_GROUP_PROFILE_MASK (BTRFS_BLOCK_GROUP_RAID0 | \
BTRFS_BLOCK_GROUP_RAID1 | \