From 18ba649928711539dd124b4bf7682696b3f2e4a8 Mon Sep 17 00:00:00 2001 From: Mark Harmstone Date: Wed, 7 Jan 2026 14:09:09 +0000 Subject: [PATCH] btrfs: redirect I/O for remapped block groups 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. Reviewed-by: Boris Burkov Signed-off-by: Mark Harmstone Signed-off-by: David Sterba --- fs/btrfs/relocation.c | 50 +++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/relocation.h | 1 + fs/btrfs/volumes.c | 18 ++++++++++++++++ 3 files changed, 69 insertions(+) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 310b7d817a277..6de508323dbda 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -3859,6 +3859,56 @@ 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) +{ + int ret; + struct btrfs_key key, found_key; + struct extent_buffer *leaf; + struct btrfs_remap_item *remap; + BTRFS_PATH_AUTO_FREE(path); + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + 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_item); + *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 5c36b3f84b578..c0ee26004fc1f 100644 --- a/fs/btrfs/relocation.h +++ b/fs/btrfs/relocation.h @@ -31,5 +31,6 @@ 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); #endif diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6280a1a4c407e..2a4bda452d855 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -6586,6 +6586,24 @@ 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; + + ret = btrfs_translate_remap(fs_info, &new_logical, length); + if (ret) + return ret; + + if (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; + } + } + num_copies = btrfs_chunk_map_num_copies(map); if (io_geom.mirror_num > num_copies) return -EINVAL; -- 2.47.3