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btrfs-progs: check: lowmem, detect and repair mismatched ram_bytes 

For non-compressed non-hole file extent items, the ram_bytes should
match disk_num_bytes.

But due to kernel bugs, we have several cases where ram_bytes is not
correctly updated.

Thankfully this is really a very minor mismatch and can never cause data
corruption since the kernel does not utilize ram_bytes for
non-compressed extents at all.

So here we just detect and repair it for lowmem mode.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2024-05-02 18:37:53 +09:30 committed by David Sterba
parent bcb887a4de
commit 97bf7a5969
2 changed files with 70 additions and 0 deletions
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69
check/mode-lowmem.c
View File

@ -2018,6 +2018,61 @@ static int check_file_extent_inline(struct btrfs_root *root,
return err;
}
static int repair_ram_bytes_mismatch(struct btrfs_root *root,
struct btrfs_path *path)
{
struct btrfs_trans_handle *trans;
struct btrfs_key key;
struct btrfs_file_extent_item *fi;
u64 disk_num_bytes;
int recover_ret;
int ret;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
btrfs_release_path(path);
UASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
errno = -ret;
error_msg(ERROR_MSG_START_TRANS, "%m");
return ret;
}
ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
/* Not really possible. */
if (ret > 0) {
ret = -ENOENT;
btrfs_release_path(path);
goto recover;
}
if (ret < 0)
goto recover;
fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_file_extent_item);
disk_num_bytes = btrfs_file_extent_disk_num_bytes(path->nodes[0], fi);
btrfs_set_file_extent_ram_bytes(path->nodes[0], fi, disk_num_bytes);
btrfs_mark_buffer_dirty(path->nodes[0]);
ret = btrfs_commit_transaction(trans, root);
if (ret < 0) {
errno = -ret;
error_msg(ERROR_MSG_COMMIT_TRANS, "%m");
} else {
printf(
"Successfully repaired ram_bytes for non-compressed extent at root %llu ino %llu file_pos %llu\n",
root->objectid, key.objectid, key.offset);
}
return ret;
recover:
recover_ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
UASSERT(recover_ret == 0);
return ret;
}
/*
* Check file extent datasum/hole, update the size of the file extents,
* check and update the last offset of the file extent.
@ -2043,6 +2098,7 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_path *path,
u64 csum_found; /* In byte size, sectorsize aligned */
u64 search_start; /* Logical range start we search for csum */
u64 search_len; /* Logical range len we search for csum */
u64 ram_bytes;
u64 gen;
u64 super_gen;
unsigned int extent_type;
@ -2077,6 +2133,7 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_path *path,
extent_num_bytes = btrfs_file_extent_num_bytes(node, fi);
extent_offset = btrfs_file_extent_offset(node, fi);
compressed = btrfs_file_extent_compression(node, fi);
ram_bytes = btrfs_file_extent_ram_bytes(node, fi);
is_hole = (disk_bytenr == 0) && (disk_num_bytes == 0);
super_gen = btrfs_super_generation(gfs_info->super_copy);
@ -2087,6 +2144,18 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_path *path,
err |= INVALID_GENERATION;
}
if (!compressed && disk_bytenr && disk_num_bytes != ram_bytes) {
error(
"minor ram_bytes mismatch for non-compressed data extents, have %llu expect %llu",
ram_bytes, disk_num_bytes);
if (opt_check_repair) {
ret = repair_ram_bytes_mismatch(root, path);
if (ret < 0)
err |= RAM_BYTES_MISMATCH;
} else {
err |= RAM_BYTES_MISMATCH;
}
}
/*
* Check EXTENT_DATA csum
*

1
check/mode-lowmem.h
View File

@ -47,6 +47,7 @@
#define INODE_MODE_ERROR (1U << 25) /* Bad inode mode */
#define INVALID_GENERATION (1U << 26) /* Generation is too new */
#define SUPER_BYTES_USED_ERROR (1U << 27) /* Super bytes_used is invalid */
#define RAM_BYTES_MISMATCH (1U << 27) /* Non-compressed extent has wrong ram_bytes */
/*
* Error bit for low memory mode check.