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btrfs: ignore incorrect btrfs_file_extent_item::ram_bytes

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[HICCUP]
Kernels can create file extent items with incorrect ram_bytes like this:

	item 6 key (257 EXTENT_DATA 0) itemoff 15816 itemsize 53
		generation 7 type 1 (regular)
		extent data disk byte 13631488 nr 32768
		extent data offset 0 nr 4096 ram 4096
		extent compression 0 (none)

Thankfully kernel can handle them properly, as in that case ram_bytes is
not utilized at all.

[ENHANCEMENT]
Since the hiccup is not going to cause any data-loss and is only a minor
violation of on-disk format, here we only need to ignore the incorrect
ram_bytes value, and use the correct one from
btrfs_file_extent_item::disk_num_bytes.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2024-06-26 09:34:40 +09:30 committed by David Sterba
parent 0edeb6ea46
commit 88e2e6d724
1 changed files with 7 additions and 0 deletions
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7
fs/btrfs/file-item.c
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@ -1306,6 +1306,13 @@ void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
if (compress_type != BTRFS_COMPRESS_NONE) {
extent_map_set_compression(em, compress_type);
} else {
/*
* Older kernels can create regular non-hole data
* extents with ram_bytes smaller than disk_num_bytes.
* Not a big deal, just always use disk_num_bytes
* for ram_bytes.
*/
em->ram_bytes = em->disk_num_bytes;
if (type == BTRFS_FILE_EXTENT_PREALLOC)
em->flags |= EXTENT_FLAG_PREALLOC;
}