btrfs: don't split NOCOW extent_maps in btrfs_extract_ordered_extent

NOCOW writes just overwrite an existing extent map, which thus should not be split in btrfs_extract_ordered_extent. The NOCOW case can't currently happen as btrfs_extract_ordered_extent is only used on zoned devices that do not support NOCOW writes, but this will change soon. Reviewed-by: Josef Bacik <[email protected]> Tested-by: Johannes Thumshirn <[email protected]> Signed-off-by: Boris Burkov <[email protected]> [ hch: split from a larger patch, wrote a commit log ] Signed-off-by: Christoph Hellwig <[email protected]> Signed-off-by: David Sterba <[email protected]>
niw · Apr 17, 2023 · f0f5329 · f0f5329
1 parent 7edd339
commit f0f5329
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
@@ -2621,6 +2621,14 @@ int btrfs_extract_ordered_extent(struct btrfs_bio *bbio,
 	ret = btrfs_split_ordered_extent(ordered, len);
 	if (ret)
 		return ret;
+
+	/*
+	 * Don't split the extent_map for NOCOW extents, as we're writing into
+	 * a pre-existing one.
+	 */
+	if (test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags))
+		return 0;
+
 	return split_extent_map(inode, bbio->file_offset, ordered_len, len);
 }