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Commit a23eaa87 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
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Btrfs: adjust len of writes if following a preallocated extent 



If we have

|0--hole--4095||4096--preallocate--12287|

instead of using preallocated space, a 8K direct write will just
create a new 8K extent and it'll end up with

|0--new extent--8191||8192--preallocate--12287|

It's because we find a hole em and then go to create a new 8K
extent directly without adjusting @len.

Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: default avatarChris Mason <clm@fb.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 7b9ea627

fs/btrfs/inode.c

+5 −3
Original line number Diff line number Diff line
@@ -7782,10 +7782,12 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, 
	}



	/*

	 * this will cow the extent, reset the len in case we changed

	 * it above

	 * this will cow the extent, if em is within [start, len], then

	 * probably we've found a preallocated/existing extent, let's

	 * give it a chance to use preallocated space.

	 */

	len = bh_result->b_size;

	len = min_t(u64, bh_result->b_size, em->len - (start - em->start));

	len = ALIGN(len, root->sectorsize);

	free_extent_map(em);

	em = btrfs_new_extent_direct(inode, start, len);

	if (IS_ERR(em)) {