From: Liu Bo Date: Fri, 4 Nov 2016 19:20:54 +0000 (-0700) Subject: Btrfs: adjust len of writes if following a preallocated extent X-Git-Tag: v4.10-rc1~68^2~24^2~22 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a23eaa875f0f1d89eb866b8c9860e78273ff5daf;p=karo-tx-linux.git 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: Liu Bo Reviewed-by: Chris Mason Signed-off-by: David Sterba --- diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 06dc95caa6f1..66c1d65bd476 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -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)) {