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authorMiao Xie <miaox@cn.fujitsu.com>2014-02-27 05:58:04 (GMT)
committerJosef Bacik <jbacik@fb.com>2014-03-10 19:17:00 (GMT)
commitc933956ddf80bc455d33cbcf39d35d935daf45a9 (patch)
tree0417dba0c65787ad3de69f92563e1824086706a6 /fs/btrfs/file.c
parent9c9ca00bd31989f1a3dcbf54e97c979024e44409 (diff)
downloadlinux-c933956ddf80bc455d33cbcf39d35d935daf45a9.tar.xz
Btrfs: fix wrong lock range and write size in check_can_nocow()
The write range may not be sector-aligned, for example: |--------|--------| <- write range, sector-unaligned, size: 2blocks |--------|--------|--------| <- correct lock range, size: 3blocks But according to the old code, we used the size of write range to calculate the lock range directly, not considered the offset, we would get a wrong lock range: |--------|--------| <- write range, sector-unaligned, size: 2blocks |--------|--------| <- wrong lock range, size: 2blocks And besides that, the old code also had the same problem when calculating the real write size. Correct them. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Josef Bacik <jbacik@fb.com>
Diffstat (limited to 'fs/btrfs/file.c')
-rw-r--r--fs/btrfs/file.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 31e48b9..fc2d21b 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1411,7 +1411,7 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos,
int ret;
lockstart = round_down(pos, root->sectorsize);
- lockend = lockstart + round_up(*write_bytes, root->sectorsize) - 1;
+ lockend = round_up(pos + *write_bytes, root->sectorsize) - 1;
while (1) {
lock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
@@ -1434,7 +1434,8 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos,
EXTENT_DIRTY | EXTENT_DELALLOC |
EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0,
NULL, GFP_NOFS);
- *write_bytes = min_t(size_t, *write_bytes, num_bytes);
+ *write_bytes = min_t(size_t, *write_bytes ,
+ num_bytes - pos + lockstart);
}
unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);