Commit c933956d authored by Miao Xie's avatar Miao Xie Committed by Josef Bacik

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: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
parent 9c9ca00b
...@@ -1411,7 +1411,7 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos, ...@@ -1411,7 +1411,7 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos,
int ret; int ret;
lockstart = round_down(pos, root->sectorsize); 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) { while (1) {
lock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend); 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, ...@@ -1434,7 +1434,8 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos,
EXTENT_DIRTY | EXTENT_DELALLOC | EXTENT_DIRTY | EXTENT_DELALLOC |
EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0, EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0,
NULL, GFP_NOFS); 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); unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment