From: Josef Bacik <[email protected]>
commit 230ed397435e85b54f055c524fcb267ae2ce3bc4 upstream.
While debugging a patch that I wrote I was hitting use-after-free panics
when accessing block groups on unmount. This turned out to be because
in the nocow case if we bail out of doing the nocow for whatever reason
we need to call btrfs_dec_nocow_writers() if we called the inc. This
puts our block group, but a few error cases does
if (nocow) {
btrfs_dec_nocow_writers();
goto error;
}
unfortunately, error is
error:
if (nocow)
btrfs_dec_nocow_writers();
so we get a double put on our block group. Fix this by dropping the
error cases calling of btrfs_dec_nocow_writers(), as it's handled at the
error label now.
Fixes: 762bf09893b4 ("btrfs: improve error handling in run_delalloc_nocow")
CC: [email protected] # 5.4+
Reviewed-by: Filipe Manana <[email protected]>
Signed-off-by: Josef Bacik <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/btrfs/inode.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1657,12 +1657,8 @@ out_check:
ret = fallback_to_cow(inode, locked_page, cow_start,
found_key.offset - 1,
page_started, nr_written);
- if (ret) {
- if (nocow)
- btrfs_dec_nocow_writers(fs_info,
- disk_bytenr);
+ if (ret)
goto error;
- }
cow_start = (u64)-1;
}
@@ -1678,9 +1674,6 @@ out_check:
ram_bytes, BTRFS_COMPRESS_NONE,
BTRFS_ORDERED_PREALLOC);
if (IS_ERR(em)) {
- if (nocow)
- btrfs_dec_nocow_writers(fs_info,
- disk_bytenr);
ret = PTR_ERR(em);
goto error;
}
