Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2025-01-09 07:23:14 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

btrfs: handle page locking in btrfs_page_end_writer_lock with no writers

Browse Source 
There are several call sites of extent_clear_unlock_delalloc() which get
@locked_page = NULL.
So that extent_clear_unlock_delalloc() will try to call
process_one_page() to unlock every page even the first page is not
locked by btrfs_page_start_writer_lock().

This will trigger an ASSERT() in btrfs_subpage_end_and_test_writer() as
previously we require every page passed to
btrfs_subpage_end_and_test_writer() to be locked by
btrfs_page_start_writer_lock().

But compression path doesn't go that way.

Thankfully it's not hard to distinguish page locked by lock_page() and
btrfs_page_start_writer_lock().

So do the check in btrfs_subpage_end_and_test_writer() so now it can
handle both cases well.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2021-09-27 15:22:06 +08:00 committed by David Sterba
parent e55a0de185
commit 164674a76b
1 changed files with 10 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
fs/btrfs/subpage.c
View File

@ -292,6 +292,16 @@ bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
btrfs_subpage_assert(fs_info, page, start, len);
/*
* We have call sites passing @lock_page into
* extent_clear_unlock_delalloc() for compression path.
*
* This @locked_page is locked by plain lock_page(), thus its
* subpage::writers is 0. Handle them in a special way.
*/
if (atomic_read(&subpage->writers) == 0)
return true;
ASSERT(atomic_read(&subpage->writers) >= nbits);
return atomic_sub_and_test(nbits, &subpage->writers);
}