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| author | Qu Wenruo <wqu@suse.com> | 2021-09-27 15:22:06 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2021-10-26 19:08:05 +0200 |
| commit | 164674a76b25da9c9ea2759eeaa8ef6f1b4ad6c8 (patch) | |
| tree | d10ceb772d8374acd62ae0dcbacc8c94c1684549 /fs | |
| parent | e55a0de185726ca43e8a31d363ad73c4f0a6770b (diff) | |
| download | linux-164674a76b25da9c9ea2759eeaa8ef6f1b4ad6c8.tar.gz | |
btrfs: handle page locking in btrfs_page_end_writer_lock with no writers
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>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/subpage.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c index 265b6aa1c662dd..29bd8c7a7706bf 100644 --- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -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); } |