From: Qu Wenruo <wqu@suse.com>
To: linux-btrfs@vger.kernel.org
Subject: [PATCH 24/27] btrfs: allow page to be unlocked by btrfs_page_end_writer_lock() even if it's locked by plain page_lock()
Date: Tue, 13 Jul 2021 14:15:13 +0800 [thread overview]
Message-ID: <20210713061516.163318-25-wqu@suse.com> (raw)
In-Reply-To: <20210713061516.163318-1-wqu@suse.com>
There are several call sites of extent_clear_unlock_delalloc() which
gets @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>
---
fs/btrfs/subpage.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c
index 3e0416e7e48b..7d0f4f1ce0bf 100644
--- a/fs/btrfs/subpage.c
+++ b/fs/btrfs/subpage.c
@@ -248,6 +248,17 @@ 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.
+ *
+ * Those @locked_page is locked by plain lock_page(), thus its
+ * subpage::writers is 0.
+ * Handle them specially.
+ */
+ if (atomic_read(&subpage->writers) == 0)
+ return true;
+
ASSERT(atomic_read(&subpage->writers) >= nbits);
return atomic_sub_and_test(nbits, &subpage->writers);
}
--
2.32.0
next prev parent reply other threads:[~2021-07-13 6:15 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 6:14 [PATCH 00/27] btrfs: limited subpage compressed write support Qu Wenruo
2021-07-13 6:14 ` [PATCH 01/27] btrfs: remove unused parameter @nr_pages in add_ra_bio_pages() Qu Wenruo
2021-07-13 6:14 ` [PATCH 02/27] btrfs: remove unnecessary parameter @delalloc_start for writepage_delalloc() Qu Wenruo
2021-07-13 6:14 ` [PATCH 03/27] btrfs: use async_chunk::async_cow to replace the confusing pending pointer Qu Wenruo
2021-07-13 7:36 ` Nikolay Borisov
2021-07-13 6:14 ` [PATCH 04/27] btrfs: don't pass compressed pages to btrfs_writepage_endio_finish_ordered() Qu Wenruo
2021-07-13 6:14 ` [PATCH 05/27] btrfs: make add_ra_bio_pages() to be subpage compatible Qu Wenruo
2021-07-13 6:14 ` [PATCH 06/27] btrfs: introduce compressed_bio::pending_sectors to trace compressed bio more elegantly Qu Wenruo
2021-07-13 6:14 ` [PATCH 07/27] btrfs: add subpage checked_bitmap to make PageChecked flag to be subpage compatible Qu Wenruo
2021-07-16 7:54 ` Qu Wenruo
2021-07-13 6:14 ` [PATCH 08/27] btrfs: handle errors properly inside btrfs_submit_compressed_read() Qu Wenruo
2021-07-13 6:14 ` [PATCH 09/27] btrfs: handle errors properly inside btrfs_submit_compressed_write() Qu Wenruo
2021-07-13 6:14 ` [PATCH 10/27] btrfs: introduce submit_compressed_bio() for compression Qu Wenruo
2021-07-13 6:15 ` [PATCH 11/27] btrfs: introduce alloc_compressed_bio() " Qu Wenruo
2021-07-13 6:15 ` [PATCH 12/27] btrfs: make btrfs_submit_compressed_read() to determine stripe boundary at bio allocation time Qu Wenruo
2021-07-13 6:15 ` [PATCH 13/27] btrfs: make btrfs_submit_compressed_write() " Qu Wenruo
2021-07-13 6:15 ` [PATCH 14/27] btrfs: remove unused function btrfs_bio_fits_in_stripe() Qu Wenruo
2021-07-13 6:15 ` [PATCH 15/27] btrfs: refactor submit_compressed_extents() Qu Wenruo
2021-07-13 6:15 ` [PATCH 16/27] btrfs: cleanup for extent_write_locked_range() Qu Wenruo
2021-07-13 6:15 ` [PATCH 17/27] btrfs: make compress_file_range() to be subpage compatible Qu Wenruo
2021-07-13 6:15 ` [PATCH 18/27] btrfs: make btrfs_submit_compressed_write() " Qu Wenruo
2021-07-13 6:15 ` [PATCH 19/27] btrfs: make end_compressed_bio_writeback() to be subpage compatble Qu Wenruo
2021-07-13 6:15 ` [PATCH 20/27] btrfs: make extent_write_locked_range() to be subpage compatible Qu Wenruo
2021-07-13 6:15 ` [PATCH 21/27] btrfs: extract uncompressed async extent submission code into a new helper Qu Wenruo
2021-07-13 6:15 ` [PATCH 22/27] btrfs: rework lzo_compress_pages() to make it subpage compatible Qu Wenruo
2021-07-13 6:15 ` [PATCH 23/27] btrfs: teach __extent_writepage() to handle locked page differently Qu Wenruo
2021-07-13 6:15 ` Qu Wenruo [this message]
2021-07-13 6:15 ` [PATCH 25/27] btrfs: allow subpage to compress a range which only covers one page Qu Wenruo
2021-07-13 6:15 ` [PATCH 26/27] btrfs: don't run delalloc range which is beyond the locked_page to prevent deadlock for subpage compression Qu Wenruo
2021-07-13 6:15 ` [PATCH 27/27] btrfs: only allow subpage compression if the range is fully page aligned Qu Wenruo
2021-07-16 9:11 ` [PATCH 00/27] btrfs: limited subpage compressed write support Qu Wenruo
2021-07-20 5:00 ` Qu Wenruo
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