From e6c28a26b799c7640b77daff3e4a67808c74381c Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 8 Mar 2023 15:25:28 +0100 Subject: [PATCH] ext4: Fix warnings when freezing filesystem with journaled data Test generic/390 in data=journal mode often triggers a warning that ext4_do_writepages() tries to start a transaction on frozen filesystem. This happens because although all dirty data is properly written, jbd2 checkpointing code writes data through submit_bh() and as a result only buffer dirty bits are cleared but page dirty bits stay set. Later when the filesystem is frozen, writeback code comes, tries to write supposedly dirty pages and the warning triggers. Fix the problem by calling sync_filesystem() once more after flushing the whole journal to clear stray page dirty bits. [ Applied fixup patches to address crashes when running data=journal tests; see links for more details -- TYT ] Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20230308142528.12384-1-jack@suse.cz Reported-by: Eric Biggers Link: https://lore.kernel.org/all/20230319183617.GA896@sol.localdomain Link: https://lore.kernel.org/r/20230323145404.21381-1-jack@suse.cz Link: https://lore.kernel.org/r/20230323145404.21381-2-jack@suse.cz Signed-off-by: Theodore Ts'o --- fs/ext4/inode.c | 19 ++++++++++++++++--- fs/ext4/super.c | 11 +++++++++++ 2 files changed, 27 insertions(+), 3 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 652efb2..6445b80 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2410,6 +2410,7 @@ static int mpage_journal_page_buffers(handle_t *handle, static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd) { struct address_space *mapping = mpd->inode->i_mapping; + struct super_block *sb = mpd->inode->i_sb; struct folio_batch fbatch; unsigned int nr_folios; pgoff_t index = mpd->first_page; @@ -2427,15 +2428,23 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd) else tag = PAGECACHE_TAG_DIRTY; - if (ext4_should_journal_data(mpd->inode)) { + mpd->map.m_len = 0; + mpd->next_page = index; + /* + * Start a transaction for writeback of journalled data. We don't start + * start the transaction if the filesystem is frozen. In that case we + * should not have any dirty data to write anymore but possibly there + * are stray page dirty bits left by the checkpointing code so this + * loop clears them. + */ + if (ext4_should_journal_data(mpd->inode) && + sb->s_writers.frozen < SB_FREEZE_FS) { handle = ext4_journal_start(mpd->inode, EXT4_HT_WRITE_PAGE, bpp); if (IS_ERR(handle)) return PTR_ERR(handle); } folio_batch_init(&fbatch); - mpd->map.m_len = 0; - mpd->next_page = index; while (index <= end) { nr_folios = filemap_get_folios_tag(mapping, &index, end, tag, &fbatch); @@ -2520,12 +2529,16 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd) */ if (!mpd->can_map) { if (ext4_page_nomap_can_writeout(&folio->page)) { + WARN_ON_ONCE(sb->s_writers.frozen == + SB_FREEZE_COMPLETE); err = mpage_submit_page(mpd, &folio->page); if (err < 0) goto out; } /* Pending dirtying of journalled data? */ if (PageChecked(&folio->page)) { + WARN_ON_ONCE(sb->s_writers.frozen >= + SB_FREEZE_FS); err = mpage_journal_page_buffers(handle, mpd, &folio->page); if (err < 0) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index f43e526..f226f8a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -6293,6 +6293,17 @@ static int ext4_freeze(struct super_block *sb) if (error < 0) goto out; + /* + * Do another sync. We really should not have any dirty data + * anymore but our checkpointing code does not clear page dirty + * bits due to locking constraints so writeback still can get + * started for inodes with journalled data which triggers + * annoying warnings. + */ + error = sync_filesystem(sb); + if (error < 0) + goto out; + /* Journal blocked and flushed, clear needs_recovery flag. */ ext4_clear_feature_journal_needs_recovery(sb); if (ext4_orphan_file_empty(sb)) -- 2.7.4