[PATCH 1/5] jbd2: Add errseq to detect client fs's bdev writeback error

[Zhihao Cheng <chengzhihao1@huawei.com>]

Add errseq in journal, so that JBD2 can detect whether metadata is
successfully fallen on fs bdev. This patch adds detection in recovery
process to replace original solution(using local variable wb_err).

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Suggested-by: Jan Kara <jack@suse.cz>
---
 fs/jbd2/journal.c    |  1 +
 fs/jbd2/recovery.c   |  7 +------
 include/linux/jbd2.h | 26 ++++++++++++++++++++++++++
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 30dec2bd2ecc..a655d9a88f79 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1535,6 +1535,7 @@ static journal_t *journal_init_common(struct block_device *bdev,
 	journal->j_fs_dev = fs_dev;
 	journal->j_blk_offset = start;
 	journal->j_total_len = len;
+	jbd2_init_fs_dev_write_error(journal);
 
 	err = journal_load_superblock(journal);
 	if (err)
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 01f744cb97a4..1f7664984d6e 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -289,8 +289,6 @@ int jbd2_journal_recover(journal_t *journal)
 	journal_superblock_t *	sb;
 
 	struct recovery_info	info;
-	errseq_t		wb_err;
-	struct address_space	*mapping;
 
 	memset(&info, 0, sizeof(info));
 	sb = journal->j_superblock;
@@ -308,9 +306,6 @@ int jbd2_journal_recover(journal_t *journal)
 		return 0;
 	}
 
-	wb_err = 0;
-	mapping = journal->j_fs_dev->bd_inode->i_mapping;
-	errseq_check_and_advance(&mapping->wb_err, &wb_err);
 	err = do_one_pass(journal, &info, PASS_SCAN);
 	if (!err)
 		err = do_one_pass(journal, &info, PASS_REVOKE);
@@ -334,7 +329,7 @@ int jbd2_journal_recover(journal_t *journal)
 	err2 = sync_blockdev(journal->j_fs_dev);
 	if (!err)
 		err = err2;
-	err2 = errseq_check_and_advance(&mapping->wb_err, &wb_err);
+	err2 = jbd2_check_fs_dev_write_error(journal);
 	if (!err)
 		err = err2;
 	/* Make sure all replayed data is on permanent storage */
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 52772c826c86..15798f88ade4 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -998,6 +998,13 @@ struct journal_s
 	 */
 	struct block_device	*j_fs_dev;
 
+	/**
+	 * @j_fs_dev_wb_err:
+	 *
+	 * Records the errseq of the client fs's backing block device.
+	 */
+	errseq_t		j_fs_dev_wb_err;
+
 	/**
 	 * @j_total_len: Total maximum capacity of the journal region on disk.
 	 */
@@ -1695,6 +1702,25 @@ static inline void jbd2_journal_abort_handle(handle_t *handle)
 	handle->h_aborted = 1;
 }
 
+static inline void jbd2_init_fs_dev_write_error(journal_t *journal)
+{
+	struct address_space *mapping = journal->j_fs_dev->bd_inode->i_mapping;
+
+	/*
+	 * Save the original wb_err value of client fs's bdev mapping which
+	 * could be used to detect the client fs's metadata async write error.
+	 */
+	errseq_check_and_advance(&mapping->wb_err, &journal->j_fs_dev_wb_err);
+}
+
+static inline int jbd2_check_fs_dev_write_error(journal_t *journal)
+{
+	struct address_space *mapping = journal->j_fs_dev->bd_inode->i_mapping;
+
+	return errseq_check(&mapping->wb_err,
+			    READ_ONCE(journal->j_fs_dev_wb_err));
+}
+
 #endif /* __KERNEL__   */
 
 /* Comparison functions for transaction IDs: perform comparisons using
-- 
2.39.2