jbd2: ensure abort the journal if detect IO error when writing original buffer back

Although we merged c044f3d8360 ("jbd2: abort journal if free a async
write error metadata buffer"), there is a race between
jbd2_journal_try_to_free_buffers() and jbd2_journal_destroy(), so the
jbd2_log_do_checkpoint() may still fail to detect the buffer write
io error flag which may lead to filesystem inconsistency.

jbd2_journal_try_to_free_buffers()     ext4_put_super()
                                        jbd2_journal_destroy()
  __jbd2_journal_remove_checkpoint()
  detect buffer write error              jbd2_log_do_checkpoint()
                                         jbd2_cleanup_journal_tail()
                                           <--- lead to inconsistency
  jbd2_journal_abort()

Fix this issue by introducing a new atomic flag which only have one
JBD2_CHECKPOINT_IO_ERROR bit now, and set it in
__jbd2_journal_remove_checkpoint() when freeing a checkpoint buffer
which has write_io_error flag. Then jbd2_journal_destroy() will detect
this mark and abort the journal to prevent updating log tail.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210610112440.3438139-3-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index bf5511d19ac563f0c6d48ce5e65004d05f95d6a1..d27c10f4502f6ffa21cb13305d88ddb63316496d 100644 (file)
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -564,6 +564,7 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
        struct transaction_chp_stats_s *stats;
        transaction_t *transaction;
        journal_t *journal;
+       struct buffer_head *bh = jh2bh(jh);
 
        JBUFFER_TRACE(jh, "entry");
 
@@ -575,6 +576,17 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
        journal = transaction->t_journal;
 
        JBUFFER_TRACE(jh, "removing from transaction");
+
+       /*
+        * If we have failed to write the buffer out to disk, the filesystem
+        * may become inconsistent. We cannot abort the journal here since
+        * we hold j_list_lock and we have to be careful about races with
+        * jbd2_journal_destroy(). So mark the writeback IO error in the
+        * journal here and we abort the journal later from a better context.
+        */
+       if (buffer_write_io_error(bh))
+               set_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags);
+
        __buffer_unlink(jh);
        jh->b_cp_transaction = NULL;
        jbd2_journal_put_journal_head(jh);

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index f88895b4920cd6d733009c81e678f09e91f08f60..8b3f5bbd65f953ba7641e1eb2690d2b439fad8b3 100644 (file)
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1610,6 +1610,10 @@ int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
 
        if (is_journal_aborted(journal))
                return -EIO;
+       if (test_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags)) {
+               jbd2_journal_abort(journal, -EIO);
+               return -EIO;
+       }
 
        BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
        jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
@@ -2091,6 +2095,16 @@ int jbd2_journal_destroy(journal_t *journal)
        J_ASSERT(journal->j_checkpoint_transactions == NULL);
        spin_unlock(&journal->j_list_lock);
 
+       /*
+        * OK, all checkpoint transactions have been checked, now check the
+        * write out io error flag and abort the journal if some buffer failed
+        * to write back to the original location, otherwise the filesystem
+        * may become inconsistent.
+        */
+       if (!is_journal_aborted(journal) &&
+           test_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags))
+               jbd2_journal_abort(journal, -EIO);
+
        if (journal->j_sb_buffer) {
                if (!is_journal_aborted(journal)) {
                        mutex_lock_io(&journal->j_checkpoint_mutex);

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 8543233b0388f4945e07c35dea07ef14b5bdcde1..d5db408ae064313f61c572f98022111d520fe0b6 100644 (file)
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -779,6 +779,11 @@ struct journal_s
         */
        unsigned long           j_flags;
 
+       /**
+        * @j_atomic_flags: Atomic journaling state flags.
+        */
+       unsigned long           j_atomic_flags;
+
        /**
         * @j_errno:
         *
@@ -1375,6 +1380,12 @@ JBD2_FEATURE_INCOMPAT_FUNCS(fast_commit, FAST_COMMIT)
 #define JBD2_JOURNAL_FLUSH_VALID       (JBD2_JOURNAL_FLUSH_DISCARD | \
                                        JBD2_JOURNAL_FLUSH_ZEROOUT)
 
+/*
+ * Journal atomic flag definitions
+ */
+#define JBD2_CHECKPOINT_IO_ERROR       0x001   /* Detect io error while writing
+                                                * buffer back to disk */
+
 /*
  * Function declarations for the journaling transaction and buffer
  * management