ext4, jbd2: ensure entering into panic after recording an error in superblock

commit 4327ba52afd03fc4b5afa0ee1d774c9c5b0e85c5 upstream.

If a EXT4 filesystem utilizes JBD2 journaling and an error occurs, the
journaling will be aborted first and the error number will be recorded
into JBD2 superblock and, finally, the system will enter into the
panic state in "errors=panic" option.  But, in the rare case, this
sequence is little twisted like the below figure and it will happen
that the system enters into panic state, which means the system reset
in mobile environment, before completion of recording an error in the
journal superblock. In this case, e2fsck cannot recognize that the
filesystem failure occurred in the previous run and the corruption
wouldn't be fixed.

Task A                        Task B
ext4_handle_error()
-> jbd2_journal_abort()
  -> __journal_abort_soft()
    -> __jbd2_journal_abort_hard()
    | -> journal->j_flags |= JBD2_ABORT;
    |
    |                         __ext4_abort()
    |                         -> jbd2_journal_abort()
    |                         | -> __journal_abort_soft()
    |                         |   -> if (journal->j_flags & JBD2_ABORT)
    |                         |           return;
    |                         -> panic()
    |
    -> jbd2_journal_update_sb_errno()

Tested-by: Hobin Woo <hobin.woo@samsung.com>
Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Zefan Li <lizefan@huawei.com>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 3de888c3894acf6b179696101873d49cbf92d52a..5862518c6737a24a3bd5a6ffe9e9100e53918446 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -483,9 +483,13 @@ static void ext4_handle_error(struct super_block *sb)
                ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only");
                sb->s_flags |= MS_RDONLY;
        }
-       if (test_opt(sb, ERRORS_PANIC))
+       if (test_opt(sb, ERRORS_PANIC)) {
+               if (EXT4_SB(sb)->s_journal &&
+                 !(EXT4_SB(sb)->s_journal->j_flags & JBD2_REC_ERR))
+                       return;
                panic("EXT4-fs (device %s): panic forced after error\n",
                        sb->s_id);
+       }
 }
 
 void __ext4_error(struct super_block *sb, const char *function,
@@ -659,8 +663,12 @@ void __ext4_abort(struct super_block *sb, const char *function,
                        jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO);
                save_error_info(sb, function, line);
        }
-       if (test_opt(sb, ERRORS_PANIC))
+       if (test_opt(sb, ERRORS_PANIC)) {
+               if (EXT4_SB(sb)->s_journal &&
+                 !(EXT4_SB(sb)->s_journal->j_flags & JBD2_REC_ERR))
+                       return;
                panic("EXT4-fs panic from previous error\n");
+       }
 }
 
 void ext4_msg(struct super_block *sb, const char *prefix, const char *fmt, ...)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index a3279442bf304c0b1defa2b46a5d8f4fca23441c..2e3063c76ab60935b4ffef17c7a8c60769d33219 100644 (file)
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1921,8 +1921,12 @@ static void __journal_abort_soft (journal_t *journal, int errno)
 
        __jbd2_journal_abort_hard(journal);
 
-       if (errno)
+       if (errno) {
                jbd2_journal_update_sb_errno(journal);
+               write_lock(&journal->j_state_lock);
+               journal->j_flags |= JBD2_REC_ERR;
+               write_unlock(&journal->j_state_lock);
+       }
 }
 
 /**

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 2179d78b6ea645081a2974cecbf522c384ffe4dd..ee8090f337571e19806bf71e1950a2fff4c0f185 100644 (file)
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -954,6 +954,7 @@ struct journal_s
 #define JBD2_ABORT_ON_SYNCDATA_ERR     0x040   /* Abort the journal on file
                                                 * data write error in ordered
                                                 * mode */
+#define JBD2_REC_ERR   0x080   /* The errno in the sb has been recorded */
 
 /*
  * Function declarations for the journaling transaction and buffer