Patch "ext4, jbd2: ensure entering into panic after recording an error in superblock" has been added to the 4.2-stable tree

Patch "ext4, jbd2: ensure entering into panic after recording an error in superblock" has been added to the 4.2-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ext4-jbd2-ensure-entering-into-panic-after-recording-an-error-in-superblock.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 4327ba52afd03fc4b5afa0ee1d774c9c5b0e85c5 Mon Sep 17 00:00:00 2001
From: Daeho Jeong <daeho.jeong@samsung.com>
Date: Sun, 18 Oct 2015 17:02:56 -0400
Subject: ext4, jbd2: ensure entering into panic after recording an error in superblock

From: Daeho Jeong <daeho.jeong@samsung.com>

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ext4/super.c      |   12 ++++++++++--
 fs/jbd2/journal.c    |    6 +++++-
 include/linux/jbd2.h |    1 +
 3 files changed, 16 insertions(+), 3 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -397,9 +397,13 @@ static void ext4_handle_error(struct sup
 		smp_wmb();
 		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);
+	}
 }
 
 #define ext4_error_ratelimit(sb)					\
@@ -588,8 +592,12 @@ void __ext4_abort(struct super_block *sb
 			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,
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2071,8 +2071,12 @@ static void __journal_abort_soft (journa
 
 	__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);
+	}
 }
 
 /**
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1007,6 +1007,7 @@ 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


Patches currently in stable-queue which might be from daeho.jeong@samsung.com are

queue-4.2/ext4-jbd2-ensure-entering-into-panic-after-recording-an-error-in-superblock.patch