Resending the message as I've screwed up the mailing list address... Honza ----- Forwarded message from Jan Kara <jack@xxxxxxx> ----- From: Jan Kara <jack@xxxxxxx> To: ext4-devel@xxxxxxxxxxxxxxx Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Mark Lord <lkml@xxxxxx> Subject: [PATCH] Fix deadlock of ext3_remount() and orphan list handling Hi, attached patch should fix deadlock Mark Lord has experienced (http://lkml.org/lkml/2007/6/8/601). Please have a look whether the change looks sane. I think so but ... Honza -- Jan Kara <jack@xxxxxxx> SuSE CR Labs ext3_orphan_add() and ext3_orphan_del() functions lock sb->s_lock with a transaction started with ext3_mark_recovery_complete() waits for a transaction holding sb->s_lock, thus leading to a possible deadlock. At the moment we call ext3_mark_recovery_complete() from ext3_remount() we have done all the work needed for remounting and thus we are safe to drop sb->s_lock before we wait for transactions to commit. Note that at this moment we are still guarded by s_umount lock against other remounts/umounts. Signed-off-by: Jan Kara <jack@xxxxxxx> diff -rupX /home/jack/.kerndiffexclude linux-2.6.22-rc4/fs/ext3/super.c linux-2.6.22-rc4-1-ext3_orphan_deadlock/fs/ext3/super.c --- linux-2.6.22-rc4/fs/ext3/super.c 2007-06-11 12:29:06.000000000 +0200 +++ linux-2.6.22-rc4-1-ext3_orphan_deadlock/fs/ext3/super.c 2007-06-12 12:51:42.000000000 +0200 @@ -2139,12 +2139,14 @@ static void ext3_mark_recovery_complete( journal_lock_updates(journal); journal_flush(journal); + lock_super(sb); if (EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER) && sb->s_flags & MS_RDONLY) { EXT3_CLEAR_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER); sb->s_dirt = 0; ext3_commit_super(sb, es, 1); } + unlock_super(sb); journal_unlock_updates(journal); } @@ -2333,7 +2335,13 @@ static int ext3_remount (struct super_bl (sbi->s_mount_state & EXT3_VALID_FS)) es->s_state = cpu_to_le16(sbi->s_mount_state); + /* + * We have to unlock super so that we can wait for + * transactions. + */ + unlock_super(sb); ext3_mark_recovery_complete(sb, es); + lock_super(sb); } else { __le32 ret; if ((ret = EXT3_HAS_RO_COMPAT_FEATURE(sb, ----- End forwarded message ----- -- Jan Kara <jack@xxxxxxx> SuSE CR Labs - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
