ext4: add support for multiple mount protection
Prevent an ext4 filesystem from being mounted multiple times.
A sequence number is stored on disk and is periodically updated (every 5
seconds by default) by a mounted filesystem.
At mount time, we now wait for s_mmp_update_interval seconds to make sure
that the MMP sequence does not change.
In case of failure, the nodename, bdevname and the time at which the MMP
block was last updated is displayed.
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Johann Lombardi <johann@whamcloud.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 266174b..d9937df 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -822,6 +822,8 @@
invalidate_bdev(sbi->journal_bdev);
ext4_blkdev_remove(sbi);
}
+ if (sbi->s_mmp_tsk)
+ kthread_stop(sbi->s_mmp_tsk);
sb->s_fs_info = NULL;
/*
* Now that we are completely done shutting down the
@@ -3486,6 +3488,11 @@
EXT4_HAS_INCOMPAT_FEATURE(sb,
EXT4_FEATURE_INCOMPAT_RECOVER));
+ if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_MMP) &&
+ !(sb->s_flags & MS_RDONLY))
+ if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
+ goto failed_mount3;
+
/*
* The first inode we look at is the journal inode. Don't try
* root first: it may be modified in the journal!
@@ -3733,6 +3740,8 @@
percpu_counter_destroy(&sbi->s_freeinodes_counter);
percpu_counter_destroy(&sbi->s_dirs_counter);
percpu_counter_destroy(&sbi->s_dirtyblocks_counter);
+ if (sbi->s_mmp_tsk)
+ kthread_stop(sbi->s_mmp_tsk);
failed_mount2:
for (i = 0; i < db_count; i++)
brelse(sbi->s_group_desc[i]);
@@ -4268,7 +4277,7 @@
int enable_quota = 0;
ext4_group_t g;
unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
- int err;
+ int err = 0;
#ifdef CONFIG_QUOTA
int i;
#endif
@@ -4394,6 +4403,13 @@
goto restore_opts;
if (!ext4_setup_super(sb, es, 0))
sb->s_flags &= ~MS_RDONLY;
+ if (EXT4_HAS_INCOMPAT_FEATURE(sb,
+ EXT4_FEATURE_INCOMPAT_MMP))
+ if (ext4_multi_mount_protect(sb,
+ le64_to_cpu(es->s_mmp_block))) {
+ err = -EROFS;
+ goto restore_opts;
+ }
enable_quota = 1;
}
}