From d240e06713007bba309b074a386b7072b73c31a6 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Sun, 9 May 2010 21:51:53 +0900 Subject: [PATCH] nilfs2: disallow remount of snapshot from/to a regular mount Snapshots and regular ro/rw mounts are essentially-different within the meaning whether the checkpoint is static or not and is marked with a snapshot flag or not. The current implemenation, however, allows to remount a snapshot to a regular rw-mount if the checkpoint number equals the latest one. This transition is actually impossible since changing a checkpoint to a snapshot makes another checkpoint, thus the condition is never satisfied. This fixes the weird state of affairs, and specifically separates snapshots and regular rw/ro-mounts. Signed-off-by: Ryusuke Konishi --- fs/nilfs2/super.c | 57 ++++++++++++++++++++++--------------------------------- 1 file changed, 23 insertions(+), 34 deletions(-) diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c index c88e664..03b34b7 100644 --- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -754,9 +754,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, goto failed_sbi; } cno = sbi->s_snapshot_cno; - } else - /* Read-only mount */ - sbi->s_snapshot_cno = cno; + } } err = nilfs_attach_checkpoint(sbi, cno); @@ -825,7 +823,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) struct the_nilfs *nilfs = sbi->s_nilfs; unsigned long old_sb_flags; struct nilfs_mount_options old_opts; - int err; + int was_snapshot, err; lock_kernel(); @@ -833,6 +831,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) old_sb_flags = sb->s_flags; old_opts.mount_opt = sbi->s_mount_opt; old_opts.snapshot_cno = sbi->s_snapshot_cno; + was_snapshot = nilfs_test_opt(sbi, SNAPSHOT); if (!parse_options(data, sb)) { err = -EINVAL; @@ -840,20 +839,32 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) } sb->s_flags = (sb->s_flags & ~MS_POSIXACL); - if ((*flags & MS_RDONLY) && - sbi->s_snapshot_cno != old_opts.snapshot_cno) { - printk(KERN_WARNING "NILFS (device %s): couldn't " - "remount to a different snapshot.\n", - sb->s_id); - err = -EINVAL; - goto restore_opts; + err = -EINVAL; + if (was_snapshot) { + if (!(*flags & MS_RDONLY)) { + printk(KERN_ERR "NILFS (device %s): cannot remount " + "snapshot read/write.\n", + sb->s_id); + goto restore_opts; + } else if (sbi->s_snapshot_cno != old_opts.snapshot_cno) { + printk(KERN_ERR "NILFS (device %s): cannot " + "remount to a different snapshot.\n", + sb->s_id); + goto restore_opts; + } + } else { + if (nilfs_test_opt(sbi, SNAPSHOT)) { + printk(KERN_ERR "NILFS (device %s): cannot change " + "a regular mount to a snapshot.\n", + sb->s_id); + goto restore_opts; + } } if (!nilfs_valid_fs(nilfs)) { printk(KERN_WARNING "NILFS (device %s): couldn't " "remount because the filesystem is in an " "incomplete recovery state.\n", sb->s_id); - err = -EINVAL; goto restore_opts; } @@ -864,9 +875,6 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) nilfs_detach_segment_constructor(sbi); sb->s_flags |= MS_RDONLY; - sbi->s_snapshot_cno = nilfs_last_cno(nilfs); - /* nilfs_set_opt(sbi, SNAPSHOT); */ - /* * Remounting a valid RW partition RDONLY, so set * the RDONLY flag and then mark the partition as valid again. @@ -885,24 +893,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) * store the current valid flag. (It may have been changed * by fsck since we originally mounted the partition.) */ - if (nilfs->ns_current && nilfs->ns_current != sbi) { - printk(KERN_WARNING "NILFS (device %s): couldn't " - "remount because an RW-mount exists.\n", - sb->s_id); - err = -EBUSY; - goto restore_opts; - } - if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) { - printk(KERN_WARNING "NILFS (device %s): couldn't " - "remount because the current RO-mount is not " - "the latest one.\n", - sb->s_id); - err = -EINVAL; - goto restore_opts; - } sb->s_flags &= ~MS_RDONLY; - nilfs_clear_opt(sbi, SNAPSHOT); - sbi->s_snapshot_cno = 0; err = nilfs_attach_segment_constructor(sbi); if (err) @@ -911,8 +902,6 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) down_write(&nilfs->ns_sem); nilfs_setup_super(sbi); up_write(&nilfs->ns_sem); - - nilfs->ns_current = sbi; } out: up_write(&nilfs->ns_super_sem); -- 2.7.4