quota: quota core changes for quotaon on remount

Currently, we just turn quotas off on remount of filesystem to read-only
state.  The patch below adds necessary framework so that we can turn quotas
off on remount RO but we are able to automatically reenable them again when
filesystem is remounted to RW state.  All we need to do is to keep references
to inodes of quota files when remounting RO and using these references to
reenable quotas when remounting RW.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 2 deletions

diff --git a/fs/super.c b/fs/super.c
index 4798350b2bc9..a5a4aca7e22f 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -179,7 +179,7 @@ void deactivate_super(struct super_block *s)
         if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
                 s->s_count -= S_BIAS-1;
                 spin_unlock(&sb_lock);
-                DQUOT_OFF(s);
+                DQUOT_OFF(s, 0);
                 down_write(&s->s_umount);
                 fs->kill_sb(s);
                 put_filesystem(fs);
@@ -608,6 +608,7 @@ retry:
 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 {
         int retval;
+        int remount_rw;
         
 #ifdef CONFIG_BLOCK
         if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
@@ -625,8 +626,11 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
                         mark_files_ro(sb);
                 else if (!fs_may_remount_ro(sb))
                         return -EBUSY;
-                DQUOT_OFF(sb);
+                retval = DQUOT_OFF(sb, 1);
+                if (retval < 0 && retval != -ENOSYS)
+                        return -EBUSY;
         }
+        remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
 
         if (sb->s_op->remount_fs) {
                 lock_super(sb);
@@ -636,6 +640,8 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
                         return retval;
         }
         sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
+        if (remount_rw)
+                DQUOT_ON_REMOUNT(sb);
         return 0;
 }