quota: move remount handling into the filesystem

Currently do_remount_sb calls into the dquot code to tell it about going
from rw to ro and ro to rw.  Move this code into the filesystem to
not depend on the dquot code in the VFS - note ocfs2 already ignores
these calls and handles remount by itself.  This gets rid of overloading
the quotactl calls and allows to unify the VFS and XFS codepaths in
that area later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext2/super.c

@@ -1241,13 +1241,22 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
 			spin_unlock(&sbi->s_lock);
 			return 0;
 		}
+
 		/*
 		 * OK, we are remounting a valid rw partition rdonly, so set
 		 * the rdonly flag and then mark the partition as valid again.
 		 */
 		es->s_state = cpu_to_le16(sbi->s_mount_state);
 		es->s_mtime = cpu_to_le32(get_seconds());
 		spin_unlock(&sbi->s_lock);
+
+		err = vfs_dq_off(sb, 1);
+		if (err < 0 && err != -ENOSYS) {
+			err = -EBUSY;
+			spin_lock(&sbi->s_lock);
+			goto restore_opts;
+		}
+
 		ext2_sync_super(sb, es, 1);
 	} else {
 		__le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
@@ -1269,8 +1278,12 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
 		if (!ext2_setup_super (sb, es, 0))
 			sb->s_flags &= ~MS_RDONLY;
 		spin_unlock(&sbi->s_lock);
+
 		ext2_write_super(sb);
+
+		vfs_dq_quota_on_remount(sb);
 	}
+
 	return 0;
 restore_opts:
 	sbi->s_mount_opt = old_opts.s_mount_opt;

fs/ext3/super.c

@@ -2551,6 +2551,7 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 	ext3_fsblk_t n_blocks_count = 0;
 	unsigned long old_sb_flags;
 	struct ext3_mount_options old_opts;
+	int enable_quota = 0;
 	int err;
 #ifdef CONFIG_QUOTA
 	int i;
@@ -2597,6 +2598,12 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 		}
 
 		if (*flags & MS_RDONLY) {
+			err = vfs_dq_off(sb, 1);
+			if (err < 0 && err != -ENOSYS) {
+				err = -EBUSY;
+				goto restore_opts;
+			}
+
 			/*
 			 * First of all, the unconditional stuff we have to do
 			 * to disable replay of the journal when we next remount
@@ -2651,6 +2658,7 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 				goto restore_opts;
 			if (!ext3_setup_super (sb, es, 0))
 				sb->s_flags &= ~MS_RDONLY;
+			enable_quota = 1;
 		}
 	}
 #ifdef CONFIG_QUOTA
@@ -2662,6 +2670,9 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 #endif
 	unlock_super(sb);
 	unlock_kernel();
+
+	if (enable_quota)
+		vfs_dq_quota_on_remount(sb);
 	return 0;
 restore_opts:
 	sb->s_flags = old_sb_flags;

fs/ext4/super.c

@@ -3574,6 +3574,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 	ext4_fsblk_t n_blocks_count = 0;
 	unsigned long old_sb_flags;
 	struct ext4_mount_options old_opts;
+	int enable_quota = 0;
 	ext4_group_t g;
 	unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
 	int err;
@@ -3630,6 +3631,12 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 		}
 
 		if (*flags & MS_RDONLY) {
+			err = vfs_dq_off(sb, 1);
+			if (err < 0 && err != -ENOSYS) {
+				err = -EBUSY;
+				goto restore_opts;
+			}
+
 			/*
 			 * First of all, the unconditional stuff we have to do
 			 * to disable replay of the journal when we next remount
@@ -3698,6 +3705,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 				goto restore_opts;
 			if (!ext4_setup_super(sb, es, 0))
 				sb->s_flags &= ~MS_RDONLY;
+			enable_quota = 1;
 		}
 	}
 	ext4_setup_system_zone(sb);
@@ -3713,6 +3721,8 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 #endif
 	unlock_super(sb);
 	unlock_kernel();
+	if (enable_quota)
+		vfs_dq_quota_on_remount(sb);
 	return 0;
 
 restore_opts:

fs/jfs/super.c

@@ -396,10 +396,20 @@ static int jfs_remount(struct super_block *sb, int *flags, char *data)
 
 		JFS_SBI(sb)->flag = flag;
 		ret = jfs_mount_rw(sb, 1);
+
+		/* mark the fs r/w for quota activity */
+		sb->s_flags &= ~MS_RDONLY;
+
 		unlock_kernel();
+		vfs_dq_quota_on_remount(sb);
 		return ret;
 	}
 	if ((!(sb->s_flags & MS_RDONLY)) && (*flags & MS_RDONLY)) {
+		rc = vfs_dq_off(sb, 1);
+		if (rc < 0 && rc != -ENOSYS) {
+			unlock_kernel();
+			return -EBUSY;
+		}
 		rc = jfs_umount_rw(sb);
 		JFS_SBI(sb)->flag = flag;
 		unlock_kernel();

fs/reiserfs/super.c

@@ -1242,6 +1242,13 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
 		if (s->s_flags & MS_RDONLY)
 			/* it is read-only already */
 			goto out_ok;
+
+		err = vfs_dq_off(s, 1);
+		if (err < 0 && err != -ENOSYS) {
+			err = -EBUSY;
+			goto out_err;
+		}
+
 		/* try to remount file system with read-only permissions */
 		if (sb_umount_state(rs) == REISERFS_VALID_FS
 		    || REISERFS_SB(s)->s_mount_state != REISERFS_VALID_FS) {
@@ -1295,6 +1302,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
 	s->s_dirt = 0;
 
 	if (!(*mount_flags & MS_RDONLY)) {
+		vfs_dq_quota_on_remount(s);
 		finish_unfinished(s);
 		reiserfs_xattr_init(s, *mount_flags);
 	}

fs/super.c

@@ -524,7 +524,7 @@ struct super_block *user_get_super(dev_t dev)
 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 {
 	int retval;
-	int remount_rw, remount_ro;
+	int remount_ro;
 
 	if (sb->s_frozen != SB_UNFROZEN)
 		return -EBUSY;
@@ -540,7 +540,6 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 	sync_filesystem(sb);
 
 	remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
-	remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
 
 	/* If we are remounting RDONLY and current sb is read/write,
 	   make sure there are no rw files opened */
@@ -549,9 +548,6 @@ 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;
-		retval = vfs_dq_off(sb, 1);
-		if (retval < 0 && retval != -ENOSYS)
-			return -EBUSY;
 	}
 
 	if (sb->s_op->remount_fs) {
@@ -560,8 +556,7 @@ 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)
-		vfs_dq_quota_on_remount(sb);
+
 	/*
 	 * Some filesystems modify their metadata via some other path than the
 	 * bdev buffer cache (eg. use a private mapping, or directories in

fs/udf/super.c

@@ -54,6 +54,7 @@
 #include <linux/vmalloc.h>
 #include <linux/errno.h>
 #include <linux/mount.h>
+#include <linux/quotaops.h>
 #include <linux/seq_file.h>
 #include <linux/bitmap.h>
 #include <linux/crc-itu-t.h>
@@ -557,6 +558,7 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
 {
 	struct udf_options uopt;
 	struct udf_sb_info *sbi = UDF_SB(sb);
+	int error = 0;
 
 	uopt.flags = sbi->s_flags;
 	uopt.uid   = sbi->s_uid;
@@ -582,17 +584,26 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
 			*flags |= MS_RDONLY;
 	}
 
-	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) {
-		unlock_kernel();
-		return 0;
-	}
-	if (*flags & MS_RDONLY)
+	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
+		goto out_unlock;
+
+	if (*flags & MS_RDONLY) {
 		udf_close_lvid(sb);
-	else
+
+		error = vfs_dq_off(sb, 1);
+		if (error < 0 && error != -ENOSYS)
+			error = -EBUSY;
+	} else {
 		udf_open_lvid(sb);
 
+		/* mark the fs r/w for quota activity */
+		sb->s_flags &= ~MS_RDONLY;
+		vfs_dq_quota_on_remount(sb);
+	}
+
+out_unlock:
 	unlock_kernel();
-	return 0;
+	return error;
 }
 
 /* Check Volume Structure Descriptors (ECMA 167 2/9.1) */

fs/ufs/super.c

@@ -1248,7 +1248,9 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
 	struct ufs_super_block_first * usb1;
 	struct ufs_super_block_third * usb3;
 	unsigned new_mount_opt, ufstype;
+	int enable_quota = 0;
 	unsigned flags;
+	int err;
 
 	lock_kernel();
 	lock_super(sb);
@@ -1289,6 +1291,13 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
 	 * fs was mouted as rw, remounting ro
 	 */
 	if (*mount_flags & MS_RDONLY) {
+		err = vfs_dq_off(sb, 1);
+		if (err < 0 && err != -ENOSYS) {
+			unlock_super(sb);
+			unlock_kernel();
+			return -EBUSY;
+		}
+
 		ufs_put_super_internal(sb);
 		usb1->fs_time = cpu_to_fs32(sb, get_seconds());
 		if ((flags & UFS_ST_MASK) == UFS_ST_SUN
@@ -1327,11 +1336,14 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
 			return -EPERM;
 		}
 		sb->s_flags &= ~MS_RDONLY;
+		enable_quota = 1;
 #endif
 	}
 	UFS_SB(sb)->s_mount_opt = new_mount_opt;
 	unlock_super(sb);
 	unlock_kernel();
+	if (enable_quota)
+		vfs_dq_quota_on_remount(sb);
 	return 0;
 }