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>
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 71e9eb1..73346de 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1241,6 +1241,7 @@
 			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.
@@ -1248,6 +1249,14 @@
 		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 @@
 		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;
diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 0fc1293..d0f8837 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2551,6 +2551,7 @@
 	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 @@
 		}
 
 		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 @@
 				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 @@
 #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;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e14d22c..fb1e191 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3574,6 +3574,7 @@
 	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 @@
 		}
 
 		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 @@
 				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 @@
 #endif
 	unlock_super(sb);
 	unlock_kernel();
+	if (enable_quota)
+		vfs_dq_quota_on_remount(sb);
 	return 0;
 
 restore_opts:
diff --git a/fs/jfs/super.c b/fs/jfs/super.c
index b66832a..5329d66 100644
--- a/fs/jfs/super.c
+++ b/fs/jfs/super.c
@@ -396,10 +396,20 @@
 
 		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();
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 59125fb..49a8ba0 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1242,6 +1242,13 @@
 		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 @@
 	s->s_dirt = 0;
 
 	if (!(*mount_flags & MS_RDONLY)) {
+		vfs_dq_quota_on_remount(s);
 		finish_unfinished(s);
 		reiserfs_xattr_init(s, *mount_flags);
 	}
diff --git a/fs/super.c b/fs/super.c
index 69688b1..a38e6e9 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -524,7 +524,7 @@
 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 @@
 	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 @@
 			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 @@
 			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
diff --git a/fs/udf/super.c b/fs/udf/super.c
index 1e4543c..9ab4e25 100644
--- a/fs/udf/super.c
+++ b/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 @@
 {
 	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 @@
 			*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) */
diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index 14743d9..be1f7b0 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -1248,7 +1248,9 @@
 	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 @@
 	 * 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 @@
 			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;
 }