---

yaml
---
r: 185696
b: refs/heads/master
c: d208bbd
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ec4f860597af41c6b71f4de86d8e86f710bfab54
+refs/heads/master: d208bbdda991b8808d9c033ce4d31cb1bd87dcfc

trunk/fs/super.c

@@ -568,7 +568,7 @@ SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 {
 	int retval;
-	int remount_rw;
+	int remount_rw, remount_ro;
 
 	if (sb->s_frozen != SB_UNFROZEN)
 		return -EBUSY;
@@ -583,9 +583,12 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 	shrink_dcache_sb(sb);
 	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 */
-	if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
+	if (remount_ro) {
 		if (force)
 			mark_files_ro(sb);
 		else if (!fs_may_remount_ro(sb))
@@ -594,7 +597,6 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 		if (retval < 0 && retval != -ENOSYS)
 			return -EBUSY;
 	}
-	remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
 
 	if (sb->s_op->remount_fs) {
 		retval = sb->s_op->remount_fs(sb, &flags, data);
@@ -604,6 +606,16 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 	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
+	 * pagecache, etc). Also file data modifications go via their own
+	 * mappings. So If we try to mount readonly then copy the filesystem
+	 * from bdev, we could get stale data, so invalidate it to give a best
+	 * effort at coherency.
+	 */
+	if (remount_ro && sb->s_bdev)
+		invalidate_bdev(sb->s_bdev);
 	return 0;
 }