mount options: add generic_show_options()

Add a new s_options field to struct super_block.  Filesystems can save
mount options passed to them in mount or remount.  It is automatically
freed when the superblock is destroyed.

A new helper function, generic_show_options() is introduced, which uses
this field to display the mount options in /proc/mounts.

Another helper function, save_mount_options() may be used by
filesystems to save the options in the super block.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3db22fc2249a..cb3a9001f3b9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1038,6 +1038,12 @@ struct super_block {
          * in /proc/mounts will be "type.subtype"
          */
         char *s_subtype;
+
+        /*
+         * Saved mount options for lazy filesystems using
+         * generic_show_options()
+         */
+        char *s_options;
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);
@@ -1970,6 +1976,9 @@ extern int __must_check inode_setattr(struct inode *, struct iattr *);
 
 extern void file_update_time(struct file *file);
 
+extern int generic_show_options(struct seq_file *m, struct vfsmount *mnt);
+extern void save_mount_options(struct super_block *sb, char *options);
+
 static inline ino_t parent_ino(struct dentry *dentry)
 {
         ino_t res;