Commit b3b304a2 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds
Browse files

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: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f84e3f52

fs/namespace.c

+44 −5
Original line number Diff line number Diff line
@@ -320,6 +320,50 @@ void mnt_unpin(struct vfsmount *mnt) 


EXPORT_SYMBOL(mnt_unpin);



static inline void mangle(struct seq_file *m, const char *s)

{

	seq_escape(m, s, " \t\n\\");

}



/*

 * Simple .show_options callback for filesystems which don't want to

 * implement more complex mount option showing.

 *

 * See also save_mount_options().

 */

int generic_show_options(struct seq_file *m, struct vfsmount *mnt)

{

	const char *options = mnt->mnt_sb->s_options;



	if (options != NULL && options[0]) {

		seq_putc(m, ',');

		mangle(m, options);

	}



	return 0;

}

EXPORT_SYMBOL(generic_show_options);



/*

 * If filesystem uses generic_show_options(), this function should be

 * called from the fill_super() callback.

 *

 * The .remount_fs callback usually needs to be handled in a special

 * way, to make sure, that previous options are not overwritten if the

 * remount fails.

 *

 * Also note, that if the filesystem's .remount_fs function doesn't

 * reset all options to their default value, but changes only newly

 * given options, then the displayed options will not reflect reality

 * any more.

 */

void save_mount_options(struct super_block *sb, char *options)

{

	kfree(sb->s_options);

	sb->s_options = kstrdup(options, GFP_KERNEL);

}

EXPORT_SYMBOL(save_mount_options);



/* iterator */

static void *m_start(struct seq_file *m, loff_t *pos)

{
@@ -341,11 +385,6 @@ static void m_stop(struct seq_file *m, void *v) 
	up_read(&namespace_sem);

}



static inline void mangle(struct seq_file *m, const char *s)

{

	seq_escape(m, s, " \t\n\\");

}



static int show_vfsmnt(struct seq_file *m, void *v)

{

	struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);

fs/super.c

+1 −0
Original line number Diff line number Diff line
@@ -105,6 +105,7 @@ static inline void destroy_super(struct super_block *s) 
{

	security_sb_free(s);

	kfree(s->s_subtype);

	kfree(s->s_options);

	kfree(s);

}

include/linux/fs.h

+9 −0
Original line number Diff line number Diff line
@@ -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;

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