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mount options: add generic_show_options()

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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>
This commit is contained in:
Miklos Szeredi 2008-02-08 04:21:35 -08:00 committed by Linus Torvalds
parent f84e3f521e
commit b3b304a23a
3 changed files with 54 additions and 5 deletions
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49
fs/namespace.c
View file

@ -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);

1
fs/super.c
View file

@ -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);
}

9
include/linux/fs.h
View file

@ -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;