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VFS: Kill off s_options and helpers 

Kill off s_options, save/replace_mount_options() and generic_show_options()
as all filesystems now implement ->show_options() for themselves.  This
should make it easier to implement a context-based mount where the mount
options can be passed individually over a file descriptor.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2017-07-05 16:25:53 +01:00 committed by Al Viro
parent 4dfdb71307
commit 1d278a8790
5 changed files with 0 additions and 76 deletions
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6
Documentation/filesystems/vfs.txt
View File

@ -1187,12 +1187,6 @@ The underlying reason for the above rules is to make sure, that a
mount can be accurately replicated (e.g. umounting and mounting again)
based on the information found in /proc/mounts.
A simple method of saving options at mount/remount time and showing
them is provided with the save_mount_options() and
generic_show_options() helper functions. Please note, that using
these may have drawbacks. For more info see header comments for these
functions in fs/namespace.c.
Resources
=========

1
fs/efivarfs/super.c
View File

@ -29,7 +29,6 @@ static const struct super_operations efivarfs_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
.evict_inode = efivarfs_evict_inode,
.show_options = generic_show_options,
};
static struct super_block *efivarfs_sb;

59
fs/namespace.c
View File

@ -1237,65 +1237,6 @@ struct vfsmount *mnt_clone_internal(const struct path *path)
return &p->mnt;
}
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 dentry *root)
{
const char *options;
rcu_read_lock();
options = rcu_dereference(root->d_sb->s_options);
if (options != NULL && options[0]) {
seq_putc(m, ',');
mangle(m, options);
}
rcu_read_unlock();
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)
{
BUG_ON(sb->s_options);
rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL));
}
EXPORT_SYMBOL(save_mount_options);
void replace_mount_options(struct super_block *sb, char *options)
{
char *old = sb->s_options;
rcu_assign_pointer(sb->s_options, options);
if (old) {
synchronize_rcu();
kfree(old);
}
}
EXPORT_SYMBOL(replace_mount_options);
#ifdef CONFIG_PROC_FS
/* iterator; we want it to have access to namespace_sem, thus here... */
static void *m_start(struct seq_file *m, loff_t *pos)

1
fs/super.c
View File

@ -168,7 +168,6 @@ static void destroy_super(struct super_block *s)
WARN_ON(!list_empty(&s->s_mounts));
put_user_ns(s->s_user_ns);
kfree(s->s_subtype);
kfree(s->s_options);
call_rcu(&s->rcu, destroy_super_rcu);
}

9
include/linux/fs.h
View File

@ -1351,11 +1351,6 @@ struct super_block {
*/
char *s_subtype;
/*
* Saved mount options for lazy filesystems using
* generic_show_options()
*/
char __rcu *s_options;
const struct dentry_operations *s_d_op; /* default d_op for dentries */
/*
@ -3033,10 +3028,6 @@ extern void setattr_copy(struct inode *inode, const struct iattr *attr);
extern int file_update_time(struct file *file);
extern int generic_show_options(struct seq_file *m, struct dentry *root);
extern void save_mount_options(struct super_block *sb, char *options);
extern void replace_mount_options(struct super_block *sb, char *options);
static inline bool io_is_direct(struct file *filp)
{
return (filp->f_flags & O_DIRECT) || IS_DAX(filp->f_mapping->host);