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new helper: iterate_supers_type()

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Call the given function for all superblocks of given type.  Function
gets a superblock (with s_umount locked shared) and (void *) argument
supplied by caller of iterator.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2011-06-03 20:16:57 -04:00
parent 44396f4b5c
commit 43e15cdbef
2 changed files with 38 additions and 0 deletions
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36
fs/super.c
View File

@ -451,6 +451,42 @@ void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
spin_unlock(&sb_lock);
}
/**
* iterate_supers_type - call function for superblocks of given type
* @type: fs type
* @f: function to call
* @arg: argument to pass to it
*
* Scans the superblock list and calls given function, passing it
* locked superblock and given argument.
*/
void iterate_supers_type(struct file_system_type *type,
void (*f)(struct super_block *, void *), void *arg)
{
struct super_block *sb, *p = NULL;
spin_lock(&sb_lock);
list_for_each_entry(sb, &type->fs_supers, s_instances) {
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
if (sb->s_root)
f(sb, arg);
up_read(&sb->s_umount);
spin_lock(&sb_lock);
if (p)
__put_super(p);
p = sb;
}
if (p)
__put_super(p);
spin_unlock(&sb_lock);
}
EXPORT_SYMBOL(iterate_supers_type);
/**
* get_super - get the superblock of a device
* @bdev: device to get the superblock for

2
include/linux/fs.h
View File

@ -2432,6 +2432,8 @@ extern struct super_block *get_active_super(struct block_device *bdev);
extern struct super_block *user_get_super(dev_t);
extern void drop_super(struct super_block *sb);
extern void iterate_supers(void (*)(struct super_block *, void *), void *);
extern void iterate_supers_type(struct file_system_type *,
void (*)(struct super_block *, void *), void *);
extern int dcache_dir_open(struct inode *, struct file *);
extern int dcache_dir_close(struct inode *, struct file *);