Commit 3c9fe8cd authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

vfs: add lookup_hash() helper 



Overlayfs needs lookup without inode_permission() and already has the name
hash (in form of dentry->d_name on overlayfs dentry).  It also doesn't
support filesystems with d_op->d_hash() so basically it only needs
the actual hashed lookup from lookup_one_len_unlocked()

So add a new helper that does unlocked lookup of a hashed name.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 9409e22a

fs/namei.c

+28 −5
Original line number Diff line number Diff line
@@ -2266,6 +2266,33 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 
}

EXPORT_SYMBOL(vfs_path_lookup);



/**

 * lookup_hash - lookup single pathname component on already hashed name

 * @name:	name and hash to lookup

 * @base:	base directory to lookup from

 *

 * The name must have been verified and hashed (see lookup_one_len()).  Using

 * this after just full_name_hash() is unsafe.

 *

 * This function also doesn't check for search permission on base directory.

 *

 * Use lookup_one_len_unlocked() instead, unless you really know what you are

 * doing.

 *

 * Do not hold i_mutex; this helper takes i_mutex if necessary.

 */

struct dentry *lookup_hash(const struct qstr *name, struct dentry *base)

{

	struct dentry *ret;



	ret = lookup_dcache(name, base, 0);

	if (!ret)

		ret = lookup_slow(name, base, 0);



	return ret;

}

EXPORT_SYMBOL(lookup_hash);



/**

 * lookup_one_len - filesystem helper to lookup single pathname component

 * @name:	pathname component to lookup
@@ -2337,7 +2364,6 @@ struct dentry *lookup_one_len_unlocked(const char *name, 
	struct qstr this;

	unsigned int c;

	int err;

	struct dentry *ret;



	this.name = name;

	this.len = len;
@@ -2369,10 +2395,7 @@ struct dentry *lookup_one_len_unlocked(const char *name, 
	if (err)

		return ERR_PTR(err);



	ret = lookup_dcache(&this, base, 0);

	if (!ret)

		ret = lookup_slow(&this, base, 0);

	return ret;

	return lookup_hash(&this, base);

}

EXPORT_SYMBOL(lookup_one_len_unlocked);

include/linux/namei.h

+2 −0
Original line number Diff line number Diff line
@@ -79,6 +79,8 @@ extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int); 


extern struct dentry *lookup_one_len(const char *, struct dentry *, int);

extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);

struct qstr;

extern struct dentry *lookup_hash(const struct qstr *, struct dentry *);



extern int follow_down_one(struct path *);

extern int follow_down(struct path *);

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