Commit fb2d5b86 authored by Nick Piggin's avatar Nick Piggin
Browse files

fs: name case update method 



smpfs and ncpfs want to update a live dentry name in-place. Rather than
have them open code the locking, provide a documented dcache API.

Signed-off-by: default avatarNick Piggin <npiggin@kernel.dk>
parent 2bc334dc

drivers/staging/smbfs/cache.c

+2 −2
Original line number Diff line number Diff line
@@ -145,8 +145,8 @@ smb_fill_cache(struct file *filp, void *dirent, filldir_t filldir, 
			goto end_advance;

	} else {

		hashed = 1;

		memcpy((char *) newdent->d_name.name, qname->name,

		       newdent->d_name.len);

		/* dir i_mutex is locked because we're in readdir */

		dentry_update_name_case(newdent, qname);

	}



	if (!newdent->d_inode) {

fs/dcache.c

+27 −0
Original line number Diff line number Diff line
@@ -1589,6 +1589,33 @@ void d_rehash(struct dentry * entry) 
}

EXPORT_SYMBOL(d_rehash);



/**

 * dentry_update_name_case - update case insensitive dentry with a new name

 * @dentry: dentry to be updated

 * @name: new name

 *

 * Update a case insensitive dentry with new case of name.

 *

 * dentry must have been returned by d_lookup with name @name. Old and new

 * name lengths must match (ie. no d_compare which allows mismatched name

 * lengths).

 *

 * Parent inode i_mutex must be held over d_lookup and into this call (to

 * keep renames and concurrent inserts, and readdir(2) away).

 */

void dentry_update_name_case(struct dentry *dentry, struct qstr *name)

{

	BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));

	BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */



	spin_lock(&dcache_lock);

	spin_lock(&dentry->d_lock);

	memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);

	spin_unlock(&dentry->d_lock);

	spin_unlock(&dcache_lock);

}

EXPORT_SYMBOL(dentry_update_name_case);



/*

 * When switching names, the actual string doesn't strictly have to

 * be preserved in the target - because we're dropping the target

fs/ncpfs/dir.c

+6 −29
Original line number Diff line number Diff line
@@ -611,35 +611,12 @@ ncp_fill_cache(struct file *filp, void *dirent, filldir_t filldir, 
			shrink_dcache_parent(newdent);



		/*

		 * It is not as dangerous as it looks.  NetWare's OS2 namespace is

		 * case preserving yet case insensitive.  So we update dentry's name

		 * as received from server.  We found dentry via d_lookup with our

		 * hash, so we know that hash does not change, and so replacing name

		 * should be reasonably safe.

		 * NetWare's OS2 namespace is case preserving yet case

		 * insensitive.  So we update dentry's name as received from

		 * server. Parent dir's i_mutex is locked because we're in

		 * readdir.

		 */

		if (qname.len == newdent->d_name.len &&

		    memcmp(newdent->d_name.name, qname.name, newdent->d_name.len)) {

			struct inode *inode = newdent->d_inode;



			/*

			 * Inside ncpfs all uses of d_name are either for debugging,

			 * or on functions which acquire inode mutex (mknod, creat,

			 * lookup).  So grab i_mutex here, to be sure.  d_path

			 * uses dcache_lock when generating path, so we should too.

			 * And finally d_compare is protected by dentry's d_lock, so

			 * here we go.

			 */

			if (inode)

				mutex_lock(&inode->i_mutex);

			spin_lock(&dcache_lock);

			spin_lock(&newdent->d_lock);

			memcpy((char *) newdent->d_name.name, qname.name,

								newdent->d_name.len);

			spin_unlock(&newdent->d_lock);

			spin_unlock(&dcache_lock);

			if (inode)

				mutex_unlock(&inode->i_mutex);

		}

		dentry_update_name_case(newdent, &qname);

	}



	if (!newdent->d_inode) {
@@ -657,7 +634,7 @@ ncp_fill_cache(struct file *filp, void *dirent, filldir_t filldir, 
	} else {

		struct inode *inode = newdent->d_inode;



		mutex_lock(&inode->i_mutex);

		mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);

		ncp_update_inode2(inode, entry);

		mutex_unlock(&inode->i_mutex);

	}

include/linux/dcache.h

+2 −0
Original line number Diff line number Diff line
@@ -290,6 +290,8 @@ static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *in 
	return res;

}



extern void dentry_update_name_case(struct dentry *, struct qstr *);



/* used for rename() and baskets */

extern void d_move(struct dentry *, struct dentry *);

extern struct dentry *d_ancestor(struct dentry *, struct dentry *);