new wrapper: alloc_file_pseudo()

takes inode, vfsmount, name, O_... flags and file_operations and
either returns a new struct file (in which case inode reference we
held is consumed) or returns ERR_PTR(), in which case no refcounts
are altered.

converted aio_private_file() and sock_alloc_file() to it

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 39 insertions, 39 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 9eea53887d6c..c3a8bac16374 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -215,9 +215,7 @@ static const struct address_space_operations aio_ctx_aops;
 
 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
 {
-        struct qstr this = QSTR_INIT("[aio]", 5);
         struct file *file;
-        struct path path;
         struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
         if (IS_ERR(inode))
                 return ERR_CAST(inode);
@@ -226,27 +224,17 @@ static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
         inode->i_mapping->private_data = ctx;
         inode->i_size = PAGE_SIZE * nr_pages;
 
-        path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
-        if (!path.dentry) {
-                iput(inode);
-                return ERR_PTR(-ENOMEM);
-        }
-        path.mnt = mntget(aio_mnt);
-
-        d_instantiate(path.dentry, inode);
-        file = alloc_file(&path, O_RDWR, &aio_ring_fops);
+        file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
+                                O_RDWR, &aio_ring_fops);
         if (IS_ERR(file))
-                path_put(&path);
+                iput(inode);
         return file;
 }
 
 static struct dentry *aio_mount(struct file_system_type *fs_type,
                                 int flags, const char *dev_name, void *data)
 {
-        static const struct dentry_operations ops = {
-                .d_dname        = simple_dname,
-        };
-        struct dentry *root = mount_pseudo(fs_type, "aio:", NULL, &ops,
+        struct dentry *root = mount_pseudo(fs_type, "aio:", NULL, NULL,
                                            AIO_RING_MAGIC);
 
         if (!IS_ERR(root))
diff --git a/fs/file_table.c b/fs/file_table.c
index 9b70ed2bbc4e..6b3723909342 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -184,6 +184,33 @@ struct file *alloc_file(const struct path *path, int flags,
 }
 EXPORT_SYMBOL(alloc_file);
 
+struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt,
+                                const char *name, int flags,
+                                const struct file_operations *fops)
+{
+        static const struct dentry_operations anon_ops = {
+                .d_dname = simple_dname
+        };
+        struct qstr this = QSTR_INIT(name, strlen(name));
+        struct path path;
+        struct file *file;
+
+        path.dentry = d_alloc_pseudo(mnt->mnt_sb, &this);
+        if (!path.dentry)
+                return ERR_PTR(-ENOMEM);
+        if (!mnt->mnt_sb->s_d_op)
+                d_set_d_op(path.dentry, &anon_ops);
+        path.mnt = mntget(mnt);
+        d_instantiate(path.dentry, inode);
+        file = alloc_file(&path, flags, fops);
+        if (IS_ERR(file)) {
+                ihold(inode);
+                path_put(&path);
+        }
+        return file;
+}
+EXPORT_SYMBOL(alloc_file_pseudo);
+
 /* the real guts of fput() - releasing the last reference to file
  */
 static void __fput(struct file *file)
diff --git a/include/linux/file.h b/include/linux/file.h
index aed45d69811e..5b25388f2f79 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -17,9 +17,12 @@ extern void fput(struct file *);
 struct file_operations;
 struct vfsmount;
 struct dentry;
+struct inode;
 struct path;
 extern struct file *alloc_file(const struct path *, int flags,
         const struct file_operations *fop);
+extern struct file *alloc_file_pseudo(struct inode *, struct vfsmount *,
+        const char *, int flags, const struct file_operations *);
 
 static inline void fput_light(struct file *file, int fput_needed)
 {
diff --git a/net/socket.c b/net/socket.c
index 2cdbe8f71b7f..4cf3568caf9f 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -391,33 +391,15 @@ static struct file_system_type sock_fs_type = {
 
 struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname)
 {
-        struct qstr name = { .name = "" };
-        struct path path;
         struct file *file;
 
-        if (dname) {
-                name.name = dname;
-                name.len = strlen(name.name);
-        } else if (sock->sk) {
-                name.name = sock->sk->sk_prot_creator->name;
-                name.len = strlen(name.name);
-        }
-        path.dentry = d_alloc_pseudo(sock_mnt->mnt_sb, &name);
-        if (unlikely(!path.dentry)) {
-                sock_release(sock);
-                return ERR_PTR(-ENOMEM);
-        }
-        path.mnt = mntget(sock_mnt);
-
-        d_instantiate(path.dentry, SOCK_INODE(sock));
+        if (!dname)
+                dname = sock->sk ? sock->sk->sk_prot_creator->name : "";
 
-        file = alloc_file(&path, O_RDWR | (flags & O_NONBLOCK),
-                  &socket_file_ops);
+        file = alloc_file_pseudo(SOCK_INODE(sock), sock_mnt, dname,
+                                O_RDWR | (flags & O_NONBLOCK),
+                                &socket_file_ops);
         if (IS_ERR(file)) {
-                /* drop dentry, keep inode for a bit */
-                ihold(d_inode(path.dentry));
-                path_put(&path);
-                /* ... and now kill it properly */
                 sock_release(sock);
                 return file;
         }