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Subject[RFC][PATCH 16/27] new wrapper: alloc_file_pseudo()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

takes inode, vfsmount, name, mode 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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/aio.c | 27 ++++++---------------------
fs/file_table.c | 27 +++++++++++++++++++++++++++
include/linux/file.h | 3 +++
net/socket.c | 27 ++++-----------------------
4 files changed, 40 insertions(+), 44 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 4d63e8e4d1b5..c5244c68f90e 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);
@@ -226,32 +224,19 @@ 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) {
+ file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
+ FMODE_READ | FMODE_WRITE, &aio_ring_fops);
+ if (IS_ERR(file))
iput(inode);
- return ERR_PTR(-ENOMEM);
- }
- path.mnt = mntget(aio_mnt);
-
- d_instantiate(path.dentry, inode);
- file = alloc_file(&path, FMODE_READ | FMODE_WRITE | FMODE_OPENED,
- &aio_ring_fops);
- if (IS_ERR(file)) {
- path_put(&path);
- return file;
- }
-
- file->f_flags = O_RDWR;
+ else
+ file->f_flags = O_RDWR;
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 7ec0b3e5f05d..d78bc97f926f 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -182,6 +182,33 @@ struct file *alloc_file(const struct path *path, fmode_t mode,
}
EXPORT_SYMBOL(alloc_file);

+struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt,
+ const char *name, fmode_t mode,
+ 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, mode | FMODE_OPENED, 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 279720db984a..37a4d2c166de 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 *, fmode_t mode,
const struct file_operations *fop);
+extern struct file *alloc_file_pseudo(struct inode *, struct vfsmount *,
+ const char *, fmode_t, 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 eff9db5fd99f..81cf9906cae5 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -391,33 +391,14 @@ 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, FMODE_READ | FMODE_WRITE | FMODE_OPENED,
- &socket_file_ops);
+ file = alloc_file_pseudo(SOCK_INODE(sock), sock_mnt, dname,
+ FMODE_READ | FMODE_WRITE, &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;
}
--
2.11.0
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