[PATCH 01/22] filesystem helpers for custom 'struct file's

Dave Hansen
2007-02-09T22:53:35Z

Some filesystems forego the vfs and may_open() and create their
own 'struct file's.

This patch creates a couple of helper functions which can be
used by these filesystems, and will provide a unified place
which the r/o bind mount code may patch.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

lxc-dave/fs/file_table.c | 36 ++++++++++++++++++++++++++++++++++++
lxc-dave/fs/hugetlbfs/inode.c | 22 +++++++++-------------
lxc-dave/include/linux/file.h | 8 ++++++++
lxc-dave/mm/shmem.c | 7 ++-----
lxc-dave/mm/tiny-shmem.c | 24 +++++++++---------------
lxc-dave/net/socket.c | 18 +++++++++---------
6 files changed, 73 insertions(+), 42 deletions(-)

diff -puN fs/file_table.c~01-24-filesystem-helpers-for-custom-struct-file-s fs/file_table.c
--- lxc/fs/file_table.c~01-24-filesystem-helpers-for-custom-struct-file-s 2007-02-09 14:26:46.000000000 -0800
+++ lxc-dave/fs/file_table.c 2007-02-09 14:26:46.000000000 -0800
@@ -140,6 +140,42 @@ fail:

EXPORT_SYMBOL(get_empty_filp);

+struct file *alloc_file(struct vfsmount *mnt, struct dentry *dentry,
+ mode_t mode, const struct file_operations *fop)
+{
+ struct file *file;
+
+ file = get_empty_filp();
+ if (!file)
+ return NULL;
+
+ init_file(file, mnt, dentry, mode, fop);
+ return file;
+}
+
+EXPORT_SYMBOL(alloc_file);
+
+/*
+ * Note: This is a crappy interface. It is here to make
+ * merging with the existing users of get_empty_filp()
+ * who have complex failure logic easier. All users
+ * of this should be moving to alloc_file().
+ */
+int init_file(struct file *file, struct vfsmount *mnt,
+ struct dentry *dentry, mode_t mode,
+ const struct file_operations *fop)
+{
+ int error = 0;
+ file->f_vfsmnt = mntget(mnt);
+ file->f_dentry = dentry;
+ file->f_mapping = dentry->d_inode->i_mapping;
+ file->f_mode = mode;
+ file->f_op = fop;
+ return error;
+}
+
+EXPORT_SYMBOL(init_file);
+
void fastcall fput(struct file *file)
{
if (atomic_dec_and_test(&file->f_count))
diff -puN fs/hugetlbfs/inode.c~01-24-filesystem-helpers-for-custom-struct-file-s fs/hugetlbfs/inode.c
--- lxc/fs/hugetlbfs/inode.c~01-24-filesystem-helpers-for-custom-struct-file-s 2007-02-09 14:26:46.000000000 -0800
+++ lxc-dave/fs/hugetlbfs/inode.c 2007-02-09 14:26:46.000000000 -0800
@@ -756,16 +756,11 @@ struct file *hugetlb_zero_setup(size_t s
if (!dentry)
goto out_shm_unlock;

- error = -ENFILE;
- file = get_empty_filp();
- if (!file)
- goto out_dentry;
-
error = -ENOSPC;
inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
current->fsgid, S_IFREG | S_IRWXUGO, 0);
if (!inode)
- goto out_file;
+ goto out_dentry;

error = -ENOMEM;
if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
@@ -774,17 +769,18 @@ struct file *hugetlb_zero_setup(size_t s
d_instantiate(dentry, inode);
inode->i_size = size;
inode->i_nlink = 0;
- file->f_path.mnt = mntget(hugetlbfs_vfsmount);
- file->f_path.dentry = dentry;
- file->f_mapping = inode->i_mapping;
- file->f_op = &hugetlbfs_file_operations;
- file->f_mode = FMODE_WRITE | FMODE_READ;
+
+ error = -ENFILE;
+ file = alloc_file(hugetlbfs_vfsmount, dentry,
+ FMODE_WRITE | FMODE_READ,
+ &hugetlbfs_file_operations);
+ if (!file)
+ goto out_inode;
+
return file;

out_inode:
iput(inode);
-out_file:
- put_filp(file);
out_dentry:
dput(dentry);
out_shm_unlock:
diff -puN include/linux/file.h~01-24-filesystem-helpers-for-custom-struct-file-s include/linux/file.h
--- lxc/include/linux/file.h~01-24-filesystem-helpers-for-custom-struct-file-s 2007-02-09 14:26:46.000000000 -0800
+++ lxc-dave/include/linux/file.h 2007-02-09 14:26:46.000000000 -0800
@@ -62,6 +62,14 @@ extern struct kmem_cache *filp_cachep;
extern void FASTCALL(__fput(struct file *));
extern void FASTCALL(fput(struct file *));

+struct file_operations;
+struct vfsmount;
+struct dentry;
+extern int init_file(struct file *, struct vfsmount *, struct dentry *dentry,
+ mode_t mode, const struct file_operations *fop);
+extern struct file *alloc_file(struct vfsmount *, struct dentry *dentry,
+ mode_t mode, const struct file_operations *fop);
+
static inline void fput_light(struct file *file, int fput_needed)
{
if (unlikely(fput_needed))
diff -puN mm/shmem.c~01-24-filesystem-helpers-for-custom-struct-file-s mm/shmem.c
--- lxc/mm/shmem.c~01-24-filesystem-helpers-for-custom-struct-file-s 2007-02-09 14:26:46.000000000 -0800
+++ lxc-dave/mm/shmem.c 2007-02-09 14:26:46.000000000 -0800
@@ -2497,11 +2497,8 @@ struct file *shmem_file_setup(char *name
d_instantiate(dentry, inode);
inode->i_size = size;
inode->i_nlink = 0; /* It is unlinked */
- file->f_path.mnt = mntget(shm_mnt);
- file->f_path.dentry = dentry;
- file->f_mapping = inode->i_mapping;
- file->f_op = &shmem_file_operations;
- file->f_mode = FMODE_WRITE | FMODE_READ;
+ init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
+ &shmem_file_operations);
return file;

close_file:
diff -puN mm/tiny-shmem.c~01-24-filesystem-helpers-for-custom-struct-file-s mm/tiny-shmem.c
--- lxc/mm/tiny-shmem.c~01-24-filesystem-helpers-for-custom-struct-file-s 2007-02-09 14:26:46.000000000 -0800
+++ lxc-dave/mm/tiny-shmem.c 2007-02-09 14:26:46.000000000 -0800
@@ -66,24 +66,19 @@ struct file *shmem_file_setup(char *name
if (!dentry)
goto put_memory;

- error = -ENFILE;
- file = get_empty_filp();
- if (!file)
- goto put_dentry;
-
error = -ENOSPC;
inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
if (!inode)
- goto close_file;
+ goto put_dentry;

d_instantiate(dentry, inode);
- inode->i_nlink = 0; /* It is unlinked */
+ error = -ENFILE;
+ file = alloc_file(shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
+ &ramfs_file_operations);
+ if (!file)
+ goto put_inode;

- file->f_path.mnt = mntget(shm_mnt);
- file->f_path.dentry = dentry;
- file->f_mapping = inode->i_mapping;
- file->f_op = &ramfs_file_operations;
- file->f_mode = FMODE_WRITE | FMODE_READ;
+ inode->i_nlink = 0; /* It is unlinked */

/* notify everyone as to the change of file size */
error = do_truncate(dentry, size, 0, file);
@@ -91,9 +86,8 @@ struct file *shmem_file_setup(char *name
goto close_file;

return file;
-
-close_file:
- put_filp(file);
+put_inode:
+ iput(inode);
put_dentry:
dput(dentry);
put_memory:
diff -puN net/socket.c~01-24-filesystem-helpers-for-custom-struct-file-s net/socket.c
--- lxc/net/socket.c~01-24-filesystem-helpers-for-custom-struct-file-s 2007-02-09 14:26:46.000000000 -0800
+++ lxc-dave/net/socket.c 2007-02-09 14:26:46.000000000 -0800
@@ -355,6 +355,7 @@ static int sock_alloc_fd(struct file **f

static int sock_attach_fd(struct socket *sock, struct file *file)
{
+ struct dentry *dentry;
struct qstr this;
char name[32];

@@ -362,24 +363,23 @@ static int sock_attach_fd(struct socket
this.name = name;
this.hash = 0;

- file->f_path.dentry = d_alloc(sock_mnt->mnt_sb->s_root, &this);
- if (unlikely(!file->f_path.dentry))
+ dentry = d_alloc(sock_mnt->mnt_sb->s_root, &this);
+ if (unlikely(!dentry))
return -ENOMEM;

- file->f_path.dentry->d_op = &sockfs_dentry_operations;
+ dentry->d_op = &sockfs_dentry_operations;
/*
* We dont want to push this dentry into global dentry hash table.
* We pretend dentry is already hashed, by unsetting DCACHE_UNHASHED
* This permits a working /proc/$pid/fd/XXX on sockets
*/
- file->f_path.dentry->d_flags &= ~DCACHE_UNHASHED;
- d_instantiate(file->f_path.dentry, SOCK_INODE(sock));
- file->f_path.mnt = mntget(sock_mnt);
- file->f_mapping = file->f_path.dentry->d_inode->i_mapping;
-
+ dentry->d_flags &= ~DCACHE_UNHASHED;
+ d_instantiate(dentry, SOCK_INODE(sock));
+ init_file(file, sock_mnt, dentry, FMODE_READ | FMODE_WRITE,
+ &socket_file_ops);
+ SOCK_INODE(sock)->i_fop = &socket_file_ops;
sock->file = file;
file->f_op = SOCK_INODE(sock)->i_fop = &socket_file_ops;
- file->f_mode = FMODE_READ | FMODE_WRITE;
file->f_flags = O_RDWR;
file->f_pos = 0;
file->private_data = sock;
_