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Message-Id: <20070920195249.0F6862CC@kernel>
Date: Thu, 20 Sep 2007 12:52:49 -0700
From: Dave Hansen <haveblue@...ibm.com>
To: akpm@...l.org
Cc: linux-kernel@...r.kernel.org, hch@...radead.org,
Dave Hansen <haveblue@...ibm.com>
Subject: [PATCH 01/25] filesystem helpers for custom 'struct file's
Christoph H. says this stands on its own and can go in before the
rest of the r/o bind mount set.
---
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.
Also, rename an existing, static-scope init_file() to a less
generic name.
Signed-off-by: Dave Hansen <haveblue@...ibm.com>
---
lxc-dave/fs/configfs/dir.c | 5 ++-
lxc-dave/fs/file_table.c | 60 ++++++++++++++++++++++++++++++++++++++++++
lxc-dave/fs/hugetlbfs/inode.c | 22 ++++++---------
lxc-dave/include/linux/file.h | 9 ++++++
lxc-dave/ipc/shm.c | 13 +++------
lxc-dave/mm/shmem.c | 7 +---
lxc-dave/mm/tiny-shmem.c | 19 ++++---------
lxc-dave/net/socket.c | 18 ++++++------
8 files changed, 104 insertions(+), 49 deletions(-)
diff -puN fs/configfs/dir.c~filesystem-helpers-for-custom-struct-file-s fs/configfs/dir.c
--- lxc/fs/configfs/dir.c~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/fs/configfs/dir.c 2007-09-20 12:16:08.000000000 -0700
@@ -142,7 +142,7 @@ static int init_dir(struct inode * inode
return 0;
}
-static int init_file(struct inode * inode)
+static int configfs_init_file(struct inode * inode)
{
inode->i_size = PAGE_SIZE;
inode->i_fop = &configfs_file_operations;
@@ -283,7 +283,8 @@ static int configfs_attach_attr(struct c
dentry->d_fsdata = configfs_get(sd);
sd->s_dentry = dentry;
- error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, init_file);
+ error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
+ configfs_init_file);
if (error) {
configfs_put(sd);
return error;
diff -puN fs/file_table.c~filesystem-helpers-for-custom-struct-file-s fs/file_table.c
--- lxc/fs/file_table.c~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/fs/file_table.c 2007-09-20 12:16:08.000000000 -0700
@@ -138,6 +138,66 @@ fail:
EXPORT_SYMBOL(get_empty_filp);
+/**
+ * alloc_file - allocate and initialize a 'struct file'
+ * @mnt: the vfsmount on which the file will reside
+ * @dentry: the dentry representing the new file
+ * @mode: the mode with which the new file will be opened
+ * @fop: the 'struct file_operations' for the new file
+ *
+ * Use this instead of get_empty_filp() to get a new
+ * 'struct file'. Do so because of the same initialization
+ * pitfalls reasons listed for init_file(). This is a
+ * preferred interface to using init_file().
+ *
+ * If all the callers of init_file() are eliminated, its
+ * code should be moved into this function.
+ */
+struct file *alloc_file(struct vfsmount *mnt, struct dentry *dentry,
+ mode_t mode, const struct file_operations *fop)
+{
+ struct file *file;
+ struct path;
+
+ file = get_empty_filp();
+ if (!file)
+ return NULL;
+
+ init_file(file, mnt, dentry, mode, fop);
+ return file;
+}
+EXPORT_SYMBOL(alloc_file);
+
+/**
+ * init_file - initialize a 'struct file'
+ * @file: the already allocated 'struct file' to initialized
+ * @mnt: the vfsmount on which the file resides
+ * @dentry: the dentry representing this file
+ * @mode: the mode the file is opened with
+ * @fop: the 'struct file_operations' for this file
+ *
+ * Use this instead of setting the members directly. Doing so
+ * avoids making mistakes like forgetting the mntget() or
+ * forgetting to take a write on the mnt.
+ *
+ * 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_path.dentry = dentry;
+ file->f_path.mnt = mntget(mnt);
+ 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~filesystem-helpers-for-custom-struct-file-s fs/hugetlbfs/inode.c
--- lxc/fs/hugetlbfs/inode.c~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/fs/hugetlbfs/inode.c 2007-09-20 12:16:08.000000000 -0700
@@ -810,16 +810,11 @@ struct file *hugetlb_file_setup(const ch
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))
@@ -828,17 +823,18 @@ struct file *hugetlb_file_setup(const ch
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~filesystem-helpers-for-custom-struct-file-s include/linux/file.h
--- lxc/include/linux/file.h~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/include/linux/file.h 2007-09-20 12:16:08.000000000 -0700
@@ -62,6 +62,15 @@ 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 *mnt,
+ 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 ipc/shm.c~filesystem-helpers-for-custom-struct-file-s ipc/shm.c
--- lxc/ipc/shm.c~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/ipc/shm.c 2007-09-20 12:16:08.000000000 -0700
@@ -906,7 +906,7 @@ long do_shmat(int shmid, char __user *sh
goto out_unlock;
path.dentry = dget(shp->shm_file->f_path.dentry);
- path.mnt = mntget(shp->shm_file->f_path.mnt);
+ path.mnt = shp->shm_file->f_path.mnt;
shp->shm_nattch++;
size = i_size_read(path.dentry->d_inode);
shm_unlock(shp);
@@ -914,18 +914,16 @@ long do_shmat(int shmid, char __user *sh
err = -ENOMEM;
sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
if (!sfd)
- goto out_put_path;
+ goto out_put_dentry;
err = -ENOMEM;
- file = get_empty_filp();
+
+ file = alloc_file(path.mnt, path.dentry, f_mode, &shm_file_operations);
if (!file)
goto out_free;
- file->f_op = &shm_file_operations;
file->private_data = sfd;
- file->f_path = path;
file->f_mapping = shp->shm_file->f_mapping;
- file->f_mode = f_mode;
sfd->id = shp->id;
sfd->ns = get_ipc_ns(ns);
sfd->file = shp->shm_file;
@@ -976,9 +974,8 @@ out_unlock:
out_free:
kfree(sfd);
-out_put_path:
+out_put_dentry:
dput(path.dentry);
- mntput(path.mnt);
goto out_nattch;
}
diff -puN mm/shmem.c~filesystem-helpers-for-custom-struct-file-s mm/shmem.c
--- lxc/mm/shmem.c~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/mm/shmem.c 2007-09-20 12:16:08.000000000 -0700
@@ -2518,11 +2518,8 @@ 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~filesystem-helpers-for-custom-struct-file-s mm/tiny-shmem.c
--- lxc/mm/tiny-shmem.c~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/mm/tiny-shmem.c 2007-09-20 12:16:08.000000000 -0700
@@ -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_dentry;
- 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);
diff -puN net/socket.c~filesystem-helpers-for-custom-struct-file-s net/socket.c
--- lxc/net/socket.c~filesystem-helpers-for-custom-struct-file-s 2007-09-20 12:16:08.000000000 -0700
+++ lxc-dave/net/socket.c 2007-09-20 12:16:08.000000000 -0700
@@ -363,26 +363,26 @@ static int sock_alloc_fd(struct file **f
static int sock_attach_fd(struct socket *sock, struct file *file)
{
+ struct dentry *dentry;
struct qstr name = { .name = "" };
- file->f_path.dentry = d_alloc(sock_mnt->mnt_sb->s_root, &name);
- if (unlikely(!file->f_path.dentry))
+ dentry = d_alloc(sock_mnt->mnt_sb->s_root, &name);
+ 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));
sock->file = file;
- file->f_op = SOCK_INODE(sock)->i_fop = &socket_file_ops;
- file->f_mode = FMODE_READ | FMODE_WRITE;
+ init_file(file, sock_mnt, dentry, FMODE_READ | FMODE_WRITE,
+ &socket_file_ops);
+ SOCK_INODE(sock)->i_fop = &socket_file_ops;
file->f_flags = O_RDWR;
file->f_pos = 0;
file->private_data = sock;
_
-
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