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    Subject[PATCH 01/24] filesystem helpers for custom 'struct file's
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    Date

    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@us.ibm.com>
    ---

    lxc-dave/fs/configfs/dir.c | 5 +++--
    lxc-dave/fs/file_table.c | 34 ++++++++++++++++++++++++++++++++++
    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, 78 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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/fs/configfs/dir.c 2007-09-17 09:43:55.000000000 -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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/fs/file_table.c 2007-09-17 09:43:55.000000000 -0700
    @@ -137,6 +137,40 @@ 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;
    + struct path;
    +
    + 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_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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/fs/hugetlbfs/inode.c 2007-09-17 09:43:55.000000000 -0700
    @@ -923,16 +923,11 @@ 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))
    @@ -941,17 +936,18 @@ 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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/include/linux/file.h 2007-09-17 09:43:55.000000000 -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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/ipc/shm.c 2007-09-17 09:43:55.000000000 -0700
    @@ -907,7 +907,7 @@ 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);
    @@ -915,18 +915,16 @@ 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;
    @@ -977,9 +975,8 @@ 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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/mm/shmem.c 2007-09-17 09:43:55.000000000 -0700
    @@ -2538,11 +2538,8 @@ 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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/mm/tiny-shmem.c 2007-09-17 09:43:55.000000000 -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 2007-09-17 09:43:55.000000000 -0700
    +++ lxc-dave/net/socket.c 2007-09-17 09:43:55.000000000 -0700
    @@ -367,26 +367,26 @@ 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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