forked from Minki/linux
vfs: Add open by file handle support
[AV: duplicate of open() guts removed; file_open_root() used instead] Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
parent
990d6c2d7a
commit
becfd1f375
13
fs/compat.c
13
fs/compat.c
@ -2284,3 +2284,16 @@ asmlinkage long compat_sys_timerfd_gettime(int ufd,
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}
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#endif /* CONFIG_TIMERFD */
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#ifdef CONFIG_FHANDLE
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/*
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* Exactly like fs/open.c:sys_open_by_handle_at(), except that it
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* doesn't set the O_LARGEFILE flag.
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*/
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asmlinkage long
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compat_sys_open_by_handle_at(int mountdirfd,
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struct file_handle __user *handle, int flags)
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{
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return do_handle_open(mountdirfd, handle, flags);
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}
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#endif
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@ -374,6 +374,8 @@ struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
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/*
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* Try to get any dentry for the given file handle from the filesystem.
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*/
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if (!nop || !nop->fh_to_dentry)
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return ERR_PTR(-ESTALE);
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result = nop->fh_to_dentry(mnt->mnt_sb, fid, fh_len, fileid_type);
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if (!result)
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result = ERR_PTR(-ESTALE);
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158
fs/fhandle.c
158
fs/fhandle.c
@ -5,6 +5,8 @@
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/exportfs.h>
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#include <linux/fs_struct.h>
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#include <linux/fsnotify.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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@ -105,3 +107,159 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
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}
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return err;
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}
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static struct vfsmount *get_vfsmount_from_fd(int fd)
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{
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struct path path;
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if (fd == AT_FDCWD) {
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struct fs_struct *fs = current->fs;
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spin_lock(&fs->lock);
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path = fs->pwd;
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mntget(path.mnt);
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spin_unlock(&fs->lock);
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} else {
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int fput_needed;
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struct file *file = fget_light(fd, &fput_needed);
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if (!file)
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return ERR_PTR(-EBADF);
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path = file->f_path;
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mntget(path.mnt);
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fput_light(file, fput_needed);
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}
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return path.mnt;
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}
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static int vfs_dentry_acceptable(void *context, struct dentry *dentry)
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{
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return 1;
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}
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static int do_handle_to_path(int mountdirfd, struct file_handle *handle,
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struct path *path)
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{
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int retval = 0;
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int handle_dwords;
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path->mnt = get_vfsmount_from_fd(mountdirfd);
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if (IS_ERR(path->mnt)) {
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retval = PTR_ERR(path->mnt);
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goto out_err;
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}
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/* change the handle size to multiple of sizeof(u32) */
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handle_dwords = handle->handle_bytes >> 2;
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path->dentry = exportfs_decode_fh(path->mnt,
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(struct fid *)handle->f_handle,
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handle_dwords, handle->handle_type,
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vfs_dentry_acceptable, NULL);
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if (IS_ERR(path->dentry)) {
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retval = PTR_ERR(path->dentry);
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goto out_mnt;
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}
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return 0;
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out_mnt:
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mntput(path->mnt);
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out_err:
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return retval;
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}
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static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
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struct path *path)
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{
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int retval = 0;
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struct file_handle f_handle;
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struct file_handle *handle = NULL;
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/*
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* With handle we don't look at the execute bit on the
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* the directory. Ideally we would like CAP_DAC_SEARCH.
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* But we don't have that
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*/
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if (!capable(CAP_DAC_READ_SEARCH)) {
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retval = -EPERM;
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goto out_err;
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}
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if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) {
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retval = -EFAULT;
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goto out_err;
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}
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if ((f_handle.handle_bytes > MAX_HANDLE_SZ) ||
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(f_handle.handle_bytes == 0)) {
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retval = -EINVAL;
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goto out_err;
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}
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handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_bytes,
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GFP_KERNEL);
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if (!handle) {
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retval = -ENOMEM;
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goto out_err;
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}
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/* copy the full handle */
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if (copy_from_user(handle, ufh,
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sizeof(struct file_handle) +
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f_handle.handle_bytes)) {
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retval = -EFAULT;
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goto out_handle;
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}
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retval = do_handle_to_path(mountdirfd, handle, path);
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out_handle:
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kfree(handle);
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out_err:
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return retval;
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}
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long do_handle_open(int mountdirfd,
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struct file_handle __user *ufh, int open_flag)
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{
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long retval = 0;
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struct path path;
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struct file *file;
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int fd;
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retval = handle_to_path(mountdirfd, ufh, &path);
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if (retval)
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return retval;
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fd = get_unused_fd_flags(open_flag);
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if (fd < 0) {
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path_put(&path);
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return fd;
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}
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file = file_open_root(path.dentry, path.mnt, "", open_flag);
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if (IS_ERR(file)) {
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put_unused_fd(fd);
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retval = PTR_ERR(file);
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} else {
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retval = fd;
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fsnotify_open(file);
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fd_install(fd, file);
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}
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path_put(&path);
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return retval;
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}
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/**
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* sys_open_by_handle_at: Open the file handle
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* @mountdirfd: directory file descriptor
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* @handle: file handle to be opened
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* @flag: open flags.
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*
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* @mountdirfd indicate the directory file descriptor
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* of the mount point. file handle is decoded relative
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* to the vfsmount pointed by the @mountdirfd. @flags
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* value is same as the open(2) flags.
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*/
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SYSCALL_DEFINE3(open_by_handle_at, int, mountdirfd,
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struct file_handle __user *, handle,
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int, flags)
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{
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long ret;
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if (force_o_largefile())
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flags |= O_LARGEFILE;
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ret = do_handle_open(mountdirfd, handle, flags);
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return ret;
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}
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@ -117,6 +117,9 @@ extern struct file *do_filp_open(int dfd, const char *pathname,
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extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
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const char *, const struct open_flags *, int lookup_flags);
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extern long do_handle_open(int mountdirfd,
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struct file_handle __user *ufh, int open_flag);
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/*
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* inode.c
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*/
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@ -836,4 +836,7 @@ asmlinkage long sys_old_mmap(struct mmap_arg_struct __user *arg);
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asmlinkage long sys_name_to_handle_at(int dfd, const char __user *name,
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struct file_handle __user *handle,
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int __user *mnt_id, int flag);
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asmlinkage long sys_open_by_handle_at(int mountdirfd,
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struct file_handle __user *handle,
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int flags);
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#endif
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@ -189,3 +189,5 @@ cond_syscall(sys_fanotify_mark);
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/* open by handle */
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cond_syscall(sys_name_to_handle_at);
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cond_syscall(sys_open_by_handle_at);
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cond_syscall(compat_sys_open_by_handle_at);
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