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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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72227eac17
Since fuse just passes ioctl args through to/from server, converting to the fileattr API is more involved, than most other filesystems. Both .fileattr_set() and .fileattr_get() need to obtain an open file to operate on. The simplest way is with the following sequence: FUSE_OPEN FUSE_IOCTL FUSE_RELEASE If this turns out to be a performance problem, it could be optimized for the case when there's already a file (any file) open for the inode. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
490 lines
12 KiB
C
490 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2017 Red Hat, Inc.
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*/
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#include "fuse_i.h"
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#include <linux/uio.h>
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#include <linux/compat.h>
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#include <linux/fileattr.h>
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/*
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* CUSE servers compiled on 32bit broke on 64bit kernels because the
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* ABI was defined to be 'struct iovec' which is different on 32bit
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* and 64bit. Fortunately we can determine which structure the server
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* used from the size of the reply.
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*/
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static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
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size_t transferred, unsigned count,
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bool is_compat)
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{
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#ifdef CONFIG_COMPAT
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if (count * sizeof(struct compat_iovec) == transferred) {
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struct compat_iovec *ciov = src;
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unsigned i;
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/*
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* With this interface a 32bit server cannot support
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* non-compat (i.e. ones coming from 64bit apps) ioctl
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* requests
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*/
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if (!is_compat)
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return -EINVAL;
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for (i = 0; i < count; i++) {
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dst[i].iov_base = compat_ptr(ciov[i].iov_base);
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dst[i].iov_len = ciov[i].iov_len;
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}
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return 0;
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}
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#endif
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if (count * sizeof(struct iovec) != transferred)
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return -EIO;
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memcpy(dst, src, transferred);
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return 0;
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}
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/* Make sure iov_length() won't overflow */
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static int fuse_verify_ioctl_iov(struct fuse_conn *fc, struct iovec *iov,
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size_t count)
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{
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size_t n;
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u32 max = fc->max_pages << PAGE_SHIFT;
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for (n = 0; n < count; n++, iov++) {
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if (iov->iov_len > (size_t) max)
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return -ENOMEM;
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max -= iov->iov_len;
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}
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return 0;
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}
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static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
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void *src, size_t transferred, unsigned count,
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bool is_compat)
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{
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unsigned i;
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struct fuse_ioctl_iovec *fiov = src;
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if (fc->minor < 16) {
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return fuse_copy_ioctl_iovec_old(dst, src, transferred,
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count, is_compat);
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}
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if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
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return -EIO;
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for (i = 0; i < count; i++) {
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/* Did the server supply an inappropriate value? */
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if (fiov[i].base != (unsigned long) fiov[i].base ||
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fiov[i].len != (unsigned long) fiov[i].len)
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return -EIO;
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dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
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dst[i].iov_len = (size_t) fiov[i].len;
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#ifdef CONFIG_COMPAT
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if (is_compat &&
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(ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
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(compat_size_t) dst[i].iov_len != fiov[i].len))
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return -EIO;
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#endif
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}
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return 0;
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}
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/*
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* For ioctls, there is no generic way to determine how much memory
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* needs to be read and/or written. Furthermore, ioctls are allowed
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* to dereference the passed pointer, so the parameter requires deep
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* copying but FUSE has no idea whatsoever about what to copy in or
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* out.
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*
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* This is solved by allowing FUSE server to retry ioctl with
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* necessary in/out iovecs. Let's assume the ioctl implementation
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* needs to read in the following structure.
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*
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* struct a {
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* char *buf;
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* size_t buflen;
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* }
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*
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* On the first callout to FUSE server, inarg->in_size and
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* inarg->out_size will be NULL; then, the server completes the ioctl
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* with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
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* the actual iov array to
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*
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* { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) } }
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*
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* which tells FUSE to copy in the requested area and retry the ioctl.
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* On the second round, the server has access to the structure and
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* from that it can tell what to look for next, so on the invocation,
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* it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
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*
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* { { .iov_base = inarg.arg, .iov_len = sizeof(struct a) },
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* { .iov_base = a.buf, .iov_len = a.buflen } }
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*
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* FUSE will copy both struct a and the pointed buffer from the
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* process doing the ioctl and retry ioctl with both struct a and the
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* buffer.
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*
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* This time, FUSE server has everything it needs and completes ioctl
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* without FUSE_IOCTL_RETRY which finishes the ioctl call.
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*
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* Copying data out works the same way.
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*
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* Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
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* automatically initializes in and out iovs by decoding @cmd with
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* _IOC_* macros and the server is not allowed to request RETRY. This
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* limits ioctl data transfers to well-formed ioctls and is the forced
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* behavior for all FUSE servers.
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*/
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long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
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unsigned int flags)
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{
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struct fuse_file *ff = file->private_data;
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struct fuse_mount *fm = ff->fm;
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struct fuse_ioctl_in inarg = {
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.fh = ff->fh,
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.cmd = cmd,
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.arg = arg,
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.flags = flags
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};
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struct fuse_ioctl_out outarg;
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struct iovec *iov_page = NULL;
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struct iovec *in_iov = NULL, *out_iov = NULL;
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unsigned int in_iovs = 0, out_iovs = 0, max_pages;
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size_t in_size, out_size, c;
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ssize_t transferred;
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int err, i;
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struct iov_iter ii;
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struct fuse_args_pages ap = {};
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#if BITS_PER_LONG == 32
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inarg.flags |= FUSE_IOCTL_32BIT;
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#else
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if (flags & FUSE_IOCTL_COMPAT) {
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inarg.flags |= FUSE_IOCTL_32BIT;
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#ifdef CONFIG_X86_X32
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if (in_x32_syscall())
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inarg.flags |= FUSE_IOCTL_COMPAT_X32;
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#endif
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}
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#endif
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/* assume all the iovs returned by client always fits in a page */
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BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
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err = -ENOMEM;
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ap.pages = fuse_pages_alloc(fm->fc->max_pages, GFP_KERNEL, &ap.descs);
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iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
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if (!ap.pages || !iov_page)
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goto out;
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fuse_page_descs_length_init(ap.descs, 0, fm->fc->max_pages);
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/*
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* If restricted, initialize IO parameters as encoded in @cmd.
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* RETRY from server is not allowed.
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*/
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if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
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struct iovec *iov = iov_page;
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iov->iov_base = (void __user *)arg;
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iov->iov_len = _IOC_SIZE(cmd);
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if (_IOC_DIR(cmd) & _IOC_WRITE) {
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in_iov = iov;
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in_iovs = 1;
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}
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if (_IOC_DIR(cmd) & _IOC_READ) {
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out_iov = iov;
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out_iovs = 1;
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}
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}
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retry:
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inarg.in_size = in_size = iov_length(in_iov, in_iovs);
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inarg.out_size = out_size = iov_length(out_iov, out_iovs);
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/*
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* Out data can be used either for actual out data or iovs,
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* make sure there always is at least one page.
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*/
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out_size = max_t(size_t, out_size, PAGE_SIZE);
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max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
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/* make sure there are enough buffer pages and init request with them */
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err = -ENOMEM;
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if (max_pages > fm->fc->max_pages)
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goto out;
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while (ap.num_pages < max_pages) {
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ap.pages[ap.num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
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if (!ap.pages[ap.num_pages])
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goto out;
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ap.num_pages++;
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}
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/* okay, let's send it to the client */
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ap.args.opcode = FUSE_IOCTL;
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ap.args.nodeid = ff->nodeid;
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ap.args.in_numargs = 1;
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ap.args.in_args[0].size = sizeof(inarg);
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ap.args.in_args[0].value = &inarg;
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if (in_size) {
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ap.args.in_numargs++;
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ap.args.in_args[1].size = in_size;
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ap.args.in_pages = true;
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err = -EFAULT;
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iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
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for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
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c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
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if (c != PAGE_SIZE && iov_iter_count(&ii))
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goto out;
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}
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}
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ap.args.out_numargs = 2;
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ap.args.out_args[0].size = sizeof(outarg);
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ap.args.out_args[0].value = &outarg;
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ap.args.out_args[1].size = out_size;
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ap.args.out_pages = true;
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ap.args.out_argvar = true;
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transferred = fuse_simple_request(fm, &ap.args);
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err = transferred;
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if (transferred < 0)
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goto out;
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/* did it ask for retry? */
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if (outarg.flags & FUSE_IOCTL_RETRY) {
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void *vaddr;
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/* no retry if in restricted mode */
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err = -EIO;
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if (!(flags & FUSE_IOCTL_UNRESTRICTED))
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goto out;
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in_iovs = outarg.in_iovs;
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out_iovs = outarg.out_iovs;
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/*
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* Make sure things are in boundary, separate checks
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* are to protect against overflow.
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*/
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err = -ENOMEM;
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if (in_iovs > FUSE_IOCTL_MAX_IOV ||
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out_iovs > FUSE_IOCTL_MAX_IOV ||
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in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
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goto out;
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vaddr = kmap_atomic(ap.pages[0]);
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err = fuse_copy_ioctl_iovec(fm->fc, iov_page, vaddr,
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transferred, in_iovs + out_iovs,
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(flags & FUSE_IOCTL_COMPAT) != 0);
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kunmap_atomic(vaddr);
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if (err)
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goto out;
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in_iov = iov_page;
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out_iov = in_iov + in_iovs;
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err = fuse_verify_ioctl_iov(fm->fc, in_iov, in_iovs);
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if (err)
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goto out;
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err = fuse_verify_ioctl_iov(fm->fc, out_iov, out_iovs);
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if (err)
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goto out;
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goto retry;
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}
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err = -EIO;
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if (transferred > inarg.out_size)
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goto out;
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err = -EFAULT;
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iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
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for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
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c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
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if (c != PAGE_SIZE && iov_iter_count(&ii))
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goto out;
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}
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err = 0;
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out:
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free_page((unsigned long) iov_page);
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while (ap.num_pages)
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__free_page(ap.pages[--ap.num_pages]);
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kfree(ap.pages);
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return err ? err : outarg.result;
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}
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EXPORT_SYMBOL_GPL(fuse_do_ioctl);
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long fuse_ioctl_common(struct file *file, unsigned int cmd,
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unsigned long arg, unsigned int flags)
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{
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struct inode *inode = file_inode(file);
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struct fuse_conn *fc = get_fuse_conn(inode);
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if (!fuse_allow_current_process(fc))
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return -EACCES;
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if (fuse_is_bad(inode))
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return -EIO;
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return fuse_do_ioctl(file, cmd, arg, flags);
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}
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long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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return fuse_ioctl_common(file, cmd, arg, 0);
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}
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long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
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}
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static int fuse_priv_ioctl(struct inode *inode, struct fuse_file *ff,
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unsigned int cmd, void *ptr, size_t size)
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{
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struct fuse_mount *fm = ff->fm;
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struct fuse_ioctl_in inarg;
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struct fuse_ioctl_out outarg;
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FUSE_ARGS(args);
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int err;
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memset(&inarg, 0, sizeof(inarg));
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inarg.fh = ff->fh;
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inarg.cmd = cmd;
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#if BITS_PER_LONG == 32
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inarg.flags |= FUSE_IOCTL_32BIT;
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#endif
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if (S_ISDIR(inode->i_mode))
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inarg.flags |= FUSE_IOCTL_DIR;
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if (_IOC_DIR(cmd) & _IOC_READ)
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inarg.out_size = size;
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if (_IOC_DIR(cmd) & _IOC_WRITE)
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inarg.in_size = size;
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args.opcode = FUSE_IOCTL;
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args.nodeid = ff->nodeid;
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args.in_numargs = 2;
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args.in_args[0].size = sizeof(inarg);
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args.in_args[0].value = &inarg;
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args.in_args[1].size = inarg.in_size;
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args.in_args[1].value = ptr;
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args.out_numargs = 2;
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args.out_args[0].size = sizeof(outarg);
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args.out_args[0].value = &outarg;
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args.out_args[1].size = inarg.out_size;
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args.out_args[1].value = ptr;
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err = fuse_simple_request(fm, &args);
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if (!err && outarg.flags & FUSE_IOCTL_RETRY)
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err = -EIO;
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return err;
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}
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static struct fuse_file *fuse_priv_ioctl_prepare(struct inode *inode)
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{
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struct fuse_mount *fm = get_fuse_mount(inode);
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bool isdir = S_ISDIR(inode->i_mode);
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if (!S_ISREG(inode->i_mode) && !isdir)
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return ERR_PTR(-ENOTTY);
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return fuse_file_open(fm, get_node_id(inode), O_RDONLY, isdir);
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}
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static void fuse_priv_ioctl_cleanup(struct inode *inode, struct fuse_file *ff)
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{
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fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
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}
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int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
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{
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struct inode *inode = d_inode(dentry);
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struct fuse_file *ff;
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unsigned int flags;
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struct fsxattr xfa;
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int err;
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ff = fuse_priv_ioctl_prepare(inode);
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if (IS_ERR(ff))
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return PTR_ERR(ff);
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if (fa->flags_valid) {
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err = fuse_priv_ioctl(inode, ff, FS_IOC_GETFLAGS,
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&flags, sizeof(flags));
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if (err)
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goto cleanup;
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fileattr_fill_flags(fa, flags);
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} else {
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err = fuse_priv_ioctl(inode, ff, FS_IOC_FSGETXATTR,
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&xfa, sizeof(xfa));
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if (err)
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goto cleanup;
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fileattr_fill_xflags(fa, xfa.fsx_xflags);
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fa->fsx_extsize = xfa.fsx_extsize;
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fa->fsx_nextents = xfa.fsx_nextents;
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fa->fsx_projid = xfa.fsx_projid;
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fa->fsx_cowextsize = xfa.fsx_cowextsize;
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}
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cleanup:
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fuse_priv_ioctl_cleanup(inode, ff);
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return err;
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}
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int fuse_fileattr_set(struct user_namespace *mnt_userns,
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struct dentry *dentry, struct fileattr *fa)
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{
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struct inode *inode = d_inode(dentry);
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struct fuse_file *ff;
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unsigned int flags = fa->flags;
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struct fsxattr xfa;
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int err;
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ff = fuse_priv_ioctl_prepare(inode);
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if (IS_ERR(ff))
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return PTR_ERR(ff);
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if (fa->flags_valid) {
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err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
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&flags, sizeof(flags));
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if (err)
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goto cleanup;
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} else {
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memset(&xfa, 0, sizeof(xfa));
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xfa.fsx_xflags = fa->fsx_xflags;
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xfa.fsx_extsize = fa->fsx_extsize;
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xfa.fsx_nextents = fa->fsx_nextents;
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xfa.fsx_projid = fa->fsx_projid;
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xfa.fsx_cowextsize = fa->fsx_cowextsize;
|
|
|
|
err = fuse_priv_ioctl(inode, ff, FS_IOC_FSSETXATTR,
|
|
&xfa, sizeof(xfa));
|
|
}
|
|
|
|
cleanup:
|
|
fuse_priv_ioctl_cleanup(inode, ff);
|
|
|
|
return err;
|
|
}
|