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file.c
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/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
*/
#include "fuse_i.h"
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/sched.h>
static const struct file_operations fuse_direct_io_file_operations;
static int fuse_send_open(struct inode *inode, struct file *file, int isdir,
struct fuse_open_out *outargp)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_open_in inarg;
struct fuse_req *req;
int err;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
memset(&inarg, 0, sizeof(inarg));
inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
if (!fc->atomic_o_trunc)
inarg.flags &= ~O_TRUNC;
req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
req->out.numargs = 1;
req->out.args[0].size = sizeof(*outargp);
req->out.args[0].value = outargp;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
return err;
}
struct fuse_file *fuse_file_alloc(void)
{
struct fuse_file *ff;
ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
if (ff) {
ff->reserved_req = fuse_request_alloc();
if (!ff->reserved_req) {
kfree(ff);
ff = NULL;
} else {
INIT_LIST_HEAD(&ff->write_entry);
atomic_set(&ff->count, 0);
}
}
return ff;
}
void fuse_file_free(struct fuse_file *ff)
{
fuse_request_free(ff->reserved_req);
kfree(ff);
}
static struct fuse_file *fuse_file_get(struct fuse_file *ff)
{
atomic_inc(&ff->count);
return ff;
}
static void fuse_release_end(struct fuse_conn *fc, struct fuse_req *req)
{
dput(req->misc.release.dentry);
mntput(req->misc.release.vfsmount);
fuse_put_request(fc, req);
}
static void fuse_file_put(struct fuse_file *ff)
{
if (atomic_dec_and_test(&ff->count)) {
struct fuse_req *req = ff->reserved_req;
struct inode *inode = req->misc.release.dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
req->end = fuse_release_end;
request_send_background(fc, req);
kfree(ff);
}
}
void fuse_finish_open(struct inode *inode, struct file *file,
struct fuse_file *ff, struct fuse_open_out *outarg)
{
if (outarg->open_flags & FOPEN_DIRECT_IO)
file->f_op = &fuse_direct_io_file_operations;
if (!(outarg->open_flags & FOPEN_KEEP_CACHE))
invalidate_inode_pages2(inode->i_mapping);
if (outarg->open_flags & FOPEN_NONSEEKABLE)
nonseekable_open(inode, file);
ff->fh = outarg->fh;
file->private_data = fuse_file_get(ff);
}
int fuse_open_common(struct inode *inode, struct file *file, int isdir)
{
struct fuse_open_out outarg;
struct fuse_file *ff;
int err;
/* VFS checks this, but only _after_ ->open() */
if (file->f_flags & O_DIRECT)
return -EINVAL;
err = generic_file_open(inode, file);
if (err)
return err;
ff = fuse_file_alloc();
if (!ff)
return -ENOMEM;
err = fuse_send_open(inode, file, isdir, &outarg);
if (err)
fuse_file_free(ff);
else {
if (isdir)
outarg.open_flags &= ~FOPEN_DIRECT_IO;
fuse_finish_open(inode, file, ff, &outarg);
}
return err;
}
void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode)
{
struct fuse_req *req = ff->reserved_req;
struct fuse_release_in *inarg = &req->misc.release.in;
inarg->fh = ff->fh;
inarg->flags = flags;
req->in.h.opcode = opcode;
req->in.h.nodeid = nodeid;
req->in.numargs = 1;
req->in.args[0].size = sizeof(struct fuse_release_in);
req->in.args[0].value = inarg;
}
int fuse_release_common(struct inode *inode, struct file *file, int isdir)
{
struct fuse_file *ff = file->private_data;
if (ff) {
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_req *req = ff->reserved_req;
fuse_release_fill(ff, get_node_id(inode), file->f_flags,
isdir ? FUSE_RELEASEDIR : FUSE_RELEASE);
/* Hold vfsmount and dentry until release is finished */
req->misc.release.vfsmount = mntget(file->f_path.mnt);
req->misc.release.dentry = dget(file->f_path.dentry);
spin_lock(&fc->lock);
list_del(&ff->write_entry);
spin_unlock(&fc->lock);
/*
* Normally this will send the RELEASE request,
* however if some asynchronous READ or WRITE requests
* are outstanding, the sending will be delayed
*/
fuse_file_put(ff);
}
/* Return value is ignored by VFS */
return 0;
}
static int fuse_open(struct inode *inode, struct file *file)
{
return fuse_open_common(inode, file, 0);
}
static int fuse_release(struct inode *inode, struct file *file)
{
return fuse_release_common(inode, file, 0);
}
/*
* Scramble the ID space with XTEA, so that the value of the files_struct
* pointer is not exposed to userspace.
*/
u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
{
u32 *k = fc->scramble_key;
u64 v = (unsigned long) id;
u32 v0 = v;
u32 v1 = v >> 32;
u32 sum = 0;
int i;
for (i = 0; i < 32; i++) {
v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
sum += 0x9E3779B9;
v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
}
return (u64) v0 + ((u64) v1 << 32);
}
/*
* Check if page is under writeback
*
* This is currently done by walking the list of writepage requests
* for the inode, which can be pretty inefficient.
*/
static bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
struct fuse_req *req;
bool found = false;
spin_lock(&fc->lock);
list_for_each_entry(req, &fi->writepages, writepages_entry) {
pgoff_t curr_index;
BUG_ON(req->inode != inode);
curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT;
if (curr_index == index) {
found = true;
break;
}
}
spin_unlock(&fc->lock);
return found;
}
/*
* Wait for page writeback to be completed.
*
* Since fuse doesn't rely on the VM writeback tracking, this has to
* use some other means.
*/
static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
{
struct fuse_inode *fi = get_fuse_inode(inode);
wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
return 0;
}
static int fuse_flush(struct file *file, fl_owner_t id)
{
struct inode *inode = file->f_path.dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_req *req;
struct fuse_flush_in inarg;
int err;
if (is_bad_inode(inode))
return -EIO;
if (fc->no_flush)
return 0;
req = fuse_get_req_nofail(fc, file);
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
inarg.lock_owner = fuse_lock_owner_id(fc, id);
req->in.h.opcode = FUSE_FLUSH;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
req->force = 1;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
if (err == -ENOSYS) {
fc->no_flush = 1;
err = 0;
}
return err;
}
/*
* Wait for all pending writepages on the inode to finish.
*
* This is currently done by blocking further writes with FUSE_NOWRITE
* and waiting for all sent writes to complete.
*
* This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
* could conflict with truncation.
*/
static void fuse_sync_writes(struct inode *inode)
{
fuse_set_nowrite(inode);
fuse_release_nowrite(inode);
}
int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
int isdir)
{
struct inode *inode = de->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_file *ff = file->private_data;
struct fuse_req *req;
struct fuse_fsync_in inarg;
int err;
if (is_bad_inode(inode))
return -EIO;
if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
return 0;
/*
* Start writeback against all dirty pages of the inode, then
* wait for all outstanding writes, before sending the FSYNC
* request.
*/
err = write_inode_now(inode, 0);
if (err)
return err;
fuse_sync_writes(inode);
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
memset(&inarg, 0, sizeof(inarg));
inarg.fh = ff->fh;
inarg.fsync_flags = datasync ? 1 : 0;
req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(inarg);
req->in.args[0].value = &inarg;
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
if (err == -ENOSYS) {
if (isdir)
fc->no_fsyncdir = 1;
else
fc->no_fsync = 1;
err = 0;
}
return err;
}
static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
{
return fuse_fsync_common(file, de, datasync, 0);
}
void fuse_read_fill(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count, int opcode)
{
struct fuse_read_in *inarg = &req->misc.read.in;
struct fuse_file *ff = file->private_data;
inarg->fh = ff->fh;
inarg->offset = pos;
inarg->size = count;
inarg->flags = file->f_flags;
req->in.h.opcode = opcode;
req->in.h.nodeid = get_node_id(inode);
req->in.numargs = 1;
req->in.args[0].size = sizeof(struct fuse_read_in);
req->in.args[0].value = inarg;
req->out.argpages = 1;
req->out.argvar = 1;
req->out.numargs = 1;
req->out.args[0].size = count;
}
static size_t fuse_send_read(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count,
fl_owner_t owner)
{
struct fuse_conn *fc = get_fuse_conn(inode);
fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
if (owner != NULL) {
struct fuse_read_in *inarg = &req->misc.read.in;
inarg->read_flags |= FUSE_READ_LOCKOWNER;
inarg->lock_owner = fuse_lock_owner_id(fc, owner);
}
request_send(fc, req);
return req->out.args[0].size;
}
static void fuse_read_update_size(struct inode *inode, loff_t size,
u64 attr_ver)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
spin_lock(&fc->lock);
if (attr_ver == fi->attr_version && size < inode->i_size) {
fi->attr_version = ++fc->attr_version;
i_size_write(inode, size);
}
spin_unlock(&fc->lock);
}
static int fuse_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_req *req;
size_t num_read;
loff_t pos = page_offset(page);
size_t count = PAGE_CACHE_SIZE;
u64 attr_ver;
int err;
err = -EIO;
if (is_bad_inode(inode))
goto out;
/*
* Page writeback can extend beyond the liftime of the
* page-cache page, so make sure we read a properly synced
* page.
*/
fuse_wait_on_page_writeback(inode, page->index);
req = fuse_get_req(fc);
err = PTR_ERR(req);
if (IS_ERR(req))
goto out;
attr_ver = fuse_get_attr_version(fc);
req->out.page_zeroing = 1;
req->num_pages = 1;
req->pages[0] = page;
num_read = fuse_send_read(req, file, inode, pos, count, NULL);
err = req->out.h.error;
fuse_put_request(fc, req);
if (!err) {
/*
* Short read means EOF. If file size is larger, truncate it
*/
if (num_read < count)
fuse_read_update_size(inode, pos + num_read, attr_ver);
SetPageUptodate(page);
}
fuse_invalidate_attr(inode); /* atime changed */
out:
unlock_page(page);
return err;
}
static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
{
int i;
size_t count = req->misc.read.in.size;
size_t num_read = req->out.args[0].size;
struct inode *inode = req->pages[0]->mapping->host;
/*
* Short read means EOF. If file size is larger, truncate it
*/
if (!req->out.h.error && num_read < count) {
loff_t pos = page_offset(req->pages[0]) + num_read;
fuse_read_update_size(inode, pos, req->misc.read.attr_ver);
}
fuse_invalidate_attr(inode); /* atime changed */
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (!req->out.h.error)
SetPageUptodate(page);
else
SetPageError(page);
unlock_page(page);
}
if (req->ff)
fuse_file_put(req->ff);
fuse_put_request(fc, req);
}
static void fuse_send_readpages(struct fuse_req *req, struct file *file,
struct inode *inode)
{
struct fuse_conn *fc = get_fuse_conn(inode);
loff_t pos = page_offset(req->pages[0]);
size_t count = req->num_pages << PAGE_CACHE_SHIFT;
req->out.page_zeroing = 1;
fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
req->misc.read.attr_ver = fuse_get_attr_version(fc);
if (fc->async_read) {
struct fuse_file *ff = file->private_data;
req->ff = fuse_file_get(ff);
req->end = fuse_readpages_end;
request_send_background(fc, req);
} else {
request_send(fc, req);
fuse_readpages_end(fc, req);
}
}
struct fuse_fill_data {
struct fuse_req *req;
struct file *file;
struct inode *inode;
};
static int fuse_readpages_fill(void *_data, struct page *page)
{
struct fuse_fill_data *data = _data;
struct fuse_req *req = data->req;
struct inode *inode = data->inode;
struct fuse_conn *fc = get_fuse_conn(inode);
fuse_wait_on_page_writeback(inode, page->index);
if (req->num_pages &&
(req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
(req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
req->pages[req->num_pages - 1]->index + 1 != page->index)) {
fuse_send_readpages(req, data->file, inode);
data->req = req = fuse_get_req(fc);
if (IS_ERR(req)) {
unlock_page(page);
return PTR_ERR(req);
}
}
req->pages[req->num_pages] = page;
req->num_pages++;
return 0;
}
static int fuse_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
struct inode *inode = mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_fill_data data;
int err;
err = -EIO;
if (is_bad_inode(inode))
goto out;
data.file = file;
data.inode = inode;
data.req = fuse_get_req(fc);
err = PTR_ERR(data.req);
if (IS_ERR(data.req))
goto out;
err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
if (!err) {
if (data.req->num_pages)
fuse_send_readpages(data.req, file, inode);
else
fuse_put_request(fc, data.req);
}
out:
return err;
}
static ssize_t fuse_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct inode *inode = iocb->ki_filp->f_mapping->host;
if (pos + iov_length(iov, nr_segs) > i_size_read(inode)) {
int err;
/*
* If trying to read past EOF, make sure the i_size
* attribute is up-to-date.
*/
err = fuse_update_attributes(inode, NULL, iocb->ki_filp, NULL);
if (err)
return err;
}
return generic_file_aio_read(iocb, iov, nr_segs, pos);
}
static void fuse_write_fill(struct fuse_req *req, struct file *file,
struct fuse_file *ff, struct inode *inode,
loff_t pos, size_t count, int writepage)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_write_in *inarg = &req->misc.write.in;
struct fuse_write_out *outarg = &req->misc.write.out;
memset(inarg, 0, sizeof(struct fuse_write_in));
inarg->fh = ff->fh;
inarg->offset = pos;
inarg->size = count;
inarg->write_flags = writepage ? FUSE_WRITE_CACHE : 0;
inarg->flags = file ? file->f_flags : 0;
req->in.h.opcode = FUSE_WRITE;
req->in.h.nodeid = get_node_id(inode);
req->in.argpages = 1;
req->in.numargs = 2;
if (fc->minor < 9)
req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
else
req->in.args[0].size = sizeof(struct fuse_write_in);
req->in.args[0].value = inarg;
req->in.args[1].size = count;
req->out.numargs = 1;
req->out.args[0].size = sizeof(struct fuse_write_out);
req->out.args[0].value = outarg;
}
static size_t fuse_send_write(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos, size_t count,
fl_owner_t owner)
{
struct fuse_conn *fc = get_fuse_conn(inode);
fuse_write_fill(req, file, file->private_data, inode, pos, count, 0);
if (owner != NULL) {
struct fuse_write_in *inarg = &req->misc.write.in;
inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
inarg->lock_owner = fuse_lock_owner_id(fc, owner);
}
request_send(fc, req);
return req->misc.write.out.size;
}
static int fuse_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
*pagep = __grab_cache_page(mapping, index);
if (!*pagep)
return -ENOMEM;
return 0;
}
static void fuse_write_update_size(struct inode *inode, loff_t pos)
{
struct fuse_conn *fc = get_fuse_conn(inode);
struct fuse_inode *fi = get_fuse_inode(inode);
spin_lock(&fc->lock);
fi->attr_version = ++fc->attr_version;
if (pos > inode->i_size)
i_size_write(inode, pos);
spin_unlock(&fc->lock);
}
static int fuse_buffered_write(struct file *file, struct inode *inode,
loff_t pos, unsigned count, struct page *page)
{
int err;
size_t nres;
struct fuse_conn *fc = get_fuse_conn(inode);
unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
struct fuse_req *req;
if (is_bad_inode(inode))
return -EIO;
/*
* Make sure writepages on the same page are not mixed up with
* plain writes.
*/
fuse_wait_on_page_writeback(inode, page->index);
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
req->num_pages = 1;
req->pages[0] = page;
req->page_offset = offset;
nres = fuse_send_write(req, file, inode, pos, count, NULL);
err = req->out.h.error;
fuse_put_request(fc, req);
if (!err && !nres)
err = -EIO;
if (!err) {
pos += nres;
fuse_write_update_size(inode, pos);
if (count == PAGE_CACHE_SIZE)
SetPageUptodate(page);
}
fuse_invalidate_attr(inode);
return err ? err : nres;
}
static int fuse_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
struct inode *inode = mapping->host;
int res = 0;
if (copied)
res = fuse_buffered_write(file, inode, pos, copied, page);
unlock_page(page);
page_cache_release(page);
return res;
}
static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
struct inode *inode, loff_t pos,
size_t count)
{
size_t res;
unsigned offset;
unsigned i;
for (i = 0; i < req->num_pages; i++)
fuse_wait_on_page_writeback(inode, req->pages[i]->index);
res = fuse_send_write(req, file, inode, pos, count, NULL);
offset = req->page_offset;
count = res;
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (!req->out.h.error && !offset && count >= PAGE_CACHE_SIZE)
SetPageUptodate(page);
if (count > PAGE_CACHE_SIZE - offset)
count -= PAGE_CACHE_SIZE - offset;
else
count = 0;
offset = 0;
unlock_page(page);
page_cache_release(page);
}
return res;
}
static ssize_t fuse_fill_write_pages(struct fuse_req *req,
struct address_space *mapping,
struct iov_iter *ii, loff_t pos)
{
struct fuse_conn *fc = get_fuse_conn(mapping->host);
unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
size_t count = 0;
int err;
req->page_offset = offset;
do {
size_t tmp;
struct page *page;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
size_t bytes = min_t(size_t, PAGE_CACHE_SIZE - offset,
iov_iter_count(ii));
bytes = min_t(size_t, bytes, fc->max_write - count);
again:
err = -EFAULT;
if (iov_iter_fault_in_readable(ii, bytes))
break;
err = -ENOMEM;
page = __grab_cache_page(mapping, index);
if (!page)
break;
pagefault_disable();
tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
pagefault_enable();
flush_dcache_page(page);
if (!tmp) {
unlock_page(page);
page_cache_release(page);
bytes = min(bytes, iov_iter_single_seg_count(ii));
goto again;
}
err = 0;
req->pages[req->num_pages] = page;
req->num_pages++;
iov_iter_advance(ii, tmp);
count += tmp;
pos += tmp;
offset += tmp;
if (offset == PAGE_CACHE_SIZE)
offset = 0;
if (!fc->big_writes)
break;
} while (iov_iter_count(ii) && count < fc->max_write &&
req->num_pages < FUSE_MAX_PAGES_PER_REQ && offset == 0);
return count > 0 ? count : err;
}
static ssize_t fuse_perform_write(struct file *file,
struct address_space *mapping,
struct iov_iter *ii, loff_t pos)
{
struct inode *inode = mapping->host;
struct fuse_conn *fc = get_fuse_conn(inode);
int err = 0;
ssize_t res = 0;
if (is_bad_inode(inode))
return -EIO;
do {
struct fuse_req *req;
ssize_t count;
req = fuse_get_req(fc);
if (IS_ERR(req)) {
err = PTR_ERR(req);
break;
}
count = fuse_fill_write_pages(req, mapping, ii, pos);
if (count <= 0) {
err = count;
} else {
size_t num_written;
num_written = fuse_send_write_pages(req, file, inode,
pos, count);
err = req->out.h.error;
if (!err) {
res += num_written;
pos += num_written;
/* break out of the loop on short write */
if (num_written != count)
err = -EIO;
}
}
fuse_put_request(fc, req);
} while (!err && iov_iter_count(ii));
if (res > 0)
fuse_write_update_size(inode, pos);
fuse_invalidate_attr(inode);
return res > 0 ? res : err;
}
static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
size_t count = 0;
ssize_t written = 0;
struct inode *inode = mapping->host;
ssize_t err;
struct iov_iter i;
WARN_ON(iocb->ki_pos != pos);
err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
if (err)
return err;
mutex_lock(&inode->i_mutex);
vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
/* We can write back this queue in page reclaim */
current->backing_dev_info = mapping->backing_dev_info;
err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
if (err)
goto out;
if (count == 0)
goto out;
err = file_remove_suid(file);
if (err)
goto out;
file_update_time(file);
iov_iter_init(&i, iov, nr_segs, count, 0);
written = fuse_perform_write(file, mapping, &i, pos);
if (written >= 0)
iocb->ki_pos = pos + written;
out:
current->backing_dev_info = NULL;
mutex_unlock(&inode->i_mutex);
return written ? written : err;
}
static void fuse_release_user_pages(struct fuse_req *req, int write)
{
unsigned i;
for (i = 0; i < req->num_pages; i++) {
struct page *page = req->pages[i];
if (write)
set_page_dirty_lock(page);
put_page(page);
}
}
static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
unsigned nbytes, int write)
{
unsigned long user_addr = (unsigned long) buf;
unsigned offset = user_addr & ~PAGE_MASK;
int npages;
/* This doesn't work with nfsd */
if (!current->mm)
return -EPERM;
nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
npages = clamp(npages, 1, FUSE_MAX_PAGES_PER_REQ);
down_read(¤t->mm->mmap_sem);
npages = get_user_pages(current, current->mm, user_addr, npages, write,
0, req->pages, NULL);
up_read(¤t->mm->mmap_sem);
if (npages < 0)
return npages;
req->num_pages = npages;
req->page_offset = offset;
return 0;
}
static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
size_t count, loff_t *ppos, int write)
{
struct inode *inode = file->f_path.dentry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
size_t nmax = write ? fc->max_write : fc->max_read;
loff_t pos = *ppos;
ssize_t res = 0;
struct fuse_req *req;
if (is_bad_inode(inode))
return -EIO;
req = fuse_get_req(fc);
if (IS_ERR(req))
return PTR_ERR(req);
while (count) {
size_t nres;
size_t nbytes_limit = min(count, nmax);
size_t nbytes;
int err = fuse_get_user_pages(req, buf, nbytes_limit, !write);
if (err) {
res = err;
break;
}
nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
nbytes = min(nbytes_limit, nbytes);
if (write)
nres = fuse_send_write(req, file, inode, pos, nbytes,
current->files);
else
nres = fuse_send_read(req, file, inode, pos, nbytes,
current->files);
fuse_release_user_pages(req, !write);
if (req->out.h.error) {
if (!res)
res = req->out.h.error;
break;
} else if (nres > nbytes) {
res = -EIO;
break;
}
count -= nres;
res += nres;
pos += nres;
buf += nres;