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dev.c
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dev.c
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/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2008 Miklos Szeredi <[email protected]>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
*/
#include "fuse_i.h"
#include <linux/init.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/sched/signal.h>
#include <linux/uio.h>
#include <linux/miscdevice.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/pipe_fs_i.h>
#include <linux/swap.h>
#include <linux/splice.h>
#include <linux/sched.h>
MODULE_ALIAS_MISCDEV(FUSE_MINOR);
MODULE_ALIAS("devname:fuse");
/* Ordinary requests have even IDs, while interrupts IDs are odd */
#define FUSE_INT_REQ_BIT (1ULL << 0)
#define FUSE_REQ_ID_STEP (1ULL << 1)
static struct kmem_cache *fuse_req_cachep;
static struct fuse_dev *fuse_get_dev(struct file *file)
{
/*
* Lockless access is OK, because file->private data is set
* once during mount and is valid until the file is released.
*/
return READ_ONCE(file->private_data);
}
static void fuse_request_init(struct fuse_req *req)
{
INIT_LIST_HEAD(&req->list);
INIT_LIST_HEAD(&req->intr_entry);
init_waitqueue_head(&req->waitq);
refcount_set(&req->count, 1);
__set_bit(FR_PENDING, &req->flags);
}
static struct fuse_req *fuse_request_alloc(gfp_t flags)
{
struct fuse_req *req = kmem_cache_zalloc(fuse_req_cachep, flags);
if (req)
fuse_request_init(req);
return req;
}
static void fuse_request_free(struct fuse_req *req)
{
kmem_cache_free(fuse_req_cachep, req);
}
static void __fuse_get_request(struct fuse_req *req)
{
refcount_inc(&req->count);
}
/* Must be called with > 1 refcount */
static void __fuse_put_request(struct fuse_req *req)
{
refcount_dec(&req->count);
}
void fuse_set_initialized(struct fuse_conn *fc)
{
/* Make sure stores before this are seen on another CPU */
smp_wmb();
fc->initialized = 1;
}
static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
{
return !fc->initialized || (for_background && fc->blocked);
}
static void fuse_drop_waiting(struct fuse_conn *fc)
{
/*
* lockess check of fc->connected is okay, because atomic_dec_and_test()
* provides a memory barrier mached with the one in fuse_wait_aborted()
* to ensure no wake-up is missed.
*/
if (atomic_dec_and_test(&fc->num_waiting) &&
!READ_ONCE(fc->connected)) {
/* wake up aborters */
wake_up_all(&fc->blocked_waitq);
}
}
static void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
static struct fuse_req *fuse_get_req(struct fuse_conn *fc, bool for_background)
{
struct fuse_req *req;
int err;
atomic_inc(&fc->num_waiting);
if (fuse_block_alloc(fc, for_background)) {
err = -EINTR;
if (wait_event_killable_exclusive(fc->blocked_waitq,
!fuse_block_alloc(fc, for_background)))
goto out;
}
/* Matches smp_wmb() in fuse_set_initialized() */
smp_rmb();
err = -ENOTCONN;
if (!fc->connected)
goto out;
err = -ECONNREFUSED;
if (fc->conn_error)
goto out;
req = fuse_request_alloc(GFP_KERNEL);
err = -ENOMEM;
if (!req) {
if (for_background)
wake_up(&fc->blocked_waitq);
goto out;
}
req->in.h.uid = from_kuid(fc->user_ns, current_fsuid());
req->in.h.gid = from_kgid(fc->user_ns, current_fsgid());
req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
__set_bit(FR_WAITING, &req->flags);
if (for_background)
__set_bit(FR_BACKGROUND, &req->flags);
if (unlikely(req->in.h.uid == ((uid_t)-1) ||
req->in.h.gid == ((gid_t)-1))) {
fuse_put_request(fc, req);
return ERR_PTR(-EOVERFLOW);
}
return req;
out:
fuse_drop_waiting(fc);
return ERR_PTR(err);
}
static void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
{
if (refcount_dec_and_test(&req->count)) {
if (test_bit(FR_BACKGROUND, &req->flags)) {
/*
* We get here in the unlikely case that a background
* request was allocated but not sent
*/
spin_lock(&fc->bg_lock);
if (!fc->blocked)
wake_up(&fc->blocked_waitq);
spin_unlock(&fc->bg_lock);
}
if (test_bit(FR_WAITING, &req->flags)) {
__clear_bit(FR_WAITING, &req->flags);
fuse_drop_waiting(fc);
}
fuse_request_free(req);
}
}
unsigned int fuse_len_args(unsigned int numargs, struct fuse_arg *args)
{
unsigned nbytes = 0;
unsigned i;
for (i = 0; i < numargs; i++)
nbytes += args[i].size;
return nbytes;
}
EXPORT_SYMBOL_GPL(fuse_len_args);
u64 fuse_get_unique(struct fuse_iqueue *fiq)
{
fiq->reqctr += FUSE_REQ_ID_STEP;
return fiq->reqctr;
}
EXPORT_SYMBOL_GPL(fuse_get_unique);
static unsigned int fuse_req_hash(u64 unique)
{
return hash_long(unique & ~FUSE_INT_REQ_BIT, FUSE_PQ_HASH_BITS);
}
/**
* A new request is available, wake fiq->waitq
*/
static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq)
__releases(fiq->lock)
{
wake_up(&fiq->waitq);
kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
spin_unlock(&fiq->lock);
}
const struct fuse_iqueue_ops fuse_dev_fiq_ops = {
.wake_forget_and_unlock = fuse_dev_wake_and_unlock,
.wake_interrupt_and_unlock = fuse_dev_wake_and_unlock,
.wake_pending_and_unlock = fuse_dev_wake_and_unlock,
};
EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops);
static void queue_request_and_unlock(struct fuse_iqueue *fiq,
struct fuse_req *req)
__releases(fiq->lock)
{
req->in.h.len = sizeof(struct fuse_in_header) +
fuse_len_args(req->args->in_numargs,
(struct fuse_arg *) req->args->in_args);
list_add_tail(&req->list, &fiq->pending);
fiq->ops->wake_pending_and_unlock(fiq);
}
void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
u64 nodeid, u64 nlookup)
{
struct fuse_iqueue *fiq = &fc->iq;
forget->forget_one.nodeid = nodeid;
forget->forget_one.nlookup = nlookup;
spin_lock(&fiq->lock);
if (fiq->connected) {
fiq->forget_list_tail->next = forget;
fiq->forget_list_tail = forget;
fiq->ops->wake_forget_and_unlock(fiq);
} else {
kfree(forget);
spin_unlock(&fiq->lock);
}
}
static void flush_bg_queue(struct fuse_conn *fc)
{
struct fuse_iqueue *fiq = &fc->iq;
while (fc->active_background < fc->max_background &&
!list_empty(&fc->bg_queue)) {
struct fuse_req *req;
req = list_first_entry(&fc->bg_queue, struct fuse_req, list);
list_del(&req->list);
fc->active_background++;
spin_lock(&fiq->lock);
req->in.h.unique = fuse_get_unique(fiq);
queue_request_and_unlock(fiq, req);
}
}
/*
* This function is called when a request is finished. Either a reply
* has arrived or it was aborted (and not yet sent) or some error
* occurred during communication with userspace, or the device file
* was closed. The requester thread is woken up (if still waiting),
* the 'end' callback is called if given, else the reference to the
* request is released
*/
void fuse_request_end(struct fuse_conn *fc, struct fuse_req *req)
{
struct fuse_iqueue *fiq = &fc->iq;
if (test_and_set_bit(FR_FINISHED, &req->flags))
goto put_request;
/*
* test_and_set_bit() implies smp_mb() between bit
* changing and below intr_entry check. Pairs with
* smp_mb() from queue_interrupt().
*/
if (!list_empty(&req->intr_entry)) {
spin_lock(&fiq->lock);
list_del_init(&req->intr_entry);
spin_unlock(&fiq->lock);
}
WARN_ON(test_bit(FR_PENDING, &req->flags));
WARN_ON(test_bit(FR_SENT, &req->flags));
if (test_bit(FR_BACKGROUND, &req->flags)) {
spin_lock(&fc->bg_lock);
clear_bit(FR_BACKGROUND, &req->flags);
if (fc->num_background == fc->max_background) {
fc->blocked = 0;
wake_up(&fc->blocked_waitq);
} else if (!fc->blocked) {
/*
* Wake up next waiter, if any. It's okay to use
* waitqueue_active(), as we've already synced up
* fc->blocked with waiters with the wake_up() call
* above.
*/
if (waitqueue_active(&fc->blocked_waitq))
wake_up(&fc->blocked_waitq);
}
if (fc->num_background == fc->congestion_threshold && fc->sb) {
clear_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
clear_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
}
fc->num_background--;
fc->active_background--;
flush_bg_queue(fc);
spin_unlock(&fc->bg_lock);
} else {
/* Wake up waiter sleeping in request_wait_answer() */
wake_up(&req->waitq);
}
if (test_bit(FR_ASYNC, &req->flags))
req->args->end(fc, req->args, req->out.h.error);
put_request:
fuse_put_request(fc, req);
}
EXPORT_SYMBOL_GPL(fuse_request_end);
static int queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
{
spin_lock(&fiq->lock);
/* Check for we've sent request to interrupt this req */
if (unlikely(!test_bit(FR_INTERRUPTED, &req->flags))) {
spin_unlock(&fiq->lock);
return -EINVAL;
}
if (list_empty(&req->intr_entry)) {
list_add_tail(&req->intr_entry, &fiq->interrupts);
/*
* Pairs with smp_mb() implied by test_and_set_bit()
* from request_end().
*/
smp_mb();
if (test_bit(FR_FINISHED, &req->flags)) {
list_del_init(&req->intr_entry);
spin_unlock(&fiq->lock);
return 0;
}
fiq->ops->wake_interrupt_and_unlock(fiq);
} else {
spin_unlock(&fiq->lock);
}
return 0;
}
static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
{
struct fuse_iqueue *fiq = &fc->iq;
int err;
if (!fc->no_interrupt) {
/* Any signal may interrupt this */
err = wait_event_interruptible(req->waitq,
test_bit(FR_FINISHED, &req->flags));
if (!err)
return;
set_bit(FR_INTERRUPTED, &req->flags);
/* matches barrier in fuse_dev_do_read() */
smp_mb__after_atomic();
if (test_bit(FR_SENT, &req->flags))
queue_interrupt(fiq, req);
}
if (!test_bit(FR_FORCE, &req->flags)) {
/* Only fatal signals may interrupt this */
err = wait_event_killable(req->waitq,
test_bit(FR_FINISHED, &req->flags));
if (!err)
return;
spin_lock(&fiq->lock);
/* Request is not yet in userspace, bail out */
if (test_bit(FR_PENDING, &req->flags)) {
list_del(&req->list);
spin_unlock(&fiq->lock);
__fuse_put_request(req);
req->out.h.error = -EINTR;
return;
}
spin_unlock(&fiq->lock);
}
/*
* Either request is already in userspace, or it was forced.
* Wait it out.
*/
wait_event(req->waitq, test_bit(FR_FINISHED, &req->flags));
}
static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
{
struct fuse_iqueue *fiq = &fc->iq;
BUG_ON(test_bit(FR_BACKGROUND, &req->flags));
spin_lock(&fiq->lock);
if (!fiq->connected) {
spin_unlock(&fiq->lock);
req->out.h.error = -ENOTCONN;
} else {
req->in.h.unique = fuse_get_unique(fiq);
/* acquire extra reference, since request is still needed
after fuse_request_end() */
__fuse_get_request(req);
queue_request_and_unlock(fiq, req);
request_wait_answer(fc, req);
/* Pairs with smp_wmb() in fuse_request_end() */
smp_rmb();
}
}
static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args)
{
if (fc->minor < 4 && args->opcode == FUSE_STATFS)
args->out_args[0].size = FUSE_COMPAT_STATFS_SIZE;
if (fc->minor < 9) {
switch (args->opcode) {
case FUSE_LOOKUP:
case FUSE_CREATE:
case FUSE_MKNOD:
case FUSE_MKDIR:
case FUSE_SYMLINK:
case FUSE_LINK:
args->out_args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
break;
case FUSE_GETATTR:
case FUSE_SETATTR:
args->out_args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
break;
}
}
if (fc->minor < 12) {
switch (args->opcode) {
case FUSE_CREATE:
args->in_args[0].size = sizeof(struct fuse_open_in);
break;
case FUSE_MKNOD:
args->in_args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE;
break;
}
}
}
static void fuse_force_creds(struct fuse_conn *fc, struct fuse_req *req)
{
req->in.h.uid = from_kuid_munged(fc->user_ns, current_fsuid());
req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid());
req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
}
static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args)
{
req->in.h.opcode = args->opcode;
req->in.h.nodeid = args->nodeid;
req->args = args;
if (args->end)
__set_bit(FR_ASYNC, &req->flags);
}
ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args)
{
struct fuse_req *req;
ssize_t ret;
if (args->force) {
atomic_inc(&fc->num_waiting);
req = fuse_request_alloc(GFP_KERNEL | __GFP_NOFAIL);
if (!args->nocreds)
fuse_force_creds(fc, req);
__set_bit(FR_WAITING, &req->flags);
__set_bit(FR_FORCE, &req->flags);
} else {
WARN_ON(args->nocreds);
req = fuse_get_req(fc, false);
if (IS_ERR(req))
return PTR_ERR(req);
}
/* Needs to be done after fuse_get_req() so that fc->minor is valid */
fuse_adjust_compat(fc, args);
fuse_args_to_req(req, args);
if (!args->noreply)
__set_bit(FR_ISREPLY, &req->flags);
__fuse_request_send(fc, req);
ret = req->out.h.error;
if (!ret && args->out_argvar) {
BUG_ON(args->out_numargs == 0);
ret = args->out_args[args->out_numargs - 1].size;
}
fuse_put_request(fc, req);
return ret;
}
static bool fuse_request_queue_background(struct fuse_conn *fc,
struct fuse_req *req)
{
bool queued = false;
WARN_ON(!test_bit(FR_BACKGROUND, &req->flags));
if (!test_bit(FR_WAITING, &req->flags)) {
__set_bit(FR_WAITING, &req->flags);
atomic_inc(&fc->num_waiting);
}
__set_bit(FR_ISREPLY, &req->flags);
spin_lock(&fc->bg_lock);
if (likely(fc->connected)) {
fc->num_background++;
if (fc->num_background == fc->max_background)
fc->blocked = 1;
if (fc->num_background == fc->congestion_threshold && fc->sb) {
set_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
}
list_add_tail(&req->list, &fc->bg_queue);
flush_bg_queue(fc);
queued = true;
}
spin_unlock(&fc->bg_lock);
return queued;
}
int fuse_simple_background(struct fuse_conn *fc, struct fuse_args *args,
gfp_t gfp_flags)
{
struct fuse_req *req;
if (args->force) {
WARN_ON(!args->nocreds);
req = fuse_request_alloc(gfp_flags);
if (!req)
return -ENOMEM;
__set_bit(FR_BACKGROUND, &req->flags);
} else {
WARN_ON(args->nocreds);
req = fuse_get_req(fc, true);
if (IS_ERR(req))
return PTR_ERR(req);
}
fuse_args_to_req(req, args);
if (!fuse_request_queue_background(fc, req)) {
fuse_put_request(fc, req);
return -ENOTCONN;
}
return 0;
}
EXPORT_SYMBOL_GPL(fuse_simple_background);
static int fuse_simple_notify_reply(struct fuse_conn *fc,
struct fuse_args *args, u64 unique)
{
struct fuse_req *req;
struct fuse_iqueue *fiq = &fc->iq;
int err = 0;
req = fuse_get_req(fc, false);
if (IS_ERR(req))
return PTR_ERR(req);
__clear_bit(FR_ISREPLY, &req->flags);
req->in.h.unique = unique;
fuse_args_to_req(req, args);
spin_lock(&fiq->lock);
if (fiq->connected) {
queue_request_and_unlock(fiq, req);
} else {
err = -ENODEV;
spin_unlock(&fiq->lock);
fuse_put_request(fc, req);
}
return err;
}
/*
* Lock the request. Up to the next unlock_request() there mustn't be
* anything that could cause a page-fault. If the request was already
* aborted bail out.
*/
static int lock_request(struct fuse_req *req)
{
int err = 0;
if (req) {
spin_lock(&req->waitq.lock);
if (test_bit(FR_ABORTED, &req->flags))
err = -ENOENT;
else
set_bit(FR_LOCKED, &req->flags);
spin_unlock(&req->waitq.lock);
}
return err;
}
/*
* Unlock request. If it was aborted while locked, caller is responsible
* for unlocking and ending the request.
*/
static int unlock_request(struct fuse_req *req)
{
int err = 0;
if (req) {
spin_lock(&req->waitq.lock);
if (test_bit(FR_ABORTED, &req->flags))
err = -ENOENT;
else
clear_bit(FR_LOCKED, &req->flags);
spin_unlock(&req->waitq.lock);
}
return err;
}
struct fuse_copy_state {
int write;
struct fuse_req *req;
struct iov_iter *iter;
struct pipe_buffer *pipebufs;
struct pipe_buffer *currbuf;
struct pipe_inode_info *pipe;
unsigned long nr_segs;
struct page *pg;
unsigned len;
unsigned offset;
unsigned move_pages:1;
};
static void fuse_copy_init(struct fuse_copy_state *cs, int write,
struct iov_iter *iter)
{
memset(cs, 0, sizeof(*cs));
cs->write = write;
cs->iter = iter;
}
/* Unmap and put previous page of userspace buffer */
static void fuse_copy_finish(struct fuse_copy_state *cs)
{
if (cs->currbuf) {
struct pipe_buffer *buf = cs->currbuf;
if (cs->write)
buf->len = PAGE_SIZE - cs->len;
cs->currbuf = NULL;
} else if (cs->pg) {
if (cs->write) {
flush_dcache_page(cs->pg);
set_page_dirty_lock(cs->pg);
}
put_page(cs->pg);
}
cs->pg = NULL;
}
/*
* Get another pagefull of userspace buffer, and map it to kernel
* address space, and lock request
*/
static int fuse_copy_fill(struct fuse_copy_state *cs)
{
struct page *page;
int err;
err = unlock_request(cs->req);
if (err)
return err;
fuse_copy_finish(cs);
if (cs->pipebufs) {
struct pipe_buffer *buf = cs->pipebufs;
if (!cs->write) {
err = pipe_buf_confirm(cs->pipe, buf);
if (err)
return err;
BUG_ON(!cs->nr_segs);
cs->currbuf = buf;
cs->pg = buf->page;
cs->offset = buf->offset;
cs->len = buf->len;
cs->pipebufs++;
cs->nr_segs--;
} else {
if (cs->nr_segs >= cs->pipe->max_usage)
return -EIO;
page = alloc_page(GFP_HIGHUSER);
if (!page)
return -ENOMEM;
buf->page = page;
buf->offset = 0;
buf->len = 0;
cs->currbuf = buf;
cs->pg = page;
cs->offset = 0;
cs->len = PAGE_SIZE;
cs->pipebufs++;
cs->nr_segs++;
}
} else {
size_t off;
err = iov_iter_get_pages(cs->iter, &page, PAGE_SIZE, 1, &off);
if (err < 0)
return err;
BUG_ON(!err);
cs->len = err;
cs->offset = off;
cs->pg = page;
iov_iter_advance(cs->iter, err);
}
return lock_request(cs->req);
}
/* Do as much copy to/from userspace buffer as we can */
static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
{
unsigned ncpy = min(*size, cs->len);
if (val) {
void *pgaddr = kmap_atomic(cs->pg);
void *buf = pgaddr + cs->offset;
if (cs->write)
memcpy(buf, *val, ncpy);
else
memcpy(*val, buf, ncpy);
kunmap_atomic(pgaddr);
*val += ncpy;
}
*size -= ncpy;
cs->len -= ncpy;
cs->offset += ncpy;
return ncpy;
}
static int fuse_check_page(struct page *page)
{
if (page_mapcount(page) ||
page->mapping != NULL ||
page_count(page) != 1 ||
(page->flags & PAGE_FLAGS_CHECK_AT_PREP &
~(1 << PG_locked |
1 << PG_referenced |
1 << PG_uptodate |
1 << PG_lru |
1 << PG_active |
1 << PG_reclaim))) {
pr_warn("trying to steal weird page\n");
pr_warn(" page=%p index=%li flags=%08lx, count=%i, mapcount=%i, mapping=%p\n", page, page->index, page->flags, page_count(page), page_mapcount(page), page->mapping);
return 1;
}
return 0;
}
static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
{
int err;
struct page *oldpage = *pagep;
struct page *newpage;
struct pipe_buffer *buf = cs->pipebufs;
err = unlock_request(cs->req);
if (err)
return err;
fuse_copy_finish(cs);
err = pipe_buf_confirm(cs->pipe, buf);
if (err)
return err;
BUG_ON(!cs->nr_segs);
cs->currbuf = buf;
cs->len = buf->len;
cs->pipebufs++;
cs->nr_segs--;
if (cs->len != PAGE_SIZE)
goto out_fallback;
if (pipe_buf_steal(cs->pipe, buf) != 0)
goto out_fallback;
newpage = buf->page;
if (!PageUptodate(newpage))
SetPageUptodate(newpage);
ClearPageMappedToDisk(newpage);
if (fuse_check_page(newpage) != 0)
goto out_fallback_unlock;
/*
* This is a new and locked page, it shouldn't be mapped or
* have any special flags on it
*/
if (WARN_ON(page_mapped(oldpage)))
goto out_fallback_unlock;
if (WARN_ON(page_has_private(oldpage)))
goto out_fallback_unlock;
if (WARN_ON(PageDirty(oldpage) || PageWriteback(oldpage)))
goto out_fallback_unlock;
if (WARN_ON(PageMlocked(oldpage)))
goto out_fallback_unlock;
err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL);
if (err) {
unlock_page(newpage);
return err;
}
get_page(newpage);
if (!(buf->flags & PIPE_BUF_FLAG_LRU))
lru_cache_add_file(newpage);
err = 0;
spin_lock(&cs->req->waitq.lock);
if (test_bit(FR_ABORTED, &cs->req->flags))
err = -ENOENT;
else
*pagep = newpage;
spin_unlock(&cs->req->waitq.lock);
if (err) {
unlock_page(newpage);
put_page(newpage);
return err;
}
unlock_page(oldpage);
put_page(oldpage);
cs->len = 0;
return 0;
out_fallback_unlock:
unlock_page(newpage);
out_fallback:
cs->pg = buf->page;
cs->offset = buf->offset;
err = lock_request(cs->req);
if (err)
return err;
return 1;
}
static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
unsigned offset, unsigned count)
{
struct pipe_buffer *buf;
int err;
if (cs->nr_segs >= cs->pipe->max_usage)
return -EIO;
err = unlock_request(cs->req);
if (err)
return err;
fuse_copy_finish(cs);
buf = cs->pipebufs;
get_page(page);
buf->page = page;
buf->offset = offset;
buf->len = count;
cs->pipebufs++;
cs->nr_segs++;
cs->len = 0;
return 0;
}
/*
* Copy a page in the request to/from the userspace buffer. Must be
* done atomically
*/
static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
unsigned offset, unsigned count, int zeroing)
{
int err;
struct page *page = *pagep;
if (page && zeroing && count < PAGE_SIZE)
clear_highpage(page);
while (count) {
if (cs->write && cs->pipebufs && page) {
return fuse_ref_page(cs, page, offset, count);
} else if (!cs->len) {
if (cs->move_pages && page &&
offset == 0 && count == PAGE_SIZE) {
err = fuse_try_move_page(cs, pagep);
if (err <= 0)
return err;
} else {
err = fuse_copy_fill(cs);
if (err)
return err;
}
}
if (page) {
void *mapaddr = kmap_atomic(page);
void *buf = mapaddr + offset;
offset += fuse_copy_do(cs, &buf, &count);
kunmap_atomic(mapaddr);
} else
offset += fuse_copy_do(cs, NULL, &count);
}
if (page && !cs->write)
flush_dcache_page(page);
return 0;
}
/* Copy pages in the request to/from userspace buffer */
static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
int zeroing)
{
unsigned i;
struct fuse_req *req = cs->req;
struct fuse_args_pages *ap = container_of(req->args, typeof(*ap), args);
for (i = 0; i < ap->num_pages && (nbytes || zeroing); i++) {
int err;
unsigned int offset = ap->descs[i].offset;
unsigned int count = min(nbytes, ap->descs[i].length);
err = fuse_copy_page(cs, &ap->pages[i], offset, count, zeroing);
if (err)
return err;
nbytes -= count;
}
return 0;
}
/* Copy a single argument in the request to/from userspace buffer */
static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
{
while (size) {
if (!cs->len) {
int err = fuse_copy_fill(cs);
if (err)
return err;
}
fuse_copy_do(cs, &val, &size);
}
return 0;
}
/* Copy request arguments to/from userspace buffer */
static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
unsigned argpages, struct fuse_arg *args,
int zeroing)
{
int err = 0;
unsigned i;
for (i = 0; !err && i < numargs; i++) {
struct fuse_arg *arg = &args[i];
if (i == numargs - 1 && argpages)
err = fuse_copy_pages(cs, arg->size, zeroing);
else
err = fuse_copy_one(cs, arg->value, arg->size);
}
return err;
}