Logo Search packages:      
Sourcecode: fuse version File versions

dev.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2006  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/init.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/uio.h>
#include <linux/miscdevice.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/slab.h>

#ifdef MODULE_ALIAS_MISCDEV
MODULE_ALIAS_MISCDEV(FUSE_MINOR);
#endif

static kmem_cache_t *fuse_req_cachep;

static struct fuse_conn *fuse_get_conn(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 file->private_data;
}

static void fuse_request_init(struct fuse_req *req)
{
      memset(req, 0, sizeof(*req));
      INIT_LIST_HEAD(&req->list);
      INIT_LIST_HEAD(&req->intr_entry);
      init_waitqueue_head(&req->waitq);
      atomic_set(&req->count, 1);
}

struct fuse_req *fuse_request_alloc(void)
{
      struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_KERNEL);
      if (req)
            fuse_request_init(req);
      return req;
}

void fuse_request_free(struct fuse_req *req)
{
      kmem_cache_free(fuse_req_cachep, req);
}

static void block_sigs(sigset_t *oldset)
{
      sigset_t mask;

      siginitsetinv(&mask, sigmask(SIGKILL));
      sigprocmask(SIG_BLOCK, &mask, oldset);
}

static void restore_sigs(sigset_t *oldset)
{
      sigprocmask(SIG_SETMASK, oldset, NULL);
}

static void __fuse_get_request(struct fuse_req *req)
{
      atomic_inc(&req->count);
}

/* Must be called with > 1 refcount */
static void __fuse_put_request(struct fuse_req *req)
{
      BUG_ON(atomic_read(&req->count) < 2);
      atomic_dec(&req->count);
}

static void fuse_req_init_context(struct fuse_req *req)
{
      req->in.h.uid = current->fsuid;
      req->in.h.gid = current->fsgid;
      req->in.h.pid = current->pid;
}

struct fuse_req *fuse_get_req(struct fuse_conn *fc)
{
      struct fuse_req *req;
      sigset_t oldset;
      int intr;
      int err;

      atomic_inc(&fc->num_waiting);
      block_sigs(&oldset);
      intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
      restore_sigs(&oldset);
      err = -EINTR;
      if (intr)
            goto out;

      err = -ENOTCONN;
      if (!fc->connected)
            goto out;

      req = fuse_request_alloc();
      err = -ENOMEM;
      if (!req)
            goto out;

      fuse_req_init_context(req);
      req->waiting = 1;
      return req;

 out:
      atomic_dec(&fc->num_waiting);
      return ERR_PTR(err);
}

/*
 * Return request in fuse_file->reserved_req.  However that may
 * currently be in use.  If that is the case, wait for it to become
 * available.
 */
static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
                               struct file *file)
{
      struct fuse_req *req = NULL;
      struct fuse_file *ff = file->private_data;

      do {
            wait_event(fc->blocked_waitq, ff->reserved_req);
            spin_lock(&fc->lock);
            if (ff->reserved_req) {
                  req = ff->reserved_req;
                  ff->reserved_req = NULL;
                  get_file(file);
                  req->stolen_file = file;
            }
            spin_unlock(&fc->lock);
      } while (!req);

      return req;
}

/*
 * Put stolen request back into fuse_file->reserved_req
 */
static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
{
      struct file *file = req->stolen_file;
      struct fuse_file *ff = file->private_data;

      spin_lock(&fc->lock);
      fuse_request_init(req);
      BUG_ON(ff->reserved_req);
      ff->reserved_req = req;
      wake_up(&fc->blocked_waitq);
      spin_unlock(&fc->lock);
      fput(file);
}

/*
 * Gets a requests for a file operation, always succeeds
 *
 * This is used for sending the FLUSH request, which must get to
 * userspace, due to POSIX locks which may need to be unlocked.
 *
 * If allocation fails due to OOM, use the reserved request in
 * fuse_file.
 *
 * This is very unlikely to deadlock accidentally, since the
 * filesystem should not have it's own file open.  If deadlock is
 * intentional, it can still be broken by "aborting" the filesystem.
 */
struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file)
{
      struct fuse_req *req;

      atomic_inc(&fc->num_waiting);
      wait_event(fc->blocked_waitq, !fc->blocked);
      req = fuse_request_alloc();
      if (!req)
            req = get_reserved_req(fc, file);

      fuse_req_init_context(req);
      req->waiting = 1;
      return req;
}

void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
{
      if (atomic_dec_and_test(&req->count)) {
            if (req->waiting)
                  atomic_dec(&fc->num_waiting);

            if (req->stolen_file)
                  put_reserved_req(fc, req);
            else
                  fuse_request_free(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
 *
 * Called with fc->lock, unlocks it
 */
static void request_end(struct fuse_conn *fc, struct fuse_req *req)
{
      void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
      req->end = NULL;
      list_del(&req->list);
      list_del(&req->intr_entry);
      req->state = FUSE_REQ_FINISHED;
      if (req->background) {
            if (fc->num_background == FUSE_MAX_BACKGROUND) {
                  fc->blocked = 0;
                  wake_up_all(&fc->blocked_waitq);
            }
            fc->num_background--;
      }
      spin_unlock(&fc->lock);
      dput(req->dentry);
      mntput(req->vfsmount);
      if (req->file)
            fput(req->file);
      wake_up(&req->waitq);
      if (end)
            end(fc, req);
      else
            fuse_put_request(fc, req);
}

static void wait_answer_interruptible(struct fuse_conn *fc,
                              struct fuse_req *req)
{
      if (signal_pending(current))
            return;

      spin_unlock(&fc->lock);
      wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
      spin_lock(&fc->lock);
}

static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
{
      list_add_tail(&req->intr_entry, &fc->interrupts);
      wake_up(&fc->waitq);
      kill_fasync(&fc->fasync, SIGIO, POLL_IN);
}

/* Called with fc->lock held.  Releases, and then reacquires it. */
static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
{
      if (!fc->no_interrupt) {
            /* Any signal may interrupt this */
            wait_answer_interruptible(fc, req);

            if (req->aborted)
                  goto aborted;
            if (req->state == FUSE_REQ_FINISHED)
                  return;

            req->interrupted = 1;
            if (req->state == FUSE_REQ_SENT)
                  queue_interrupt(fc, req);
      }

      if (req->force) {
            spin_unlock(&fc->lock);
            wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
            spin_lock(&fc->lock);
      } else {
            sigset_t oldset;

            /* Only fatal signals may interrupt this */
            block_sigs(&oldset);
            wait_answer_interruptible(fc, req);
            restore_sigs(&oldset);
      }

      if (req->aborted)
            goto aborted;
      if (req->state == FUSE_REQ_FINISHED)
            return;

      req->out.h.error = -EINTR;
      req->aborted = 1;

 aborted:
      if (req->locked) {
            /* This is uninterruptible sleep, because data is
               being copied to/from the buffers of req.  During
               locked state, there mustn't be any filesystem
               operation (e.g. page fault), since that could lead
               to deadlock */
            spin_unlock(&fc->lock);
            wait_event(req->waitq, !req->locked);
            spin_lock(&fc->lock);
      }
      if (req->state == FUSE_REQ_PENDING) {
            list_del(&req->list);
            __fuse_put_request(req);
      } else if (req->state == FUSE_REQ_SENT) {
            spin_unlock(&fc->lock);
            wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
            spin_lock(&fc->lock);
      }
}

static unsigned len_args(unsigned numargs, struct fuse_arg *args)
{
      unsigned nbytes = 0;
      unsigned i;

      for (i = 0; i < numargs; i++)
            nbytes += args[i].size;

      return nbytes;
}

static u64 fuse_get_unique(struct fuse_conn *fc)
 {
      fc->reqctr++;
      /* zero is special */
      if (fc->reqctr == 0)
            fc->reqctr = 1;

      return fc->reqctr;
}

static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
{
      req->in.h.unique = fuse_get_unique(fc);
      req->in.h.len = sizeof(struct fuse_in_header) +
            len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
      list_add_tail(&req->list, &fc->pending);
      req->state = FUSE_REQ_PENDING;
      if (!req->waiting) {
            req->waiting = 1;
            atomic_inc(&fc->num_waiting);
      }
      wake_up(&fc->waitq);
      kill_fasync(&fc->fasync, SIGIO, POLL_IN);
}

void request_send(struct fuse_conn *fc, struct fuse_req *req)
{
      req->isreply = 1;
      spin_lock(&fc->lock);
      if (!fc->connected)
            req->out.h.error = -ENOTCONN;
      else if (fc->conn_error)
            req->out.h.error = -ECONNREFUSED;
      else {
            queue_request(fc, req);
            /* acquire extra reference, since request is still needed
               after request_end() */
            __fuse_get_request(req);

            request_wait_answer(fc, req);
      }
      spin_unlock(&fc->lock);
}

static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
{
      spin_lock(&fc->lock);
      if (fc->connected) {
            req->background = 1;
            fc->num_background++;
            if (fc->num_background == FUSE_MAX_BACKGROUND)
                  fc->blocked = 1;

            queue_request(fc, req);
            spin_unlock(&fc->lock);
      } else {
            req->out.h.error = -ENOTCONN;
            request_end(fc, req);
      }
}

void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
{
      req->isreply = 0;
      request_send_nowait(fc, req);
}

void request_send_background(struct fuse_conn *fc, struct fuse_req *req)
{
      req->isreply = 1;
      request_send_nowait(fc, req);
}

/*
 * 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_conn *fc, struct fuse_req *req)
{
      int err = 0;
      if (req) {
            spin_lock(&fc->lock);
            if (req->aborted)
                  err = -ENOENT;
            else
                  req->locked = 1;
            spin_unlock(&fc->lock);
      }
      return err;
}

/*
 * Unlock request.  If it was aborted during being locked, the
 * requester thread is currently waiting for it to be unlocked, so
 * wake it up.
 */
static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
{
      if (req) {
            spin_lock(&fc->lock);
            req->locked = 0;
            if (req->aborted)
                  wake_up(&req->waitq);
            spin_unlock(&fc->lock);
      }
}

struct fuse_copy_state {
      struct fuse_conn *fc;
      int write;
      struct fuse_req *req;
      const struct iovec *iov;
      unsigned long nr_segs;
      unsigned long seglen;
      unsigned long addr;
      struct page *pg;
      void *mapaddr;
      void *buf;
      unsigned len;
};

static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
                     int write, struct fuse_req *req,
                     const struct iovec *iov, unsigned long nr_segs)
{
      memset(cs, 0, sizeof(*cs));
      cs->fc = fc;
      cs->write = write;
      cs->req = req;
      cs->iov = iov;
      cs->nr_segs = nr_segs;
}

/* Unmap and put previous page of userspace buffer */
static void fuse_copy_finish(struct fuse_copy_state *cs)
{
      if (cs->mapaddr) {
            kunmap_atomic(cs->mapaddr, KM_USER0);
            if (cs->write) {
                  flush_dcache_page(cs->pg);
                  set_page_dirty_lock(cs->pg);
            }
            put_page(cs->pg);
            cs->mapaddr = 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)
{
      unsigned long offset;
      int err;
#ifdef DCACHE_BUG
      struct vm_area_struct *vma;
#endif

      unlock_request(cs->fc, cs->req);
      fuse_copy_finish(cs);
      if (!cs->seglen) {
            BUG_ON(!cs->nr_segs);
            cs->seglen = cs->iov[0].iov_len;
            cs->addr = (unsigned long) cs->iov[0].iov_base;
            cs->iov ++;
            cs->nr_segs --;
      }
      down_read(&current->mm->mmap_sem);
#ifndef DCACHE_BUG
      err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
                       &cs->pg, NULL);
#else
      err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
                       &cs->pg, &vma);
#endif
      up_read(&current->mm->mmap_sem);
      if (err < 0)
            return err;
      BUG_ON(err != 1);
      offset = cs->addr % PAGE_SIZE;
      cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);
#ifdef DCACHE_BUG
      flush_cache_page(vma, cs->addr, page_to_pfn(cs->pg));
#endif
      cs->buf = cs->mapaddr + offset;
      cs->len = min(PAGE_SIZE - offset, cs->seglen);
      cs->seglen -= cs->len;
      cs->addr += cs->len;

      return lock_request(cs->fc, 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) {
            if (cs->write)
                  memcpy(cs->buf, *val, ncpy);
            else
                  memcpy(*val, cs->buf, ncpy);
            *val += ncpy;
      }
      *size -= ncpy;
      cs->len -= ncpy;
      cs->buf += ncpy;
      return ncpy;
}

/*
 * 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 *page,
                    unsigned offset, unsigned count, int zeroing)
{
      if (page && zeroing && count < PAGE_SIZE) {
            void *mapaddr = kmap_atomic(page, KM_USER1);
            memset(mapaddr, 0, PAGE_SIZE);
            kunmap_atomic(mapaddr, KM_USER1);
      }
      while (count) {
            int err;
            if (!cs->len && (err = fuse_copy_fill(cs)))
                  return err;
            if (page) {
                  void *mapaddr = kmap_atomic(page, KM_USER1);
                  void *buf = mapaddr + offset;
                  offset += fuse_copy_do(cs, &buf, &count);
                  kunmap_atomic(mapaddr, KM_USER1);
            } 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;
      unsigned offset = req->page_offset;
      unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);

      for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
            struct page *page = req->pages[i];
            int err = fuse_copy_page(cs, page, offset, count, zeroing);
            if (err)
                  return err;

            nbytes -= count;
            count = min(nbytes, (unsigned) PAGE_SIZE);
            offset = 0;
      }
      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) {
            int err;
            if (!cs->len && (err = fuse_copy_fill(cs)))
                  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;
}

static int request_pending(struct fuse_conn *fc)
{
      return !list_empty(&fc->pending) || !list_empty(&fc->interrupts);
}

/* Wait until a request is available on the pending list */
static void request_wait(struct fuse_conn *fc)
{
      DECLARE_WAITQUEUE(wait, current);

      add_wait_queue_exclusive(&fc->waitq, &wait);
      while (fc->connected && !request_pending(fc)) {
            set_current_state(TASK_INTERRUPTIBLE);
            if (signal_pending(current))
                  break;

            spin_unlock(&fc->lock);
            schedule();
            spin_lock(&fc->lock);
      }
      set_current_state(TASK_RUNNING);
      remove_wait_queue(&fc->waitq, &wait);
}

/*
 * Transfer an interrupt request to userspace
 *
 * Unlike other requests this is assembled on demand, without a need
 * to allocate a separate fuse_req structure.
 *
 * Called with fc->lock held, releases it
 */
static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req,
                         const struct iovec *iov, unsigned long nr_segs)
{
      struct fuse_copy_state cs;
      struct fuse_in_header ih;
      struct fuse_interrupt_in arg;
      unsigned reqsize = sizeof(ih) + sizeof(arg);
      int err;

      list_del_init(&req->intr_entry);
      req->intr_unique = fuse_get_unique(fc);
      memset(&ih, 0, sizeof(ih));
      memset(&arg, 0, sizeof(arg));
      ih.len = reqsize;
      ih.opcode = FUSE_INTERRUPT;
      ih.unique = req->intr_unique;
      arg.unique = req->in.h.unique;

      spin_unlock(&fc->lock);
      if (iov_length(iov, nr_segs) < reqsize)
            return -EINVAL;

      fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
      err = fuse_copy_one(&cs, &ih, sizeof(ih));
      if (!err)
            err = fuse_copy_one(&cs, &arg, sizeof(arg));
      fuse_copy_finish(&cs);

      return err ? err : reqsize;
}

/*
 * Read a single request into the userspace filesystem's buffer.  This
 * function waits until a request is available, then removes it from
 * the pending list and copies request data to userspace buffer.  If
 * no reply is needed (FORGET) or request has been aborted or there
 * was an error during the copying then it's finished by calling
 * request_end().  Otherwise add it to the processing list, and set
 * the 'sent' flag.
 */
static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov,
                        unsigned long nr_segs, loff_t *off)
{
      int err;
      struct fuse_req *req;
      struct fuse_in *in;
      struct fuse_copy_state cs;
      unsigned reqsize;
      struct fuse_conn *fc = fuse_get_conn(file);
      if (!fc)
            return -EPERM;

 restart:
      spin_lock(&fc->lock);
      err = -EAGAIN;
      if ((file->f_flags & O_NONBLOCK) && fc->connected &&
          !request_pending(fc))
            goto err_unlock;

      request_wait(fc);
      err = -ENODEV;
      if (!fc->connected)
            goto err_unlock;
      err = -ERESTARTSYS;
      if (!request_pending(fc))
            goto err_unlock;

      if (!list_empty(&fc->interrupts)) {
            req = list_entry(fc->interrupts.next, struct fuse_req,
                         intr_entry);
            return fuse_read_interrupt(fc, req, iov, nr_segs);
      }

      req = list_entry(fc->pending.next, struct fuse_req, list);
      req->state = FUSE_REQ_READING;
      list_move(&req->list, &fc->io);

      in = &req->in;
      reqsize = in->h.len;
      /* If request is too large, reply with an error and restart the read */
      if (iov_length(iov, nr_segs) < reqsize) {
            req->out.h.error = -EIO;
            /* SETXATTR is special, since it may contain too large data */
            if (in->h.opcode == FUSE_SETXATTR)
                  req->out.h.error = -E2BIG;
            request_end(fc, req);
            goto restart;
      }
      spin_unlock(&fc->lock);
      fuse_copy_init(&cs, fc, 1, req, iov, nr_segs);
      err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
      if (!err)
            err = fuse_copy_args(&cs, in->numargs, in->argpages,
                             (struct fuse_arg *) in->args, 0);
      fuse_copy_finish(&cs);
      spin_lock(&fc->lock);
      req->locked = 0;
      if (!err && req->aborted)
            err = -ENOENT;
      if (err) {
            if (!req->aborted)
                  req->out.h.error = -EIO;
            request_end(fc, req);
            return err;
      }
      if (!req->isreply)
            request_end(fc, req);
      else {
            req->state = FUSE_REQ_SENT;
            list_move_tail(&req->list, &fc->processing);
            if (req->interrupted)
                  queue_interrupt(fc, req);
            spin_unlock(&fc->lock);
      }
      return reqsize;

 err_unlock:
      spin_unlock(&fc->lock);
      return err;
}

#ifndef KERNEL_2_6_19_PLUS
static ssize_t fuse_dev_read(struct file *file, char __user *buf,
                       size_t nbytes, loff_t *off)
{
      struct iovec iov;
      iov.iov_len = nbytes;
      iov.iov_base = buf;
      return fuse_dev_readv(file, &iov, 1, off);
}
#else
static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
                       unsigned long nr_segs, loff_t pos)
{
      return fuse_dev_readv(iocb->ki_filp, iov, nr_segs, &pos);
}
#endif

/* Look up request on processing list by unique ID */
static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
{
      struct list_head *entry;

      list_for_each(entry, &fc->processing) {
            struct fuse_req *req;
            req = list_entry(entry, struct fuse_req, list);
            if (req->in.h.unique == unique || req->intr_unique == unique)
                  return req;
      }
      return NULL;
}

static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
                   unsigned nbytes)
{
      unsigned reqsize = sizeof(struct fuse_out_header);

      if (out->h.error)
            return nbytes != reqsize ? -EINVAL : 0;

      reqsize += len_args(out->numargs, out->args);

      if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
            return -EINVAL;
      else if (reqsize > nbytes) {
            struct fuse_arg *lastarg = &out->args[out->numargs-1];
            unsigned diffsize = reqsize - nbytes;
            if (diffsize > lastarg->size)
                  return -EINVAL;
            lastarg->size -= diffsize;
      }
      return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
                        out->page_zeroing);
}

/*
 * Write a single reply to a request.  First the header is copied from
 * the write buffer.  The request is then searched on the processing
 * list by the unique ID found in the header.  If found, then remove
 * it from the list and copy the rest of the buffer to the request.
 * The request is finished by calling request_end()
 */
static ssize_t fuse_dev_writev(struct file *file, const struct iovec *iov,
                         unsigned long nr_segs, loff_t *off)
{
      int err;
      unsigned nbytes = iov_length(iov, nr_segs);
      struct fuse_req *req;
      struct fuse_out_header oh;
      struct fuse_copy_state cs;
      struct fuse_conn *fc = fuse_get_conn(file);
      if (!fc)
            return -EPERM;

      fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
      if (nbytes < sizeof(struct fuse_out_header))
            return -EINVAL;

      err = fuse_copy_one(&cs, &oh, sizeof(oh));
      if (err)
            goto err_finish;
      err = -EINVAL;
      if (!oh.unique || oh.error <= -1000 || oh.error > 0 ||
          oh.len != nbytes)
            goto err_finish;

      spin_lock(&fc->lock);
      err = -ENOENT;
      if (!fc->connected)
            goto err_unlock;

      req = request_find(fc, oh.unique);
      if (!req)
            goto err_unlock;

      if (req->aborted) {
            spin_unlock(&fc->lock);
            fuse_copy_finish(&cs);
            spin_lock(&fc->lock);
            request_end(fc, req);
            return -ENOENT;
      }
      /* Is it an interrupt reply? */
      if (req->intr_unique == oh.unique) {
            err = -EINVAL;
            if (nbytes != sizeof(struct fuse_out_header))
                  goto err_unlock;

            if (oh.error == -ENOSYS)
                  fc->no_interrupt = 1;
            else if (oh.error == -EAGAIN)
                  queue_interrupt(fc, req);

            spin_unlock(&fc->lock);
            fuse_copy_finish(&cs);
            return nbytes;
      }

      req->state = FUSE_REQ_WRITING;
      list_move(&req->list, &fc->io);
      req->out.h = oh;
      req->locked = 1;
      cs.req = req;
      spin_unlock(&fc->lock);

      err = copy_out_args(&cs, &req->out, nbytes);
      fuse_copy_finish(&cs);

      spin_lock(&fc->lock);
      req->locked = 0;
      if (!err) {
            if (req->aborted)
                  err = -ENOENT;
      } else if (!req->aborted)
            req->out.h.error = -EIO;
      request_end(fc, req);

      return err ? err : nbytes;

 err_unlock:
      spin_unlock(&fc->lock);
 err_finish:
      fuse_copy_finish(&cs);
      return err;
}

#ifndef KERNEL_2_6_19_PLUS
static ssize_t fuse_dev_write(struct file *file, const char __user *buf,
                        size_t nbytes, loff_t *off)
{
      struct iovec iov;
      iov.iov_len = nbytes;
      iov.iov_base = (char __user *) buf;
      return fuse_dev_writev(file, &iov, 1, off);
}
#else
static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
                        unsigned long nr_segs, loff_t pos)
{
      return fuse_dev_writev(iocb->ki_filp, iov, nr_segs, &pos);
}
#endif

static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
{
      unsigned mask = POLLOUT | POLLWRNORM;
      struct fuse_conn *fc = fuse_get_conn(file);
      if (!fc)
            return POLLERR;

      poll_wait(file, &fc->waitq, wait);

      spin_lock(&fc->lock);
      if (!fc->connected)
            mask = POLLERR;
      else if (request_pending(fc))
            mask |= POLLIN | POLLRDNORM;
      spin_unlock(&fc->lock);

      return mask;
}

/*
 * Abort all requests on the given list (pending or processing)
 *
 * This function releases and reacquires fc->lock
 */
static void end_requests(struct fuse_conn *fc, struct list_head *head)
{
      while (!list_empty(head)) {
            struct fuse_req *req;
            req = list_entry(head->next, struct fuse_req, list);
            req->out.h.error = -ECONNABORTED;
            request_end(fc, req);
            spin_lock(&fc->lock);
      }
}

/*
 * Abort requests under I/O
 *
 * The requests are set to aborted and finished, and the request
 * waiter is woken up.  This will make request_wait_answer() wait
 * until the request is unlocked and then return.
 *
 * If the request is asynchronous, then the end function needs to be
 * called after waiting for the request to be unlocked (if it was
 * locked).
 */
static void end_io_requests(struct fuse_conn *fc)
{
      while (!list_empty(&fc->io)) {
            struct fuse_req *req =
                  list_entry(fc->io.next, struct fuse_req, list);
            void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;

            req->aborted = 1;
            req->out.h.error = -ECONNABORTED;
            req->state = FUSE_REQ_FINISHED;
            list_del_init(&req->list);
            wake_up(&req->waitq);
            if (end) {
                  req->end = NULL;
                  /* The end function will consume this reference */
                  __fuse_get_request(req);
                  spin_unlock(&fc->lock);
                  wait_event(req->waitq, !req->locked);
                  end(fc, req);
                  spin_lock(&fc->lock);
            }
      }
}

/*
 * Abort all requests.
 *
 * Emergency exit in case of a malicious or accidental deadlock, or
 * just a hung filesystem.
 *
 * The same effect is usually achievable through killing the
 * filesystem daemon and all users of the filesystem.  The exception
 * is the combination of an asynchronous request and the tricky
 * deadlock (see Documentation/filesystems/fuse.txt).
 *
 * During the aborting, progression of requests from the pending and
 * processing lists onto the io list, and progression of new requests
 * onto the pending list is prevented by req->connected being false.
 *
 * Progression of requests under I/O to the processing list is
 * prevented by the req->aborted flag being true for these requests.
 * For this reason requests on the io list must be aborted first.
 */
void fuse_abort_conn(struct fuse_conn *fc)
{
      spin_lock(&fc->lock);
      if (fc->connected) {
            fc->connected = 0;
            fc->blocked = 0;
            end_io_requests(fc);
            end_requests(fc, &fc->pending);
            end_requests(fc, &fc->processing);
            wake_up_all(&fc->waitq);
            wake_up_all(&fc->blocked_waitq);
            kill_fasync(&fc->fasync, SIGIO, POLL_IN);
      }
      spin_unlock(&fc->lock);
}

static int fuse_dev_release(struct inode *inode, struct file *file)
{
      struct fuse_conn *fc = fuse_get_conn(file);
      if (fc) {
            spin_lock(&fc->lock);
            fc->connected = 0;
            end_requests(fc, &fc->pending);
            end_requests(fc, &fc->processing);
            spin_unlock(&fc->lock);
            fasync_helper(-1, file, 0, &fc->fasync);
            fuse_conn_put(fc);
      }

      return 0;
}

static int fuse_dev_fasync(int fd, struct file *file, int on)
{
      struct fuse_conn *fc = fuse_get_conn(file);
      if (!fc)
            return -EPERM;

      /* No locking - fasync_helper does its own locking */
      return fasync_helper(fd, file, on, &fc->fasync);
}

struct file_operations fuse_dev_operations = {
      .owner            = THIS_MODULE,
      .llseek           = no_llseek,
#ifndef KERNEL_2_6_19_PLUS
      .read       = fuse_dev_read,
      .readv            = fuse_dev_readv,
      .write            = fuse_dev_write,
      .writev           = fuse_dev_writev,
#else
      .read       = do_sync_read,
      .aio_read   = fuse_dev_read,
      .write            = do_sync_write,
      .aio_write  = fuse_dev_write,
#endif
      .poll       = fuse_dev_poll,
      .release    = fuse_dev_release,
      .fasync           = fuse_dev_fasync,
};

static struct miscdevice fuse_miscdevice = {
      .minor = FUSE_MINOR,
      .name  = "fuse",
      .fops = &fuse_dev_operations,
};

int __init fuse_dev_init(void)
{
      int err = -ENOMEM;
      fuse_req_cachep = kmem_cache_create("fuse_request",
                                  sizeof(struct fuse_req),
                                  0, 0, NULL, NULL);
      if (!fuse_req_cachep)
            goto out;

      err = misc_register(&fuse_miscdevice);
      if (err)
            goto out_cache_clean;

      return 0;

 out_cache_clean:
      kmem_cache_destroy(fuse_req_cachep);
 out:
      return err;
}

void fuse_dev_cleanup(void)
{
      misc_deregister(&fuse_miscdevice);
      kmem_cache_destroy(fuse_req_cachep);
}

Generated by  Doxygen 1.6.0   Back to index