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authorTejun Heo <tj@kernel.org>2008-11-26 12:03:55 +0100
committerMiklos Szeredi <miklos@szeredi.hu>2008-11-26 12:03:55 +0100
commit95668a69a4bb862063c4d28a746e55107dee7b98 (patch)
tree0679e0f43274648bad70e694a9efb8bcfed55adc /fs/fuse/file.c
parent8599396b5062bf6bd2a0b433503849e2322df1c2 (diff)
fuse: implement poll support
Implement poll support. Polled files are indexed using kh in a RB tree rooted at fuse_conn->polled_files. Client should send FUSE_NOTIFY_POLL notification once after processing FUSE_POLL which has FUSE_POLL_SCHEDULE_NOTIFY set. Sending notification unconditionally after the latest poll or everytime file content might have changed is inefficient but won't cause malfunction. fuse_file_poll() can sleep and requires patches from the following thread which allows f_op->poll() to sleep. http://thread.gmane.org/gmane.linux.kernel/726176 Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Diffstat (limited to 'fs/fuse/file.c')
-rw-r--r--fs/fuse/file.c132
1 files changed, 132 insertions, 0 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index a28ced678d38..b3a944e4bb9c 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -62,6 +62,8 @@ struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
ff->kh = ++fc->khctr;
spin_unlock(&fc->lock);
}
+ RB_CLEAR_NODE(&ff->polled_node);
+ init_waitqueue_head(&ff->poll_wait);
}
return ff;
}
@@ -170,7 +172,11 @@ int fuse_release_common(struct inode *inode, struct file *file, int isdir)
spin_lock(&fc->lock);
list_del(&ff->write_entry);
+ if (!RB_EMPTY_NODE(&ff->polled_node))
+ rb_erase(&ff->polled_node, &fc->polled_files);
spin_unlock(&fc->lock);
+
+ wake_up_interruptible_sync(&ff->poll_wait);
/*
* Normally this will send the RELEASE request,
* however if some asynchronous READ or WRITE requests
@@ -1749,6 +1755,130 @@ static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
return fuse_file_do_ioctl(file, cmd, arg, FUSE_IOCTL_COMPAT);
}
+/*
+ * All files which have been polled are linked to RB tree
+ * fuse_conn->polled_files which is indexed by kh. Walk the tree and
+ * find the matching one.
+ */
+static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
+ struct rb_node **parent_out)
+{
+ struct rb_node **link = &fc->polled_files.rb_node;
+ struct rb_node *last = NULL;
+
+ while (*link) {
+ struct fuse_file *ff;
+
+ last = *link;
+ ff = rb_entry(last, struct fuse_file, polled_node);
+
+ if (kh < ff->kh)
+ link = &last->rb_left;
+ else if (kh > ff->kh)
+ link = &last->rb_right;
+ else
+ return link;
+ }
+
+ if (parent_out)
+ *parent_out = last;
+ return link;
+}
+
+/*
+ * The file is about to be polled. Make sure it's on the polled_files
+ * RB tree. Note that files once added to the polled_files tree are
+ * not removed before the file is released. This is because a file
+ * polled once is likely to be polled again.
+ */
+static void fuse_register_polled_file(struct fuse_conn *fc,
+ struct fuse_file *ff)
+{
+ spin_lock(&fc->lock);
+ if (RB_EMPTY_NODE(&ff->polled_node)) {
+ struct rb_node **link, *parent;
+
+ link = fuse_find_polled_node(fc, ff->kh, &parent);
+ BUG_ON(*link);
+ rb_link_node(&ff->polled_node, parent, link);
+ rb_insert_color(&ff->polled_node, &fc->polled_files);
+ }
+ spin_unlock(&fc->lock);
+}
+
+static unsigned fuse_file_poll(struct file *file, poll_table *wait)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ struct fuse_file *ff = file->private_data;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
+ struct fuse_poll_out outarg;
+ struct fuse_req *req;
+ int err;
+
+ if (fc->no_poll)
+ return DEFAULT_POLLMASK;
+
+ poll_wait(file, &ff->poll_wait, wait);
+
+ /*
+ * Ask for notification iff there's someone waiting for it.
+ * The client may ignore the flag and always notify.
+ */
+ if (waitqueue_active(&ff->poll_wait)) {
+ inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
+ fuse_register_polled_file(fc, ff);
+ }
+
+ req = fuse_get_req(fc);
+ if (IS_ERR(req))
+ return PTR_ERR(req);
+
+ req->in.h.opcode = FUSE_POLL;
+ 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(outarg);
+ req->out.args[0].value = &outarg;
+ request_send(fc, req);
+ err = req->out.h.error;
+ fuse_put_request(fc, req);
+
+ if (!err)
+ return outarg.revents;
+ if (err == -ENOSYS) {
+ fc->no_poll = 1;
+ return DEFAULT_POLLMASK;
+ }
+ return POLLERR;
+}
+
+/*
+ * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
+ * wakes up the poll waiters.
+ */
+int fuse_notify_poll_wakeup(struct fuse_conn *fc,
+ struct fuse_notify_poll_wakeup_out *outarg)
+{
+ u64 kh = outarg->kh;
+ struct rb_node **link;
+
+ spin_lock(&fc->lock);
+
+ link = fuse_find_polled_node(fc, kh, NULL);
+ if (*link) {
+ struct fuse_file *ff;
+
+ ff = rb_entry(*link, struct fuse_file, polled_node);
+ wake_up_interruptible_sync(&ff->poll_wait);
+ }
+
+ spin_unlock(&fc->lock);
+ return 0;
+}
+
static const struct file_operations fuse_file_operations = {
.llseek = fuse_file_llseek,
.read = do_sync_read,
@@ -1765,6 +1895,7 @@ static const struct file_operations fuse_file_operations = {
.splice_read = generic_file_splice_read,
.unlocked_ioctl = fuse_file_ioctl,
.compat_ioctl = fuse_file_compat_ioctl,
+ .poll = fuse_file_poll,
};
static const struct file_operations fuse_direct_io_file_operations = {
@@ -1779,6 +1910,7 @@ static const struct file_operations fuse_direct_io_file_operations = {
.flock = fuse_file_flock,
.unlocked_ioctl = fuse_file_ioctl,
.compat_ioctl = fuse_file_compat_ioctl,
+ .poll = fuse_file_poll,
/* no mmap and splice_read */
};

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