Commit 95668a69 authored by Tejun Heo's avatar Tejun Heo Committed by Miklos Szeredi
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent 8599396b
......@@ -816,10 +816,29 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
return err;
}
static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
struct fuse_copy_state *cs)
{
struct fuse_notify_poll_wakeup_out outarg;
int err;
if (size != sizeof(outarg))
return -EINVAL;
err = fuse_copy_one(cs, &outarg, sizeof(outarg));
if (err)
return err;
return fuse_notify_poll_wakeup(fc, &outarg);
}
static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
unsigned int size, struct fuse_copy_state *cs)
{
switch (code) {
case FUSE_NOTIFY_POLL:
return fuse_notify_poll(fc, size, cs);
default:
return -EINVAL;
}
......
......@@ -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 */
};
......
......@@ -19,6 +19,8 @@
#include <linux/backing-dev.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/rbtree.h>
#include <linux/poll.h>
/** Max number of pages that can be used in a single read request */
#define FUSE_MAX_PAGES_PER_REQ 32
......@@ -111,6 +113,12 @@ struct fuse_file {
/** Entry on inode's write_files list */
struct list_head write_entry;
/** RB node to be linked on fuse_conn->polled_files */
struct rb_node polled_node;
/** Wait queue head for poll */
wait_queue_head_t poll_wait;
};
/** One input argument of a request */
......@@ -328,6 +336,9 @@ struct fuse_conn {
/** The next unique kernel file handle */
u64 khctr;
/** rbtree of fuse_files waiting for poll events indexed by ph */
struct rb_root polled_files;
/** Number of requests currently in the background */
unsigned num_background;
......@@ -416,6 +427,9 @@ struct fuse_conn {
/** Is bmap not implemented by fs? */
unsigned no_bmap:1;
/** Is poll not implemented by fs? */
unsigned no_poll:1;
/** Do multi-page cached writes */
unsigned big_writes:1;
......@@ -524,6 +538,12 @@ int fuse_release_common(struct inode *inode, struct file *file, int isdir);
int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
int isdir);
/**
* Notify poll wakeup
*/
int fuse_notify_poll_wakeup(struct fuse_conn *fc,
struct fuse_notify_poll_wakeup_out *outarg);
/**
* Initialize file operations on a regular file
*/
......
......@@ -486,6 +486,7 @@ static struct fuse_conn *new_conn(struct super_block *sb)
/* fuse does it's own writeback accounting */
fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB;
fc->khctr = 0;
fc->polled_files = RB_ROOT;
fc->dev = sb->s_dev;
err = bdi_init(&fc->bdi);
if (err)
......
......@@ -163,6 +163,13 @@ struct fuse_file_lock {
#define FUSE_IOCTL_MAX_IOV 256
/**
* Poll flags
*
* FUSE_POLL_SCHEDULE_NOTIFY: request poll notify
*/
#define FUSE_POLL_SCHEDULE_NOTIFY (1 << 0)
enum fuse_opcode {
FUSE_LOOKUP = 1,
FUSE_FORGET = 2, /* no reply */
......@@ -201,9 +208,11 @@ enum fuse_opcode {
FUSE_BMAP = 37,
FUSE_DESTROY = 38,
FUSE_IOCTL = 39,
FUSE_POLL = 40,
};
enum fuse_notify_code {
FUSE_NOTIFY_POLL = 1,
FUSE_NOTIFY_CODE_MAX,
};
......@@ -421,6 +430,22 @@ struct fuse_ioctl_out {
__u32 out_iovs;
};
struct fuse_poll_in {
__u64 fh;
__u64 kh;
__u32 flags;
__u32 padding;
};
struct fuse_poll_out {
__u32 revents;
__u32 padding;
};
struct fuse_notify_poll_wakeup_out {
__u64 kh;
};
struct fuse_in_header {
__u32 len;
__u32 opcode;
......
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