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fuse: iqueue locking
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Use fiq->waitq.lock for protecting members of struct fuse_iqueue and
FR_PENDING request flag, previously protected by fc->lock.

Following patches will remove fc->lock protection from these members.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>
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Miklos Szeredi committed Jul 1, 2015
1 parent ef75925 commit 4ce6081
Showing 1 changed file with 45 additions and 6 deletions.
51 changes: 45 additions & 6 deletions fs/fuse/dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -328,7 +328,7 @@ static void queue_request(struct fuse_iqueue *fiq, struct fuse_req *req)
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, &fiq->pending);
wake_up(&fiq->waitq);
wake_up_locked(&fiq->waitq);
kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
}

Expand All @@ -341,14 +341,16 @@ void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
forget->forget_one.nlookup = nlookup;

spin_lock(&fc->lock);
spin_lock(&fiq->waitq.lock);
if (fiq->connected) {
fiq->forget_list_tail->next = forget;
fiq->forget_list_tail = forget;
wake_up(&fiq->waitq);
wake_up_locked(&fiq->waitq);
kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
} else {
kfree(forget);
}
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);
}

Expand All @@ -362,8 +364,10 @@ static void flush_bg_queue(struct fuse_conn *fc)
req = list_entry(fc->bg_queue.next, struct fuse_req, list);
list_del(&req->list);
fc->active_background++;
spin_lock(&fiq->waitq.lock);
req->in.h.unique = fuse_get_unique(fiq);
queue_request(fiq, req);
spin_unlock(&fiq->waitq.lock);
}
}

Expand All @@ -380,10 +384,13 @@ static void flush_bg_queue(struct fuse_conn *fc)
static void request_end(struct fuse_conn *fc, struct fuse_req *req)
__releases(fc->lock)
{
struct fuse_iqueue *fiq = &fc->iq;
void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
req->end = NULL;
list_del_init(&req->list);
spin_lock(&fiq->waitq.lock);
list_del_init(&req->intr_entry);
spin_unlock(&fiq->waitq.lock);
WARN_ON(test_bit(FR_PENDING, &req->flags));
WARN_ON(test_bit(FR_SENT, &req->flags));
smp_wmb();
Expand Down Expand Up @@ -415,13 +422,16 @@ __releases(fc->lock)

static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
{
spin_lock(&fiq->waitq.lock);
list_add_tail(&req->intr_entry, &fiq->interrupts);
wake_up(&fiq->waitq);
wake_up_locked(&fiq->waitq);
spin_unlock(&fiq->waitq.lock);
kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
}

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) {
Expand All @@ -434,7 +444,7 @@ static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
spin_lock(&fc->lock);
set_bit(FR_INTERRUPTED, &req->flags);
if (test_bit(FR_SENT, &req->flags))
queue_interrupt(&fc->iq, req);
queue_interrupt(fiq, req);
spin_unlock(&fc->lock);
}

Expand All @@ -451,14 +461,17 @@ static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
return;

spin_lock(&fc->lock);
spin_lock(&fiq->waitq.lock);
/* Request is not yet in userspace, bail out */
if (test_bit(FR_PENDING, &req->flags)) {
list_del(&req->list);
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);
__fuse_put_request(req);
req->out.h.error = -EINTR;
return;
}
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);
}

Expand All @@ -475,15 +488,18 @@ static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)

BUG_ON(test_bit(FR_BACKGROUND, &req->flags));
spin_lock(&fc->lock);
spin_lock(&fiq->waitq.lock);
if (!fiq->connected) {
spin_unlock(&fc->lock);
spin_unlock(&fiq->waitq.lock);
req->out.h.error = -ENOTCONN;
} else {
req->in.h.unique = fuse_get_unique(fiq);
queue_request(fiq, req);
/* acquire extra reference, since request is still needed
after request_end() */
__fuse_get_request(req);
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);

request_wait_answer(fc, req);
Expand Down Expand Up @@ -619,10 +635,12 @@ static int fuse_request_send_notify_reply(struct fuse_conn *fc,
__clear_bit(FR_ISREPLY, &req->flags);
req->in.h.unique = unique;
spin_lock(&fc->lock);
spin_lock(&fiq->waitq.lock);
if (fiq->connected) {
queue_request(fiq, req);
err = 0;
}
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);

return err;
Expand Down Expand Up @@ -1064,8 +1082,10 @@ static int request_pending(struct fuse_iqueue *fiq)

/* Wait until a request is available on the pending list */
static void request_wait(struct fuse_conn *fc)
__releases(fc->iq.waitq.lock)
__releases(fc->lock)
__acquires(fc->lock)
__acquires(fc->iq.waitq.lock)
{
struct fuse_iqueue *fiq = &fc->iq;
DECLARE_WAITQUEUE(wait, current);
Expand All @@ -1076,9 +1096,11 @@ __acquires(fc->lock)
if (signal_pending(current))
break;

spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);
schedule();
spin_lock(&fc->lock);
spin_lock(&fiq->waitq.lock);
}
set_current_state(TASK_RUNNING);
remove_wait_queue(&fiq->waitq, &wait);
Expand All @@ -1094,22 +1116,25 @@ __acquires(fc->lock)
*/
static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_copy_state *cs,
size_t nbytes, struct fuse_req *req)
__releases(fc->iq.waitq.lock)
__releases(fc->lock)
{
struct fuse_iqueue *fiq = &fc->iq;
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->iq);
req->intr_unique = fuse_get_unique(fiq);
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(&fiq->waitq.lock);
spin_unlock(&fc->lock);
if (nbytes < reqsize)
return -EINVAL;
Expand Down Expand Up @@ -1147,6 +1172,7 @@ static struct fuse_forget_link *dequeue_forget(struct fuse_iqueue *fiq,
static int fuse_read_single_forget(struct fuse_conn *fc,
struct fuse_copy_state *cs,
size_t nbytes)
__releases(fc->iq.waitq.lock)
__releases(fc->lock)
{
int err;
Expand All @@ -1162,6 +1188,7 @@ __releases(fc->lock)
.len = sizeof(ih) + sizeof(arg),
};

spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);
kfree(forget);
if (nbytes < ih.len)
Expand All @@ -1180,6 +1207,7 @@ __releases(fc->lock)

static int fuse_read_batch_forget(struct fuse_conn *fc,
struct fuse_copy_state *cs, size_t nbytes)
__releases(fc->iq.waitq.lock)
__releases(fc->lock)
{
int err;
Expand All @@ -1195,12 +1223,14 @@ __releases(fc->lock)
};

if (nbytes < ih.len) {
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);
return -EINVAL;
}

max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);
head = dequeue_forget(fiq, max_forgets, &count);
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);

arg.count = count;
Expand Down Expand Up @@ -1230,6 +1260,7 @@ __releases(fc->lock)

static int fuse_read_forget(struct fuse_conn *fc, struct fuse_copy_state *cs,
size_t nbytes)
__releases(fc->iq.waitq.lock)
__releases(fc->lock)
{
struct fuse_iqueue *fiq = &fc->iq;
Expand Down Expand Up @@ -1260,6 +1291,7 @@ static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file,

restart:
spin_lock(&fc->lock);
spin_lock(&fiq->waitq.lock);
err = -EAGAIN;
if ((file->f_flags & O_NONBLOCK) && fiq->connected &&
!request_pending(fiq))
Expand Down Expand Up @@ -1290,6 +1322,8 @@ static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file,
req = list_entry(fiq->pending.next, struct fuse_req, list);
clear_bit(FR_PENDING, &req->flags);
list_del_init(&req->list);
spin_unlock(&fiq->waitq.lock);

list_add(&req->list, &fc->io);

in = &req->in;
Expand Down Expand Up @@ -1333,6 +1367,7 @@ static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file,
return reqsize;

err_unlock:
spin_unlock(&fiq->waitq.lock);
spin_unlock(&fc->lock);
return err;
}
Expand Down Expand Up @@ -2055,10 +2090,12 @@ static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
poll_wait(file, &fiq->waitq, wait);

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

return mask;
Expand Down Expand Up @@ -2141,11 +2178,13 @@ void fuse_abort_conn(struct fuse_conn *fc)
fc->max_background = UINT_MAX;
flush_bg_queue(fc);

spin_lock(&fiq->waitq.lock);
fiq->connected = 0;
list_splice_init(&fiq->pending, &to_end2);
while (forget_pending(fiq))
kfree(dequeue_forget(fiq, 1, NULL));
wake_up_all(&fiq->waitq);
wake_up_all_locked(&fiq->waitq);
spin_unlock(&fiq->waitq.lock);
kill_fasync(&fiq->fasync, SIGIO, POLL_IN);

list_splice_init(&fc->processing, &to_end2);
Expand Down

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