Backport from ml:
commit c47752673acb130e5132db0e52363e15be260ca4
Author: Miklos Szeredi <[email protected]>
Date: Wed Jul 1 16:26:00 2015 +0200
fuse: don't hold lock over request_wait_answer()
Only hold fc->lock over sections of request_wait_answer() that actually
need it. If wait_event_interruptible() returns zero, it means that the
request finished. Need to add memory barriers, though, to make sure that
all relevant data in the request is synchronized.
Signed-off-by: Miklos Szeredi <[email protected]>
Signed-off-by: Maxim Patlasov <[email protected]>
---
fs/fuse/dev.c | 61 +++++++++++++++++++++------------------------------------
1 file changed, 22 insertions(+), 39 deletions(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 22e2547..016a854 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -364,6 +364,7 @@ __releases(fc->lock)
req->end = NULL;
list_del_init(&req->list);
list_del_init(&req->intr_entry);
+ smp_wmb();
req->state = FUSE_REQ_FINISHED;
if (test_bit(FR_BACKGROUND, &req->flags)) {
clear_bit(FR_BACKGROUND, &req->flags);
@@ -390,32 +391,6 @@ __releases(fc->lock)
fuse_put_request(fc, req);
}
-static void wait_answer_interruptible(struct fuse_conn *fc,
- struct fuse_req *req)
-__releases(fc->lock)
-__acquires(fc->lock)
-{
- 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 wait_answer_killable(struct fuse_conn *fc,
- struct fuse_req *req)
-__releases(fc->lock)
-__acquires(fc->lock)
-{
- if (fatal_signal_pending(current))
- return;
-
- spin_unlock(&fc->lock);
- wait_event_killable(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);
@@ -424,44 +399,48 @@ static void queue_interrupt(struct fuse_conn *fc, struct
fuse_req *req)
}
static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
-__releases(fc->lock)
-__acquires(fc->lock)
{
+ int err;
+
if (!fc->no_interrupt) {
/* Any signal may interrupt this */
- wait_answer_interruptible(fc, req);
-
- if (req->state == FUSE_REQ_FINISHED)
+ err = wait_event_interruptible(req->waitq,
+ req->state == FUSE_REQ_FINISHED);
+ if (!err)
return;
+ spin_lock(&fc->lock);
set_bit(FR_INTERRUPTED, &req->flags);
if (req->state == FUSE_REQ_SENT)
queue_interrupt(fc, req);
+ spin_unlock(&fc->lock);
}
if (!test_bit(FR_FORCE, &req->flags)) {
/* Only fatal signals may interrupt this */
- wait_answer_killable(fc, req);
+ err = wait_event_killable(req->waitq,
+ req->state == FUSE_REQ_FINISHED);
- if (req->state == FUSE_REQ_FINISHED)
+ if (!err)
return;
+ spin_lock(&fc->lock);
/* Request is not yet in userspace, bail out */
if (req->state == FUSE_REQ_PENDING) {
list_del(&req->list);
+ spin_unlock(&fc->lock);
__fuse_put_request(req);
req->out.h.error = -EINTR;
return;
}
+ spin_unlock(&fc->lock);
}
/*
* Either request is already in userspace, or it was forced.
* Wait it out.
*/
- spin_unlock(&fc->lock);
wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
- spin_lock(&fc->lock);
}
static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req,
@@ -469,20 +448,24 @@ 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);
- if (!fc->connected)
+ if (!fc->connected) {
+ spin_unlock(&fc->lock);
req->out.h.error = -ENOTCONN;
- else if (ff && test_bit(FUSE_S_FAIL_IMMEDIATELY, &ff->ff_state))
+ } else if (ff && test_bit(FUSE_S_FAIL_IMMEDIATELY, &ff->ff_state)) {
+ spin_unlock(&fc->lock);
req->out.h.error = -EIO;
- else {
+ } else {
req->in.h.unique = fuse_get_unique(fc);
queue_request(fc, req);
/* acquire extra reference, since request is still needed
after request_end() */
__fuse_get_request(req);
+ spin_unlock(&fc->lock);
request_wait_answer(fc, req);
+ /* Pairs with smp_wmb() in request_end() */
+ smp_rmb();
}
- spin_unlock(&fc->lock);
}
void fuse_request_check_and_send(struct fuse_conn *fc, struct fuse_req *req,
_______________________________________________
Devel mailing list
[email protected]
https://lists.openvz.org/mailman/listinfo/devel
