[Devel] [PATCH RHEL7 COMMIT] ms/fuse: do not take fc->lock in fuse_request_send_background()
Konstantin Khorenko
khorenko at virtuozzo.com
Tue Apr 30 14:35:36 MSK 2019
The commit is pushed to "branch-rh7-3.10.0-957.12.1.vz7.95.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-957.12.1.vz7.95.2
------>
commit 086bce82f96e484eceb680618439655663c8d426
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date: Tue Apr 30 14:35:34 2019 +0300
ms/fuse: do not take fc->lock in fuse_request_send_background()
ms commit 63825b4e1da5
Currently, we take fc->lock there only to check for fc->connected.
But this flag is changed only on connection abort, which is very
rare operation.
So allow checking fc->connected under just fc->bg_lock and use this lock
(as well as fc->lock) when resetting fc->connected.
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi at redhat.com>
=====================
Patchset description:
fuse: Backport of ms locking patches part 2
Here is backport of locking patches: introducing of fc->bg_lock and fi->lock.
This may need additional changes for kio and NOT verified for fast-path.
Reviewed-by: Pavel Butsykin <pbutsykin at virtuozzo.com>
Kirill Tkhai (9):
fuse: introduce fc->bg_lock
fuse: Remove bogus list_del_init() from-fuse_request_send_background
fuse: do not take fc->lock in fuse_request_send_background()
fuse: Add fuse_inode argument to fuse_prepare_release()
fuse: Convert fc->attr_version into atomic64_t
fuse: Introduce fi->lock to protect write related fields
fuse: Protect fi->nlookup with fi->lock
fuse: Protect ff->reserved_req via corresponding fi->lock
fuse: do not take fc->lock in fuse_request_send_background() - fixup
---
fs/fuse/dev.c | 73 ++++++++++++++++++++++++++++----------------------------
fs/fuse/file.c | 4 +++-
fs/fuse/fuse_i.h | 3 +--
3 files changed, 41 insertions(+), 39 deletions(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 1ffc10ff18ba..1355f4a0a8e4 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -598,69 +598,70 @@ void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
}
EXPORT_SYMBOL_GPL(fuse_request_send);
-/*
- * Called under fc->lock
- *
- * fc->connected must have been checked previously
- */
-void fuse_request_send_background_nocheck(struct fuse_conn *fc,
- struct fuse_req *req)
+bool fuse_request_queue_background(struct fuse_conn *fc, struct fuse_req *req)
{
struct fuse_iqueue *fiq = req->fiq;
+ bool queued = false;
- BUG_ON(!test_bit(FR_BACKGROUND, &req->flags));
-
+ WARN_ON(!test_bit(FR_BACKGROUND, &req->flags));
if (!test_bit(FR_WAITING, &req->flags)) {
__set_bit(FR_WAITING, &req->flags);
atomic_inc(&fc->num_waiting);
}
__set_bit(FR_ISREPLY, &req->flags);
spin_lock(&fc->bg_lock);
- fc->num_background++;
- if (fc->num_background == fc->max_background)
- fc->blocked = 1;
- if (fc->num_background == fc->congestion_threshold &&
- fc->bdi_initialized) {
- set_bdi_congested(&fc->bdi, BLK_RW_SYNC);
- set_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
- }
+ if (likely(fc->connected)) {
+ fc->num_background++;
+ if (fc->num_background == fc->max_background)
+ fc->blocked = 1;
+ if (fc->num_background == fc->congestion_threshold && fc->sb) {
+ set_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
+ set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
+ }
- if (test_bit(FR_NONBLOCKING, &req->flags)) {
- 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);
- goto unlock;
- }
+ if (test_bit(FR_NONBLOCKING, &req->flags)) {
+ 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);
+ queued = true;
+ goto unlock;
+ }
- list_add_tail(&req->list, &fc->bg_queue);
- flush_bg_queue(fc, fiq);
+ list_add_tail(&req->list, &fc->bg_queue);
+ flush_bg_queue(fc, fiq);
+ queued = true;
+ }
unlock:
spin_unlock(&fc->bg_lock);
+ return queued;
}
void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
{
- BUG_ON(!req->end);
+ bool fail;
+ WARN_ON(!req->end);
if (fc->kio.op && !fc->kio.op->req_send(fc, req, true, false))
return;
spin_lock(&fc->lock);
- if (req->page_cache && req->ff &&
- test_bit(FUSE_S_FAIL_IMMEDIATELY, &req->ff->ff_state)) {
+ fail = (req->page_cache && req->ff &&
+ test_bit(FUSE_S_FAIL_IMMEDIATELY, &req->ff->ff_state));
+ spin_unlock(&fc->lock);
+
+ if (fail) {
+ /* FIXME */
BUG_ON(req->in.h.opcode != FUSE_READ);
req->out.h.error = -EIO;
__clear_bit(FR_BACKGROUND, &req->flags);
__clear_bit(FR_PENDING, &req->flags);
- spin_unlock(&fc->lock);
request_end(fc, req);
- } else if (fc->connected) {
- fuse_request_send_background_nocheck(fc, req);
- spin_unlock(&fc->lock);
- } else {
- spin_unlock(&fc->lock);
+ return;
+ }
+
+ if (!fuse_request_queue_background(fc, req)) {
req->out.h.error = -ENOTCONN;
req->end(fc, req);
fuse_put_request(fc, req);
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index edc314bd7156..6bffa1eef4dd 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1941,6 +1941,7 @@ __acquires(fc->lock)
loff_t size = i_size_read(req->inode);
struct fuse_write_in *inarg = &req->misc.write.in;
__u64 data_size = req->num_pages * PAGE_CACHE_SIZE;
+ bool queued;
if (!fc->connected ||
test_bit(FUSE_S_FAIL_IMMEDIATELY, &req->ff->ff_state))
@@ -1957,7 +1958,8 @@ __acquires(fc->lock)
req->in.args[1].size = inarg->size;
fi->writectr++;
- fuse_request_send_background_nocheck(fc, req);
+ queued = fuse_request_queue_background(fc, req);
+ WARN_ON(!queued);
return;
out_free:
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a6eb566f8789..ee8b367f2956 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -979,8 +979,7 @@ void fuse_request_check_and_send(struct fuse_conn *fc, struct fuse_req *req,
*/
void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req);
-void fuse_request_send_background_nocheck(struct fuse_conn *fc,
- struct fuse_req *req);
+bool fuse_request_queue_background(struct fuse_conn *fc, struct fuse_req *req);
/* Abort all requests */
void fuse_abort_conn(struct fuse_conn *fc);
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