fuse: introduce fc->bg_lock

To reduce contention of fc->lock, this patch introduces bg_lock for
protection of fields related to background queue. These are:
max_background, congestion_threshold, num_background, active_background,
bg_queue and blocked.

This allows next patch to make async reads not requiring fc->lock, so async
reads and writes will have better performance executed in parallel.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index eaa0e2b..989df5a 100644 (file)
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -125,12 +125,12 @@ static ssize_t fuse_conn_max_background_write(struct file *file,
        if (ret > 0) {
                struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
                if (fc) {
-                       spin_lock(&fc->lock);
+                       spin_lock(&fc->bg_lock);
                        fc->max_background = val;
                        fc->blocked = fc->num_background >= fc->max_background;
                        if (!fc->blocked)
                                wake_up(&fc->blocked_waitq);
-                       spin_unlock(&fc->lock);
+                       spin_unlock(&fc->bg_lock);
                        fuse_conn_put(fc);
                }
        }
@@ -171,7 +171,7 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
        if (!fc)
                goto out;
 
-       spin_lock(&fc->lock);
+       spin_lock(&fc->bg_lock);
        fc->congestion_threshold = val;
        if (fc->sb) {
                if (fc->num_background < fc->congestion_threshold) {
@@ -182,7 +182,7 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
                        set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
                }
        }
-       spin_unlock(&fc->lock);
+       spin_unlock(&fc->bg_lock);
        fuse_conn_put(fc);
 out:
        return ret;

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 6a7d3b4..d4b9ffc 100644 (file)
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -287,10 +287,10 @@ void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
                         * We get here in the unlikely case that a background
                         * request was allocated but not sent
                         */
-                       spin_lock(&fc->lock);
+                       spin_lock(&fc->bg_lock);
                        if (!fc->blocked)
                                wake_up(&fc->blocked_waitq);
-                       spin_unlock(&fc->lock);
+                       spin_unlock(&fc->bg_lock);
                }
 
                if (test_bit(FR_WAITING, &req->flags)) {
@@ -390,7 +390,7 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
        WARN_ON(test_bit(FR_PENDING, &req->flags));
        WARN_ON(test_bit(FR_SENT, &req->flags));
        if (test_bit(FR_BACKGROUND, &req->flags)) {
-               spin_lock(&fc->lock);
+               spin_lock(&fc->bg_lock);
                clear_bit(FR_BACKGROUND, &req->flags);
                if (fc->num_background == fc->max_background) {
                        fc->blocked = 0;
@@ -413,7 +413,7 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
                fc->num_background--;
                fc->active_background--;
                flush_bg_queue(fc);
-               spin_unlock(&fc->lock);
+               spin_unlock(&fc->bg_lock);
        }
        wake_up(&req->waitq);
        if (req->end)
@@ -586,8 +586,8 @@ ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args)
  *
  * fc->connected must have been checked previously
  */
-void fuse_request_send_background_locked(struct fuse_conn *fc,
-                                        struct fuse_req *req)
+void fuse_request_send_background_nocheck(struct fuse_conn *fc,
+                                         struct fuse_req *req)
 {
        BUG_ON(!test_bit(FR_BACKGROUND, &req->flags));
        if (!test_bit(FR_WAITING, &req->flags)) {
@@ -595,6 +595,7 @@ void fuse_request_send_background_locked(struct fuse_conn *fc,
                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;
@@ -604,6 +605,7 @@ void fuse_request_send_background_locked(struct fuse_conn *fc,
        }
        list_add_tail(&req->list, &fc->bg_queue);
        flush_bg_queue(fc);
+       spin_unlock(&fc->bg_lock);
 }
 
 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
@@ -611,7 +613,7 @@ void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
        BUG_ON(!req->end);
        spin_lock(&fc->lock);
        if (fc->connected) {
-               fuse_request_send_background_locked(fc, req);
+               fuse_request_send_background_nocheck(fc, req);
                spin_unlock(&fc->lock);
        } else {
                spin_unlock(&fc->lock);
@@ -2118,7 +2120,6 @@ void fuse_abort_conn(struct fuse_conn *fc, bool is_abort)
                LIST_HEAD(to_end);
 
                fc->connected = 0;
-               fc->blocked = 0;
                fc->aborted = is_abort;
                fuse_set_initialized(fc);
                list_for_each_entry(fud, &fc->devices, entry) {
@@ -2140,8 +2141,11 @@ void fuse_abort_conn(struct fuse_conn *fc, bool is_abort)
                        list_splice_tail_init(&fpq->processing, &to_end);
                        spin_unlock(&fpq->lock);
                }
+               spin_lock(&fc->bg_lock);
+               fc->blocked = 0;
                fc->max_background = UINT_MAX;
                flush_bg_queue(fc);
+               spin_unlock(&fc->bg_lock);
 
                spin_lock(&fiq->waitq.lock);
                fiq->connected = 0;

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 63136a2..65351d4 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1502,7 +1502,7 @@ __acquires(fc->lock)
 
        req->in.args[1].size = inarg->size;
        fi->writectr++;
-       fuse_request_send_background_locked(fc, req);
+       fuse_request_send_background_nocheck(fc, req);
        return;
 
  out_free:

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 3e45d40..d6d5564 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -500,6 +500,10 @@ struct fuse_conn {
        /** The list of background requests set aside for later queuing */
        struct list_head bg_queue;
 
+       /** Protects: max_background, congestion_threshold, num_background,
+        * active_background, bg_queue, blocked */
+       spinlock_t bg_lock;
+
        /** Flag indicating that INIT reply has been received. Allocating
         * any fuse request will be suspended until the flag is set */
        int initialized;
@@ -860,8 +864,8 @@ ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args);
  */
 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 
-void fuse_request_send_background_locked(struct fuse_conn *fc,
-                                        struct fuse_req *req);
+void fuse_request_send_background_nocheck(struct fuse_conn *fc,
+                                         struct fuse_req *req);
 
 /* Abort all requests */
 void fuse_abort_conn(struct fuse_conn *fc, bool is_abort);

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index db9e60b..ed3f496 100644 (file)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -605,6 +605,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns)
 {
        memset(fc, 0, sizeof(*fc));
        spin_lock_init(&fc->lock);
+       spin_lock_init(&fc->bg_lock);
        init_rwsem(&fc->killsb);
        refcount_set(&fc->count, 1);
        atomic_set(&fc->dev_count, 1);
@@ -852,6 +853,7 @@ static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
        sanitize_global_limit(&max_user_bgreq);
        sanitize_global_limit(&max_user_congthresh);
 
+       spin_lock(&fc->bg_lock);
        if (arg->max_background) {
                fc->max_background = arg->max_background;
 
@@ -865,6 +867,7 @@ static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
                    fc->congestion_threshold > max_user_congthresh)
                        fc->congestion_threshold = max_user_congthresh;
        }
+       spin_unlock(&fc->bg_lock);
 }
 
 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)