NFS: Separate functions for counting outstanding NFS direct I/Os

Factor out the logic that increments and decrements the outstanding I/O
count.  This will be a commonly used bit of code in upcoming patches.
Also make this an atomic_t again, since it will be very often manipulated
outside dreq->spin lock.

Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 20 insertions, 19 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 402005c35ab3..d78c61a41ec3 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -80,8 +80,8 @@ struct nfs_direct_req {
         unsigned int            npages;         /* count of pages */
 
         /* completion state */
+        atomic_t                io_count;       /* i/os we're waiting for */
         spinlock_t              lock;           /* protect completion state */
-        int                     outstanding;    /* i/os we're waiting for */
         ssize_t                 count,          /* bytes actually processed */
                                 error;          /* any reported error */
         struct completion       completion;     /* wait for i/o completion */
@@ -97,6 +97,16 @@ struct nfs_direct_req {
 static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync);
 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
 
+static inline void get_dreq(struct nfs_direct_req *dreq)
+{
+        atomic_inc(&dreq->io_count);
+}
+
+static inline int put_dreq(struct nfs_direct_req *dreq)
+{
+        return atomic_dec_and_test(&dreq->io_count);
+}
+
 /**
  * nfs_direct_IO - NFS address space operation for direct I/O
  * @rw: direction (read or write)
@@ -180,7 +190,7 @@ static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
         dreq->iocb = NULL;
         dreq->ctx = NULL;
         spin_lock_init(&dreq->lock);
-        dreq->outstanding = 0;
+        atomic_set(&dreq->io_count, 0);
         dreq->count = 0;
         dreq->error = 0;
         dreq->flags = 0;
@@ -278,7 +288,7 @@ static struct nfs_direct_req *nfs_direct_read_alloc(size_t nbytes, size_t rsize)
                 list_add(&data->pages, list);
 
                 data->req = (struct nfs_page *) dreq;
-                dreq->outstanding++;
+                get_dreq(dreq);
                 if (nbytes <= rsize)
                         break;
                 nbytes -= rsize;
@@ -302,13 +312,10 @@ static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
         else
                 dreq->error = task->tk_status;
 
-        if (--dreq->outstanding) {
-                spin_unlock(&dreq->lock);
-                return;
-        }
-
         spin_unlock(&dreq->lock);
-        nfs_direct_complete(dreq);
+
+        if (put_dreq(dreq))
+                nfs_direct_complete(dreq);
 }
 
 static const struct rpc_call_ops nfs_read_direct_ops = {
@@ -432,7 +439,7 @@ static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 
         list_splice_init(&dreq->rewrite_list, &dreq->list);
         list_for_each(pos, &dreq->list)
-                dreq->outstanding++;
+                get_dreq(dreq);
         dreq->count = 0;
 
         nfs_direct_write_schedule(dreq, FLUSH_STABLE);
@@ -564,7 +571,7 @@ static struct nfs_direct_req *nfs_direct_write_alloc(size_t nbytes, size_t wsize
                 list_add(&data->pages, list);
 
                 data->req = (struct nfs_page *) dreq;
-                dreq->outstanding++;
+                get_dreq(dreq);
                 if (nbytes <= wsize)
                         break;
                 nbytes -= wsize;
@@ -620,14 +627,8 @@ static void nfs_direct_write_release(void *calldata)
         struct nfs_write_data *data = calldata;
         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 
-        spin_lock(&dreq->lock);
-        if (--dreq->outstanding) {
-                spin_unlock(&dreq->lock);
-                return;
-        }
-        spin_unlock(&dreq->lock);
-
-        nfs_direct_write_complete(dreq, data->inode);
+        if (put_dreq(dreq))
+                nfs_direct_write_complete(dreq, data->inode);
 }
 
 static const struct rpc_call_ops nfs_write_direct_ops = {