NFS: Do not serialise O_DIRECT reads and writes

Allow dio requests to be scheduled in parallel, but ensuring that they
do not conflict with buffered I/O.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 9 insertions, 32 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 0169eca..6d0e880 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -578,17 +578,12 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
 	if (!count)
 		goto out;
 
-	inode_lock(inode);
-	result = nfs_sync_mapping(mapping);
-	if (result)
-		goto out_unlock;
-
 	task_io_account_read(count);
 
 	result = -ENOMEM;
 	dreq = nfs_direct_req_alloc();
 	if (dreq == NULL)
-		goto out_unlock;
+		goto out;
 
 	dreq->inode = inode;
 	dreq->bytes_left = dreq->max_count = count;
@@ -603,10 +598,12 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
 	if (!is_sync_kiocb(iocb))
 		dreq->iocb = iocb;
 
+	nfs_start_io_direct(inode);
+
 	NFS_I(inode)->read_io += count;
 	result = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
 
-	inode_unlock(inode);
+	nfs_end_io_direct(inode);
 
 	if (!result) {
 		result = nfs_direct_wait(dreq);
@@ -614,13 +611,8 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
 			iocb->ki_pos += result;
 	}
 
-	nfs_direct_req_release(dreq);
-	return result;
-
 out_release:
 	nfs_direct_req_release(dreq);
-out_unlock:
-	inode_unlock(inode);
 out:
 	return result;
 }
@@ -1008,25 +1000,12 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
 	pos = iocb->ki_pos;
 	end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
 
-	inode_lock(inode);
-
-	result = nfs_sync_mapping(mapping);
-	if (result)
-		goto out_unlock;
-
-	if (mapping->nrpages) {
-		result = invalidate_inode_pages2_range(mapping,
-					pos >> PAGE_SHIFT, end);
-		if (result)
-			goto out_unlock;
-	}
-
 	task_io_account_write(count);
 
 	result = -ENOMEM;
 	dreq = nfs_direct_req_alloc();
 	if (!dreq)
-		goto out_unlock;
+		goto out;
 
 	dreq->inode = inode;
 	dreq->bytes_left = dreq->max_count = count;
@@ -1041,6 +1020,8 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
 	if (!is_sync_kiocb(iocb))
 		dreq->iocb = iocb;
 
+	nfs_start_io_direct(inode);
+
 	result = nfs_direct_write_schedule_iovec(dreq, iter, pos);
 
 	if (mapping->nrpages) {
@@ -1048,7 +1029,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
 					      pos >> PAGE_SHIFT, end);
 	}
 
-	inode_unlock(inode);
+	nfs_end_io_direct(inode);
 
 	if (!result) {
 		result = nfs_direct_wait(dreq);
@@ -1058,13 +1039,9 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
 			generic_write_sync(iocb, result);
 		}
 	}
-	nfs_direct_req_release(dreq);
-	return result;
-
 out_release:
 	nfs_direct_req_release(dreq);
-out_unlock:
-	inode_unlock(inode);
+out:
 	return result;
 }