2 files changed, 54 insertions, 23 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 07f4379..5595b32 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -177,6 +177,31 @@ static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
 }
 
 /*
+ * Helper for nfs_file_flush() and nfs_fsync()
+ *
+ * Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
+ * disk, but it retrieves and clears ctx->error after synching, despite
+ * the two being set at the same time in nfs_context_set_write_error().
+ * This is because the former is used to notify the _next_ call to
+ * nfs_file_write() that a write error occured, and hence cause it to
+ * fall back to doing a synchronous write.
+ */
+static int nfs_do_fsync(struct nfs_open_context *ctx, struct inode *inode)
+{
+	int have_error, status;
+	int ret = 0;
+
+	have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
+	status = nfs_wb_all(inode);
+	have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
+	if (have_error)
+		ret = xchg(&ctx->error, 0);
+	if (!ret)
+		ret = status;
+	return ret;
+}
+
+/*
  * Flush all dirty pages, and check for write errors.
  *
  */
@@ -192,16 +217,11 @@ nfs_file_flush(struct file *file, fl_owner_t id)
 	if ((file->f_mode & FMODE_WRITE) == 0)
 		return 0;
 	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
-	lock_kernel();
+
 	/* Ensure that data+attribute caches are up to date after close() */
-	status = nfs_wb_all(inode);
-	if (!status) {
-		status = ctx->error;
-		ctx->error = 0;
-		if (!status)
-			nfs_revalidate_inode(NFS_SERVER(inode), inode);
-	}
-	unlock_kernel();
+	status = nfs_do_fsync(ctx, inode);
+	if (!status)
+		nfs_revalidate_inode(NFS_SERVER(inode), inode);
 	return status;
 }
 
@@ -278,19 +298,11 @@ nfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 {
 	struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 	struct inode *inode = dentry->d_inode;
-	int status;
 
 	dfprintk(VFS, "nfs: fsync(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
 
 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
-	lock_kernel();
-	status = nfs_wb_all(inode);
-	if (!status) {
-		status = ctx->error;
-		ctx->error = 0;
-	}
-	unlock_kernel();
-	return status;
+	return nfs_do_fsync(ctx, inode);
 }
 
 /*
@@ -377,6 +389,18 @@ static struct vm_operations_struct nfs_file_vm_ops = {
 	.page_mkwrite = nfs_vm_page_mkwrite,
 };
 
+static int nfs_need_sync_write(struct file *filp, struct inode *inode)
+{
+	struct nfs_open_context *ctx;
+
+	if (IS_SYNC(inode) || (filp->f_flags & O_SYNC))
+		return 1;
+	ctx = filp->private_data;
+	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags))
+		return 1;
+	return 0;
+}
+
 static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
 				unsigned long nr_segs, loff_t pos)
 {
@@ -413,8 +437,8 @@ static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
 	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, count);
 	result = generic_file_aio_write(iocb, iov, nr_segs, pos);
 	/* Return error values for O_SYNC and IS_SYNC() */
-	if (result >= 0 && (IS_SYNC(inode) || (iocb->ki_filp->f_flags & O_SYNC))) {
-		int err = nfs_fsync(iocb->ki_filp, dentry, 1);
+	if (result >= 0 && nfs_need_sync_write(iocb->ki_filp, inode)) {
+		int err = nfs_do_fsync(iocb->ki_filp->private_data, inode);
 		if (err < 0)
 			result = err;
 	}
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index b3c5f5d..fb396ea 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -110,6 +110,13 @@ void nfs_writedata_release(void *wdata)
 	nfs_writedata_free(wdata);
 }
 
+static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
+{
+	ctx->error = error;
+	smp_wmb();
+	set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
+}
+
 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 {
 	struct nfs_page *req = NULL;
@@ -945,7 +952,7 @@ static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
 
 	if (task->tk_status < 0) {
 		nfs_set_pageerror(page);
-		req->wb_context->error = task->tk_status;
+		nfs_context_set_write_error(req->wb_context, task->tk_status);
 		dprintk(", error = %d\n", task->tk_status);
 		goto out;
 	}
@@ -1008,7 +1015,7 @@ static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
 
 		if (task->tk_status < 0) {
 			nfs_set_pageerror(page);
-			req->wb_context->error = task->tk_status;
+			nfs_context_set_write_error(req->wb_context, task->tk_status);
 			dprintk(", error = %d\n", task->tk_status);
 			goto remove_request;
 		}
@@ -1222,7 +1229,7 @@ static void nfs_commit_done(struct rpc_task *task, void *calldata)
 			req->wb_bytes,
 			(long long)req_offset(req));
 		if (task->tk_status < 0) {
-			req->wb_context->error = task->tk_status;
+			nfs_context_set_write_error(req->wb_context, task->tk_status);
 			nfs_inode_remove_request(req);
 			dprintk(", error = %d\n", task->tk_status);
 			goto next;