3 files changed, 57 insertions, 23 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 07f43791f696..5595b32c0915 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 b3c5f5db73a4..fb396ea5accf 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;
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 15eec27cb60b..1d1343fd2ddd 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -77,6 +77,9 @@ struct nfs_open_context {
         struct nfs4_state *state;
         fl_owner_t lockowner;
         int mode;
+
+        unsigned long flags;
+#define NFS_CONTEXT_ERROR_WRITE         (0)
         int error;
 
         struct list_head list;