[25/48] NFS - fix recent breakage to NFS error handling.

[Greg KH]

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: NeilBrown <neilb@xxxxxxx>

commit 2edb6bc3852c681c0d948245bd55108dc6407604 upstream.

>From c6d615d2b97fe305cbf123a8751ced859dca1d5e Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@xxxxxxx>
Date: Wed, 16 Nov 2011 09:39:05 +1100
Subject: [25/48] NFS - fix recent breakage to NFS error handling.

commit 02c24a82187d5a628c68edfe71ae60dc135cd178 made a small and
presumably unintended change to write error handling in NFS.

Previously an error from filemap_write_and_wait_range would only be of
interest if nfs_file_fsync did not return an error.  After this commit,
an error from filemap_write_and_wait_range would mean that (the rest of)
nfs_file_fsync would not even be called.

This means that:
 1/ you are more likely to see EIO than e.g. EDQUOT or ENOSPC.
 2/ NFS_CONTEXT_ERROR_WRITE remains set for longer so more writes are
    synchronous.

This patch restores previous behaviour.

Cc: Josef Bacik <josef@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/nfs/file.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -321,13 +321,13 @@ nfs_file_fsync(struct file *file, loff_t
 			datasync);
 
 	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
-	if (ret)
-		return ret;
 	mutex_lock(&inode->i_mutex);
 
 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
 	have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 	status = nfs_commit_inode(inode, FLUSH_SYNC);
+	if (status >= 0 && ret < 0)
+		status = ret;
 	have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 	if (have_error)
 		ret = xchg(&ctx->error, 0);


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