nfsd: fix hung up of nfs client while sync write data to nfs server

Commit 'Short write in nfsd becomes a full write to the client'
(31dec2538e45e9fff2007ea1f4c6bae9f78db724) broken the sync write.
With the following commands to reproduce:

  $ mount -t nfs -o sync 192.168.0.21:/nfsroot /mnt
  $ cd /mnt
  $ echo aaaa > temp.txt

Then nfs client is hung up.

In SYNC mode the server alaways return the write count 0 to the
client. This is because the value of host_err in nfsd_vfs_write()
will be overwrite in SYNC mode by 'host_err=nfsd_sync(file);',
and then we return host_err(which is now 0) as write count.

This patch fixed the problem.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 6c68ffd6b4bb..b660435978d2 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1015,6 +1015,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
         host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &offset);
         set_fs(oldfs);
         if (host_err >= 0) {
+                *cnt = host_err;
                 nfsdstats.io_write += host_err;
                 fsnotify_modify(file->f_path.dentry);
         }
@@ -1060,10 +1061,9 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
         }
 
         dprintk("nfsd: write complete host_err=%d\n", host_err);
-        if (host_err >= 0) {
+        if (host_err >= 0)
                 err = 0;
-                *cnt = host_err;
-        } else
+        else
                 err = nfserrno(host_err);
 out:
         return err;