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

commit a0d24b295aed7a9daf4ca36bd4784e4d40f82303 upstream.

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>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 8b38bcf7a49bc0d042f00fb6f9fd6ef58076c951..ac31e0c7afce35bd6f02d9f163c22d32cfa25780 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1003,6 +1003,7 @@ 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);
        }
@@ -1048,10 +1049,9 @@ 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;