nfsd: use vfs_fsync_range(), not O_SYNC, for stable writes

NFSv4 shares the same struct file across multiple writes.  (And we'd
like NFSv2 and NFSv3 to do that as well some day.)

So setting O_SYNC on the struct file as a way to request a synchronous
write doesn't work.

Instead, do a vfs_fsync_range() in that case.

Reported-by: Peter Staubach <pstaubach@exagrid.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index ed3eb59b607e..b584205b25b4 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1024,11 +1024,6 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 
         if (!EX_ISSYNC(exp))
                 stable = 0;
-        if (stable && !use_wgather) {
-                spin_lock(&file->f_lock);
-                file->f_flags |= O_SYNC;
-                spin_unlock(&file->f_lock);
-        }
 
         /* Write the data. */
         oldfs = get_fs(); set_fs(KERNEL_DS);
@@ -1044,8 +1039,12 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
         if (inode->i_mode & (S_ISUID | S_ISGID))
                 kill_suid(dentry);
 
-        if (stable && use_wgather)
-                host_err = wait_for_concurrent_writes(file);
+        if (stable) {
+                if (use_wgather)
+                        host_err = wait_for_concurrent_writes(file);
+                else
+                        host_err = vfs_fsync_range(file, offset, offset+*cnt, 0);
+        }
 
 out_nfserr:
         dprintk("nfsd: write complete host_err=%d\n", host_err);