nfsd: Use vfs_fsync_range() in nfsd_commit

The NFS COMMIT operation allows the client to specify the exact byte range
that it wishes to sync to disk in order to optimise server performance.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 20 insertions, 10 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 79d216f276d9..ed024d329056 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1141,8 +1141,9 @@ out:
 #ifdef CONFIG_NFSD_V3
 /*
  * Commit all pending writes to stable storage.
- * Strictly speaking, we could sync just the indicated file region here,
- * but there's currently no way we can ask the VFS to do so.
+ *
+ * Note: we only guarantee that data that lies within the range specified
+ * by the 'offset' and 'count' parameters will be synced.
  *
  * Unfortunately we cannot lock the file to make sure we return full WCC
  * data to the client, as locking happens lower down in the filesystem.
@@ -1152,23 +1153,32 @@ nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
                loff_t offset, unsigned long count)
 {
         struct file     *file;
-        __be32          err;
+        loff_t          end = LLONG_MAX;
+        __be32          err = nfserr_inval;
 
-        if ((u64)count > ~(u64)offset)
-                return nfserr_inval;
+        if (offset < 0)
+                goto out;
+        if (count != 0) {
+                end = offset + (loff_t)count - 1;
+                if (end < offset)
+                        goto out;
+        }
 
         err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_WRITE, &file);
         if (err)
-                return err;
+                goto out;
         if (EX_ISSYNC(fhp->fh_export)) {
-                if (file->f_op && file->f_op->fsync) {
-                        err = nfserrno(vfs_fsync(file, file->f_path.dentry, 0));
-                } else {
+                int err2 = vfs_fsync_range(file, file->f_path.dentry,
+                                offset, end, 0);
+
+                if (err2 != -EINVAL)
+                        err = nfserrno(err2);
+                else
                         err = nfserr_notsupp;
-                }
         }
 
         nfsd_close(file);
+out:
         return err;
 }
 #endif /* CONFIG_NFSD_V3 */