nfsd: skip some unnecessary stats in the v4 case

In the typical case of v4 and an i_version-supporting filesystem, we can
skip a stat which is only required to fake up a change attribute from
ctime.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 00a96054280a6f99d4d556f74ef2387c4d43698f..9d9a01ce0b270835129cfc90d40f6cbb54b0c3c0 100644 (file)
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -364,6 +364,11 @@ encode_wcc_data(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp)
        return encode_post_op_attr(rqstp, p, fhp);
 }
 
+static bool fs_supports_change_attribute(struct super_block *sb)
+{
+       return sb->s_flags & SB_I_VERSION || sb->s_export_op->fetch_iversion;
+}
+
 /*
  * Fill in the pre_op attr for the wcc data
  */
@@ -372,24 +377,26 @@ void fill_pre_wcc(struct svc_fh *fhp)
        struct inode    *inode;
        struct kstat    stat;
        bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
-       __be32 err;
 
        if (fhp->fh_no_wcc || fhp->fh_pre_saved)
                return;
        inode = d_inode(fhp->fh_dentry);
-       err = fh_getattr(fhp, &stat);
-       if (err) {
-               /* Grab the times from inode anyway */
-               stat.mtime = inode->i_mtime;
-               stat.ctime = inode->i_ctime;
-               stat.size  = inode->i_size;
+       if (fs_supports_change_attribute(inode->i_sb) || !v4) {
+               __be32 err = fh_getattr(fhp, &stat);
+
+               if (err) {
+                       /* Grab the times from inode anyway */
+                       stat.mtime = inode->i_mtime;
+                       stat.ctime = inode->i_ctime;
+                       stat.size  = inode->i_size;
+               }
+               fhp->fh_pre_mtime = stat.mtime;
+               fhp->fh_pre_ctime = stat.ctime;
+               fhp->fh_pre_size  = stat.size;
        }
        if (v4)
                fhp->fh_pre_change = nfsd4_change_attribute(&stat, inode);
 
-       fhp->fh_pre_mtime = stat.mtime;
-       fhp->fh_pre_ctime = stat.ctime;
-       fhp->fh_pre_size  = stat.size;
        fhp->fh_pre_saved = true;
 }
 
@@ -400,7 +407,6 @@ void fill_post_wcc(struct svc_fh *fhp)
 {
        bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
        struct inode *inode = d_inode(fhp->fh_dentry);
-       __be32 err;
 
        if (fhp->fh_no_wcc)
                return;
@@ -408,12 +414,16 @@ void fill_post_wcc(struct svc_fh *fhp)
        if (fhp->fh_post_saved)
                printk("nfsd: inode locked twice during operation.\n");
 
-       err = fh_getattr(fhp, &fhp->fh_post_attr);
-       if (err) {
-               fhp->fh_post_saved = false;
-               fhp->fh_post_attr.ctime = inode->i_ctime;
-       } else
-               fhp->fh_post_saved = true;
+       fhp->fh_post_saved = true;
+
+       if (fs_supports_change_attribute(inode->i_sb) || !v4) {
+               __be32 err = fh_getattr(fhp, &fhp->fh_post_attr);
+
+               if (err) {
+                       fhp->fh_post_saved = false;
+                       fhp->fh_post_attr.ctime = inode->i_ctime;
+               }
+       }
        if (v4)
                fhp->fh_post_change =
                        nfsd4_change_attribute(&fhp->fh_post_attr, inode);