nfsd: only call inode_query_iversion in the I_VERSION case

inode_query_iversion() can modify i_version.  Depending on the exported
filesystem, that may not be safe.  For example, if you're re-exporting
NFS, NFS stores the server's change attribute in i_version and does not
expect it to be modified locally.  This has been observed causing
unnecessary cache invalidations.

The way a filesystem indicates that it's OK to call
inode_query_iverson() is by setting SB_I_VERSION.

So, move the I_VERSION check out of encode_change(), where it's used
only in GETATTR responses, to nfsd4_change_attribute(), which is
also called for pre- and post- operation attributes.

(Note we could also pull the NFSEXP_V4ROOT case into
nfsd4_change_attribute() as well.  That would actually be a no-op,
since pre/post attrs are only used for metadata-modifying operations,
and V4ROOT exports are read-only.  But we might make the change in
the future just for simplicity.)

Reported-by: Daire Byrne <daire@dneg.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index a6718b952975db389ad8c03187ca9d9fb96769e1..4599de24ef1aa134867efe2abf132ece18fb85af 100644 (file)
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -291,14 +291,13 @@ void fill_post_wcc(struct svc_fh *fhp)
                printk("nfsd: inode locked twice during operation.\n");
 
        err = fh_getattr(fhp, &fhp->fh_post_attr);
-       fhp->fh_post_change = nfsd4_change_attribute(&fhp->fh_post_attr,
-                                                    d_inode(fhp->fh_dentry));
        if (err) {
                fhp->fh_post_saved = false;
-               /* Grab the ctime anyway - set_change_info might use it */
                fhp->fh_post_attr.ctime = d_inode(fhp->fh_dentry)->i_ctime;
        } else
                fhp->fh_post_saved = true;
+       fhp->fh_post_change = nfsd4_change_attribute(&fhp->fh_post_attr,
+                                                    d_inode(fhp->fh_dentry));
 }
 
 /*

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 7142b0501451e56bd79f086b8888d44073536202..ef1f553666168ae29926ba7abaf9f979eb63c406 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2426,12 +2426,8 @@ static __be32 *encode_change(__be32 *p, struct kstat *stat, struct inode *inode,
        if (exp->ex_flags & NFSEXP_V4ROOT) {
                *p++ = cpu_to_be32(convert_to_wallclock(exp->cd->flush_time));
                *p++ = 0;
-       } else if (IS_I_VERSION(inode)) {
+       } else
                p = xdr_encode_hyper(p, nfsd4_change_attribute(stat, inode));
-       } else {
-               *p++ = cpu_to_be32(stat->ctime.tv_sec);
-               *p++ = cpu_to_be32(stat->ctime.tv_nsec);
-       }
        return p;
 }
 

diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
index 56cfbc36156184657590ec14f58dd050afa431d6..39d764b129fa3c6a3cef2e15362e23a07ac8383e 100644 (file)
--- a/fs/nfsd/nfsfh.h
+++ b/fs/nfsd/nfsfh.h
@@ -261,10 +261,16 @@ static inline u64 nfsd4_change_attribute(struct kstat *stat,
 {
        u64 chattr;
 
-       chattr =  stat->ctime.tv_sec;
-       chattr <<= 30;
-       chattr += stat->ctime.tv_nsec;
-       chattr += inode_query_iversion(inode);
+       if (IS_I_VERSION(inode)) {
+               chattr =  stat->ctime.tv_sec;
+               chattr <<= 30;
+               chattr += stat->ctime.tv_nsec;
+               chattr += inode_query_iversion(inode);
+       } else {
+               chattr = stat->ctime.tv_sec;
+               chattr <<= 32;
+               chattr += stat->ctime.tv_nsec;
+       }
        return chattr;
 }