Author: jhb
Date: Thu Jun 10 20:13:23 2010
New Revision: 209005
URL: http://svn.freebsd.org/changeset/base/209005
Log:
MFC 208603:
More gracefully handle stale file handles and attributes when opening a
file via NFS. Specifically, to satisfy close-to-open-consistency, the NFS
client always performs at least one RPC on a file during an open(2) to see
if the file has changed. Normally this RPC is an ACCESS or GETATTR RPC
that is forced by flushing a file's attribute cache during nfs_open() and
then requesting new attributes. However, if the file is noticed to be
stale during nfs_open(), the only recourse is to fail the open(2) call
with ESTALE. On the other hand, if the ACCESS or GETATTR RPC is sent
during nfs_lookup(), then the NFS client can fall back to a LOOKUP RPC to
obtain the new file handle in the case that a file has been replaced.
This change causes the NFS client to flush the attribute cache during
nfs_lookup() when validating a name cache hit if the attributes fetched
during nfs_lookup() can be reused in nfs_open(). This allows the client
to open a replaced file via the new file handle the first time that it
notices a replaced file rather than failing with ESTALE in some cases.
Modified:
stable/7/sys/nfsclient/nfs_vnops.c
Directory Properties:
stable/7/sys/ (props changed)
stable/7/sys/cddl/contrib/opensolaris/ (props changed)
stable/7/sys/contrib/dev/acpica/ (props changed)
stable/7/sys/contrib/pf/ (props changed)
Modified: stable/7/sys/nfsclient/nfs_vnops.c
==============================================================================
--- stable/7/sys/nfsclient/nfs_vnops.c Thu Jun 10 20:13:10 2010
(r209004)
+++ stable/7/sys/nfsclient/nfs_vnops.c Thu Jun 10 20:13:23 2010
(r209005)
@@ -875,7 +875,7 @@ nfs_lookup(struct vop_lookup_args *ap)
struct mbuf *mreq, *mrep, *md, *mb;
long len;
nfsfh_t *fhp;
- struct nfsnode *np;
+ struct nfsnode *np, *newnp;
int error = 0, attrflag, fhsize;
int v3 = NFS_ISV3(dvp);
struct thread *td = cnp->cn_thread;
@@ -901,10 +901,26 @@ nfs_lookup(struct vop_lookup_args *ap)
* change time of the file matches our cached copy.
* Otherwise, we discard the cache entry and fallback
* to doing a lookup RPC.
+ *
+ * To better handle stale file handles and attributes,
+ * clear the attribute cache of this node if it is a
+ * leaf component, part of an open() call, and not
+ * locally modified before fetching the attributes.
+ * This should allow stale file handles to be detected
+ * here where we can fall back to a LOOKUP RPC to
+ * recover rather than having nfs_open() detect the
+ * stale file handle and failing open(2) with ESTALE.
*/
newvp = *vpp;
- if (!VOP_GETATTR(newvp, &vattr, cnp->cn_cred, td)
- && vattr.va_ctime.tv_sec == VTONFS(newvp)->n_ctime) {
+ newnp = VTONFS(newvp);
+ if ((cnp->cn_flags & (ISLASTCN | ISOPEN)) ==
+ (ISLASTCN | ISOPEN) && !(newnp->n_flag & NMODIFIED)) {
+ mtx_lock(&newnp->n_mtx);
+ newnp->n_attrstamp = 0;
+ mtx_unlock(&newnp->n_mtx);
+ }
+ if (VOP_GETATTR(newvp, &vattr, cnp->cn_cred, td) == 0 &&
+ vattr.va_ctime.tv_sec == newnp->n_ctime) {
nfsstats.lookupcache_hits++;
if (cnp->cn_nameiop != LOOKUP &&
(flags & ISLASTCN))
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
