From: Andrew Deason <adeason@sinenomine.net>
Date: Thu, 13 Jul 2017 22:40:21 +0000 (-0500)
Subject: afs: Change VerifyVCache2 calls to VerifyVCache
X-Git-Tag: openafs-devel-1_9_0~49
X-Git-Url: http://git.openafs.org/?p=openafs.git;a=commitdiff_plain;h=a05d5b7503e466e18f5157006c1de2a2f7d019f7

afs: Change VerifyVCache2 calls to VerifyVCache

afs_VerifyVCache is a macro that (on most platforms) effectively
expands to:

    if ((avc->f.states & CStatd)) {
        return 0;
    } else {
        return afs_VerifyVCache2(...);
    }

Some callers call afs_VerifyVCache2 directly, since they already check
for CStatd for other reasons. A few callers currently call
afs_VerifyVCache2, but without guaranteeing that CStatd is not set.
Specifically, in afs_getattr and afs_linux_VerifyVCache, CStatd could
be set while afs_CreateReq drops GLOCK. And in afs_linux_readdir,
CStatd could be cleared at multiple different points before the
VerifyVCache call.

This can result in afs_VerifyVCache2 acquiring a write-lock on the
vcache, even when CStatd is already set, which is an unnecessary
performance hit.

To avoid this, change these call sites to use afs_VerifyVCache instead
of calling afs_VerifyVCache2 directly, which skips the write lock when
CStatd is already set.

Change-Id: I7b75c9755af147b42a48160fa90c9849f2f03ddb
Reviewed-on: https://gerrit.openafs.org/12655
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
---

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 48c25aa..5017ef4 100644
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -171,7 +171,7 @@ afs_linux_VerifyVCache(struct vcache *avc, cred_t **retcred) {
 
     code = afs_CreateReq(&treq, credp);
     if (code == 0) {
-        code = afs_VerifyVCache2(avc, treq);
+	code = afs_VerifyVCache(avc, treq);
 	afs_DestroyReq(treq);
     }
 
@@ -413,7 +413,7 @@ afs_linux_readdir(struct file *fp, void *dirbuf, filldir_t filldir)
 
     /* update the cache entry */
   tagain:
-    code = afs_convert_code(afs_VerifyVCache2(avc, treq));
+    code = afs_convert_code(afs_VerifyVCache(avc, treq));
     if (code)
 	goto out;
 
diff --git a/src/afs/VNOPS/afs_vnop_attrs.c b/src/afs/VNOPS/afs_vnop_attrs.c
index a22331a..7166bf3 100644
--- a/src/afs/VNOPS/afs_vnop_attrs.c
+++ b/src/afs/VNOPS/afs_vnop_attrs.c
@@ -248,7 +248,7 @@ afs_getattr(OSI_VC_DECL(avc), struct vattr *attrs, afs_ucred_t *acred)
 
     if (!(avc->f.states & CStatd)) {
 	if (!(code = afs_CreateReq(&treq, acred))) {
-	    code = afs_VerifyVCache2(avc, treq);
+	    code = afs_VerifyVCache(avc, treq);
 	    inited = 1;
 	}
     } else