path: root/0010-afs-Introduce-afs_IsDCacheFresh.patch

From 2fcade1caea1e81f8b5b54c5c08e363649a4664c Mon Sep 17 00:00:00 2001
From: Andrew Deason <adeason@sinenomine.net>
Date: Thu, 17 Jan 2019 15:45:36 -0600
Subject: [PATCH 10/12] afs: Introduce afs_IsDCacheFresh

Numerous places in libafs check the DV of a dcache against the DV of
the vcache for the same file, in order to check if the dcache is up to
date and can be used. Consolidate all of these checks into a new
function, afs_IsDCacheFresh, to make it easier for future commits to
alter this logic.

This commit should have no visible impact; it is just code
reorganization.

Change-Id: Iedc02b0f5d7d0542ab00ff1effdde03c2a851df4
Reviewed-on: https://gerrit.openafs.org/13435
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: Andrew Deason <adeason@sinenomine.net>
(cherry picked from commit 0d8ce846ab2e6c45166a61f04eb3af271cbd27db)
---
 src/afs/LINUX/osi_export.c       |  8 ++++----
 src/afs/LINUX/osi_vnodeops.c     |  8 ++++----
 src/afs/SOLARIS/osi_vnodeops.c   |  6 +++---
 src/afs/VNOPS/afs_vnop_create.c  |  4 ++--
 src/afs/VNOPS/afs_vnop_lookup.c  |  8 ++++----
 src/afs/VNOPS/afs_vnop_read.c    |  4 ++--
 src/afs/VNOPS/afs_vnop_readdir.c |  4 ++--
 src/afs/VNOPS/afs_vnop_remove.c  |  2 +-
 src/afs/VNOPS/afs_vnop_rename.c  |  2 +-
 src/afs/afs_dcache.c             | 30 ++++++++++++++++++++++++------
 src/afs/afs_prototypes.h         |  1 +
 11 files changed, 48 insertions(+), 29 deletions(-)

diff --git a/src/afs/LINUX/osi_export.c b/src/afs/LINUX/osi_export.c
index a3175b5d5..926bd0df9 100644
--- a/src/afs/LINUX/osi_export.c
+++ b/src/afs/LINUX/osi_export.c
@@ -349,7 +349,7 @@ redo:
      */
     while ((adp->f.states & CStatd)
 	   && (tdc->dflags & DFFetching)
-	   && hsame(adp->f.m.DataVersion, tdc->f.versionNo)) {
+	   && afs_IsDCacheFresh(tdc, adp)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseSharedLock(&adp->lock);
 	afs_osi_Sleep(&tdc->validPos);
@@ -357,7 +357,7 @@ redo:
 	ObtainReadLock(&tdc->lock);
     }
     if (!(adp->f.states & CStatd)
-	|| !hsame(adp->f.m.DataVersion, tdc->f.versionNo)) {
+	|| !afs_IsDCacheFresh(tdc, adp)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseSharedLock(&adp->lock);
 	afs_PutDCache(tdc);
@@ -770,7 +770,7 @@ redo:
      */
     while ((vcp->f.states & CStatd)
 	   && (tdc->dflags & DFFetching)
-	   && hsame(vcp->f.m.DataVersion, tdc->f.versionNo)) {
+	   && afs_IsDCacheFresh(tdc, vcp)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseReadLock(&vcp->lock);
 	afs_osi_Sleep(&tdc->validPos);
@@ -778,7 +778,7 @@ redo:
 	ObtainReadLock(&tdc->lock);
     }
     if (!(vcp->f.states & CStatd)
-	|| !hsame(vcp->f.m.DataVersion, tdc->f.versionNo)) {
+	|| !afs_IsDCacheFresh(tdc, vcp)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseReadLock(&vcp->lock);
 	afs_PutDCache(tdc);
diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 1631d3d3d..9f164f395 100644
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -447,7 +447,7 @@ afs_linux_readdir(struct file *fp, void *dirbuf, filldir_t filldir)
      */
     while ((avc->f.states & CStatd)
 	   && (tdc->dflags & DFFetching)
-	   && hsame(avc->f.m.DataVersion, tdc->f.versionNo)) {
+	   && afs_IsDCacheFresh(tdc, avc)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseWriteLock(&avc->lock);
 	afs_osi_Sleep(&tdc->validPos);
@@ -455,7 +455,7 @@ afs_linux_readdir(struct file *fp, void *dirbuf, filldir_t filldir)
 	ObtainReadLock(&tdc->lock);
     }
     if (!(avc->f.states & CStatd)
-	|| !hsame(avc->f.m.DataVersion, tdc->f.versionNo)) {
+	|| !afs_IsDCacheFresh(tdc, avc)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseWriteLock(&avc->lock);
 	afs_PutDCache(tdc);
@@ -2386,7 +2386,7 @@ afs_linux_readpage_fastpath(struct file *fp, struct page *pp, int *codep)
 	ObtainReadLock(&tdc->lock);
 
     /* Is the dcache we've been given currently up to date */
-    if (!hsame(avc->f.m.DataVersion, tdc->f.versionNo) ||
+    if (!afs_IsDCacheFresh(tdc, avc) ||
 	(tdc->dflags & DFFetching))
 	goto out;
 
@@ -2799,7 +2799,7 @@ afs_linux_readpages(struct file *fp, struct address_space *mapping,
 	    AFS_GLOCK();
 	    if ((tdc = afs_FindDCache(avc, offset))) {
 		ObtainReadLock(&tdc->lock);
-		if (!hsame(avc->f.m.DataVersion, tdc->f.versionNo) ||
+		if (!afs_IsDCacheFresh(tdc, avc) ||
 		    (tdc->dflags & DFFetching)) {
 		    ReleaseReadLock(&tdc->lock);
 		    afs_PutDCache(tdc);
diff --git a/src/afs/SOLARIS/osi_vnodeops.c b/src/afs/SOLARIS/osi_vnodeops.c
index fde268401..76b55b351 100644
--- a/src/afs/SOLARIS/osi_vnodeops.c
+++ b/src/afs/SOLARIS/osi_vnodeops.c
@@ -350,7 +350,7 @@ afs_GetOnePage(struct vnode *vp, u_offset_t off, u_int alen, u_int *protp,
 
     /* Check to see whether the cache entry is still valid */
     if (!(avc->f.states & CStatd)
-	|| !hsame(avc->f.m.DataVersion, tdc->f.versionNo)) {
+	|| !afs_IsDCacheFresh(tdc, avc)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseReadLock(&avc->lock);
 	afs_PutDCache(tdc);
@@ -882,12 +882,12 @@ afs_nfsrdwr(struct vcache *avc, struct uio *auio, enum uio_rw arw,
 		AFS_GLOCK();
 		dcp_newpage = afs_FindDCache(avc, pageBase);
 		if (dcp_newpage
-		    && hsame(avc->f.m.DataVersion, dcp_newpage->f.versionNo)) {
+		    && afs_IsDCacheFresh(dcp_newpage, avc)) {
 		    ObtainWriteLock(&avc->lock, 251);
 		    ObtainWriteLock(&avc->vlock, 576);
 		    ObtainReadLock(&dcp_newpage->lock);
 		    if ((avc->activeV == 0)
-			&& hsame(avc->f.m.DataVersion, dcp_newpage->f.versionNo)
+			&& afs_IsDCacheFresh(dcp_newpage, avc)
 			&& !(dcp_newpage->dflags & (DFFetching))) {
 			AFS_GUNLOCK();
 			segmap_pagecreate(segkmap, raddr, rsize, 1);
diff --git a/src/afs/VNOPS/afs_vnop_create.c b/src/afs/VNOPS/afs_vnop_create.c
index fe37eed36..70b531a6a 100644
--- a/src/afs/VNOPS/afs_vnop_create.c
+++ b/src/afs/VNOPS/afs_vnop_create.c
@@ -149,7 +149,7 @@ afs_create(OSI_VC_DECL(adp), char *aname, struct vattr *attrs,
      * received a callback while we were waiting for the write lock.
      */
     if (!(adp->f.states & CStatd)
-	|| (tdc && !hsame(adp->f.m.DataVersion, tdc->f.versionNo))) {
+	|| (tdc && !afs_IsDCacheFresh(tdc, adp))) {
 	ReleaseWriteLock(&adp->lock);
 	if (tdc) {
 	    ReleaseSharedLock(&tdc->lock);
@@ -543,7 +543,7 @@ afs_LocalHero(struct vcache *avc, struct dcache *adc,
     if (adc) {
 	/* does what's in the dcache *now* match what's in the vcache *now*,
 	 * and do we have a valid callback? if not, our local copy is not "ok" */
-	ok = (hsame(avc->f.m.DataVersion, adc->f.versionNo) && avc->callback
+	ok = (afs_IsDCacheFresh(adc, avc) && avc->callback
 	      && (avc->f.states & CStatd) && avc->cbExpires >= osi_Time());
     } else {
 	ok = 0;
diff --git a/src/afs/VNOPS/afs_vnop_lookup.c b/src/afs/VNOPS/afs_vnop_lookup.c
index b42d6db43..f47a505a7 100644
--- a/src/afs/VNOPS/afs_vnop_lookup.c
+++ b/src/afs/VNOPS/afs_vnop_lookup.c
@@ -752,7 +752,7 @@ afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
      */
     while ((adp->f.states & CStatd)
 	   && (dcp->dflags & DFFetching)
-	   && hsame(adp->f.m.DataVersion, dcp->f.versionNo)) {
+	   && afs_IsDCacheFresh(dcp, adp)) {
 	afs_Trace4(afs_iclSetp, CM_TRACE_DCACHEWAIT, ICL_TYPE_STRING,
 		   __FILE__, ICL_TYPE_INT32, __LINE__, ICL_TYPE_POINTER, dcp,
 		   ICL_TYPE_INT32, dcp->dflags);
@@ -763,7 +763,7 @@ afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
 	ObtainReadLock(&dcp->lock);
     }
     if (!(adp->f.states & CStatd)
-	|| !hsame(adp->f.m.DataVersion, dcp->f.versionNo)) {
+	|| !afs_IsDCacheFresh(dcp, adp)) {
 	ReleaseReadLock(&dcp->lock);
 	ReleaseReadLock(&adp->lock);
 	afs_PutDCache(dcp);
@@ -1685,7 +1685,7 @@ afs_lookup(OSI_VC_DECL(adp), char *aname, struct vcache **avcp, afs_ucred_t *acr
 	if (!afs_InReadDir(adp)) {
 	    while ((adp->f.states & CStatd)
 		   && (tdc->dflags & DFFetching)
-		   && hsame(adp->f.m.DataVersion, tdc->f.versionNo)) {
+		   && afs_IsDCacheFresh(tdc, adp)) {
 		ReleaseReadLock(&tdc->lock);
 		ReleaseReadLock(&adp->lock);
 		afs_osi_Sleep(&tdc->validPos);
@@ -1693,7 +1693,7 @@ afs_lookup(OSI_VC_DECL(adp), char *aname, struct vcache **avcp, afs_ucred_t *acr
 		ObtainReadLock(&tdc->lock);
 	    }
 	    if (!(adp->f.states & CStatd)
-		|| !hsame(adp->f.m.DataVersion, tdc->f.versionNo)) {
+		|| !afs_IsDCacheFresh(tdc, adp)) {
 		ReleaseReadLock(&tdc->lock);
 		ReleaseReadLock(&adp->lock);
 		afs_PutDCache(tdc);
diff --git a/src/afs/VNOPS/afs_vnop_read.c b/src/afs/VNOPS/afs_vnop_read.c
index dba411715..e5c664207 100644
--- a/src/afs/VNOPS/afs_vnop_read.c
+++ b/src/afs/VNOPS/afs_vnop_read.c
@@ -190,7 +190,7 @@ afs_read(struct vcache *avc, struct uio *auio, afs_ucred_t *acred,
 	     * 2 requests never return a null dcache entry, btw.
 	     */
 	    if (!(tdc->dflags & DFFetching)
-		&& !hsame(avc->f.m.DataVersion, tdc->f.versionNo)) {
+		&& !afs_IsDCacheFresh(tdc, avc)) {
 		/* have cache entry, it is not coming in now,
 		 * and we'll need new data */
 	      tagain:
@@ -270,7 +270,7 @@ afs_read(struct vcache *avc, struct uio *auio, afs_ucred_t *acred,
 	    } else {
 		/* no longer fetching, verify data version 
 		 * (avoid new GetDCache call) */
-		if (hsame(avc->f.m.DataVersion, tdc->f.versionNo)
+		if (afs_IsDCacheFresh(tdc, avc)
 		    && ((len = tdc->validPos - filePos) > 0)) {
 		    offset = filePos - AFS_CHUNKTOBASE(tdc->f.chunk);
 		} else {
diff --git a/src/afs/VNOPS/afs_vnop_readdir.c b/src/afs/VNOPS/afs_vnop_readdir.c
index cdc5af56d..8d41c3ef2 100644
--- a/src/afs/VNOPS/afs_vnop_readdir.c
+++ b/src/afs/VNOPS/afs_vnop_readdir.c
@@ -702,7 +702,7 @@ afs_readdir(OSI_VC_DECL(avc), struct uio *auio, afs_ucred_t *acred)
      */
     while ((avc->f.states & CStatd)
 	   && (tdc->dflags & DFFetching)
-	   && hsame(avc->f.m.DataVersion, tdc->f.versionNo)) {
+	   && afs_IsDCacheFresh(tdc, avc)) {
 	afs_Trace4(afs_iclSetp, CM_TRACE_DCACHEWAIT, ICL_TYPE_STRING,
 		   __FILE__, ICL_TYPE_INT32, __LINE__, ICL_TYPE_POINTER, tdc,
 		   ICL_TYPE_INT32, tdc->dflags);
@@ -713,7 +713,7 @@ afs_readdir(OSI_VC_DECL(avc), struct uio *auio, afs_ucred_t *acred)
 	ObtainReadLock(&tdc->lock);
     }
     if (!(avc->f.states & CStatd)
-	|| !hsame(avc->f.m.DataVersion, tdc->f.versionNo)) {
+	|| !afs_IsDCacheFresh(tdc, avc)) {
 	ReleaseReadLock(&tdc->lock);
 	ReleaseReadLock(&avc->lock);
 	afs_PutDCache(tdc);
diff --git a/src/afs/VNOPS/afs_vnop_remove.c b/src/afs/VNOPS/afs_vnop_remove.c
index eca9eed24..06a84b060 100644
--- a/src/afs/VNOPS/afs_vnop_remove.c
+++ b/src/afs/VNOPS/afs_vnop_remove.c
@@ -234,7 +234,7 @@ afs_remove(OSI_VC_DECL(adp), char *aname, afs_ucred_t *acred)
      * received a callback while we were waiting for the write lock.
      */
     if (!(adp->f.states & CStatd)
-	|| (tdc && !hsame(adp->f.m.DataVersion, tdc->f.versionNo))) {
+	|| (tdc && !afs_IsDCacheFresh(tdc, adp))) {
 	ReleaseWriteLock(&adp->lock);
 	if (tdc) {
 	    ReleaseSharedLock(&tdc->lock);
diff --git a/src/afs/VNOPS/afs_vnop_rename.c b/src/afs/VNOPS/afs_vnop_rename.c
index 59a1d5032..d61c80e29 100644
--- a/src/afs/VNOPS/afs_vnop_rename.c
+++ b/src/afs/VNOPS/afs_vnop_rename.c
@@ -133,7 +133,7 @@ afsrename(struct vcache *aodp, char *aname1, struct vcache *andp,
      */
     if (tdc1) {
 	if (!(aodp->f.states & CStatd)
-	    || !hsame(aodp->f.m.DataVersion, tdc1->f.versionNo)) {
+	    || !afs_IsDCacheFresh(tdc1, aodp)) {
 
 	    ReleaseWriteLock(&aodp->lock);
 	    if (!oneDir) {
diff --git a/src/afs/afs_dcache.c b/src/afs/afs_dcache.c
index 6a18f80d5..ac9e52269 100644
--- a/src/afs/afs_dcache.c
+++ b/src/afs/afs_dcache.c
@@ -1734,6 +1734,24 @@ afs_AllocDCache(struct vcache *avc, afs_int32 chunk, afs_int32 lock,
     return tdc;
 }
 
+/*!
+ * Check if a dcache is "fresh". That is, if the dcache's DV matches the DV of
+ * the vcache for that file.
+ *
+ * \param adc The dcache to check
+ * \param avc The vcache for adc
+ *
+ * \return 1 if the dcache does match avc's DV; 0 otherwise.
+ */
+int
+afs_IsDCacheFresh(struct dcache *adc, struct vcache *avc)
+{
+    if (!hsame(adc->f.versionNo, avc->f.m.DataVersion)) {
+	return 0;
+    }
+    return 1;
+}
+
 /*
  * afs_GetDCache
  *
@@ -1772,7 +1790,7 @@ void
 updateV2DC(int lockVc, struct vcache *v, struct dcache *d, int src)
 {
     if (!lockVc || 0 == NBObtainWriteLock(&v->lock, src)) {
-	if (hsame(v->f.m.DataVersion, d->f.versionNo) && v->callback)
+	if (afs_IsDCacheFresh(d, v) && v->callback)
 	    v->dchint = d;
 	if (lockVc)
 	    ReleaseWriteLock(&v->lock);
@@ -1882,7 +1900,7 @@ afs_GetDCache(struct vcache *avc, afs_size_t abyte,
 	    ReleaseReadLock(&afs_xdcache);
 	    shortcut = 1;
 
-	    if (hsame(tdc->f.versionNo, avc->f.m.DataVersion)
+	    if (afs_IsDCacheFresh(tdc, avc)
 		&& !(tdc->dflags & DFFetching)) {
 
 		afs_stats_cmperf.dcacheHits++;
@@ -2119,7 +2137,7 @@ afs_GetDCache(struct vcache *avc, afs_size_t abyte,
 	if (AFS_CHUNKTOBASE(chunk) >= avc->f.m.Length &&
 #endif
 #endif /* defined(AFS_AIX32_ENV) || defined(AFS_SGI_ENV) */
-	    !hsame(avc->f.m.DataVersion, tdc->f.versionNo))
+	    !afs_IsDCacheFresh(tdc, avc))
 	    doReallyAdjustSize = 1;
 
 	if (doReallyAdjustSize || overWriteWholeChunk) {
@@ -2183,7 +2201,7 @@ afs_GetDCache(struct vcache *avc, afs_size_t abyte,
      * avc->lock(W) if !setLocks || slowPass
      * tdc->lock(S)
      */
-    if (!hsame(avc->f.m.DataVersion, tdc->f.versionNo) && !overWriteWholeChunk) {
+    if (!afs_IsDCacheFresh(tdc, avc) && !overWriteWholeChunk) {
 	/*
 	 * Version number mismatch.
 	 */
@@ -2253,7 +2271,7 @@ afs_GetDCache(struct vcache *avc, afs_size_t abyte,
 	 */
 
 	/* Watch for standard race condition around osi_FlushText */
-	if (hsame(avc->f.m.DataVersion, tdc->f.versionNo)) {
+	if (afs_IsDCacheFresh(tdc, avc)) {
 	    updateV2DC(setLocks, avc, tdc, 569);	/* set hint */
 	    afs_stats_cmperf.dcacheHits++;
 	    ConvertWToSLock(&tdc->lock);
@@ -3592,7 +3610,7 @@ afs_ObtainDCacheForWriting(struct vcache *avc, afs_size_t filePos,
 	tdc = afs_FindDCache(avc, filePos);
 	if (tdc) {
 	    ObtainWriteLock(&tdc->lock, 658);
-	    if (!hsame(tdc->f.versionNo, avc->f.m.DataVersion)
+	    if (!afs_IsDCacheFresh(tdc, avc)
 		|| (tdc->dflags & DFFetching)) {
 		ReleaseWriteLock(&tdc->lock);
 		afs_PutDCache(tdc);
diff --git a/src/afs/afs_prototypes.h b/src/afs/afs_prototypes.h
index b9fd0782b..c8ed43fa7 100644
--- a/src/afs/afs_prototypes.h
+++ b/src/afs/afs_prototypes.h
@@ -288,6 +288,7 @@ extern struct dcache *afs_ObtainDCacheForWriting(struct vcache *avc,
 						 int noLock);
 extern void afs_PopulateDCache(struct vcache *avc, afs_size_t apos,
 			       struct vrequest *areq);
+extern int afs_IsDCacheFresh(struct dcache *adc, struct vcache *avc);
 
 /* afs_disconnected.c */
 
-- 
2.36.1