From 5e0e1ea2540d0cb7d7274350eb1fadfd41733ea4 Mon Sep 17 00:00:00 2001
From: Felix Frank <Felix.Frank@Desy.de>
Date: Tue, 12 May 2009 18:56:30 +0000
Subject: [PATCH] linux-mmap-antirecursion-fix-20090512

LICENSE IPL10
FIXES 124627

fix the mmap anti-recursion protection to set and mask CPageWrite appropriately
and with the correct lock protection. this leaves us with an issue to handle
when the mmap'd file is larger (possibly considerably larger) than the
cache
---
 src/afs/LINUX/osi_vm.c       |  5 +----
 src/afs/LINUX/osi_vnodeops.c | 22 +++++++++++++++-------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/afs/LINUX/osi_vm.c b/src/afs/LINUX/osi_vm.c
index c96babd668..55a3737e78 100644
--- a/src/afs/LINUX/osi_vm.c
+++ b/src/afs/LINUX/osi_vm.c
@@ -102,9 +102,7 @@ osi_VM_StoreAllSegments(struct vcache *avc)
 {
     struct inode *ip = AFSTOV(avc);
 
-    if (!avc->f.states & CPageWrite)
-	avc->f.states |= CPageWrite;
-    else 
+    if (avc->f.states & CPageWrite)
 	return; /* someone already writing */
 
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,5)
@@ -120,7 +118,6 @@ osi_VM_StoreAllSegments(struct vcache *avc)
     AFS_GLOCK();
     ObtainWriteLock(&avc->lock, 121);
 #endif
-    avc->f.states &= ~CPageWrite;
 }
 
 /* Purge VM for a file when its callback is revoked.
diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index 67e7bad36b..39bd08151b 100644
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -1188,7 +1188,7 @@ afs_linux_lookup(struct inode *dip, struct dentry *dp)
     if (code == ENOENT)
 	return ERR_PTR(0);
 #endif
-    else if ((code >= 0) && (code <= MAX_ERRNO))
+    else if ((code > 0) && (code <= MAX_ERRNO))
         return ERR_PTR(-code);
     else 
 	return ERR_PTR(-EIO);
@@ -1895,9 +1895,9 @@ afs_linux_writepage_sync(struct inode *ip, struct page *pp,
 	       ICL_TYPE_POINTER, pp, ICL_TYPE_INT32, page_count(pp),
 	       ICL_TYPE_INT32, 99999);
 
-    ObtainReadLock(&vcp->lock);
+    ObtainWriteLock(&vcp->lock, 532);
     if (vcp->f.states & CPageWrite) {
-	ReleaseReadLock(&vcp->lock);
+	ReleaseWriteLock(&vcp->lock);
 	AFS_GUNLOCK();
 	maybe_unlock_kernel();
 	crfree(credp);
@@ -1913,7 +1913,8 @@ afs_linux_writepage_sync(struct inode *ip, struct page *pp,
 	return(0); 
 #endif
     }
-    ReleaseReadLock(&vcp->lock);
+    vcp->states |= CPageWrite;
+    ReleaseWriteLock(&vcp->lock);
 
     setup_uio(&tuio, &iovec, buffer, base, count, UIO_WRITE, AFS_UIOSYS);
 
@@ -1922,16 +1923,18 @@ afs_linux_writepage_sync(struct inode *ip, struct page *pp,
     i_size_write(ip, vcp->f.m.Length);
     ip->i_blocks = ((vcp->f.m.Length + 1023) >> 10) << 1;
 
+    ObtainWriteLock(&vcp->lock, 533);
     if (!code) {
 	struct vrequest treq;
 
-	ObtainWriteLock(&vcp->lock, 533);
 	if (!afs_InitReq(&treq, credp))
 	    code = afs_DoPartialWrite(vcp, &treq);
-	ReleaseWriteLock(&vcp->lock);
     }
     code = code ? -code : count - tuio.uio_resid;
 
+    vcp->states &= ~CPageWrite;
+    ReleaseWriteLock(&vcp->lock);
+
     afs_Trace4(afs_iclSetp, CM_TRACE_UPDATEPAGE, ICL_TYPE_POINTER, vcp,
 	       ICL_TYPE_POINTER, pp, ICL_TYPE_INT32, page_count(pp),
 	       ICL_TYPE_INT32, code);
@@ -1986,7 +1989,12 @@ afs_linux_writepage(struct page *pp)
   do_it:
     status = afs_linux_writepage_sync(inode, pp, 0, offset);
     SetPageUptodate(pp);
-    UnlockPage(pp);
+#if defined(WRITEPAGE_ACTIVATE)
+    if ( status != WRITEPAGE_ACTIVATE )
+#else
+    if ( status != AOP_WRITEPAGE_ACTIVATE )
+#endif
+	UnlockPage(pp);
     if (status == offset)
 	return 0;
     else