From: Nickolai Zeldovich <kolya@mit.edu>
Date: Wed, 10 Oct 2001 00:58:44 +0000 (+0000)
Subject: release-buffer-cache-lock-before-opening-file-20011009
X-Git-Tag: openafs-devel-1_3_0~225
X-Git-Url: https://git.michaelhowe.org/gitweb/?a=commitdiff_plain;h=a60bb0c5510d5272458bc1cc368a4c4cd77114a2;p=packages%2Fo%2Fopenafs.git

release-buffer-cache-lock-before-opening-file-20011009

  make the buffer cache release
  the buffer hash lock before trying to open the corresponding file.
  Since we're already holding a buffer cache entry, we can lock it
  instead and let other threads obtain the big hash lock.
---

diff --git a/src/afs/afs_buffer.c b/src/afs/afs_buffer.c
index 8f019ba24..3fc6e4f22 100644
--- a/src/afs/afs_buffer.c
+++ b/src/afs/afs_buffer.c
@@ -232,17 +232,18 @@ char *DRead(fid,page)
       MReleaseWriteLock(&afs_bufferLock);
       return 0;
     }
+    MObtainWriteLock(&tb->lock,260);
+    MReleaseWriteLock(&afs_bufferLock);
+    tb->lockers++;
     tfile = afs_CFileOpen(fid[0]);
     sizep = (afs_int32 *)tfile;
     if (page * AFS_BUFFER_PAGESIZE >= *sizep) {
 	dirp_Zap(tb->fid);
+	tb->lockers--;
+	MReleaseWriteLock(&tb->lock);
 	afs_CFileClose(tfile);
-	MReleaseWriteLock(&afs_bufferLock);
 	return 0;
     }
-    MObtainWriteLock(&tb->lock,260);
-    MReleaseWriteLock(&afs_bufferLock);
-    tb->lockers++;
     code = afs_CFileRead(tfile, tb->page * AFS_BUFFER_PAGESIZE,
 			 tb->data, AFS_BUFFER_PAGESIZE);
     afs_CFileClose(tfile);