From da002a48fbbf69a0d965755d9f6b66817e8a15a5 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Sun, 4 Oct 2020 13:29:04 -0400
Subject: [PATCH] don't unpin if recovering -- the resulting negative refcnt
 suppresses next unpin

---
 kernel/log.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/log.c b/kernel/log.c
index 5e884bb..c8af5bd 100644
--- a/kernel/log.c
+++ b/kernel/log.c
@@ -66,7 +66,7 @@ initlog(int dev, struct superblock *sb)
 
 // Copy committed blocks from log to their home location
 static void
-install_trans(void)
+install_trans(int recovering)
 {
   int tail;
 
@@ -75,7 +75,8 @@ install_trans(void)
     struct buf *dbuf = bread(log.dev, log.lh.block[tail]); // read dst
     memmove(dbuf->data, lbuf->data, BSIZE);  // copy block to dst
     bwrite(dbuf);  // write dst to disk
-    bunpin(dbuf);
+    if(recovering == 0)
+      bunpin(dbuf);
     brelse(lbuf);
     brelse(dbuf);
   }
@@ -116,7 +117,7 @@ static void
 recover_from_log(void)
 {
   read_head();
-  install_trans(); // if committed, copy from log to disk
+  install_trans(1); // if committed, copy from log to disk
   log.lh.n = 0;
   write_head(); // clear the log
 }
@@ -195,7 +196,7 @@ commit()
   if (log.lh.n > 0) {
     write_log();     // Write modified blocks from cache to log
     write_head();    // Write header to disk -- the real commit
-    install_trans(); // Now install writes to home locations
+    install_trans(0); // Now install writes to home locations
     log.lh.n = 0;
     write_head();    // Erase the transaction from the log
   }