From 5053dd6a6d2b481bfcddbd91bacc885b9f0e0ff5 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Mon, 15 Aug 2011 12:44:20 -0400
Subject: avoid deadlock by calling begin_trans() before locking any inodes

---
 file.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'file.c')

diff --git a/file.c b/file.c
index 7101a50..f8a14ad 100644
--- a/file.c
+++ b/file.c
@@ -118,7 +118,6 @@ filewrite(struct file *f, char *addr, int n)
   if(f->type == FD_PIPE)
     return pipewrite(f->pipe, addr, n);
   if(f->type == FD_INODE){
-    ilock(f->ip);
     // write a few blocks at a time to avoid exceeding
     // the maximum log transaction size, including
     // i-node, indirect block, allocation blocks,
@@ -131,9 +130,13 @@ filewrite(struct file *f, char *addr, int n)
       int n1 = n - i;
       if(n1 > max)
         n1 = max;
+
       begin_trans();
+      ilock(f->ip);
       r = writei(f->ip, addr + i, f->off, n1);
+      iunlock(f->ip);
       commit_trans();
+
       if(r < 0)
         break;
       if(r != n1)
@@ -141,7 +144,6 @@ filewrite(struct file *f, char *addr, int n)
       f->off += r;
       i += r;
     }
-    iunlock(f->ip);
     return i == n ? n : -1;
   }
   panic("filewrite");
-- 
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