Introduce and use sleeplocks instead of BUSY flags

Remove I_BUSY, B_BUSY, and intrans defs and usages
One spinlock per buf to avoid ugly loop in bget
fix race in filewrite (don't update f->off after releasing lock)

1 files changed, 4 insertions, 3 deletions

diff --git a/buf.h b/buf.h
index 9c586f2..cfeb8c6 100644
--- a/buf.h
+++ b/buf.h
@@ -2,12 +2,13 @@ struct buf {
   int flags;
   uint dev;
   uint sector;
+  struct spinlock lock;
+  struct sleeplock sleeplock;
   struct buf *prev; // LRU cache list
   struct buf *next;
   struct buf *qnext; // disk queue
   uchar data[512];
 };
-#define B_BUSY  0x1  // buffer is locked by some process
-#define B_VALID 0x2  // buffer has been read from disk
-#define B_DIRTY 0x4  // buffer needs to be written to disk
+#define B_VALID 0x1  // buffer has been read from disk
+#define B_DIRTY 0x2  // buffer needs to be written to disk