clarify some FS comments

1 files changed, 8 insertions, 8 deletions

diff --git a/bio.c b/bio.c
index 6a3968b..88b0964 100644
--- a/bio.c
+++ b/bio.c
@@ -7,7 +7,7 @@
 // 
 // Interface:
 // * To get a buffer for a particular disk block, call bread.
-// * After changing buffer data, call bwrite to flush it to disk.
+// * After changing buffer data, call bwrite to write it to disk.
 // * When done with the buffer, call brelse.
 // * Do not use the buffer after calling brelse.
 // * Only one process at a time can use a buffer,
@@ -16,8 +16,7 @@
 // The implementation uses three state flags internally:
 // * B_BUSY: the block has been returned from bread
 //     and has not been passed back to brelse.  
-// * B_VALID: the buffer data has been initialized
-//     with the associated disk block contents.
+// * B_VALID: the buffer data has been read from the disk.
 // * B_DIRTY: the buffer data has been modified
 //     and needs to be written to disk.
 
@@ -58,7 +57,7 @@ binit(void)
 
 // Look through buffer cache for sector on device dev.
 // If not found, allocate fresh block.
-// In either case, return locked buffer.
+// In either case, return B_BUSY buffer.
 static struct buf*
 bget(uint dev, uint sector)
 {
@@ -67,7 +66,7 @@ bget(uint dev, uint sector)
   acquire(&bcache.lock);
 
  loop:
-  // Try for cached block.
+  // Is the sector already cached?
   for(b = bcache.head.next; b != &bcache.head; b = b->next){
     if(b->dev == dev && b->sector == sector){
       if(!(b->flags & B_BUSY)){
@@ -80,7 +79,7 @@ bget(uint dev, uint sector)
     }
   }
 
-  // Allocate fresh block.
+  // Not cached; recycle some existing buffer.
   for(b = bcache.head.prev; b != &bcache.head; b = b->prev){
     if((b->flags & B_BUSY) == 0){
       b->dev = dev;
@@ -105,7 +104,7 @@ bread(uint dev, uint sector)
   return b;
 }
 
-// Write b's contents to disk.  Must be locked.
+// Write b's contents to disk.  Must be B_BUSY.
 void
 bwrite(struct buf *b)
 {
@@ -115,7 +114,8 @@ bwrite(struct buf *b)
   iderw(b);
 }
 
-// Release the buffer b.
+// Release a B_BUSY buffer.
+// Move to the head of the MRU list.
 void
 brelse(struct buf *b)
 {