diff options
Diffstat (limited to 'kernel/bio.c')
| -rw-r--r-- | kernel/bio.c | 20 |
1 files changed, 7 insertions, 13 deletions
diff --git a/kernel/bio.c b/kernel/bio.c index a08884b..7455c06 100644 --- a/kernel/bio.c +++ b/kernel/bio.c @@ -12,11 +12,7 @@ // * Do not use the buffer after calling brelse. // * Only one process at a time can use a buffer, // so do not keep them longer than necessary. -// -// The implementation uses two state flags internally: -// * 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. + #include "types.h" #include "param.h" @@ -76,13 +72,11 @@ bget(uint dev, uint blockno) } // Not cached; recycle an unused buffer. - // Even if refcnt==0, B_DIRTY indicates a buffer is in use - // because log.c has modified it but not yet committed it. for(b = bcache.head.prev; b != &bcache.head; b = b->prev){ - if(b->refcnt == 0 && (b->flags & B_DIRTY) == 0) { + if(b->refcnt == 0) { b->dev = dev; b->blockno = blockno; - b->flags = 0; + b->valid = 0; b->refcnt = 1; release(&bcache.lock); acquiresleep(&b->lock); @@ -99,8 +93,9 @@ bread(uint dev, uint blockno) struct buf *b; b = bget(dev, blockno); - if((b->flags & B_VALID) == 0) { - virtio_disk_rw(b); + if(!b->valid) { + virtio_disk_rw(b, 0); + b->valid = 1; } return b; } @@ -111,8 +106,7 @@ bwrite(struct buf *b) { if(!holdingsleep(&b->lock)) panic("bwrite"); - b->flags |= B_DIRTY; - virtio_disk_rw(b); + virtio_disk_rw(b, 1); } // Release a locked buffer. |