diff options
Diffstat (limited to 'bio.c')
| -rw-r--r-- | bio.c | 19 |
1 files changed, 10 insertions, 9 deletions
@@ -4,15 +4,14 @@ // holding cached copies of disk block contents. // Each buf has two state bits B_BUSY and B_VALID. // If B_BUSY is set, it means that some code is currently -// editing buf, so other code is not allowed to look at it. +// modifying buf, so other code is not allowed to look at it. // To wait for a buffer that is B_BUSY, sleep on buf. // (See bget below.) // -// If B_VALID is set, it means that the memory contents -// have been initialized by reading them off the disk. -// (Conversely, if B_VALID is not set, the memory contents +// If B_VALID is set, it means that the sector in b->data is +// the same as on the disk. If B_VALID is not set, the contents // of buf must be initialized, often by calling bread, -// before being used.) +// before being used. // // After making changes to a buf's memory, call bwrite to flush // the changes out to disk, to keep the disk and memory copies @@ -79,7 +78,6 @@ bget(uint dev, uint sector) goto loop; } b->flags |= B_BUSY; - // b->flags &= ~B_VALID; // Force reread from disk release(&buf_table_lock); return b; } @@ -98,7 +96,8 @@ bget(uint dev, uint sector) panic("bget: no buffers"); } -// Read buf's contents from disk. +// Return a B_BUSY buf with the contents of the indicated +// disk sector. struct buf* bread(uint dev, uint sector) { @@ -108,7 +107,8 @@ bread(uint dev, uint sector) if(b->flags & B_VALID) return b; - ide_rw(dev & 0xff, sector, b->data, 1, 1); + b->flags &= ~B_WRITE; + ide_rw(b); b->flags |= B_VALID; return b; @@ -121,7 +121,8 @@ bwrite(struct buf *b) { if((b->flags & B_BUSY) == 0) panic("bwrite"); - ide_rw(b->dev & 0xff, b->sector, b->data, 1, 0); + b->flags |= B_WRITE; + ide_rw(b); b->flags |= B_VALID; } |