Re: GSOC: Device mapper mirror target

[Adam Hoka <adam.hoka@xxxxxxxxx>]

On Sun, 10 Apr 2011 18:08:33 -0400
Venkatesh Srinivas <me@endeavour.zapto.org> wrote:

> static int
> dmirror_strategy(dm_table_entry_t *table_en, struct buf *bp)
> {
> 	struct bio *bio;
> 	struct dmirror_pdev *pdev;
> 	struct dmirror_dev *dmcfg;
> 	struct dmirror_write_group *wg;
> 	struct dmirror_write_tx *tx;
> 	int ndevs;
> 	int i;	
> 
> 	dmcfg = table_en->target_config;
> 
> 	switch (bp->b_cmd) {
> 	case (BUF_CMD_READ):
> 		pdev = dmirror_read_pick(dmcfg, &bp->b_bio1);	
> 		if (pdev == NULL) {
> 			bp->b_flags |= B_ERROR | B_INVAL;
> 			bp->b_resid = 0;
> 			biodone(&bp->b_bio1);
> 			break;
> 		}
> 		
> 		disk_issue_read(dmcfg, pdev, &bp->b_bio1);
> 		break;
> 	case (BUF_CMD_WRITE):
> 		/* Allocate a write group */
> 		wg = kmalloc(sizeof(struct dmirror_write_group), M_DMIRROR_WG,
> 			     M_WAITOK);
> 		dmirror_wg_ctor(dmcfg, &bp->b_bio1, wg);
> 		
> 		/* Allocate one transaction per device */
> 		for (i = 0; i < ndevs; i++) {
> 			tx = kmalloc(sizeof(struct dmirror_write_tx),
> 					M_DMIRROR_TX, M_WAITOK);
> 			dmirror_write_tx_ctor(wg, tx);
> 
> 		}	
> 	
> 		/* Setup transactions */
> 		
> 		/* Issue requests */
> 		// do some stuff, then call vn_strategy() on each tx->bio
> 
> 		break;
> 	case (BUF_CMD_FLUSH):
> 	default:
> 		break;
> 	}
> }
> 

A bit off topic, but I dont think its a good idea to allocate memory
during I/O. :-)

-- 
Adam Hoka <adam.hoka@gmail.com>