int
spec_strategy(void *v)
{
struct vop_strategy_args *ap = v;
struct buf *bp = ap->a_bp;
int maj = major(bp->b_dev);
if (LIST_FIRST(&bp->b_dep) != NULL)
buf_start(bp);
(*bdevsw[maj].d_strategy)(bp);
return (0);
}
/*
* Convert a vnode strategy call into a device strategy call. Vnode strategy
* calls are not limited to device DMA limits so we have to deal with the
* case.
*
* spec_strategy(struct vnode *a_vp, struct bio *a_bio)
*/
static int
devfs_spec_strategy(struct vop_strategy_args *ap)
{
struct bio *bio = ap->a_bio;
struct buf *bp = bio->bio_buf;
struct buf *nbp;
struct vnode *vp;
struct mount *mp;
int chunksize;
int maxiosize;
if (bp->b_cmd != BUF_CMD_READ && LIST_FIRST(&bp->b_dep) != NULL)
buf_start(bp);
/*
* Collect statistics on synchronous and asynchronous read
* and write counts for disks that have associated filesystems.
*/
vp = ap->a_vp;
KKASSERT(vp->v_rdev != NULL); /* XXX */
if (vn_isdisk(vp, NULL) && (mp = vp->v_rdev->si_mountpoint) != NULL) {
if (bp->b_cmd == BUF_CMD_READ) {
if (bp->b_flags & BIO_SYNC)
mp->mnt_stat.f_syncreads++;
else
mp->mnt_stat.f_asyncreads++;
} else {
if (bp->b_flags & BIO_SYNC)
mp->mnt_stat.f_syncwrites++;
else
mp->mnt_stat.f_asyncwrites++;
}
}
/*
* Device iosize limitations only apply to read and write. Shortcut
* the I/O if it fits.
*/
if ((maxiosize = vp->v_rdev->si_iosize_max) == 0) {
devfs_debug(DEVFS_DEBUG_DEBUG,
"%s: si_iosize_max not set!\n",
dev_dname(vp->v_rdev));
maxiosize = MAXPHYS;
}
#if SPEC_CHAIN_DEBUG & 2
maxiosize = 4096;
#endif
if (bp->b_bcount <= maxiosize ||
(bp->b_cmd != BUF_CMD_READ && bp->b_cmd != BUF_CMD_WRITE)) {
dev_dstrategy_chain(vp->v_rdev, bio);
return (0);
}
/*
* Clone the buffer and set up an I/O chain to chunk up the I/O.
*/
nbp = kmalloc(sizeof(*bp), M_DEVBUF, M_INTWAIT|M_ZERO);
initbufbio(nbp);
buf_dep_init(nbp);
BUF_LOCK(nbp, LK_EXCLUSIVE);
BUF_KERNPROC(nbp);
nbp->b_vp = vp;
nbp->b_flags = B_PAGING | (bp->b_flags & B_BNOCLIP);
nbp->b_data = bp->b_data;
nbp->b_bio1.bio_done = devfs_spec_strategy_done;
nbp->b_bio1.bio_offset = bio->bio_offset;
nbp->b_bio1.bio_caller_info1.ptr = bio;
/*
* Start the first transfer
*/
if (vn_isdisk(vp, NULL))
chunksize = vp->v_rdev->si_bsize_phys;
else
chunksize = DEV_BSIZE;
chunksize = maxiosize / chunksize * chunksize;
#if SPEC_CHAIN_DEBUG & 1
devfs_debug(DEVFS_DEBUG_DEBUG,
"spec_strategy chained I/O chunksize=%d\n",
chunksize);
#endif
nbp->b_cmd = bp->b_cmd;
nbp->b_bcount = chunksize;
nbp->b_bufsize = chunksize; /* used to detect a short I/O */
nbp->b_bio1.bio_caller_info2.index = chunksize;
#if SPEC_CHAIN_DEBUG & 1
devfs_debug(DEVFS_DEBUG_DEBUG,
"spec_strategy: chain %p offset %d/%d bcount %d\n",
bp, 0, bp->b_bcount, nbp->b_bcount);
#endif
dev_dstrategy(vp->v_rdev, &nbp->b_bio1);
if (DEVFS_NODE(vp)) {
nanotime(&DEVFS_NODE(vp)->atime);
nanotime(&DEVFS_NODE(vp)->mtime);
}
return (0);
}