static void __map_bio(struct dm_target *ti, struct bio *clone,
struct target_io *tio)
{
int r;
/*
* Sanity checks.
*/
BUG_ON(!clone->bi_size);
clone->bi_end_io = clone_endio;
clone->bi_private = tio;
/*
* Map the clone. If r == 0 we don't need to do
* anything, the target has assumed ownership of
* this io.
*/
atomic_inc(&tio->io->io_count);
r = ti->type->map(ti, clone, &tio->info);
if (r > 0)
/* the bio has been remapped so dispatch it */
generic_make_request(clone);
else if (r < 0) {
/* error the io and bail out */
struct dm_io *io = tio->io;
free_tio(tio->io->md, tio);
dec_pending(io, -EIO);
}
}
/*
* Split the bio into several clones.
*/
static void __split_bio(struct mapped_device *md, struct bio *bio)
{
struct clone_info ci;
ci.map = dm_get_table(md);
if (!ci.map) {
bio_io_error(bio, bio->bi_size);
return;
}
ci.md = md;
ci.bio = bio;
ci.io = alloc_io(md);
ci.io->error = 0;
atomic_set(&ci.io->io_count, 1);
ci.io->bio = bio;
ci.io->md = md;
ci.sector = bio->bi_sector;
ci.sector_count = bio_sectors(bio);
ci.idx = bio->bi_idx;
atomic_inc(&md->pending);
while (ci.sector_count)
__clone_and_map(&ci);
/* drop the extra reference count */
dec_pending(ci.io, 0);
dm_table_put(ci.map);
}
static void cb_expect_one(void *conn_private, void *msg_private,
mrpc_status_t status)
{
if (status != 1)
die("%s: received status %d", msg_private, status);
dec_pending();
}
static int clone_endio(struct bio *bio, unsigned int done, int error)
{
int r = 0;
struct target_io *tio = bio->bi_private;
struct dm_io *io = tio->io;
dm_endio_fn endio = tio->ti->type->end_io;
if (bio->bi_size)
return 1;
if (!bio_flagged(bio, BIO_UPTODATE) && !error)
error = -EIO;
if (endio) {
r = endio(tio->ti, bio, error, &tio->info);
if (r < 0)
error = r;
else if (r > 0)
/* the target wants another shot at the io */
return 1;
}
free_tio(io->md, tio);
dec_pending(io, error);
bio_put(bio);
return r;
}
static void cb_expect_success(void *conn_private, void *msg_private,
mrpc_status_t status)
{
if (status != MINIRPC_OK)
die("%s: received status %d", msg_private, status);
dec_pending();
}
/**ltl
* 功能: 分割bio请求
* 参数:
* 返回值:
* 说明:
*/
static void __split_bio(struct mapped_device *md, struct bio *bio)
{
struct clone_info ci;
ci.map = dm_get_table(md);
if (!ci.map) {
bio_io_error(bio, bio->bi_size);
return;
}
ci.md = md;
ci.bio = bio;
ci.io = alloc_io(md);
ci.io->error = 0;
atomic_set(&ci.io->io_count, 1);
ci.io->bio = bio;
ci.io->md = md;
ci.sector = bio->bi_sector; /* 请求起始扇区 */
/* 从这里可以看出数据长度必定是512的整数倍 */
ci.sector_count = bio_sectors(bio); /* 数据长度(扇区数) */
ci.idx = bio->bi_idx; /* 当前bi_vec数组下标 */
start_io_acct(ci.io);
while (ci.sector_count) /* 分发各个请求 */
__clone_and_map(&ci);
/* drop the extra reference count */
dec_pending(ci.io, 0);
dm_table_put(ci.map);
}
static void cb_loop(void *conn_private, void *msg_private,
mrpc_status_t status, struct IntParam *reply)
{
if (msg_private != MSGPRIV)
die("Received incorrect msg_private parameter");
if (status)
die("Loop RPC returned %d", status);
if (reply->val != INT_VALUE)
die("Reply body contained %d", reply->val);
dec_pending();
}
static void cb_error(void *conn_private, void *msg_private,
mrpc_status_t status, struct IntParam *reply)
{
if (msg_private != MSGPRIV)
die("Received incorrect msg_private parameter");
if (status != 1)
die("Error received status %d", status);
if (reply != NULL)
die("Error callback received non-null reply pointer");
dec_pending();
}
static void __map_bio(struct dm_target *ti, struct bio *clone,
struct target_io *tio)
{
int r;
sector_t sector;
struct mapped_device *md;
/*
* Sanity checks.
*/
BUG_ON(!clone->bi_size);
clone->bi_end_io = clone_endio;
clone->bi_private = tio;
/*
* Map the clone. If r == 0 we don't need to do
* anything, the target has assumed ownership of
* this io.
*/
atomic_inc(&tio->io->io_count);
sector = clone->bi_sector;
r = ti->type->map(ti, clone, &tio->info);
if (r == DM_MAPIO_REMAPPED) {
/* the bio has been remapped so dispatch it */
blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
tio->io->bio->bi_bdev->bd_dev, sector,
clone->bi_sector);
generic_make_request(clone);
} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
/* error the io and bail out, or requeue it if needed */
md = tio->io->md;
dec_pending(tio->io, r);
/*
* Store bio_set for cleanup.
*/
clone->bi_private = md->bs;
bio_put(clone);
free_tio(md, tio);
} else if (r) {
DMWARN("unimplemented target map return value: %d", r);
BUG();
}
}
static int clone_endio(struct bio *bio, unsigned int done, int error)
{
int r = 0;
struct target_io *tio = bio->bi_private;
struct mapped_device *md = tio->io->md;
dm_endio_fn endio = tio->ti->type->end_io;
if (bio->bi_size)
return 1;
if (!bio_flagged(bio, BIO_UPTODATE) && !error)
error = -EIO;
if (endio) {
r = endio(tio->ti, bio, error, &tio->info);
if (r < 0 || r == DM_ENDIO_REQUEUE)
/*
* error and requeue request are handled
* in dec_pending().
*/
error = r;
else if (r == DM_ENDIO_INCOMPLETE)
/* The target will handle the io */
return 1;
else if (r) {
DMWARN("unimplemented target endio return value: %d", r);
BUG();
}
}
dec_pending(tio->io, error);
/*
* Store md for cleanup instead of tio which is about to get freed.
*/
bio->bi_private = md->bs;
bio_put(bio);
free_tio(md, tio);
return r;
}
/**ltl
* 功能: 映射bio请求到目标设备上
* 参数: ti -> 目标设备
* clone-> bio请求
* tio -> 目标io请求对象
* 返回值:
* 说明:
*/
static void __map_bio(struct dm_target *ti, struct bio *clone,
struct target_io *tio)
{
int r;
sector_t sector;
/*
* Sanity checks.
*/
BUG_ON(!clone->bi_size);
clone->bi_end_io = clone_endio;
clone->bi_private = tio;
/*
* Map the clone. If r == 0 we don't need to do
* anything, the target has assumed ownership of
* this io.
*/
atomic_inc(&tio->io->io_count);
sector = clone->bi_sector;
/* 将请求映射到目标设备上 */
r = ti->type->map(ti, clone, &tio->info);/* 调用linear_map函数 */
if (r > 0) {
/* the bio has been remapped so dispatch it */
blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
tio->io->bio->bi_bdev->bd_dev, sector,
clone->bi_sector);
/* 将请求提交到块设备层(插入到IO调度队列中) */
generic_make_request(clone);
}
else if (r < 0) {
/* error the io and bail out */
struct dm_io *io = tio->io;
free_tio(tio->io->md, tio);
dec_pending(io, r);
bio_put(clone);
}
}
