lo_rw_aio() is capable of doing simple buffered read/write, not
necessary to use lo_simple_read()/lo_simple_write() for that.
Add cmd->use_dio for real loop dio, then cmd->use_aio is only used
in case that lo_rw_aio() is used for submitting IO against backing file.
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
drivers/block/loop.c | 83 +++++++++-----------------------------------
drivers/block/loop.h | 1 +
2 files changed, 18 insertions(+), 66 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 769cf84c6899..d1784f825b6b 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -339,23 +339,6 @@ static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
return bw;
}
-static int lo_write_simple(struct loop_device *lo, struct request *rq,
- loff_t pos)
-{
- struct bio_vec bvec;
- struct req_iterator iter;
- int ret = 0;
-
- rq_for_each_segment(bvec, rq, iter) {
- ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
- if (ret < 0)
- break;
- cond_resched();
- }
-
- return ret;
-}
-
/*
* This is the slow, transforming version that needs to double buffer the
* data as it cannot do the transformations in place without having direct
@@ -391,33 +374,6 @@ static int lo_write_transfer(struct loop_device *lo, struct request *rq,
return ret;
}
-static int lo_read_simple(struct loop_device *lo, struct request *rq,
- loff_t pos)
-{
- struct bio_vec bvec;
- struct req_iterator iter;
- struct iov_iter i;
- ssize_t len;
-
- rq_for_each_segment(bvec, rq, iter) {
- iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len);
- len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
- if (len < 0)
- return len;
-
- if (len != bvec.bv_len) {
- struct bio *bio;
-
- __rq_for_each_bio(bio, rq)
- zero_fill_bio(bio);
- break;
- }
- cond_resched();
- }
-
- return 0;
-}
-
static int lo_read_transfer(struct loop_device *lo, struct request *rq,
loff_t pos)
{
@@ -520,10 +476,10 @@ static void lo_complete_rq(struct request *rq)
blk_status_t ret = BLK_STS_OK;
/* Kernel wrote to our pages, call flush_dcache_page */
- if (req_op(rq) == REQ_OP_READ && !cmd->use_aio && cmd->ret >= 0)
+ if (req_op(rq) == REQ_OP_READ && !cmd->use_dio && cmd->ret >= 0)
lo_flush_dcache_for_read(rq);
- if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
+ if (!cmd->use_dio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
req_op(rq) != REQ_OP_READ) {
if (cmd->ret < 0)
ret = errno_to_blk_status(cmd->ret);
@@ -625,17 +581,24 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
offset = bio->bi_iter.bi_bvec_done;
bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
}
- atomic_set(&cmd->ref, 2);
-
iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
iter.iov_offset = offset;
cmd->iocb.ki_pos = pos;
cmd->iocb.ki_filp = file;
- cmd->iocb.ki_complete = lo_rw_aio_complete;
- cmd->iocb.ki_flags = IOCB_DIRECT;
+
cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
+ if (!cmd->use_dio) {
+ atomic_set(&cmd->ref, 1);
+ cmd->iocb.ki_flags = 0;
+ cmd->ret = lo_call_backing_rw_iter(file, &cmd->iocb, &iter, rw);
+ lo_rw_aio_do_completion(cmd);
+ return 0;
+ }
+ atomic_set(&cmd->ref, 2);
+ cmd->iocb.ki_complete = lo_rw_aio_complete;
+ cmd->iocb.ki_flags = IOCB_DIRECT;
ret = lo_call_backing_rw_iter(file, &cmd->iocb, &iter, rw);
lo_rw_aio_do_completion(cmd);
@@ -650,15 +613,6 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
- /*
- * lo_write_simple and lo_read_simple should have been covered
- * by io submit style function like lo_rw_aio(), one blocker
- * is that lo_read_simple() need to call flush_dcache_page after
- * the page is written from kernel, and it isn't easy to handle
- * this in io submit style function which submits all segments
- * of the req at one time. And direct read IO doesn't need to
- * run flush_dcache_page().
- */
switch (req_op(rq)) {
case REQ_OP_FLUSH:
return lo_req_flush(lo, rq);
@@ -676,17 +630,13 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
case REQ_OP_WRITE:
if (lo->transfer)
return lo_write_transfer(lo, rq, pos);
- else if (cmd->use_aio)
- return lo_rw_aio(lo, cmd, pos, WRITE);
else
- return lo_write_simple(lo, rq, pos);
+ return lo_rw_aio(lo, cmd, pos, WRITE);
case REQ_OP_READ:
if (lo->transfer)
return lo_read_transfer(lo, rq, pos);
- else if (cmd->use_aio)
- return lo_rw_aio(lo, cmd, pos, READ);
else
- return lo_read_simple(lo, rq, pos);
+ return lo_rw_aio(lo, cmd, pos, READ);
default:
WARN_ON_ONCE(1);
return -EIO;
@@ -2171,7 +2121,8 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
cmd->use_aio = false;
break;
default:
- cmd->use_aio = lo->use_dio;
+ cmd->use_aio = !lo->transfer;
+ cmd->use_dio = lo->use_dio && cmd->use_aio;
break;
}
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index 04c88dd6eabd..b7d611e4f517 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -74,6 +74,7 @@ struct loop_device {
struct loop_cmd {
struct list_head list_entry;
bool use_aio; /* use AIO interface to handle I/O */
+ bool use_dio;
atomic_t ref; /* only for aio */
long ret;
struct kiocb iocb;
--
2.31.1
