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loop: make do_req_filebacked more robust 

Use a switch statement to iterate over the possible operations and
error out if it's an incorrect one.

Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2016-08-04 16:10:01 +02:00 committed by Jens Axboe
parent f0225cacfe
commit c1c87c2ba9
1 changed files with 23 additions and 34 deletions
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57
drivers/block/loop.c
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@ -510,14 +510,10 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
return 0;
}
static inline int lo_rw_simple(struct loop_device *lo,
struct request *rq, loff_t pos, bool rw)
static int do_req_filebacked(struct loop_device *lo, struct request *rq)
{
struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
if (cmd->use_aio)
return lo_rw_aio(lo, cmd, pos, rw);
loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
/*
* lo_write_simple and lo_read_simple should have been covered
@ -528,37 +524,30 @@ static inline int lo_rw_simple(struct loop_device *lo,
* of the req at one time. And direct read IO doesn't need to
* run flush_dcache_page().
*/
if (rw == WRITE)
return lo_write_simple(lo, rq, pos);
else
return lo_read_simple(lo, rq, pos);
}
static int do_req_filebacked(struct loop_device *lo, struct request *rq)
{
loff_t pos;
int ret;
pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
if (op_is_write(req_op(rq))) {
if (req_op(rq) == REQ_OP_FLUSH)
ret = lo_req_flush(lo, rq);
else if (req_op(rq) == REQ_OP_DISCARD)
ret = lo_discard(lo, rq, pos);
else if (lo->transfer)
ret = lo_write_transfer(lo, rq, pos);
else
ret = lo_rw_simple(lo, rq, pos, WRITE);
} else {
switch (req_op(rq)) {
case REQ_OP_FLUSH:
return lo_req_flush(lo, rq);
case REQ_OP_DISCARD:
return lo_discard(lo, rq, pos);
case REQ_OP_WRITE:
if (lo->transfer)
ret = lo_read_transfer(lo, rq, pos);
return lo_write_transfer(lo, rq, pos);
else if (cmd->use_aio)
return lo_rw_aio(lo, cmd, pos, WRITE);
else
ret = lo_rw_simple(lo, rq, pos, READ);
return lo_write_simple(lo, rq, pos);
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);
default:
WARN_ON_ONCE(1);
return -EIO;
break;
}
return ret;
}
struct switch_request {