Commit 20578bdf authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe

block: Initialize BIO I/O priority early

For the synchronous I/O path case (read(), write() etc system calls), a
BIO I/O priority is not initialized until the execution of
blk_init_request_from_bio() when the BIO is submitted and a request
initialized for the BIO execution. This is due to the ki_ioprio field of
the struct kiocb defined on stack being always initialized to
IOPRIO_CLASS_NONE, regardless of the calling process I/O context ioprio
value set with ioprio_set(). This late initialization can result in the
BIO being merged to pending requests even when the I/O priorities
differ.

Fix this by initializing the ki_iopriority field of on stack struct
kiocb using the get_current_ioprio() helper, ensuring that all BIOs
allocated and submitted for the system call execution see the correct
intended I/O priority early. With this, since a BIO I/O priority is
always set to the intended effective value for both the sync and async
path, blk_init_request_from_bio() can be simplified.
Reviewed-by: default avatarChristoph Hellwig <[email protected]>
Reviewed-by: default avatarAdam Manzanares <[email protected]>
Signed-off-by: default avatarDamien Le Moal <[email protected]>
Signed-off-by: default avatarJens Axboe <[email protected]>
parent 668ffc03
......@@ -814,10 +814,7 @@ void blk_init_request_from_bio(struct request *req, struct bio *bio)
req->cmd_flags |= REQ_FAILFAST_MASK;
req->__sector = bio->bi_iter.bi_sector;
if (ioprio_valid(bio_prio(bio)))
req->ioprio = bio_prio(bio);
else
req->ioprio = get_current_ioprio();
req->ioprio = bio_prio(bio);
req->write_hint = bio->bi_write_hint;
blk_rq_bio_prep(req->q, req, bio);
}
......
......@@ -2021,7 +2021,7 @@ static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
.ki_filp = filp,
.ki_flags = iocb_flags(filp),
.ki_hint = ki_hint_validate(file_write_hint(filp)),
.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0),
.ki_ioprio = get_current_ioprio(),
};
}
......
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