Commit 775d7831 authored by David Jeffery's avatar David Jeffery Committed by Song Liu
Browse files

md: improve handling of bio with REQ_PREFLUSH in md_flush_request() 



If pers->make_request fails in md_flush_request(), the bio is lost. To
fix this, pass back a bool to indicate if the original make_request call
should continue to handle the I/O and instead of assuming the flush logic
will push it to completion.

Convert md_flush_request to return a bool and no longer calls the raid
driver's make_request function.  If the return is true, then the md flush
logic has or will complete the bio and the md make_request call is done.
If false, then the md make_request function needs to keep processing like
it is a normal bio. Let the original call to md_handle_request handle any
need to retry sending the bio to the raid driver's make_request function
should it be needed.

Also mark md_flush_request and the make_request function pointer as
__must_check to issue warnings should these critical return values be
ignored.

Fixes: 2bc13b83 ("md: batch flush requests.")
Cc: stable@vger.kernel.org # # v4.19+
Cc: NeilBrown <neilb@suse.com>
Signed-off-by: default avatarDavid Jeffery <djeffery@redhat.com>
Reviewed-by: default avatarXiao Ni <xni@redhat.com>
Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
parent fadcbd29

drivers/md/md-linear.c

+2 −3
Original line number Diff line number Diff line
@@ -244,10 +244,9 @@ static bool linear_make_request(struct mddev *mddev, struct bio *bio) 
	sector_t start_sector, end_sector, data_offset;

	sector_t bio_sector = bio->bi_iter.bi_sector;



	if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {

		md_flush_request(mddev, bio);

	if (unlikely(bio->bi_opf & REQ_PREFLUSH)

	    && md_flush_request(mddev, bio))

		return true;

	}



	tmp_dev = which_dev(mddev, bio_sector);

	start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;

drivers/md/md-multipath.c

+2 −3
Original line number Diff line number Diff line
@@ -104,10 +104,9 @@ static bool multipath_make_request(struct mddev *mddev, struct bio * bio) 
	struct multipath_bh * mp_bh;

	struct multipath_info *multipath;



	if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {

		md_flush_request(mddev, bio);

	if (unlikely(bio->bi_opf & REQ_PREFLUSH)

	    && md_flush_request(mddev, bio))

		return true;

	}



	mp_bh = mempool_alloc(&conf->pool, GFP_NOIO);

drivers/md/md.c

+9 −2
Original line number Diff line number Diff line
@@ -550,7 +550,13 @@ static void md_submit_flush_data(struct work_struct *ws) 
	}

}



void md_flush_request(struct mddev *mddev, struct bio *bio)

/*

 * Manages consolidation of flushes and submitting any flushes needed for

 * a bio with REQ_PREFLUSH.  Returns true if the bio is finished or is

 * being finished in another context.  Returns false if the flushing is

 * complete but still needs the I/O portion of the bio to be processed.

 */

bool md_flush_request(struct mddev *mddev, struct bio *bio)

{

	ktime_t start = ktime_get_boottime();

	spin_lock_irq(&mddev->lock);
@@ -575,9 +581,10 @@ void md_flush_request(struct mddev *mddev, struct bio *bio) 
			bio_endio(bio);

		else {

			bio->bi_opf &= ~REQ_PREFLUSH;

			mddev->pers->make_request(mddev, bio);

			return false;

		}

	}

	return true;

}

EXPORT_SYMBOL(md_flush_request);

drivers/md/md.h

+2 −2
Original line number Diff line number Diff line
@@ -550,7 +550,7 @@ struct md_personality 
	int level;

	struct list_head list;

	struct module *owner;

	bool (*make_request)(struct mddev *mddev, struct bio *bio);

	bool __must_check (*make_request)(struct mddev *mddev, struct bio *bio);

	/*

	 * start up works that do NOT require md_thread. tasks that

	 * requires md_thread should go into start()
@@ -703,7 +703,7 @@ extern void md_error(struct mddev *mddev, struct md_rdev *rdev); 
extern void md_finish_reshape(struct mddev *mddev);



extern int mddev_congested(struct mddev *mddev, int bits);

extern void md_flush_request(struct mddev *mddev, struct bio *bio);

extern bool __must_check md_flush_request(struct mddev *mddev, struct bio *bio);

extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,

			   sector_t sector, int size, struct page *page);

extern int md_super_wait(struct mddev *mddev);

drivers/md/raid0.c

+2 −3
Original line number Diff line number Diff line
@@ -575,10 +575,9 @@ static bool raid0_make_request(struct mddev *mddev, struct bio *bio) 
	unsigned chunk_sects;

	unsigned sectors;



	if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {

		md_flush_request(mddev, bio);

	if (unlikely(bio->bi_opf & REQ_PREFLUSH)

	    && md_flush_request(mddev, bio))

		return true;

	}



	if (unlikely((bio_op(bio) == REQ_OP_DISCARD))) {

		raid0_handle_discard(mddev, bio);

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