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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: 2bc13b83e6 ("md: batch flush requests.")
Cc: stable@vger.kernel.org # # v4.19+
Cc: NeilBrown <neilb@suse.com>
Signed-off-by: David Jeffery <djeffery@redhat.com>
Reviewed-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
This commit is contained in:
David Jeffery 2019-09-16 13:15:14 -04:00 committed by Song Liu
parent fadcbd2901
commit 775d78319f
8 changed files with 23 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/md/md-linear.c
View File

@ -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;

5
drivers/md/md-multipath.c
View File

@ -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);

11
drivers/md/md.c
View File

@ -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);

4
drivers/md/md.h
View File

@ -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);

5
drivers/md/raid0.c
View File

@ -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);

5
drivers/md/raid1.c
View File

@ -1567,10 +1567,9 @@ static bool raid1_make_request(struct mddev *mddev, struct bio *bio)
{
sector_t 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;
}
/*
* There is a limit to the maximum size, but

5
drivers/md/raid10.c
View File

@ -1525,10 +1525,9 @@ static bool raid10_make_request(struct mddev *mddev, struct bio *bio)
int chunk_sects = chunk_mask + 1;
int sectors = bio_sectors(bio);
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 (!md_write_start(mddev, bio))
return false;

4
drivers/md/raid5.c
View File

@ -5592,8 +5592,8 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
if (ret == 0)
return true;
if (ret == -ENODEV) {
md_flush_request(mddev, bi);
return true;
if (md_flush_request(mddev, bi))
return true;
}
/* ret == -EAGAIN, fallback */
/*