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Commit 627ccd20 authored by Kent Overstreet's avatar Kent Overstreet Committed by Jens Axboe
Browse files

bcache: Change refill_dirty() to always scan entire disk if necessary 



Previously, it would only scan the entire disk if it was starting from
the very start of the disk - i.e. if the previous scan got to the end.

This was broken by refill_full_stripes(), which updates last_scanned so
that refill_dirty was never triggering the searched_from_start path.

But if we change refill_dirty() to always scan the entire disk if
necessary, regardless of what last_scanned was, the code gets cleaner
and we fix that bug too.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 8d16ce54

drivers/md/bcache/writeback.c

+30 −7
Original line number Diff line number Diff line
@@ -323,6 +323,10 @@ void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode, 


static bool dirty_pred(struct keybuf *buf, struct bkey *k)

{

	struct cached_dev *dc = container_of(buf, struct cached_dev, writeback_keys);



	BUG_ON(KEY_INODE(k) != dc->disk.id);



	return KEY_DIRTY(k);

}
@@ -372,11 +376,24 @@ static void refill_full_stripes(struct cached_dev *dc) 
	}

}



/*

 * Returns true if we scanned the entire disk

 */

static bool refill_dirty(struct cached_dev *dc)

{

	struct keybuf *buf = &dc->writeback_keys;

	struct bkey start = KEY(dc->disk.id, 0, 0);

	struct bkey end = KEY(dc->disk.id, MAX_KEY_OFFSET, 0);

	bool searched_from_start = false;

	struct bkey start_pos;



	/*

	 * make sure keybuf pos is inside the range for this disk - at bringup

	 * we might not be attached yet so this disk's inode nr isn't

	 * initialized then

	 */

	if (bkey_cmp(&buf->last_scanned, &start) < 0 ||

	    bkey_cmp(&buf->last_scanned, &end) > 0)

		buf->last_scanned = start;



	if (dc->partial_stripes_expensive) {

		refill_full_stripes(dc);
@@ -384,14 +401,20 @@ static bool refill_dirty(struct cached_dev *dc) 
			return false;

	}



	if (bkey_cmp(&buf->last_scanned, &end) >= 0) {

		buf->last_scanned = KEY(dc->disk.id, 0, 0);

		searched_from_start = true;

	}



	start_pos = buf->last_scanned;

	bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);



	return bkey_cmp(&buf->last_scanned, &end) >= 0 && searched_from_start;

	if (bkey_cmp(&buf->last_scanned, &end) < 0)

		return false;



	/*

	 * If we get to the end start scanning again from the beginning, and

	 * only scan up to where we initially started scanning from:

	 */

	buf->last_scanned = start;

	bch_refill_keybuf(dc->disk.c, buf, &start_pos, dirty_pred);



	return bkey_cmp(&buf->last_scanned, &start_pos) >= 0;

}



static int bch_writeback_thread(void *arg)