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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: Kent Overstreet <kent.overstreet@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Kent Overstreet 2015-11-29 18:47:01 -08:00 committed by Jens Axboe
parent 8d16ce540c
commit 627ccd20b4
1 changed files with 30 additions and 7 deletions
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37
drivers/md/bcache/writeback.c
View File

@ -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 @@ next:
}
}
/*
* 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)