On 1/20/25 21:33, Alexander Atanasov wrote:
On 20.01.25 6:15, Pavel Tikhomirov wrote:
On 12/6/24 05:55, Alexander Atanasov wrote:
From: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
Drop extra ploop_cluster_is_in_top_delta() as we are planning to
access BAT anyway
https://virtuozzo.atlassian.net/browse/VSTOR-91817
Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
---
drivers/md/dm-ploop-map.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index ad7ca7d43dfc..b00dd364072d 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -711,12 +711,15 @@ static void ploop_complete_cow(struct ploop_cow
*cow, blk_status_t bi_status)
kmem_cache_free(cow_cache, cow);
}
-static void ploop_release_cluster(struct ploop *ploop, u32 clu)
+static void ploop_piwb_discard_completed(struct ploop *ploop,
+ bool success, u32 clu, u32 new_dst_clu)
{
u32 id, *bat_entries, dst_clu;
struct md_page *md;
+ u8 level;
- lockdep_assert_held(&ploop->bat_rwlock);
+ if (new_dst_clu)
+ return;
id = ploop_bat_clu_to_page_nr(clu);
md = ploop_md_page_find(ploop, id);
Is this md the same to md in caller function
ploop_advance_local_after_bat_wb?
It can be the same or different, it is iterating over the clusters and
it is possible the page to change, so this needs a rewrite.
May be pass md as argument and check if it is the same, if not the same
lock or something like that. i have to think about how to do it.
Also we need not forget that if we'll have nested md->md_lock we should
be aware about ABBA deadlocks. E.g.: if md->md_lock B is nested under
md->md_lock A in one thread and vice versa A is nested under B in
another thread, we can get deadlock.
@@ -726,22 +729,15 @@ static void ploop_release_cluster(struct ploop
*ploop, u32 clu)
bat_entries = md->kmpage;
dst_clu = READ_ONCE(bat_entries[clu]);
- WRITE_ONCE(bat_entries[clu], BAT_ENTRY_NONE);
- WRITE_ONCE(md->bat_levels[clu], 0);
-
- ploop_hole_set_bit(dst_clu, ploop);
-}
-
-static void ploop_piwb_discard_completed(struct ploop *ploop,
- bool success, u32 clu, u32 new_dst_clu)
-{
- if (new_dst_clu)
- return;
+ level = md->bat_levels[clu];
If for previous comment the answer is no, should not we take md-
>md_lock here to make the use of md->bat_levels and md->kmpage
atomic / consistent? In the next patch we introduce md->md_lock to
"use it when accessing md->levels and md->page at the sime time to
protect readers against writers".
If the answer is yes, should not we do a lockdep check for md->md_lock?
if it comes as an argument lockdep can be added but if it is different
we will get false alarm.
- if (ploop_cluster_is_in_top_delta(ploop, clu)) {
+ if (!(dst_clu == BAT_ENTRY_NONE || level <
ploop_top_level(ploop))) {
WARN_ON_ONCE(ploop->nr_deltas != 1);
- if (success)
- ploop_release_cluster(ploop, clu);
+ if (success) {
+ WRITE_ONCE(bat_entries[clu], BAT_ENTRY_NONE);
+ WRITE_ONCE(md->bat_levels[clu], 0);
+ ploop_hole_set_bit(dst_clu, ploop);
+ }
}
}
--
Best regards, Tikhomirov Pavel
Senior Software Developer, Virtuozzo.
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