On 1/20/25 11:25, Pavel Tikhomirov wrote:
On 12/6/24 05:55, Alexander Atanasov wrote:
From: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
Do not bother with locked clusters. For llseek we can ignore all
concurrent operations.
Do not call ploop_bat_entries() on every cluster as this is slow.
Just remember md and read it directly.
https://virtuozzo.atlassian.net/browse/VSTOR-91817
Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
---
drivers/md/dm-ploop-map.c | 27 ++++++++-------------------
1 file changed, 8 insertions(+), 19 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 7ecf79fcd2cc..ad7ca7d43dfc 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -2088,32 +2088,21 @@
ALLOW_ERROR_INJECTION(ploop_prepare_reloc_index_wb, ERRNO);
loff_t ploop_llseek_hole(struct dm_target *ti, loff_t offset, int
whence)
{
struct ploop *ploop = ti->private;
- u32 clu, dst_clu;
+ u32 clu, dst_clu, id, *bat;
+ struct md_page *md;
loff_t result;
clu = SEC_TO_CLU(ploop, to_sector(offset) + ploop->skip_off);
+ id = U32_MAX;
while (clu < ploop->nr_bat_entries) {
-
- /*
- * Assume a locked cluster to have a data.
- * In worst case someone will read zeroes
- */
- if (ploop_postpone_if_cluster_locked(ploop, NULL, clu)) {
- if (whence & SEEK_DATA)
- break;
- if (whence & SEEK_HOLE) {
- clu++;
- continue;
- }
+ if (id != ploop_bat_clu_to_page_nr(clu)) {
+ id = ploop_bat_clu_to_page_nr(clu);
+ md = ploop_md_page_find(ploop, id);
}
- /*
- * It *may* be possible to speed this up by iterating over
clusters
- * in mapped metadata page, but this is a bit problematic
- * since we want to check if cluster is locked
- */
- dst_clu = ploop_bat_entries(ploop, clu, NULL, NULL);
+ bat = md->kmpage;
+ dst_clu = READ_ONCE(bat[ploop_bat_clu_idx_in_page(clu)]);
Before this patch we used ploop_bat_entries which takes md->md_lock
around dst_clu reading, shouldn't we do the same here too?
Ah, I see, we have md_lock in ploop_bat_entries to make returned
bat_level and dst_clu in sync. And as we don't use level here we don't
need a lock.
if (whence & SEEK_DATA && dst_clu != BAT_ENTRY_NONE)
break;
--
Best regards, Tikhomirov Pavel
Senior Software Developer, Virtuozzo.
_______________________________________________
Devel mailing list
Devel@openvz.org
https://lists.openvz.org/mailman/listinfo/devel
