[Devel] [PATCH RHEL8 COMMIT] ploop: Reread piwb after ploop_prepare_bat_update()

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.6.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.el8
------>
commit 13db08409d552bdee908086d947aa13553406df3
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Fri Jul 2 22:43:27 2021 +0300

    ploop: Reread piwb after ploop_prepare_bat_update()
    
    Currently it's noop
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    ==========================
    Parallel async BAT pages submission and improvements
    
    [1-15]:
    https://jira.sw.ru/browse/PSBM-124550
    
    [16-22]:
    following improvements
    
    Kirill Tkhai (22):
          ploop: Remove absolet comment
          ploop: Add md and piwb cross pointers
          ploop: Add @md argument to locate_new_cluster_and_attach_pio()
          ploop: Refactoring in process_one_discard_pio()
          ploop: Pass type argument to ploop_prepare_bat_update()
          ploop: Move md is busy check to delay_if_md_busy()
          ploop: Introduce batch list for md pages writeback
          ploop: Check for md dirty instead of md piwb
          ploop: Reread piwb after ploop_prepare_bat_update()
          ploop: Change argument in ploop_prepare_bat_update()
          ploop: Return md from ploop_prepare_reloc_index_wb()
          ploop: Change arguments and rename ploop_reset_bat_update()
          ploop: Allow parallel wb of md pages
          ploop: Async md writeback
          ploop: Rename ploop_submit_index_wb_sync()
          ploop: Resubmit pios from main kwork
          ploop: Rename process_delta_wb()
          ploop: Do fsync after bat page write
          ploop: Do not iterate excess clusters in notify_delta_merged()
          ploop: Use kvec in ploop_delta_check_header()
          ploop: Add argument to ploop_read_delta_metadata()
          ploop: Underline clu and page is u32
---
 drivers/md/dm-ploop-map.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index a8459c0f75d6..06060e798a40 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1281,6 +1281,8 @@ static void submit_cow_index_wb(struct ploop_cow *cow,
 		ploop_md_make_dirty(ploop, md);
 	}
 
+	piwb = md->piwb;
+
 	clu -= page_id * PAGE_SIZE / sizeof(map_index_t) - PLOOP_MAP_OFFSET;
 
 	to = kmap_atomic(piwb->bat_page);
@@ -1370,6 +1372,8 @@ static bool locate_new_cluster_and_attach_pio(struct ploop *ploop,
 		bat_update_prepared = true;
 	}
 
+	piwb = md->piwb;
+
 	if (ploop_alloc_cluster(ploop, piwb, clu, dst_clu)) {
 		pio->bi_status = BLK_STS_IOERR;
 		goto error;
@@ -1510,6 +1514,8 @@ static void process_one_discard_pio(struct ploop *ploop, struct pio *pio,
 		bat_update_prepared = true;
 	}
 
+	piwb = md->piwb;
+
 	/* Cluster index related to the page[page_id] start */
 	clu -= piwb->page_id * PAGE_SIZE / sizeof(map_index_t) - PLOOP_MAP_OFFSET;
 
@@ -1817,6 +1823,9 @@ int ploop_prepare_reloc_index_wb(struct ploop *ploop,
 	if ((md->status & (MD_DIRTY|MD_WRITEBACK)) ||
 	    ploop_prepare_bat_update(ploop, page_id, piwb, type))
 		goto out_eio;
+
+	piwb = md->piwb;
+
 	if (dst_clu) {
 		/*
 		 * For ploop_advance_local_after_bat_wb(): do not concern