[Devel] [PATCH RHEL8 COMMIT] ploop: Check for md dirty instead of md piwb

[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 0892d0ea63dea0d03b3823b12dfea124c9f88ef1
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Fri Jul 2 22:43:26 2021 +0300

    ploop: Check for md dirty instead of md piwb
    
    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 | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index d91baef66973..a8459c0f75d6 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1274,8 +1274,8 @@ static void submit_cow_index_wb(struct ploop_cow *cow,
 	if (delay_if_md_busy(ploop, piwb, md, PIWB_TYPE_ALLOC, cow->aux_pio))
 		goto out;
 
-	if (!md->piwb) {
-		/* No index wb in process. Prepare a new one */
+	if (!(md->status & MD_DIRTY)) {
+		/* Unlocked, since MD_DIRTY is set and cleared from this work */
 		if (ploop_prepare_bat_update(ploop, page_id, piwb, PIWB_TYPE_ALLOC) < 0)
 			goto err_resource;
 		ploop_md_make_dirty(ploop, md);
@@ -1360,7 +1360,8 @@ static bool locate_new_cluster_and_attach_pio(struct ploop *ploop,
 	if (delay_if_md_busy(ploop, piwb, md, PIWB_TYPE_ALLOC, pio))
 		goto out;
 
-	if (!md->piwb) {
+	if (!(md->status & MD_DIRTY)) {
+		 /* Unlocked since MD_DIRTY is set and cleared from this work */
 		page_id = bat_clu_to_page_nr(clu);
 		if (ploop_prepare_bat_update(ploop, page_id, piwb, PIWB_TYPE_ALLOC) < 0) {
 			pio->bi_status = BLK_STS_RESOURCE;
@@ -1500,7 +1501,8 @@ static void process_one_discard_pio(struct ploop *ploop, struct pio *pio,
 	if (delay_if_md_busy(ploop, piwb, md, PIWB_TYPE_DISCARD, pio))
 		goto out;
 
-	if (!md->piwb) {
+	if (!(md->status & MD_DIRTY)) {
+		 /* Unlocked since MD_DIRTY is set and cleared from this work */
 		if (ploop_prepare_bat_update(ploop, page_id, piwb, PIWB_TYPE_DISCARD) < 0) {
 			pio->bi_status = BLK_STS_RESOURCE;
 			goto err;
@@ -1807,11 +1809,12 @@ int ploop_prepare_reloc_index_wb(struct ploop *ploop,
 {
 	unsigned int page_id = bat_clu_to_page_nr(clu);
 	enum piwb_type type = PIWB_TYPE_ALLOC;
+	struct md_page *md = md_page_find(ploop, page_id);
 
 	if (dst_clu)
 		type = PIWB_TYPE_RELOC;
 
-	if (piwb->page_id != PAGE_NR_NONE ||
+	if ((md->status & (MD_DIRTY|MD_WRITEBACK)) ||
 	    ploop_prepare_bat_update(ploop, page_id, piwb, type))
 		goto out_eio;
 	if (dst_clu) {