[Devel] [PATCH RHEL8 COMMIT] ploop: Do not iterate excess clusters in notify_delta_merged()

[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 bd47d2d281205c6ae95697f91a4286b3201de22b
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Fri Jul 2 22:43:32 2021 +0300

    ploop: Do not iterate excess clusters in notify_delta_merged()
    
    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-cmd.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
index 00cb83345853..0bfd759347a8 100644
--- a/drivers/md/dm-ploop-cmd.c
+++ b/drivers/md/dm-ploop-cmd.c
@@ -684,13 +684,15 @@ static int ploop_merge_latest_snapshot(struct ploop *ploop)
 	return ret;
 }
 
-static void notify_delta_merged(struct ploop *ploop, u8 level,
-				void *hdr, bool forward)
+static void notify_delta_merged(struct ploop *ploop, u8 level, void *hdr,
+				bool forward, u32 size_in_clus)
 {
 	unsigned int i, end, *bat_entries, *delta_bat_entries;
 	struct rb_node *node;
 	struct md_page *md;
 	struct file *file;
+	bool stop = false;
+	u32 clu;
 
 	/* Points to hdr since md_page[0] also contains hdr. */
 	delta_bat_entries = (map_index_t *)hdr;
@@ -700,6 +702,12 @@ static void notify_delta_merged(struct ploop *ploop, u8 level,
 		init_bat_entries_iter(ploop, md->id, &i, &end);
 		bat_entries = kmap_atomic(md->page);
 		for (; i <= end; i++) {
+			clu = page_clu_idx_to_bat_clu(md->id, i);
+			if (clu >= size_in_clus) {
+				stop = true;
+				goto unmap;
+			}
+
 			if (md_page_cluster_is_in_top_delta(ploop, md, i) ||
 			    delta_bat_entries[i] == BAT_ENTRY_NONE ||
 			    md->bat_levels[i] < level)
@@ -721,7 +729,10 @@ static void notify_delta_merged(struct ploop *ploop, u8 level,
 			if (!forward)
 				md->bat_levels[i]--;
 		}
+unmap:
 		kunmap_atomic(bat_entries);
+		if (stop)
+			break;
 		delta_bat_entries += PAGE_SIZE / sizeof(map_index_t);
 	}
 
@@ -767,22 +778,25 @@ static int process_update_delta_index(struct ploop *ploop, u8 level,
 static int ploop_delta_clusters_merged(struct ploop *ploop, u8 level,
 				       bool forward)
 {
-	void *d_hdr = NULL;
+	struct ploop_pvd_header *d_hdr = NULL;
 	struct file *file;
+	u32 size_in_clus;
 	int ret;
 
 	/* Reread BAT of deltas[@level + 1] (or [@level - 1]) */
 	file = ploop->deltas[level + forward ? 1 : -1].file;
 
-	ret = ploop_read_delta_metadata(ploop, file, &d_hdr);
+	ret = ploop_read_delta_metadata(ploop, file, (void *)&d_hdr);
 	if (ret)
 		goto out;
 
+	size_in_clus = le32_to_cpu(d_hdr->m_Size);
+
 	ret = ploop_suspend_submitting_pios(ploop);
 	if (ret)
 		goto out;
 
-	notify_delta_merged(ploop, level, d_hdr, forward);
+	notify_delta_merged(ploop, level, d_hdr, forward, size_in_clus);
 
 	ploop_resume_submitting_pios(ploop);
 	ret = 0;