[Devel] [RFC PATCH vz9 2/5] ploop: move md status to use proper bitops

[Alexander Atanasov]

Fix direct bitops to use set_bit/clear_bit which
are atomic - this is required since there are
some places in code that do not use locking when
operating on that bits. this is also a preparation
to relax locking.

https://virtuozzo.atlassian.net/browse/VSTOR-91820
Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
 drivers/md/dm-ploop-cmd.c |  2 +-
 drivers/md/dm-ploop-map.c | 32 +++++++++++++++-----------------
 drivers/md/dm-ploop.h     |  2 +-
 3 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
index ea6974f72385..f10850d801eb 100644
--- a/drivers/md/dm-ploop-cmd.c
+++ b/drivers/md/dm-ploop-cmd.c
@@ -274,7 +274,7 @@ static int ploop_write_zero_cluster_sync(struct ploop *ploop,
 static void ploop_make_md_wb(struct ploop *ploop, struct md_page *md)
 {
 	write_lock_irq(&ploop->bat_rwlock);
-	md->status |= MD_WRITEBACK;
+	set_bit(MD_WRITEBACK, &md->status);
 	write_unlock_irq(&ploop->bat_rwlock);
 }
 
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 9f7efed45c2a..e8e543d566d1 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -384,7 +384,7 @@ static bool ploop_delay_if_md_busy(struct ploop *ploop, struct md_page *md,
 
 	write_lock_irqsave(&ploop->bat_rwlock, flags);
 	piwb = md->piwb;
-	if (piwb && (piwb->type != type || (md->status & MD_WRITEBACK))) {
+	if (piwb && (piwb->type != type || test_bit(MD_WRITEBACK, &md->status))) {
 		list_add_tail(&pio->list, &md->wait_list);
 		busy = true;
 	}
@@ -551,9 +551,8 @@ static bool ploop_md_make_dirty(struct ploop *ploop, struct md_page *md)
 	bool new = false;
 
 	write_lock_irqsave(&ploop->bat_rwlock, flags);
-	WARN_ON_ONCE((md->status & MD_WRITEBACK));
-	if (!(md->status & MD_DIRTY)) {
-		md->status |= MD_DIRTY;
+	WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
+	if (!test_and_set_bit(MD_DIRTY, &md->status)) {
 		list_add_tail(&md->wb_link, &ploop->wb_batch_list);
 		new = true;
 	}
@@ -801,8 +800,8 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
 		}
 	}
 
-	WARN_ON_ONCE(!(md->status & MD_WRITEBACK));
-	md->status &= ~MD_WRITEBACK;
+	WARN_ON_ONCE(!test_bit(MD_WRITEBACK, &md->status));
+	clear_bit(MD_WRITEBACK, &md->status);
 	md->piwb = NULL;
 	list_splice_tail_init(&md->wait_list, &list);
 	write_unlock_irqrestore(&ploop->bat_rwlock, flags);
@@ -1373,8 +1372,8 @@ static void ploop_submit_cow_index_wb(struct ploop_cow *cow)
 	if (ploop_delay_if_md_busy(ploop, md, PIWB_TYPE_ALLOC, cow->aux_pio))
 		goto out;
 
-	if (!(md->status & MD_DIRTY)) {
-		/* Unlocked, since MD_DIRTY is set and cleared from this work */
+	if (!test_bit(MD_DIRTY, &md->status)) {
+		/* MD_DIRTY is set and cleared from this work */
 		if (ploop_prepare_bat_update(ploop, md, PIWB_TYPE_ALLOC) < 0)
 			goto err_resource;
 		ploop_md_make_dirty(ploop, md);
@@ -1460,7 +1459,7 @@ static bool ploop_locate_new_cluster_and_attach_pio(struct ploop *ploop,
 	if (ploop_delay_if_md_busy(ploop, md, PIWB_TYPE_ALLOC, pio))
 		goto out;
 
-	if (!(md->status & MD_DIRTY)) {
+	if (!test_bit(MD_DIRTY, &md->status)) {
 		 /* Unlocked since MD_DIRTY is set and cleared from this work */
 		page_id = ploop_bat_clu_to_page_nr(clu);
 		if (ploop_prepare_bat_update(ploop, md, PIWB_TYPE_ALLOC) < 0) {
@@ -1703,7 +1702,7 @@ static void ploop_process_one_discard_pio(struct ploop *ploop, struct pio *pio)
 	if (ploop_delay_if_md_busy(ploop, md, PIWB_TYPE_DISCARD, pio))
 		goto out;
 
-	if (!(md->status & MD_DIRTY)) {
+	if (!test_bit(MD_DIRTY, &md->status)) {
 		 /* Unlocked since MD_DIRTY is set and cleared from this work */
 		if (ploop_prepare_bat_update(ploop, md, PIWB_TYPE_DISCARD) < 0) {
 			pio->bi_status = BLK_STS_RESOURCE;
@@ -1759,7 +1758,6 @@ static void ploop_process_resubmit_pios(struct ploop *ploop,
 static void ploop_submit_metadata_writeback(struct ploop *ploop)
 {
 	struct md_page *md;
-
 	while (1) {
 		write_lock_irq(&ploop->bat_rwlock);
 		md = list_first_entry_or_null(&ploop->wb_batch_list,
@@ -1770,10 +1768,10 @@ static void ploop_submit_metadata_writeback(struct ploop *ploop)
 		}
 		list_del_init(&md->wb_link);
 		/* L1L2 mustn't be redirtyed, when wb in-flight! */
-		WARN_ON_ONCE(!(md->status & MD_DIRTY) ||
-			     (md->status & MD_WRITEBACK));
-		md->status |= MD_WRITEBACK;
-		md->status &= ~MD_DIRTY;
+		WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
+		WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
+		set_bit(MD_WRITEBACK, &md->status);
+		clear_bit(MD_DIRTY, &md->status);
 		write_unlock_irq(&ploop->bat_rwlock);
 
 		ploop_index_wb_submit(ploop, md->piwb);
@@ -1950,8 +1948,8 @@ int ploop_prepare_reloc_index_wb(struct ploop *ploop,
 		type = PIWB_TYPE_RELOC;
 
 	err = -EIO;
-	if ((md->status & (MD_DIRTY|MD_WRITEBACK))) {
-		PL_ERR("Unexpected md status: %x", md->status);
+	if (test_bit(MD_DIRTY, &md->status) || test_bit(MD_WRITEBACK, &md->status)) {
+		PL_ERR("Unexpected md status: %lx", md->status);
 		goto out_error;
 	}
 	err = ploop_prepare_bat_update(ploop, md, type);
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index 90c80954c198..5fa176affc4e 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -117,7 +117,7 @@ struct md_page {
 	u32 id; /* Number of this page starting from hdr */
 #define MD_DIRTY	(1U << 1) /* Page contains changes and wants writeback */
 #define MD_WRITEBACK	(1U << 2) /* Writeback was submitted */
-	unsigned int status;
+	unsigned long status;
 	struct page *page;
 	void *kmpage;
 	u8 *bat_levels;
-- 
2.43.0