[Devel] [PATCH vz9] dm-ploop: fix resize and grow to use the new way of updating md pages

[Alexander Atanasov]

We missed the fact that resize/grow touch md0 page to update ploop
parameters, other pages are not linked so there is no issue.
But in case there is a concurrent update to md0 piwb is not handled
correctly, also using sync updates in parallel is not okay.
To fix this update code to use the new mechanism with MD_UPDATING
flag and instead of using sync operations pass the updates to
runner threads.

https://virtuozzo.atlassian.net/browse/VSTOR-101871
Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c | 37 ++++++++++++++++++++++++++++---------
 drivers/md/dm-ploop.h     |  7 ++++++-
 2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index ef280a8b0f90..04e71c851b64 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -613,11 +613,6 @@ static void ploop_unlink_completed_pio(struct ploop *ploop, struct pio *pio)
 		ploop_dispatch_pios(ploop, NULL, &pio_list);
 }
 
-static void ploop_add_dirty_for_wb(struct ploop *ploop, struct md_page *md)
-{
-	llist_add((struct llist_node *)&md->wb_link, &ploop->wb_batch_llist);
-}
-
 static bool ploop_md_make_dirty(struct ploop *ploop, struct md_page *md)
 {
 	bool new = false;
@@ -1031,6 +1026,7 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 	struct pio *pio;
 	map_index_t *to;
 	u8 level;
+	int ret = -ENOMEM;
 
 	lockdep_assert_held(&ploop->bat_lock);
 
@@ -1050,6 +1046,9 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 	if (WARN_ON(md->piwb)) {
 		PL_ERR("md %p has piwb: %p type:%d ourtype:%d\n",
 			md, md->piwb, md->piwb->type, type);
+		spin_unlock(&md->md_lock);
+		ret = -EBUSY;
+		goto err;
 	}
 	md->piwb = piwb;
 	piwb->md = md;
@@ -1094,7 +1093,7 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 	return 0;
 err:
 	ploop_free_piwb(piwb);
-	return -ENOMEM;
+	return ret;
 }
 
 void ploop_break_bat_update(struct ploop *ploop, struct md_page *md,
@@ -2692,31 +2691,45 @@ static void ploop_handle_cleanup(struct ploop *ploop, struct pio *pio)
  * another index instead of existing. If so, management of
  * old bat_entries[@clu] and of related holes_bitmap bit
  * is caller duty.
+ * Caller must clear MD_UPDATING and comply to add_for_wb
  */
 int ploop_prepare_reloc_index_wb(struct ploop *ploop,
 				 struct md_page **ret_md,
 				 u32 clu, u32 *dst_clu,
-				 struct file *file)
+				 struct file *file,
+				 int *add_for_wb)
 {
 	enum piwb_type type = PIWB_TYPE_ALLOC;
 	u32 page_id = ploop_bat_clu_to_page_nr(clu);
 	struct md_page *md = ploop_md_page_find(ploop, page_id);
 	struct ploop_index_wb *piwb;
 	int err;
+	bool add_to_wblist;
 
 	if (dst_clu)
 		type = PIWB_TYPE_RELOC;
 
 	err = -EIO;
+
+
 	spin_lock_irq(&ploop->bat_lock);
-	if (test_bit(MD_DIRTY, &md->status) || test_bit(MD_WRITEBACK, &md->status)) {
-		PL_ERR("Unexpected md status: %lx", md->status);
+	spin_lock(&md->md_lock);
+	if (test_bit(MD_DIRTY, &md->status) || test_bit(MD_WRITEBACK, &md->status)
+	    || test_bit(MD_UPDATING, &md->status)) {
+		err = -EBUSY;
+		spin_unlock(&md->md_lock);
 		goto out_error;
+	} else {
+		set_bit(MD_UPDATING, &md->status);
 	}
+	spin_unlock(&md->md_lock);
+
 	err = ploop_prepare_bat_update(ploop, md, type);
 	if (err)
 		goto out_error;
 
+	add_to_wblist = ploop_md_make_dirty(ploop, md);
+
 	piwb = md->piwb;
 
 	if (dst_clu) {
@@ -2734,12 +2747,18 @@ int ploop_prepare_reloc_index_wb(struct ploop *ploop,
 	spin_unlock_irq(&ploop->bat_lock);
 
 	*ret_md = md;
+	*add_for_wb = add_to_wblist ? 1 : 0;
+
 	return 0;
 
 out_reset:
 	ploop_break_bat_update(ploop, md, piwb);
 out_error:
+	if (add_to_wblist)
+		clear_bit(MD_DIRTY, &md->status);
+	clear_bit(MD_UPDATING, &md->status);
 	spin_unlock_irq(&ploop->bat_lock);
+
 	return err;
 }
 ALLOW_ERROR_INJECTION(ploop_prepare_reloc_index_wb, ERRNO);
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index 46450cac8c7d..db4d92c9679a 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -578,6 +578,11 @@ static inline const char *ploop_device_name(struct ploop *ploop)
 	return ploop->ti->table->md->disk->disk_name;
 }
 
+static inline void ploop_add_dirty_for_wb(struct ploop *ploop, struct md_page *md)
+{
+	llist_add((struct llist_node *)&md->wb_link, &ploop->wb_batch_llist);
+}
+
 #define PL_FMT(fmt) "ploop: %s: " fmt "\n"
 #define PL_ERR(fmt, ...) pr_err(PL_FMT(fmt), ploop_device_name(ploop), ##__VA_ARGS__)
 #define PL_ERR_ONCE(fmt, ...) pr_err_once(PL_FMT(fmt), ploop_device_name(ploop), ##__VA_ARGS__)
@@ -612,7 +617,7 @@ extern void ploop_map_and_submit_rw(struct ploop *ploop, u32 dst_clu,
 				    struct pio *pio, u8 level);
 extern int ploop_prepare_reloc_index_wb(struct ploop *ploop,
 					struct md_page **ret_md, u32 clu, u32 *dst_clu,
-					struct file *file);
+					struct file *file, int *add_for_wb);
 extern void ploop_break_bat_update(struct ploop *ploop, struct md_page *md,
 				   struct ploop_index_wb *piwb);
 extern void ploop_index_wb_submit(struct ploop *, struct ploop_index_wb *);
-- 
2.43.0