[RFC PATCH v2 0/4] add parameter for pmem cache device init

[RFC PATCH v2 0/4] add parameter for pmem cache device init

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

This patch set could be used for dm-writecache when use persistent
memory as cache data device.

Patch 1 and 2 go towards removing unused parameter and codes which
actually doesn't really work.

Patch 3 and 4 are targeted at solving problem fn ctr failed to work
due to invalid magic or version, which is caused by the super block
of pmem has messy data stored.

Changes Since v1:
	- add optional parameter reinit to avoid invalid magic or
	  version.
	[1]: https://lkml.org/lkml/2019/1/3/43

Huaisheng Ye (4):
  dm-writecache: remove unused size to writecache_flush_region
  dm-writecache: get rid of memory_data flush to writecache_flush_entry
  dm-writecache: expand pmem_reinit for struct dm_writecache
  Documentation/device-mapper: add optional parameter reinit

 Documentation/device-mapper/writecache.txt |  4 ++++
 drivers/md/dm-writecache.c                 | 19 +++++++++++--------
 2 files changed, 15 insertions(+), 8 deletions(-)

-- 
1.8.3.1

[RFC PATCH v2 1/4] dm-writecache: remove unused size to writecache_flush_region

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

writecache_flush_region doesn't use size to calculate flush region.
That uses _set_bits to mark the region in dirty_bitmap directly.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
---
 drivers/md/dm-writecache.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 2d50eec..2d8e0c0 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -418,7 +418,7 @@ static void writecache_flush_all_metadata(struct dm_writecache *wc)
 		memset(wc->dirty_bitmap, -1, wc->dirty_bitmap_size);
 }
 
-static void writecache_flush_region(struct dm_writecache *wc, void *ptr, size_t size)
+static void writecache_flush_region(struct dm_writecache *wc, void *ptr)
 {
 	if (!WC_MODE_PMEM(wc))
 		__set_bit(((char *)ptr - (char *)wc->memory_map) / BITMAP_GRANULARITY,
@@ -657,7 +657,7 @@ static void writecache_free_entry(struct dm_writecache *wc, struct wc_entry *e)
 	writecache_unlink(wc, e);
 	writecache_add_to_freelist(wc, e);
 	clear_seq_count(wc, e);
-	writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
+	writecache_flush_region(wc, memory_entry(wc, e));
 	if (unlikely(waitqueue_active(&wc->freelist_wait)))
 		wake_up(&wc->freelist_wait);
 }
@@ -687,9 +687,9 @@ static void writecache_poison_lists(struct dm_writecache *wc)
 
 static void writecache_flush_entry(struct dm_writecache *wc, struct wc_entry *e)
 {
-	writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
+	writecache_flush_region(wc, memory_entry(wc, e));
 	if (WC_MODE_PMEM(wc))
-		writecache_flush_region(wc, memory_data(wc, e), wc->block_size);
+		writecache_flush_region(wc, memory_data(wc, e));
 }
 
 static bool writecache_entry_is_committed(struct dm_writecache *wc, struct wc_entry *e)
@@ -733,7 +733,7 @@ static void writecache_flush(struct dm_writecache *wc)
 
 	wc->seq_count++;
 	pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
-	writecache_flush_region(wc, &sb(wc)->seq_count, sizeof sb(wc)->seq_count);
+	writecache_flush_region(wc, &sb(wc)->seq_count);
 	writecache_commit_flushed(wc);
 
 	wc->overwrote_committed = false;
@@ -1757,7 +1757,7 @@ static int init_memory(struct dm_writecache *wc)
 	writecache_flush_all_metadata(wc);
 	writecache_commit_flushed(wc);
 	pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
-	writecache_flush_region(wc, &sb(wc)->magic, sizeof sb(wc)->magic);
+	writecache_flush_region(wc, &sb(wc)->magic);
 	writecache_commit_flushed(wc);
 
 	return 0;
-- 
1.8.3.1

[RFC PATCH v2 2/4] dm-writecache: get rid of memory_data flush to writecache_flush_entry

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

writecache_flush_region only works when SSD mode.
If wc->pmem_mode sets, writecache_flush_region doesn't need to be called in
writecache_flush_entry.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
---
 drivers/md/dm-writecache.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 2d8e0c0..c69317c 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -688,8 +688,6 @@ static void writecache_poison_lists(struct dm_writecache *wc)
 static void writecache_flush_entry(struct dm_writecache *wc, struct wc_entry *e)
 {
 	writecache_flush_region(wc, memory_entry(wc, e));
-	if (WC_MODE_PMEM(wc))
-		writecache_flush_region(wc, memory_data(wc, e));
 }
 
 static bool writecache_entry_is_committed(struct dm_writecache *wc, struct wc_entry *e)
-- 
1.8.3.1

[RFC PATCH v2 3/4] dm-writecache: expand pmem_reinit for struct dm_writecache

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

When use persistent memory as cache data device, sometimes
the super block of pmem has messy data stored in it. That would
have risk to lead fn ctr failed to work due to invalid magic or
version.

Here we expand pmem_reinit to optional parameters in order to solve
this issue. When user gets pmem device, which has unrelated data in it,
as cache device, he should use paramenter 'reinit' to avoid s.magic
and s.version don't equal to NULL or correct
MEMORY_SUPERBLOCK_MAGIC/VERSION.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
---
 drivers/md/dm-writecache.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index c69317c..2c1e825 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -149,6 +149,7 @@ struct dm_writecache {
 
 	bool pmem_mode:1;
 	bool writeback_fua:1;
+	bool pmem_reinit:1;
 
 	bool overwrote_committed:1;
 	bool memory_vmapped:1;
@@ -2026,6 +2027,10 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
 				wc->writeback_fua = false;
 				wc->writeback_fua_set = true;
 			} else goto invalid_optional;
+		} else if (!strcasecmp(string, "reinit")) {
+			if (WC_MODE_PMEM(wc))
+				wc->pmem_reinit = true;
+			else goto invalid_optional;
 		} else {
 invalid_optional:
 			r = -EINVAL;
@@ -2127,7 +2132,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
 		ti->error = "Hardware memory error when reading superblock";
 		goto bad;
 	}
-	if (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version)) {
+	if (wc->pmem_reinit || (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version))) {
 		r = init_memory(wc);
 		if (r) {
 			ti->error = "Unable to initialize device";
-- 
1.8.3.1

[RFC PATCH v2 4/4] Documentation/device-mapper: add optional parameter reinit

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

Add intro and usage guide for reinit.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
---
 Documentation/device-mapper/writecache.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/device-mapper/writecache.txt b/Documentation/device-mapper/writecache.txt
index 01532b3..255c68c 100644
--- a/Documentation/device-mapper/writecache.txt
+++ b/Documentation/device-mapper/writecache.txt
@@ -45,6 +45,10 @@ Constructor parameters:
 		afterwards
 		- some underlying devices perform better with fua, some
 		  with nofua. The user should test it
+	reinit		(by default off)
+		applicable only to persistent memory - use the REINIT flag
+		when the surper block has messy data, that would cause fn ctr
+		failed to work with invalid magic or version in the superblock
 
 Status:
 1. error indicator - 0 if there was no error, otherwise error number
-- 
1.8.3.1