[PATCH v1 07/11] pstore/blk: skip broken zone for mtd device

WeiXiong Liao
2020-01-20T01:05:34Z

It's one of a series of patches for adaptive to MTD device.

MTD device is not block device. As the block of flash (MTD device) will
be broken, it's necessary for pstore/blk to skip the broken block
(bad block).

If device drivers return -ENEXT, pstore/blk will try next zone of dmesg.

Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
---
Documentation/admin-guide/pstore-block.rst | 3 +-
fs/pstore/blkzone.c | 74 +++++++++++++++++++++++-------
include/linux/blkoops.h | 4 +-
include/linux/pstore_blk.h | 4 ++
4 files changed, 66 insertions(+), 19 deletions(-)

diff --git a/Documentation/admin-guide/pstore-block.rst b/Documentation/admin-guide/pstore-block.rst
index 58418d429c55..aea6d2664a22 100644
--- a/Documentation/admin-guide/pstore-block.rst
+++ b/Documentation/admin-guide/pstore-block.rst
@@ -185,7 +185,8 @@ The parameter @offset is the relative position of the device.
Normally the number of bytes read/written should be returned, while for error,
negative number will be returned. The following return numbers mean more:

--EBUSY: pstore/blk should try again later.
+1. -EBUSY: pstore/blk should try again later.
+#. -ENEXT: this zone is used or broken, pstore/blk should try next one.

panic_write (for non-block device)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/fs/pstore/blkzone.c b/fs/pstore/blkzone.c
index 66ae8e2a924b..3f58ff85f49c 100644
--- a/fs/pstore/blkzone.c
+++ b/fs/pstore/blkzone.c
@@ -223,6 +223,9 @@ static int blkz_zone_write(struct blkz_zone *zone,

return 0;
set_dirty:
+ /* no need to mark dirty if going to try next zone */
+ if (wcnt == -ENEXT)
+ return -ENEXT;
atomic_set(&zone->dirty, true);
/* flush dirty zones nicely */
if (wcnt == -EBUSY && !is_on_panic())
@@ -376,7 +379,11 @@ static int blkz_recover_dmesg_meta(struct blkz_context *cxt)
return -EINVAL;

rcnt = info->read((char *)buf, len, zone->off);
- if (rcnt != len) {
+ if (rcnt == -ENEXT) {
+ pr_debug("%s with id %lu may be broken, skip\n",
+ zone->name, i);
+ continue;
+ } else if (rcnt != len) {
pr_err("read %s with id %lu failed\n", zone->name, i);
return (int)rcnt < 0 ? (int)rcnt : -EIO;
}
@@ -666,24 +673,58 @@ static void blkz_write_kmsg_hdr(struct blkz_zone *zone,
hdr->counter = 0;
}

+/*
+ * In case zone is broken, which may occur to MTD device, we try each zones,
+ * start at cxt->dmesg_write_cnt.
+ */
static inline int notrace blkz_dmesg_write_do(struct blkz_context *cxt,
struct pstore_record *record)
{
+ int ret = -EBUSY;
size_t size, hlen;
struct blkz_zone *zone;
- unsigned int zonenum;
+ unsigned int i;

- zonenum = cxt->dmesg_write_cnt;
- zone = cxt->dbzs[zonenum];
- if (unlikely(!zone))
- return -ENOSPC;
- cxt->dmesg_write_cnt = (zonenum + 1) % cxt->dmesg_max_cnt;
+ for (i = 0; i < cxt->dmesg_max_cnt; i++) {
+ unsigned int zonenum, len;
+
+ zonenum = (cxt->dmesg_write_cnt + i) % cxt->dmesg_max_cnt;
+ zone = cxt->dbzs[zonenum];
+ if (unlikely(!zone))
+ return -ENOSPC;

- pr_debug("write %s to zone id %d\n", zone->name, zonenum);
- blkz_write_kmsg_hdr(zone, record);
- hlen = sizeof(struct blkz_dmesg_header);
- size = min_t(size_t, record->size, zone->buffer_size - hlen);
- return blkz_zone_write(zone, FLUSH_ALL, record->buf, size, hlen);
+ /* avoid destorying old data, allocate a new one */
+ len = zone->buffer_size + sizeof(*zone->buffer);
+ zone->oldbuf = zone->buffer;
+ zone->buffer = kzalloc(len, GFP_KERNEL);
+ if (!zone->buffer) {
+ zone->buffer = zone->oldbuf;
+ return -ENOMEM;
+ }
+ zone->buffer->sig = zone->oldbuf->sig;
+
+ pr_debug("write %s to zone id %d\n", zone->name, zonenum);
+ blkz_write_kmsg_hdr(zone, record);
+ hlen = sizeof(struct blkz_dmesg_header);
+ size = min_t(size_t, record->size, zone->buffer_size - hlen);
+ ret = blkz_zone_write(zone, FLUSH_ALL, record->buf, size, hlen);
+ if (likely(!ret || ret != -ENEXT)) {
+ cxt->dmesg_write_cnt = zonenum + 1;
+ cxt->dmesg_write_cnt %= cxt->dmesg_max_cnt;
+ /* no need to try next zone, free last zone buffer */
+ kfree(zone->oldbuf);
+ zone->oldbuf = NULL;
+ return ret;
+ }
+
+ pr_debug("zone %u may be broken, try next dmesg zone\n",
+ zonenum);
+ kfree(zone->buffer);
+ zone->buffer = zone->oldbuf;
+ zone->oldbuf = NULL;
+ }
+
+ return -EBUSY;
}

static int notrace blkz_dmesg_write(struct blkz_context *cxt,
@@ -807,7 +848,6 @@ static int notrace blkz_pstore_write(struct pstore_record *record)
}
}

-#define READ_NEXT_ZONE ((ssize_t)(-1024))
static struct blkz_zone *blkz_read_next_zone(struct blkz_context *cxt)
{
struct blkz_zone *zone = NULL;
@@ -868,7 +908,7 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
if (blkz_read_dmesg_hdr(zone, record)) {
atomic_set(&zone->buffer->datalen, 0);
atomic_set(&zone->dirty, 0);
- return READ_NEXT_ZONE;
+ return -ENEXT;
}
size -= sizeof(struct blkz_dmesg_header);

@@ -893,7 +933,7 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
if (unlikely(blkz_zone_read(zone, record->buf + hlen, size,
sizeof(struct blkz_dmesg_header)) < 0)) {
kfree(record->buf);
- return READ_NEXT_ZONE;
+ return -ENEXT;
}

return size + hlen;
@@ -907,7 +947,7 @@ static ssize_t blkz_record_read(struct blkz_zone *zone,

buf = (struct blkz_buffer *)zone->oldbuf;
if (!buf)
- return READ_NEXT_ZONE;
+ return -ENEXT;

size = atomic_read(&buf->datalen);
start = atomic_read(&buf->start);
@@ -959,7 +999,7 @@ static ssize_t blkz_pstore_read(struct pstore_record *record)
}

ret = readop(zone, record);
- if (ret == READ_NEXT_ZONE)
+ if (ret == -ENEXT)
goto next_zone;
return ret;
}
diff --git a/include/linux/blkoops.h b/include/linux/blkoops.h
index 8f40f225545d..71c596fd4cc8 100644
--- a/include/linux/blkoops.h
+++ b/include/linux/blkoops.h
@@ -27,6 +27,7 @@
* On error, negative number should be returned. The following returning
* number means more:
* -EBUSY: pstore/blk should try again later.
+ * -ENEXT: this zone is used or broken, pstore/blk should try next one.
* @panic_write:
* The write operation only used for panic.
*
@@ -45,7 +46,8 @@ struct blkoops_device {

/*
* Panic write for block device who should write alignmemt to SECTOR_SIZE.
- * On success, zero should be returned. Others mean error.
+ * On success, zero should be returned. Others mean error except that -ENEXT
+ * means the zone is used or broken, pstore/blk should try next one.
*/
typedef int (*blkoops_blk_panic_write_op)(const char *buf, sector_t start_sect,
sector_t sects);
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index 77704c1b404a..bbbe4fe37f7c 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -6,6 +6,9 @@
#include <linux/types.h>
#include <linux/blkdev.h>

+/* read/write function return -ENEXT means try next zone */
+#define ENEXT ((ssize_t)(1024))
+
/**
* struct blkz_info - backend blkzone driver structure
*
@@ -42,6 +45,7 @@
* On error, negative number should be returned. The following returning
* number means more:
* -EBUSY: pstore/blk should try again later.
+ * -ENEXT: this zone is used or broken, pstore/blk should try next one.
* @panic_write:
* The write operation only used for panic. It's optional if you do not
* care panic record. If panic occur but blkzone do not recover yet, the
--
1.9.1