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Message-Id: <20200508064004.57898-10-keescook@chromium.org>
Date: Thu, 7 May 2020 23:40:01 -0700
From: Kees Cook <keescook@...omium.org>
To: WeiXiong Liao <liaoweixiong@...winnertech.com>
Cc: Kees Cook <keescook@...omium.org>,
Anton Vorontsov <anton@...msg.org>,
Colin Cross <ccross@...roid.com>,
Tony Luck <tony.luck@...el.com>,
Petr Mladek <pmladek@...e.com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
linux-doc@...r.kernel.org, linux-mtd@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v4 09/12] pstore/zone: Provide way to skip "broken" zone for MTD devices
From: WeiXiong Liao <liaoweixiong@...winnertech.com>
One requirement to support MTD devices in pstore/zone is having a
way to declare certain regions as broken. Add this support to
pstore/zone.
The MTD driver should return -ENOMSG when encountering a bad region,
which tells pstore/zone to skip and try the next one.
Signed-off-by: WeiXiong Liao <liaoweixiong@...winnertech.com>
Link: https://lore.kernel.org/r/1585126506-18635-9-git-send-email-liaoweixiong@allwinnertech.com
Signed-off-by: Kees Cook <keescook@...omium.org>
---
fs/pstore/blk.c | 10 ++++--
fs/pstore/zone.c | 65 ++++++++++++++++++++++++++++++-------
include/linux/pstore_blk.h | 3 +-
include/linux/pstore_zone.h | 12 ++++---
4 files changed, 71 insertions(+), 19 deletions(-)
diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
index 5db811b7018d..e33e58afd4cb 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -101,9 +101,12 @@ static struct bdev_info {
* means error.
* @write: The same as @read, but the following error number:
* -EBUSY means try to write again later.
+ * -ENOMSG means to try next zone.
* @panic_write:The write operation only used for panic case. It's optional
- * if you do not care panic log. The parameters and return value
- * are the same as @read.
+ * if you do not care panic log. The parameters are relative
+ * value to storage.
+ * On success, the number of bytes should be returned, others
+ * excluding -ENOMSG mean error. -ENOMSG means to try next zone.
*/
struct psblk_device {
unsigned long total_size;
@@ -315,6 +318,9 @@ static ssize_t psblk_blk_panic_write(const char *buf, size_t size,
/* size and off must align to SECTOR_SIZE for block device */
ret = blkdev_panic_write(buf, off >> SECTOR_SHIFT,
size >> SECTOR_SHIFT);
+ /* try next zone */
+ if (ret == -ENOMSG)
+ return ret;
return ret ? -EIO : size;
}
diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
index 36d78c63bd20..43d44d016039 100644
--- a/fs/pstore/zone.c
+++ b/fs/pstore/zone.c
@@ -247,6 +247,9 @@ static int psz_zone_write(struct pstore_zone *zone,
return 0;
dirty:
+ /* no need to mark dirty if going to try next zone */
+ if (wcnt == -ENOMSG)
+ return -ENOMSG;
atomic_set(&zone->dirty, true);
/* flush dirty zones nicely */
if (wcnt == -EBUSY && !is_on_panic())
@@ -382,7 +385,11 @@ static int psz_recover_oops_meta(struct psz_context *cxt)
return -EINVAL;
rcnt = info->read((char *)buf, len, zone->off);
- if (rcnt != len) {
+ if (rcnt == -ENOMSG) {
+ 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;
}
@@ -717,24 +724,58 @@ static void psz_write_kmsg_hdr(struct pstore_zone *zone,
hdr->counter = 0;
}
+/*
+ * In case zone is broken, which may occur to MTD device, we try each zones,
+ * start at cxt->oops_write_cnt.
+ */
static inline int notrace psz_oops_write_record(struct psz_context *cxt,
struct pstore_record *record)
{
+ int ret = -EBUSY;
size_t size, hlen;
struct pstore_zone *zone;
- unsigned int zonenum;
+ unsigned int i;
- zonenum = cxt->oops_write_cnt;
- zone = cxt->opszs[zonenum];
- if (unlikely(!zone))
- return -ENOSPC;
- cxt->oops_write_cnt = (zonenum + 1) % cxt->oops_max_cnt;
+ for (i = 0; i < cxt->oops_max_cnt; i++) {
+ unsigned int zonenum, len;
+
+ zonenum = (cxt->oops_write_cnt + i) % cxt->oops_max_cnt;
+ zone = cxt->opszs[zonenum];
+ if (unlikely(!zone))
+ return -ENOSPC;
- pr_debug("write %s to zone id %d\n", zone->name, zonenum);
- psz_write_kmsg_hdr(zone, record);
- hlen = sizeof(struct psz_oops_header);
- size = min_t(size_t, record->size, zone->buffer_size - hlen);
- return psz_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);
+ psz_write_kmsg_hdr(zone, record);
+ hlen = sizeof(struct psz_oops_header);
+ size = min_t(size_t, record->size, zone->buffer_size - hlen);
+ ret = psz_zone_write(zone, FLUSH_ALL, record->buf, size, hlen);
+ if (likely(!ret || ret != -ENOMSG)) {
+ cxt->oops_write_cnt = zonenum + 1;
+ cxt->oops_write_cnt %= cxt->oops_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 psz_oops_write(struct psz_context *cxt,
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index d8f609e60288..828b0763d477 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -14,7 +14,8 @@
* @start_sect: start sector to block device
* @sects: sectors count on buf
*
- * Return: On success, zero should be returned. Others mean error.
+ * Return: On success, zero should be returned. Others excluding -ENOMSG
+ * mean error. -ENOMSG means to try next zone.
*
* Panic write to block device must be aligned to SECTOR_SIZE.
*/
diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h
index 94f441b8b616..ddb3dfea4ea6 100644
--- a/include/linux/pstore_zone.h
+++ b/include/linux/pstore_zone.h
@@ -23,11 +23,15 @@ typedef ssize_t (*psz_write_op)(const char *, size_t, loff_t);
* @read: The general read operation. Both of the function parameters
* @size and @offset are relative value to storage.
* On success, the number of bytes should be returned, others
- * means error.
- * @write: The same as @read, but -EBUSY means try to write again later.
+ * mean error.
+ * @write: The same as @read, but the following error number:
+ * -EBUSY means try to write again later.
+ * -ENOMSG means to try next zone.
* @panic_write:The write operation only used for panic case. It's optional
- * if you do not care panic log. The parameters and return value
- * are the same as @read.
+ * if you do not care panic log. The parameters are relative
+ * value to storage.
+ * On success, the number of bytes should be returned, others
+ * excluding -ENOMSG mean error. -ENOMSG means to try next zone.
*/
struct pstore_zone_info {
struct module *owner;
--
2.20.1
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