[RFC v10 3/4] pstore/blk: support pmsg for pstore block

[liaoweixiong]

To enable pmsg, just set pmsg_size when block device register blkzone.

Signed-off-by: liaoweixiong <liaoweixiong@xxxxxxxxxxxxxxxxx>
---
 fs/pstore/Kconfig          |  21 ++++
 fs/pstore/blkoops.c        |  10 ++
 fs/pstore/blkzone.c        | 253 +++++++++++++++++++++++++++++++++++++++++----
 include/linux/pstore_blk.h |   1 +
 4 files changed, 264 insertions(+), 21 deletions(-)

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 7dfe00b..b417bf5 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -210,6 +210,27 @@ config PSTORE_BLKOOPS_DMESG_SIZE
 	     It is the first priority. Take care of that blkoops will take lower
 	     priority settings if higher priority one do not set.
 
+config PSTORE_BLKOOPS_PMSG_SIZE
+	int "pmsg size in kbytes for blkoops"
+	depends on PSTORE_BLKOOPS
+	default 64
+	help
+	  This just sets size of pmsg (pmsg_size) for pstore/blk. The value must
+	  be a multiple of 4096. Pmsg work only if "blkdev" is set.
+
+	  NOTE that, there are three ways to set parameters of blkoops and
+	  prioritize according to configuration flexibility. That is
+	  Kconfig < device tree < module parameters. It means that the value can
+	  be overwritten by higher priority settings.
+	  1. Kconfig
+	     It	just sets a default value.
+	  2. device tree
+	     It is set on device tree, which will overwrites value from Kconfig,
+	     but can also be overwritten by module parameters.
+	  3. module parameters
+	     It is the first priority. Take care of that blkoops will take lower
+	     priority settings if higher priority one do not set.
+
 config PSTORE_BLKOOPS_TOTAL_SIZE
 	int "total size in kbytes for blkoops"
 	depends on PSTORE_BLKOOPS
diff --git a/fs/pstore/blkoops.c b/fs/pstore/blkoops.c
index 22c0c84..05140fd 100644
--- a/fs/pstore/blkoops.c
+++ b/fs/pstore/blkoops.c
@@ -30,6 +30,10 @@
 module_param(dmesg_size, long, 0400);
 MODULE_PARM_DESC(dmesg_size, "demsg size in kbytes");
 
+static long pmsg_size = -1;
+module_param(pmsg_size, long, 0400);
+MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
+
 static long total_size = -1;
 module_param(total_size, long, 0400);
 MODULE_PARM_DESC(total_size, "total size in kbytes");
@@ -47,11 +51,13 @@ struct blkz_info blkz_info = {
 
 struct blkoops_info {
 	unsigned long dmesg_size;
+	unsigned long pmsg_size;
 	unsigned long total_size;
 	const char *blkdev;
 };
 struct blkoops_info blkoops_info = {
 	.dmesg_size = CONFIG_PSTORE_BLKOOPS_DMESG_SIZE * 1024,
+	.pmsg_size = CONFIG_PSTORE_BLKOOPS_PMSG_SIZE * 1024,
 	.total_size = CONFIG_PSTORE_BLKOOPS_TOTAL_SIZE * 1024,
 	.blkdev = CONFIG_PSTORE_BLKOOPS_BLKDEV,
 };
@@ -104,6 +110,7 @@ static int blkoops_probe(struct platform_device *pdev)
 
 	check_size(total_size, 4096);
 	check_size(dmesg_size, 4096);
+	check_size(pmsg_size, 4096);
 
 #undef check_size
 
@@ -112,6 +119,7 @@ static int blkoops_probe(struct platform_device *pdev)
 	 * through /sys/module/blkoops/parameters/
 	 */
 	dmesg_size = blkz_info.dmesg_size;
+	pmsg_size = blkz_info.pmsg_size;
 	total_size = blkz_info.total_size;
 	if (blkz_info.blkdev)
 		strncpy(blkdev, blkz_info.blkdev, 80 - 1);
@@ -156,6 +164,8 @@ void blkoops_register_dummy(void)
 			info->blkdev = (const char *)blkdev;
 		if (dmesg_size >= 0)
 			info->dmesg_size = (unsigned long)dmesg_size * 1024;
+		if (pmsg_size >= 0)
+			info->pmsg_size = (unsigned long)pmsg_size * 1024;
 	} else if (info->total_size > 0 || strlen(info->blkdev)) {
 		pr_info("using kconfig value\n");
 	} else {
diff --git a/fs/pstore/blkzone.c b/fs/pstore/blkzone.c
index cba55b3..cd3d4ed 100644
--- a/fs/pstore/blkzone.c
+++ b/fs/pstore/blkzone.c
@@ -40,12 +40,14 @@
  *
  * @sig: signature to indicate header (BLK_SIG xor BLKZONE-type value)
  * @datalen: length of data in @data
+ * @start: offset into @data where the beginning of the stored bytes begin
  * @data: zone data.
  */
 struct blkz_buffer {
 #define BLK_SIG (0x43474244) /* DBGC */
 	uint32_t sig;
 	atomic_t datalen;
+	atomic_t start;
 	uint8_t data[];
 };
 
@@ -78,6 +80,9 @@ struct blkz_dmesg_header {
  *	frontent name for this zone
  * @buffer:
  *	pointer to data buffer managed by this zone
+ * @oldbuf:
+ *	pointer to old data buffer. It is used for single zone such as pmsg,
+ *	saving the old buffer.
  * @buffer_size:
  *	bytes in @buffer->data
  * @should_recover:
@@ -91,6 +96,7 @@ struct blkz_zone {
 	enum pstore_type_id type;
 
 	struct blkz_buffer *buffer;
+	struct blkz_buffer *oldbuf;
 	size_t buffer_size;
 	bool should_recover;
 	atomic_t dirty;
@@ -98,8 +104,10 @@ struct blkz_zone {
 
 struct blkz_context {
 	struct blkz_zone **dbzs;	/* dmesg block zones */
+	struct blkz_zone *pbz;		/* Pmsg block zone */
 	unsigned int dmesg_max_cnt;
 	unsigned int dmesg_read_cnt;
+	unsigned int pmsg_read_cnt;
 	unsigned int dmesg_write_cnt;
 	/*
 	 * the counter should be recovered when do recovery
@@ -132,6 +140,11 @@ static inline int buffer_datalen(struct blkz_zone *zone)
 	return atomic_read(&zone->buffer->datalen);
 }
 
+static inline int buffer_start(struct blkz_zone *zone)
+{
+	return atomic_read(&zone->buffer->start);
+}
+
 static inline bool is_on_panic(void)
 {
 	struct blkz_context *cxt = &blkz_cxt;
@@ -388,6 +401,72 @@ static int blkz_recover_dmesg(struct blkz_context *cxt)
 	return ret;
 }
 
+static int blkz_recover_pmsg(struct blkz_context *cxt)
+{
+	struct blkz_info *info = cxt->bzinfo;
+	struct blkz_buffer *oldbuf;
+	struct blkz_zone *zone = NULL;
+	ssize_t (*readop)(char *buf, size_t bytes, loff_t pos);
+	int ret = 0;
+	ssize_t rcnt, len;
+
+	zone = cxt->pbz;
+	if (!zone || zone->oldbuf)
+		return 0;
+
+	if (is_on_panic())
+		goto out;
+
+	readop = info->read;
+	if (unlikely(!readop))
+		return -EINVAL;
+
+	len = zone->buffer_size + sizeof(*oldbuf);
+	oldbuf = kzalloc(len, GFP_KERNEL);
+	if (!oldbuf)
+		return -ENOMEM;
+
+	rcnt = readop((char *)oldbuf, len, zone->off);
+	if (rcnt != len) {
+		pr_debug("recover pmsg failed\n");
+		ret = (int)rcnt < 0 ? (int)rcnt : -EIO;
+		goto free_oldbuf;
+	}
+
+	if (oldbuf->sig != zone->buffer->sig) {
+		pr_debug("no valid data in zone %s\n", zone->name);
+		goto free_oldbuf;
+	}
+
+	if (zone->buffer_size < atomic_read(&oldbuf->datalen) ||
+		zone->buffer_size < atomic_read(&oldbuf->start)) {
+		pr_info("found overtop zone: %s: off %lu, size %zu\n",
+				zone->name, zone->off, zone->buffer_size);
+		goto free_oldbuf;
+	}
+
+	if (!atomic_read(&oldbuf->datalen)) {
+		pr_debug("found erased zone: %s: id 0, off %lu, size %zu, datalen %d\n",
+				zone->name, zone->off, zone->buffer_size,
+				atomic_read(&oldbuf->datalen));
+		kfree(oldbuf);
+		goto out;
+	}
+
+	pr_debug("found nice zone: %s: id 0, off %lu, size %zu, datalen %d\n",
+			zone->name, zone->off, zone->buffer_size,
+			atomic_read(&oldbuf->datalen));
+	zone->oldbuf = oldbuf;
+out:
+	if (atomic_read(&zone->dirty))
+		blkz_zone_write(zone, FLUSH_ALL, NULL, buffer_datalen(zone), 0);
+	return 0;
+
+free_oldbuf:
+	kfree(oldbuf);
+	return ret;
+}
+
 static inline int blkz_recovery(struct blkz_context *cxt)
 {
 	int ret = -EBUSY;
@@ -399,6 +478,10 @@ static inline int blkz_recovery(struct blkz_context *cxt)
 	if (ret)
 		goto recover_fail;
 
+	ret = blkz_recover_pmsg(cxt);
+	if (ret)
+		goto recover_fail;
+
 	atomic_set(&cxt->recovery, 1);
 	pr_debug("recover end!\n");
 	return 0;
@@ -416,11 +499,18 @@ static int blkz_pstore_open(struct pstore_info *psi)
 	return 0;
 }
 
+static inline bool blkz_old_ok(struct blkz_zone *zone)
+{
+	if (zone && zone->oldbuf && atomic_read(&zone->oldbuf->datalen))
+		return true;
+	return false;
+}
+
 static inline bool blkz_ok(struct blkz_zone *zone)
 {
-	if (!zone || !zone->buffer || !buffer_datalen(zone))
-		return false;
-	return true;
+	if (zone && zone->buffer && buffer_datalen(zone))
+		return true;
+	return false;
 }
 
 static int blkz_pstore_erase(struct pstore_record *record)
@@ -428,13 +518,29 @@ static int blkz_pstore_erase(struct pstore_record *record)
 	struct blkz_context *cxt = record->psi->data;
 	struct blkz_zone *zone = NULL;
 
-	if (record->type == PSTORE_TYPE_DMESG)
+	if (record->type == PSTORE_TYPE_DMESG) {
 		zone = cxt->dbzs[record->id];
-	if (!blkz_ok(zone))
-		return 0;
+		if (unlikely(!blkz_ok(zone)))
+			return 0;
 
-	atomic_set(&zone->buffer->datalen, 0);
-	return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
+		atomic_set(&zone->buffer->datalen, 0);
+		return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
+	} else if (record->type == PSTORE_TYPE_PMSG) {
+		zone = cxt->pbz;
+		if (unlikely(!blkz_old_ok(zone)))
+			return 0;
+
+		kfree(zone->oldbuf);
+		zone->oldbuf = NULL;
+		/**
+		 * if there is new data in zone buffer, there is no need to
+		 * flush 0 (erase) to block device
+		 */
+		if (buffer_datalen(zone))
+			return 0;
+		return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
+	}
+	return -EINVAL;
 }
 
 static void blkz_write_kmsg_hdr(struct blkz_zone *zone,
@@ -452,8 +558,10 @@ static void blkz_write_kmsg_hdr(struct blkz_zone *zone,
 	hdr->reason = record->reason;
 	if (hdr->reason == KMSG_DUMP_OOPS)
 		hdr->counter = ++cxt->oops_counter;
-	else
+	else if (hdr->reason == KMSG_DUMP_PANIC)
 		hdr->counter = ++cxt->panic_counter;
+	else
+		hdr->counter = 0;
 }
 
 static int notrace blkz_dmesg_write(struct blkz_context *cxt,
@@ -503,6 +611,55 @@ static int notrace blkz_dmesg_write(struct blkz_context *cxt,
 	return 0;
 }
 
+static int notrace blkz_pmsg_write(struct blkz_context *cxt,
+		struct pstore_record *record)
+{
+	struct blkz_zone *zone;
+	size_t start, rem;
+	int cnt = record->size;
+	bool is_full_data = false;
+	char *buf = record->buf;
+
+	zone = cxt->pbz;
+	if (!zone)
+		return -ENOSPC;
+
+	if (atomic_read(&zone->buffer->datalen) >= zone->buffer_size)
+		is_full_data = true;
+
+	if (unlikely(cnt > zone->buffer_size)) {
+		buf += cnt - zone->buffer_size;
+		cnt = zone->buffer_size;
+	}
+
+	start = buffer_start(zone);
+	rem = zone->buffer_size - start;
+	if (unlikely(rem < cnt)) {
+		blkz_zone_write(zone, FLUSH_PART, buf, rem, start);
+		buf += rem;
+		cnt -= rem;
+		start = 0;
+		is_full_data = true;
+	}
+
+	atomic_set(&zone->buffer->start, cnt + start);
+	blkz_zone_write(zone, FLUSH_PART, buf, cnt, start);
+
+	/**
+	 * blkz_zone_write will set datalen as start + cnt.
+	 * It work if actual data length lesser than buffer size.
+	 * If data length greater than buffer size, pmsg will rewrite to
+	 * beginning of zone, which make buffer->datalen wrongly.
+	 * So we should reset datalen as buffer size once actual data length
+	 * greater than buffer size.
+	 */
+	if (is_full_data) {
+		atomic_set(&zone->buffer->datalen, zone->buffer_size);
+		blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
+	}
+	return 0;
+}
+
 static int notrace blkz_pstore_write(struct pstore_record *record)
 {
 	struct blkz_context *cxt = record->psi->data;
@@ -520,6 +677,8 @@ static int notrace blkz_pstore_write(struct pstore_record *record)
 	switch (record->type) {
 	case PSTORE_TYPE_DMESG:
 		return blkz_dmesg_write(cxt, record);
+	case PSTORE_TYPE_PMSG:
+		return blkz_pmsg_write(cxt, record);
 	default:
 		return -EINVAL;
 	}
@@ -536,6 +695,13 @@ static struct blkz_zone *blkz_read_next_zone(struct blkz_context *cxt)
 			return zone;
 	}
 
+	if (cxt->pmsg_read_cnt == 0) {
+		cxt->pmsg_read_cnt++;
+		zone = cxt->pbz;
+		if (blkz_old_ok(zone))
+			return zone;
+	}
+
 	return NULL;
 }
 
@@ -574,7 +740,8 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
 		char *buf = kasprintf(GFP_KERNEL,
 				"%s: Total %d times\n",
 				record->reason == KMSG_DUMP_OOPS ? "Oops" :
-				"Panic", record->count);
+				record->reason == KMSG_DUMP_PANIC ? "Panic" :
+				"Unknown", record->count);
 		hlen = strlen(buf);
 		record->buf = krealloc(buf, hlen + size, GFP_KERNEL);
 		if (!record->buf) {
@@ -596,6 +763,29 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
 	return size + hlen;
 }
 
+static ssize_t blkz_pmsg_read(struct blkz_zone *zone,
+		struct pstore_record *record)
+{
+	size_t size, start;
+	struct blkz_buffer *buf;
+
+	buf = (struct blkz_buffer *)zone->oldbuf;
+	if (!buf)
+		return READ_NEXT_ZONE;
+
+	size = atomic_read(&buf->datalen);
+	start = atomic_read(&buf->start);
+
+	record->buf = kmalloc(size, GFP_KERNEL);
+	if (!record->buf)
+		return -ENOMEM;
+
+	memcpy(record->buf, buf->data + start, size - start);
+	memcpy(record->buf + size - start, buf->data, start);
+
+	return size;
+}
+
 static ssize_t blkz_pstore_read(struct pstore_record *record)
 {
 	struct blkz_context *cxt = record->psi->data;
@@ -621,6 +811,9 @@ static ssize_t blkz_pstore_read(struct pstore_record *record)
 		blkz_read = blkz_dmesg_read;
 		record->id = cxt->dmesg_read_cnt - 1;
 		break;
+	case PSTORE_TYPE_PMSG:
+		blkz_read = blkz_pmsg_read;
+		break;
 	default:
 		goto next_zone;
 	}
@@ -810,8 +1003,10 @@ static struct blkz_zone *blkz_init_zone(enum pstore_type_id type,
 	zone->type = type;
 	zone->buffer_size = size - sizeof(struct blkz_buffer);
 	zone->buffer->sig = type ^ BLK_SIG;
+	zone->oldbuf = NULL;
 	atomic_set(&zone->dirty, 0);
 	atomic_set(&zone->buffer->datalen, 0);
+	atomic_set(&zone->buffer->start, 0);
 
 	*off += size;
 
@@ -893,7 +1088,7 @@ static int blkz_cut_zones(struct blkz_context *cxt)
 	int err;
 	size_t size;
 
-	size = info->total_size;
+	size = info->total_size - info->pmsg_size;
 	cxt->dbzs = blkz_init_zones(PSTORE_TYPE_DMESG, &off, size,
 			info->dmesg_size, &cxt->dmesg_max_cnt);
 	if (IS_ERR(cxt->dbzs)) {
@@ -901,7 +1096,16 @@ static int blkz_cut_zones(struct blkz_context *cxt)
 		goto fail_out;
 	}
 
+	size = info->pmsg_size;
+	cxt->pbz = blkz_init_zone(PSTORE_TYPE_PMSG, &off, size);
+	if (IS_ERR(cxt->pbz)) {
+		err = PTR_ERR(cxt->pbz);
+		goto free_dmesg_zones;
+	}
+
 	return 0;
+free_dmesg_zones:
+	blkz_free_zones(&cxt->dbzs, &cxt->dmesg_max_cnt);
 fail_out:
 	return err;
 }
@@ -924,7 +1128,7 @@ int blkz_register(struct blkz_info *info)
 		pr_info("using block device %s\n", info->blkdev);
 	}
 
-	if (!info->total_size || !info->dmesg_size) {
+	if (!info->total_size || (!info->dmesg_size && !info->pmsg_size)) {
 		pr_warn("The total size and the dmesg size must be non-zero\n");
 		return -EINVAL;
 	}
@@ -944,6 +1148,7 @@ int blkz_register(struct blkz_info *info)
 
 	check_size(total_size, 4096);
 	check_size(dmesg_size, SECTOR_SIZE);
+	check_size(pmsg_size, SECTOR_SIZE);
 
 #undef check_size
 
@@ -975,20 +1180,25 @@ int blkz_register(struct blkz_info *info)
 		goto fail_out;
 	}
 
-	cxt->pstore.bufsize = cxt->dbzs[0]->buffer_size -
+	if (info->dmesg_size) {
+		cxt->pstore.bufsize = cxt->dbzs[0]->buffer_size -
 			sizeof(struct blkz_dmesg_header);
-	cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
-	if (!cxt->pstore.buf) {
-		pr_err("cannot allocate pstore crash dump buffer\n");
-		err = -ENOMEM;
-		goto fail_out;
+		cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
+		if (!cxt->pstore.buf) {
+			err = -ENOMEM;
+			goto fail_out;
+		}
 	}
 	cxt->pstore.data = cxt;
-	cxt->pstore.flags = PSTORE_FLAGS_DMESG;
+	if (info->dmesg_size)
+		cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
+	if (info->pmsg_size)
+		cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
 
-	pr_info("Registered %s as blkzone backend for %s%s\n", info->name,
+	pr_info("Registered %s as blkzone backend for %s%s%s\n", info->name,
 			cxt->dbzs && cxt->bzinfo->dump_oops ? "Oops " : "",
-			cxt->dbzs && cxt->bzinfo->panic_write ? "Panic " : "");
+			cxt->dbzs && cxt->bzinfo->panic_write ? "Panic " : "",
+			cxt->pbz ? "Pmsg" : "");
 
 	err = pstore_register(&cxt->pstore);
 	if (err) {
@@ -1022,6 +1232,7 @@ void blkz_unregister(struct blkz_info *info)
 	spin_unlock(&cxt->bzinfo_lock);
 
 	blkz_free_zones(&cxt->dbzs, &cxt->dmesg_max_cnt);
+	blkz_free_zone(&cxt->pbz);
 	blkz_remove_dev();
 }
 EXPORT_SYMBOL_GPL(blkz_unregister);
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index 2d2ff97..9f2b9a9 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -69,6 +69,7 @@ struct blkz_info {
 	const char *blkdev;
 	unsigned long total_size;
 	unsigned long dmesg_size;
+	unsigned long pmsg_size;
 	int dump_oops;
 	blkz_read_op read;
 	blkz_write_op write;
-- 
1.9.1