[RFC v5 3/4] pstore/blk: support pmsg for pstore block

From: liaoweixiong
Date: Mon Jan 07 2019 - 07:02:04 EST

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

Signed-off-by: liaoweixiong <liaoweixiong@xxxxxxxxxxxxxxxxx>
---
fs/pstore/blkzone.c | 254 +++++++++++++++++++++++++++++++++++++++++----
include/linux/pstore_blk.h | 1 +
2 files changed, 233 insertions(+), 22 deletions(-)

diff --git a/fs/pstore/blkzone.c b/fs/pstore/blkzone.c
index e1b7f26..157f1cfd 100644
--- a/fs/pstore/blkzone.c
+++ b/fs/pstore/blkzone.c
@@ -32,12 +32,14 @@
*
* @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[0];
};

@@ -70,6 +72,9 @@ 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:
@@ -83,6 +88,7 @@ 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;
@@ -90,8 +96,10 @@ struct blkz_zone {

struct blkoops_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
@@ -125,6 +133,11 @@ 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 blkoops_context *cxt = &blkz_cxt;
@@ -394,6 +407,72 @@ static int blkz_recover_dmesg(struct blkoops_context *cxt)
return ret;
}

+static int blkz_recover_pmsg(struct blkoops_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("recovery 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 blkoops_context *cxt)
{
int ret = -EBUSY;
@@ -408,6 +487,10 @@ static inline int blkz_recovery(struct blkoops_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;
@@ -425,11 +508,18 @@ static int blkoops_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 blkoops_pstore_erase(struct pstore_record *record)
@@ -443,13 +533,29 @@ static int blkoops_pstore_erase(struct pstore_record *record)
*/
blkz_recovery(cxt);

- 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 blkoops_write_kmsg_hdr(struct blkz_zone *zone,
@@ -467,8 +573,10 @@ static void blkoops_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 blkoops_context *cxt,
@@ -518,6 +626,55 @@ static int notrace blkz_dmesg_write(struct blkoops_context *cxt,
return 0;
}

+static int notrace blkz_pmsg_write(struct blkoops_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 blkoops_pstore_write(struct pstore_record *record)
{
struct blkoops_context *cxt = record->psi->data;
@@ -535,6 +692,8 @@ static int notrace blkoops_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;
}
@@ -551,6 +710,13 @@ static struct blkz_zone *blkz_read_next_zone(struct blkoops_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;
}

@@ -589,7 +755,8 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
char *buf = kasprintf(GFP_KERNEL,
"blkoops: %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) {
@@ -611,6 +778,29 @@ 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 blkoops_pstore_read(struct pstore_record *record)
{
struct blkoops_context *cxt = record->psi->data;
@@ -642,6 +832,9 @@ static ssize_t blkoops_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;
}
@@ -754,8 +947,10 @@ 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;

@@ -837,7 +1032,7 @@ static int blkz_cut_zones(struct blkoops_context *cxt)
int err;
size_t size;

- size = info->part_size;
+ size = info->part_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)) {
@@ -845,7 +1040,16 @@ static int blkz_cut_zones(struct blkoops_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;
}
@@ -856,7 +1060,7 @@ int blkz_register(struct blkz_info *info)
struct blkoops_context *cxt = &blkz_cxt;
struct module *owner = info->owner;

- if (!info->part_size || !info->dmesg_size) {
+ if (!info->part_size || (!info->dmesg_size && !info->pmsg_size)) {
pr_warn("The memory size and the dmesg size must be non-zero\n");
return -EINVAL;
}
@@ -876,6 +1080,7 @@ int blkz_register(struct blkz_info *info)

check_size(part_size, 4096 - 1);
check_size(dmesg_size, SECTOR_SIZE - 1);
+ check_size(pmsg_size, SECTOR_SIZE - 1);

#undef check_size

@@ -902,16 +1107,20 @@ 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;

err = pstore_register(&cxt->pstore);
if (err) {
@@ -919,9 +1128,10 @@ int blkz_register(struct blkz_info *info)
goto free_pstore_buf;
}

- 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" : "");

module_put(owner);
return 0;
@@ -949,7 +1159,7 @@ 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);
}
EXPORT_SYMBOL_GPL(blkz_unregister);

diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index 426cae4..6c6b4eb 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -48,6 +48,7 @@ struct blkz_info {
const char *part_path;
unsigned long part_size;
unsigned long dmesg_size;
+ unsigned long pmsg_size;
int dump_oops;
ssize_t (*read)(char *buf, size_t bytes, loff_t pos);
ssize_t (*write)(const char *buf, size_t bytes, loff_t pos);
--
1.9.1

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