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Subject[PATCH v3 10/11] pstore/zone: pstore/blk: support non-block devices
Date
To support non-block device like MTD device. A non-block driver calls
psblk_register_device() to register to pstore/blk.

In addition, pstore/zone should also fix to non-block devices like
MTD device. MTD device is not block device and an erase must be done
before write. To adapt to non block device like MTD device,
pstore/zone must call the special erase job rather than set the
@datalen of zone to 0, which works on block device but not MTD device.
If no this patch, pstore on MTD disables to remove log file.

Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
---
Documentation/admin-guide/pstore-block.rst | 17 +++++++---
fs/pstore/pstore_blk.c | 52 ++++++++++++------------------
fs/pstore/pstore_zone.c | 8 ++++-
include/linux/pstore_blk.h | 37 +++++++++++++++++++++
include/linux/pstore_zone.h | 6 ++++
5 files changed, 83 insertions(+), 37 deletions(-)

diff --git a/Documentation/admin-guide/pstore-block.rst b/Documentation/admin-guide/pstore-block.rst
index a96415eaaf24..a31155b36e62 100644
--- a/Documentation/admin-guide/pstore-block.rst
+++ b/Documentation/admin-guide/pstore-block.rst
@@ -7,8 +7,8 @@ Introduction
------------

Pstore block (pstore/blk) is an oops/panic logger that writes its logs to a
-block device before the system crashes. You can get these log files by
-mounting pstore filesystem like::
+block device and non-block device before the system crashes. You can get
+these log files by mounting pstore filesystem like::

mount -t pstore pstore /sys/fs/pstore

@@ -24,8 +24,8 @@ Configurations for user determine how pstore/blk works, such as pmsg_size,
oops_size and so on. All of them support both Kconfig and module parameters,
but module parameters have priority over Kconfig.

-Configurations for driver are all about block device, such as total_size
-of block device and read/write operations.
+Configurations for driver are all about block device and non-block device,
+such as total_size of block device and read/write operations.

Configurations for user
-----------------------
@@ -146,6 +146,15 @@ driver uses ``psblk_register_blkdev`` to register to pstore/blk.
.. kernel-doc:: fs/pstore/pstore_blk.c
:identifiers: psblk_register_blkdev

+A non-block device driver uses ``psblk_register_device`` with
+``struct psblk_device`` to register to pstore/blk.
+
+.. kernel-doc:: fs/pstore/pstore_blk.c
+ :identifiers: psblk_register_device
+
+.. kernel-doc:: include/linux/pstore_blk.h
+ :identifiers: psblk_device
+
Compression and header
----------------------

diff --git a/fs/pstore/pstore_blk.c b/fs/pstore/pstore_blk.c
index 061609b66d8a..5c8006376677 100644
--- a/fs/pstore/pstore_blk.c
+++ b/fs/pstore/pstore_blk.c
@@ -96,36 +96,15 @@
})

/**
- * struct psblk_device - back-end pstore/blk driver structure.
+ * psblk_register_device() - register non-block device to pstore/blk
*
- * @total_size: The total size in bytes pstore/blk can use. It must be greater
- * than 4096 and be multiple of 4096.
- * @flags: Refer to macro starting with PSTORE_FLAGS defined in
- * linux/pstore.h. It means what front-ends this device support.
- * Zero means all recorders for compatible.
- * @read: The general read operation. Both of the function parameters
- * @size and @offset are relative value to bock device (not the
- * whole disk).
- * On success, the number of bytes should be returned, others
- * 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 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.
+ * @dev: non-block device information
+ *
+ * Return:
+ * * 0 - OK
+ * * Others - something error.
*/
-struct psblk_device {
- unsigned long total_size;
- unsigned int flags;
- psz_read_op read;
- psz_write_op write;
- psz_write_op panic_write;
-};
-
-static int psblk_register_do(struct psblk_device *dev)
+int psblk_register_device(struct psblk_device *dev)
{
int ret;

@@ -169,6 +148,7 @@ static int psblk_register_do(struct psblk_device *dev)
psz_info->dump_oops = dump_oops;
psz_info->read = dev->read;
psz_info->write = dev->write;
+ psz_info->erase = dev->erase;
psz_info->panic_write = dev->panic_write;
psz_info->name = MODNAME;
psz_info->owner = THIS_MODULE;
@@ -181,8 +161,14 @@ static int psblk_register_do(struct psblk_device *dev)
mutex_unlock(&psz_lock);
return ret;
}
+EXPORT_SYMBOL_GPL(psblk_register_device);

-static void psblk_unregister_do(struct psblk_device *dev)
+/**
+ * psblk_unregister_blkdev() - unregister block device from pstore/blk
+ *
+ * @dev: non-block device information
+ */
+void psblk_unregister_device(struct psblk_device *dev)
{
mutex_lock(&psz_lock);
if (psz_info && psz_info->read == dev->read) {
@@ -192,6 +178,7 @@ static void psblk_unregister_do(struct psblk_device *dev)
}
mutex_unlock(&psz_lock);
}
+EXPORT_SYMBOL_GPL(psblk_unregister_device);

/**
* psblk_get_bdev() - open block device
@@ -405,11 +392,12 @@ int psblk_register_blkdev(unsigned int major, unsigned int flags,

dev.total_size = psblk_bdev_size(bdev);
dev.flags = flags;
- dev.panic_write = panic_write ? psblk_blk_panic_write : NULL;
dev.read = psblk_generic_blk_read;
dev.write = psblk_generic_blk_write;
+ dev.erase = NULL;
+ dev.panic_write = panic_write ? psblk_blk_panic_write : NULL;

- ret = psblk_register_do(&dev);
+ ret = psblk_register_device(&dev);
if (ret)
goto err_put_bdev;

@@ -435,7 +423,7 @@ void psblk_unregister_blkdev(unsigned int major)
void *holder = blkdev;

if (psblk_bdev && MAJOR(psblk_bdev->bd_dev) == major) {
- psblk_unregister_do(&dev);
+ psblk_unregister_device(&dev);
psblk_put_bdev(psblk_bdev, holder);
blkdev_panic_write = NULL;
psblk_bdev = NULL;
diff --git a/fs/pstore/pstore_zone.c b/fs/pstore/pstore_zone.c
index 84ff53c1aaae..e51bc794f908 100644
--- a/fs/pstore/pstore_zone.c
+++ b/fs/pstore/pstore_zone.c
@@ -652,15 +652,21 @@ static inline int psz_oops_erase(struct psz_context *cxt,
struct psz_buffer *buffer = zone->buffer;
struct psz_oops_header *hdr =
(struct psz_oops_header *)buffer->data;
+ size_t size;

if (unlikely(!psz_ok(zone)))
return 0;
+
/* this zone is already updated, no need to erase */
if (record->count != hdr->counter)
return 0;

+ size = buffer_datalen(zone) + sizeof(*zone->buffer);
atomic_set(&zone->buffer->datalen, 0);
- return psz_zone_write(zone, FLUSH_META, NULL, 0, 0);
+ if (cxt->psz_info->erase)
+ return cxt->psz_info->erase(size, zone->off);
+ else
+ return psz_zone_write(zone, FLUSH_META, NULL, 0, 0);
}

static inline int psz_record_erase(struct psz_context *cxt,
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index d2ea1733b51a..e733f28aef2c 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -8,6 +8,41 @@
#include <linux/pstore_zone.h>

/**
+ * struct psblk_device - back-end pstore/blk driver structure.
+ *
+ * @total_size: The total size in bytes pstore/blk can use. It must be greater
+ * than 4096 and be multiple of 4096.
+ * @flags: Refer to macro starting with PSTORE_FLAGS defined in
+ * linux/pstore.h. It means what front-ends this device support.
+ * Zero means all recorders for compatible.
+ * @read: The general read operation. Both of the function parameters
+ * @size and @offset are relative value to bock device (not the
+ * whole disk).
+ * On success, the number of bytes should be returned, others
+ * 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.
+ * @erase: The general erase operation for device with special removing
+ * job. Both of the function parameters @size and @offset are
+ * relative value to storage.
+ * Return 0 on success and others on failure.
+ * @panic_write:The write operation only used for panic case. It's optional
+ * 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;
+ unsigned int flags;
+ psz_read_op read;
+ psz_write_op write;
+ psz_erase_op erase;
+ psz_write_op panic_write;
+};
+
+/**
* typedef psblk_panic_write_op - panic write operation to block device
*
* @buf: the data to write
@@ -22,6 +57,8 @@
typedef int (*psblk_panic_write_op)(const char *buf, sector_t start_sect,
sector_t sects);

+int psblk_register_device(struct psblk_device *dev);
+void psblk_unregister_device(struct psblk_device *dev);
int psblk_register_blkdev(unsigned int major, unsigned int flags,
psblk_panic_write_op panic_write);
void psblk_unregister_blkdev(unsigned int major);
diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h
index 2bfa79bff97b..c2db8e5c6542 100644
--- a/include/linux/pstore_zone.h
+++ b/include/linux/pstore_zone.h
@@ -7,6 +7,7 @@

typedef ssize_t (*psz_read_op)(char *, size_t, loff_t);
typedef ssize_t (*psz_write_op)(const char *, size_t, loff_t);
+typedef ssize_t (*psz_erase_op)(size_t, loff_t);
/**
* struct psz_info - pstore/zone back-end driver structure
*
@@ -27,6 +28,10 @@
* @write: The same as @read, but the following error number:
* -EBUSY means try to write again later.
* -ENOMSG means to try next zone.
+ * @erase: The general erase operation for device with special removing
+ * job. Both of the function parameters @size and @offset are
+ * relative value to storage.
+ * Return 0 on success and others on failure.
* @panic_write:The write operation only used for panic case. It's optional
* if you do not care panic log. The parameters are relative
* value to storage.
@@ -45,6 +50,7 @@ struct psz_info {
int dump_oops;
psz_read_op read;
psz_write_op write;
+ psz_erase_op erase;
psz_write_op panic_write;
};

--
1.9.1
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