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Message-Id: <1352379984-18381-5-git-send-email-dragos.tatulea@intel.com>
Date: Thu, 8 Nov 2012 15:06:02 +0200
From: dragos.tatulea@...el.com
To: linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
cjb@...top.org
Cc: kirill.shutemov@...ux.intel.com, irina.tirdea@...el.com,
octavian.purdila@...el.com, tony.luck@...el.com,
keescook@...omium.org, dragos.tatulea@...il.com,
Adrian Hunter <adrian.hunter@...el.com>
Subject: [PATCH v2 04/26] blkoops: add a block device oops / panic logger
From: Adrian Hunter <adrian.hunter@...el.com>
blkoops is a pstore back end to write panic / oops logs to a block
device. It is initially intended for use with eMMC as an alternative to
using a crash kernel.
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Irina Tirdea <irina.tirdea@...el.com>
---
Documentation/blockdev/00-INDEX | 2 +
Documentation/blockdev/blkoops.txt | 104 +++
drivers/block/Kconfig | 10 +
drivers/block/Makefile | 1 +
drivers/block/blkoops.c | 1569 ++++++++++++++++++++++++++++++++++++
5 files changed, 1686 insertions(+)
create mode 100644 Documentation/blockdev/blkoops.txt
create mode 100644 drivers/block/blkoops.c
diff --git a/Documentation/blockdev/00-INDEX b/Documentation/blockdev/00-INDEX
index c08df56..c45cef8 100644
--- a/Documentation/blockdev/00-INDEX
+++ b/Documentation/blockdev/00-INDEX
@@ -2,6 +2,8 @@
- this file
README.DAC960
- info on Mylex DAC960/DAC1100 PCI RAID Controller Driver for Linux.
+blkoops.txt
+ - info on block device oops / panic logger
cciss.txt
- info, major/minor #'s for Compaq's SMART Array Controllers.
cpqarray.txt
diff --git a/Documentation/blockdev/blkoops.txt b/Documentation/blockdev/blkoops.txt
new file mode 100644
index 0000000..fb08664
--- /dev/null
+++ b/Documentation/blockdev/blkoops.txt
@@ -0,0 +1,104 @@
+Block device oops / panic logger
+--------------------------------
+
+Contents:
+
+ 1) Overview
+ 2) Format
+ 3) Parameters
+ 4) blkoops and pstore
+ 5) debugfs
+
+1) Overview
+-----------
+
+ blkoops is a pstore back end to write panic / oops logs to a block
+ device. It is initially intended for use with eMMC as an alternative to
+ using a crash kernel.
+
+2) Format
+---------
+
+ Data is written in chunks called nodes which are preceded by a
+ header. The header is always aligned to a block boundary. Nodes are
+ written sequentially starting at the second block. The first block
+ contains a special node that fulfils 2 purposes: 1) the blkoops magic
+ number must be present or blkoops will not attach to the block device,
+ and 2) erase information is recorded there. Nodes can be arbitrarily
+ long.
+
+ Nodes are identified by session number, file number and part number.
+ A session may have up to 2^32 - 1 files each with up to 2^32 - 1 parts.
+
+ A new session begins when blkoops attaches to a block device and ends
+ when it detaches or there is a reboot. A new session overwrites the
+ previous session. Once the media is full no more nodes are written.
+
+3) Parameters
+-------------
+
+devname
+
+ Canonical block device name or number
+
+ devname may be set on the kernel command line e.g.
+
+ blkoops.devname=/dev/mmcblk0p7
+
+ or by writing to sysfs e.g.
+
+ echo /dev/mmcblk0p1 > /sys/module/blkoops/parameters/devname
+
+ devname is NOT the name of a file system object. e.g. /dev/mmcblk0p7
+ does NOT mean the block device special file mmcblk0p7 in the /dev
+ directory. Instead it means partition 7 of the device named mmcblk0.
+ For more information see name_to_dev_t comment in init/do_mounts.c
+
+ When devname is changed, the old devname (if any) is detached from
+ blkoops and the new devname (if any) is attached.
+
+ blkoops will reject a block device that does not have the blkoops magic
+ number written on the 1st sector. For example, to prepare
+ /dev/mmcblk0p7 for blkoops:
+
+ sudo bash -c "echo -e -n '\0034\0327\0130\0350' \
+ | dd count=1 conv=sync \
+ > /dev/mmcblk0p7"
+
+dump_oops
+
+ set to 1 to dump oopses, 0 to dump only panics (default 1)
+
+4) blkoops and pstore
+---------------------
+
+ pstore creates file names from pstore type code, back end name and
+ pstore 64-bit id. blkoops records the pstore type code, uses back end
+ name "blkoops", and creates the pstore 64-bit id from session number and
+ file number (session << 32 | file). blkoops concatenates all parts
+ together and presents them as one file.
+
+ pstore noramally reads back end data entirely into memory when mounting.
+ However if a blkoops file is too big it will be read from media as
+ needed instead.
+
+ blkoops suppreses pstore heading lines from dumped data.
+
+ blkoops increases pstore default kmsg_bytes to ULONG_MAX.
+
+5) debugfs
+----------
+
+blkoops/type
+
+ pstore type code to use when dumping data via blkoops/data
+
+blkoops/reason
+
+ kmsg dump reason code to use when dumping data via blkoops/data
+
+blkoops/data
+
+ Data written to blkoops/data is dumped to the block device
+ using blkoops/type. blkoops/reason must be the numberical value of
+ KMSG_DUMP_PANIC or (if dump_oops is 1) KMSG_DUMP_OOPS.
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 824e09c..af5b325 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -544,4 +544,14 @@ config BLK_DEV_RBD
If unsure, say N.
+config BLK_DEV_OOPS
+ bool "Block Oops / Panic Logger"
+ select BLK_DEV_PANIC_WRITE
+ select PSTORE
+ default n
+ help
+ This enables panic and oops messages to be logged to a block device.
+
+ See <file:Documentation/blockdev/blkoops.txt> for more information.
+
endif # BLK_DEV
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index 17e82df..db44850 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_MG_DISK) += mg_disk.o
obj-$(CONFIG_SUNVDC) += sunvdc.o
obj-$(CONFIG_BLK_DEV_NVME) += nvme.o
obj-$(CONFIG_BLK_DEV_OSD) += osdblk.o
+obj-$(CONFIG_BLK_DEV_OOPS) += blkoops.o
obj-$(CONFIG_BLK_DEV_UMEM) += umem.o
obj-$(CONFIG_BLK_DEV_NBD) += nbd.o
diff --git a/drivers/block/blkoops.c b/drivers/block/blkoops.c
new file mode 100644
index 0000000..bafe17e
--- /dev/null
+++ b/drivers/block/blkoops.c
@@ -0,0 +1,1569 @@
+/*
+ * Block Oops / Panic Logger
+ *
+ * Copyright (C) 2012 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/module.h>
+#include <linux/swap.h> /* For nr_free_buffer_pages() */
+#include <linux/debugfs.h>
+#include <linux/completion.h>
+#include <linux/blkdev.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/pstore.h>
+
+#undef DEBUG
+
+#ifdef DEBUG
+#define DBG_PRINTK printk
+#else
+#define DBG_PRINTK no_printk
+#endif
+
+#define DBG(fmt, ...) \
+ DBG_PRINTK(KERN_DEBUG "%s: " fmt "\n", __func__, ##__VA_ARGS__)
+
+#define BLKOOPS_BUFSIZE (32 * 1024)
+
+#define BLKOOPS_MAGIC 0xe858d71c
+
+#define BLKOOPS_VERSION 1
+
+#define BLKOOPS_HDR_SZ (sizeof(struct blkoops_header))
+
+#define BLKOOPS_MODE (FMODE_READ | FMODE_WRITE | FMODE_EXCL)
+
+#define BLKOOPS_DEVNAME_SZ 256
+
+static char devname[BLKOOPS_DEVNAME_SZ];
+static int dump_oops;
+static int init_done;
+
+static DEFINE_MUTEX(blkoops_mutex);
+static DEFINE_SPINLOCK(blkoops_lock);
+
+/**
+ * struct blkoops - blkoops private data.
+ * @psi: pstore information
+ * @present: non-zero if blkoops is attached to a block device
+ * @bdev: block device to which that blkoops is attached
+ * @devid: block device (major, minor) number
+ * @blksize: block device block size
+ * @sects_per_blk: block device sectors per block
+ * @nr_sects: block device size in sectors
+ * @size: block device size in bytes
+ * @bdev_name: block device name
+ * @buf: panic write buffer
+ * @bufsize: panic write buffer size
+ * @last_session: last session number on media
+ * @next_session: next session number to write
+ * @next_file: next file number to write
+ * @next_sect: next sector to write
+ * @cache_invalid: page cache is invalid because
+ * @root: rb-tree of all blkoops nodes sorted by session / file / part numbers
+ * @file_cnt: number of (non-erased) files on media
+ * @max_file: maximum file number on media
+ * @used_sects: number of sectors used on media by the last session
+ * @erased_session: session number of a completely or partly erased session
+ * @erased_file: maximum erased file number of @erased_session
+ * @erased_sects: number of sectors used on media by @erased_session
+ * @read_anew: start reading from the first file
+ * @read_file: last file number read
+ * @dbg_root: blkoops debugfs root directory
+ * @dbg_type: pstore type code to use when writing
+ * @dbg_reason: kmsg dump reason code to use when writing
+ * @dbg_part: next part number to use when writing
+ * @dbg_lock: with @dbg_open, prevent debugfs 'data' file from having more than
+ 1 user, and also cause the call to 'blkoops_write()' to be in an
+ atomic context
+ * @dbg_open: non-zero if debugfs 'data' file is open
+ * @dbg_buf: debug write buffer
+ * @dbg_bufsize: debug write buffer size
+ * @dbg_used: number of bytes used in @dbg_buf
+ */
+struct blkoops {
+ struct pstore_info psi;
+
+ int present;
+
+ struct block_device *bdev;
+ dev_t devid;
+ unsigned int blksize;
+ unsigned int sects_per_blk;
+ sector_t nr_sects;
+ loff_t size;
+ char bdev_name[BDEVNAME_SIZE];
+
+ char *buf;
+ size_t bufsize;
+
+ unsigned int last_session;
+
+ unsigned int next_session;
+ unsigned int next_file;
+ sector_t next_sect;
+
+ int flush_needed;
+ int cache_invalid;
+
+ struct rb_root root;
+ unsigned int file_cnt;
+ unsigned int max_file;
+ sector_t used_sects;
+
+ unsigned int erased_session;
+ unsigned int erased_file;
+ sector_t erased_sects;
+
+ int read_anew;
+ unsigned int read_file;
+
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *dbg_root;
+ u32 dbg_type;
+ u32 dbg_reason;
+ u32 dbg_part;
+ spinlock_t dbg_lock; /* debug serialization */
+ int dbg_open;
+ void *dbg_buf;
+ size_t dbg_bufsize;
+ size_t dbg_used;
+#endif
+};
+
+/**
+ * struct blkoops_node - blkoops node.
+ * @node: rb-tree of all blkoops nodes
+ * @session: session number
+ * @file: file number
+ * @part: part number
+ * @len: length in bytes (excluding header)
+ * @nr_sects: length in sectors including header
+ * @type: pstore type code
+ * @timestamp: time the node was written to media
+ * @offs: offset on block device
+ * @file_offs: offset within file
+ * @tot_len: total length of file (only recorded on the first part)
+ */
+struct blkoops_node {
+ struct rb_node node;
+ unsigned int session;
+ unsigned int file;
+ unsigned int part;
+ loff_t len;
+ sector_t nr_sects;
+ enum pstore_type_id type;
+ struct timespec timestamp;
+ loff_t offs;
+ loff_t file_offs;
+ loff_t tot_len;
+};
+
+/**
+ * struct blkoops_header - blkoops on-media node header.
+ * @magic: blkoops magic number
+ * @version: blkoops media format version
+ * @session: session number
+ * @file: file number
+ * @part: part number
+ * @type: pstore type code
+ * @timestamp: time the node was written to media
+ * @len: length in bytes (excluding header)
+ * @nr_sects: length in sectors including header
+ * @padding: reserved for future, zeroes
+ *
+ * Data is written in chunks called nodes which are preceded by this header.
+ * The header is always aligned to a block boundary. Nodes are written
+ * sequentially starting at the second block. The first block contains a
+ * special node that fulfils 2 purposes: 1) the blkoops magic number must be
+ * present or blkoops will not attach to the block device, and 2) erase
+ * information is recorded there. Nodes can be arbitrarily long.
+ *
+ * Nodes are identified by session number, file number and part number. A
+ * session may have up to 2^32 - 1 files each with up to 2^32 - 1 parts.
+ *
+ * A new session begins when blkoops attaches to a block device and ends when it
+ * detaches or there is a reboot. A new session overwrites the previous session.
+ * Once the media is full no more nodes are written.
+ */
+struct blkoops_header {
+ __le32 magic;
+ __le32 version;
+ __le32 session;
+ __le32 file;
+ __le32 part;
+ __le32 type;
+ __le64 timestamp;
+ __le64 len;
+ __le64 nr_sects;
+ __u8 padding[16];
+} __packed;
+
+static int blkoops_lt(struct blkoops_node *bn1, struct blkoops_node *bn2)
+{
+ if (bn1->session == bn2->session) {
+ if (bn1->file == bn2->file)
+ return bn1->part < bn2->part;
+ return bn1->file < bn2->file;
+ }
+
+ return bn1->session < bn2->session;
+}
+
+static void blkoops_add_node(struct blkoops *c, struct blkoops_node *bn)
+{
+ struct rb_node **p = &c->root.rb_node;
+ struct rb_node *parent = NULL;
+ struct blkoops_node *t;
+
+ while (*p) {
+ parent = *p;
+ t = rb_entry(parent, struct blkoops_node, node);
+
+ if (blkoops_lt(bn, t))
+ p = &(*p)->rb_left;
+ else
+ p = &(*p)->rb_right;
+ }
+
+ rb_link_node(&bn->node, parent, p);
+ rb_insert_color(&bn->node, &c->root);
+}
+
+static int blkoops_lt_file(unsigned int session, unsigned int file,
+ struct blkoops_node *bn)
+{
+ if (session == bn->session)
+ return file < bn->file;
+ return session < bn->session;
+}
+
+static struct blkoops_node *blkoops_lookup_next(struct blkoops *c,
+ unsigned int session,
+ unsigned int file)
+{
+ struct rb_node *node = c->root.rb_node;
+ struct blkoops_node *bn, *next = NULL;
+
+ while (node) {
+ bn = rb_entry(node, struct blkoops_node, node);
+
+ if (blkoops_lt_file(session, file, bn)) {
+ node = node->rb_left;
+ next = bn;
+ } else {
+ node = node->rb_right;
+ }
+ }
+ return next;
+}
+
+static int blkoops_cmp_offs(unsigned int session, unsigned int file, loff_t pos,
+ struct blkoops_node *bn)
+{
+ if (session == bn->session) {
+ if (file == bn->file) {
+ if (pos < bn->file_offs)
+ return -1;
+ else if (pos >= bn->file_offs + bn->len)
+ return 1;
+ return 0;
+ }
+ return file < bn->file ? -1 : 1;
+ }
+ return session < bn->session ? -1 : 1;
+}
+
+static struct blkoops_node *blkoops_lookup_pos(struct blkoops *c,
+ unsigned int session,
+ unsigned int file, loff_t pos)
+{
+ struct rb_node *node = c->root.rb_node;
+ struct blkoops_node *bn;
+ int cmp;
+
+ while (node) {
+ bn = rb_entry(node, struct blkoops_node, node);
+ cmp = blkoops_cmp_offs(session, file, pos, bn);
+ if (cmp == -1)
+ node = node->rb_left;
+ else if (cmp == 1)
+ node = node->rb_right;
+ else
+ return bn;
+ }
+ return NULL;
+}
+
+static struct page *blkoops_read_page(struct blkoops *c, loff_t pos)
+{
+ pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+
+ return read_mapping_page(c->bdev->bd_inode->i_mapping, index, NULL);
+}
+
+static int blkoops_validate_node(struct blkoops *c, struct blkoops_node *bn)
+{
+ sector_t nr_sects;
+ loff_t len;
+
+ if (bn->offs + bn->len > c->size) {
+ DBG("bad node size (offs %lld + len %lld > size %lld)",
+ bn->offs, bn->len, c->size);
+ return -EINVAL;
+ }
+ len = bn->len + BLKOOPS_HDR_SZ;
+ nr_sects = (len >> 9) + (len & 511 ? 1 : 0);
+ if (bn->nr_sects < nr_sects) {
+ DBG("bad node nr sects %llu vs len %lld",
+ (u64)bn->nr_sects, bn->len);
+ return -EINVAL;
+ }
+ if (bn->offs - BLKOOPS_HDR_SZ + ((loff_t)bn->nr_sects << 9) > c->size) {
+ DBG("bad node nr sects %llu vs size %lld",
+ (u64)bn->nr_sects, c->size);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static struct blkoops_node *blkoops_alloc_node(struct blkoops *c,
+ struct blkoops_header *hdr,
+ loff_t pos)
+{
+ struct blkoops_node *bn;
+
+ if (__le32_to_cpu(hdr->magic) != BLKOOPS_MAGIC) {
+ DBG("bad magic at pos %lld", pos);
+ return ERR_PTR(-EINVAL);
+ }
+
+ bn = kzalloc(sizeof(struct blkoops_node), GFP_KERNEL);
+ if (!bn)
+ return ERR_PTR(-ENOMEM);
+
+ RB_CLEAR_NODE(&bn->node);
+
+ bn->session = __le32_to_cpu(hdr->session);
+ bn->file = __le32_to_cpu(hdr->file);
+ bn->part = __le32_to_cpu(hdr->part);
+ bn->type = __le32_to_cpu(hdr->type);
+ bn->timestamp.tv_sec = __le64_to_cpu(hdr->timestamp);
+ bn->len = __le64_to_cpu(hdr->len);
+ bn->nr_sects = __le64_to_cpu(hdr->nr_sects);
+ bn->offs = pos + BLKOOPS_HDR_SZ;
+
+ return bn;
+}
+
+static struct blkoops_node *blkoops_read_node(struct blkoops *c, loff_t pos)
+{
+ struct blkoops_header *hdr;
+ struct blkoops_node *bn;
+ struct page *page;
+
+ if (pos >= c->size || pos & 511) {
+ DBG("bad pos %lld", pos);
+ return ERR_PTR(-EINVAL);
+ }
+
+ page = blkoops_read_page(c, pos);
+ if (IS_ERR(page)) {
+ pr_err("blkoops: bad page at pos %lld", pos);
+ return ERR_CAST(page);
+ }
+ /*
+ * Whole header must be within page because the header is sector aligned
+ * and smaller than 1 sector.
+ */
+ hdr = page_address(page) + (pos & (PAGE_CACHE_SIZE - 1));
+
+ bn = blkoops_alloc_node(c, hdr, pos);
+
+ page_cache_release(page);
+ return bn;
+}
+
+static inline loff_t blkoops_scan_start(struct blkoops *c)
+{
+ return c->blksize;
+}
+
+static loff_t blkoops_do_scan(struct blkoops *c, loff_t pos)
+{
+ struct blkoops_node *bn;
+ int err;
+
+ c->used_sects = pos >> 9;
+
+ if (pos >= c->size) {
+ DBG("end of scan at pos %lld (size %lld)", pos, c->size);
+ return 0;
+ }
+
+ bn = blkoops_read_node(c, pos);
+ if (IS_ERR(bn))
+ return PTR_ERR(bn);
+
+ err = blkoops_validate_node(c, bn);
+ if (err) {
+ DBG("bad node at pos %lld", pos);
+ goto out_free;
+ }
+
+ DBG("node at %lld sess %u file %u part %u len %lld nr sects %llu",
+ pos, bn->session, bn->file, bn->part, bn->len, (u64)bn->nr_sects);
+
+ /* A new oops may have written an updated session number */
+ if (pos == blkoops_scan_start(c))
+ c->last_session = bn->session;
+
+ /* Only scan the last session */
+ if (bn->session != c->last_session) {
+ DBG("wrong session %u (expected %u) at pos %lld",
+ bn->session, c->last_session, pos);
+ err = 0;
+ goto out_free;
+ }
+
+ /* Skip erased files */
+ if (c->erased_file && bn->session == c->erased_session &&
+ bn->file <= c->erased_file) {
+ loff_t next_pos, new_pos;
+
+ /*
+ * Try to skip to next non-erased node, but only if it makes
+ * sense.
+ */
+ next_pos = pos + ((loff_t)bn->nr_sects << 9);
+ new_pos = (loff_t)c->erased_sects << 9;
+ if (new_pos < next_pos || new_pos > c->size)
+ new_pos = next_pos;
+ DBG("skipping erased node at pos %lld continuing from pos %lld",
+ pos, new_pos);
+ pos = new_pos;
+ } else {
+ blkoops_add_node(c, bn);
+ pos += (loff_t)bn->nr_sects << 9;
+ }
+
+ return pos;
+
+out_free:
+ kfree(bn);
+ return err;
+}
+
+static void blkoops_free_tree(struct blkoops *c)
+{
+ struct rb_node *node, *next;
+ struct blkoops_node *bn;
+
+ node = rb_first(&c->root);
+ while (node) {
+ bn = rb_entry(node, struct blkoops_node, node);
+ next = rb_next(node);
+ rb_erase(node, &c->root);
+ kfree(bn);
+ node = next;
+ }
+
+ c->file_cnt = 0;
+}
+
+static void blkoops_count_files(struct blkoops *c)
+{
+ struct rb_node *node;
+ struct blkoops_node *bn, *last = NULL;
+
+ c->file_cnt = 0;
+ c->max_file = 0;
+
+ for (node = rb_first(&c->root); node; node = rb_next(node)) {
+ bn = rb_entry(node, struct blkoops_node, node);
+ if (last && bn->session == last->session &&
+ bn->file == last->file) {
+ bn->file_offs = last->tot_len;
+ last->tot_len += bn->len;
+ continue;
+ }
+ last = bn;
+ last->file_offs = 0;
+ last->tot_len = bn->len;
+ c->file_cnt += 1;
+ if (bn->file > c->max_file)
+ c->max_file = bn->file;
+ }
+ DBG("file cnt %u max file %u used sects %llu",
+ c->file_cnt, c->max_file, (u64)c->used_sects);
+}
+
+static int blkoops_scan(struct blkoops *c)
+{
+ loff_t pos = blkoops_scan_start(c);
+
+ blkoops_free_tree(c);
+
+ if (c->cache_invalid) {
+ DBG("cache_invalid");
+ c->cache_invalid = 0;
+ invalidate_mapping_pages(c->bdev->bd_inode->i_mapping, 0, -1);
+ }
+
+ do {
+ pos = blkoops_do_scan(c, pos);
+ } while (pos > 0);
+
+ blkoops_count_files(c);
+
+ return pos;
+}
+
+static int blkoops_open(struct pstore_info *psi)
+{
+ struct blkoops *c = psi->data;
+
+ mutex_lock(&blkoops_mutex);
+ if (!c->present)
+ goto out;
+ blkoops_scan(c);
+ c->read_anew = 1;
+out:
+ mutex_unlock(&blkoops_mutex);
+ return 0;
+}
+
+static struct blkoops_node *blkoops_next_node(struct blkoops_node *bn)
+{
+ struct rb_node *node;
+ struct blkoops_node *t;
+
+ node = rb_next(&bn->node);
+ if (!node)
+ return NULL;
+ t = rb_entry(node, struct blkoops_node, node);
+ if (t->session == bn->session && t->file == bn->file)
+ return t;
+ return NULL;
+}
+
+static int blkoops_read_to_buf(struct blkoops *c, char *buf, loff_t pos,
+ loff_t len)
+{
+ struct page *page;
+ loff_t offs;
+ size_t n;
+ int err = 0;
+
+ while (len) {
+ page = blkoops_read_page(c, pos);
+
+ offs = pos & (PAGE_CACHE_SIZE - 1);
+ n = PAGE_CACHE_SIZE - offs;
+ if (n > len)
+ n = len;
+
+ if (IS_ERR(page)) {
+ if (!err)
+ err = PTR_ERR(page);
+ memset(buf, 0, n);
+ } else {
+ memcpy(buf, page_address(page) + offs, n);
+ }
+
+ pos += n;
+ buf += n;
+ len -= n;
+
+ page_cache_release(page);
+ }
+
+ return err;
+}
+
+static int blkoops_fill_buf(struct blkoops *c, char *buf,
+ struct blkoops_node *bn)
+{
+ loff_t tot_len = bn->tot_len;
+ int err = 0, err1;
+
+ while (bn && tot_len) {
+ err1 = blkoops_read_to_buf(c, buf, bn->offs, bn->len);
+ if (!err)
+ err = err1;
+ tot_len -= bn->len;
+ buf += bn->len;
+ bn = blkoops_next_node(bn);
+ }
+ return err;
+}
+
+static struct blkoops_node *blkoops_read_next(struct blkoops *c)
+{
+ struct blkoops_node *bn = NULL;
+ struct rb_node *node;
+
+ if (c->read_anew) {
+ c->read_anew = 0;
+ node = rb_first(&c->root);
+ if (node)
+ bn = rb_entry(node, struct blkoops_node, node);
+ } else {
+ bn = blkoops_lookup_next(c, c->last_session, c->read_file);
+ }
+ if (bn)
+ c->read_file = bn->file;
+ return bn;
+}
+
+static ssize_t blkoops_read_to_userbuf(struct blkoops *c, char __user *userbuf,
+ loff_t pos, size_t len)
+{
+ struct page *page;
+ ssize_t ret = 0;
+ loff_t offs;
+ size_t n, rn;
+ int err;
+
+ while (len) {
+ page = blkoops_read_page(c, pos);
+
+ offs = pos & (PAGE_CACHE_SIZE - 1);
+ n = PAGE_CACHE_SIZE - offs;
+ if (n > len)
+ n = len;
+
+ if (IS_ERR(page)) {
+ err = PTR_ERR(page);
+ goto out_err;
+ }
+
+ rn = copy_to_user(userbuf, page_address(page) + offs, n);
+ if (rn) {
+ page_cache_release(page);
+ ret += n - rn;
+ err = -EFAULT;
+ goto out_err;
+ }
+
+ pos += n;
+ userbuf += n;
+ len -= n;
+ ret += n;
+
+ page_cache_release(page);
+ }
+
+ return ret;
+
+out_err:
+ if (!ret)
+ ret = err;
+ return ret;
+}
+
+static inline unsigned int blkoops_session(u64 id)
+{
+ return id >> 32;
+}
+
+static inline unsigned int blkoops_file(u64 id)
+{
+ return id;
+}
+
+static ssize_t blkoops_file_read(u64 id, enum pstore_type_id type,
+ char __user *userbuf, size_t count,
+ loff_t *ppos, struct pstore_info *psi)
+{
+ struct blkoops *c = psi->data;
+ struct blkoops_node *bn;
+ unsigned int session, file;
+ ssize_t done, res = 0;
+ loff_t noffs, dpos;
+ size_t len;
+ int err;
+
+ if (*ppos < 0)
+ return -EINVAL;
+
+ session = blkoops_session(id);
+ file = blkoops_file(id);
+
+ mutex_lock(&blkoops_mutex);
+ if (!c->present) {
+ err = -ENODEV;
+ goto out_err;
+ }
+
+ DBG("sess %u file %u pos %lld count %zu", session, file, *ppos, count);
+
+ while (count) {
+ bn = blkoops_lookup_pos(c, session, file, *ppos);
+ if (!bn)
+ break;
+ noffs = *ppos - bn->file_offs;
+ len = min_t(loff_t, count, bn->len - noffs);
+ dpos = bn->offs + noffs;
+ done = blkoops_read_to_userbuf(c, userbuf, dpos, len);
+ if (done < 0) {
+ err = done;
+ goto out_err;
+ }
+ res += done;
+ if (done < len)
+ break;
+ *ppos += len;
+ userbuf += len;
+ count -= len;
+ }
+out:
+ DBG("sess %u file %u pos %lld res %zd", session, file, *ppos, res);
+ mutex_unlock(&blkoops_mutex);
+ return res;
+
+out_err:
+ if (!res)
+ res = err;
+ goto out;
+}
+
+static inline u64 blkoops_id(u32 session, u32 file)
+{
+ return (u64)session << 32 | file;
+}
+
+static int blkoops_read(u64 *id, enum pstore_type_id *type,
+ struct timespec *time, char **buf, loff_t *size,
+ struct pstore_info *psi)
+{
+ struct blkoops *c = psi->data;
+ struct blkoops_node *bn;
+ unsigned long limit;
+ u64 bn_id;
+ int err;
+
+ mutex_lock(&blkoops_mutex);
+ if (!c->present) {
+ err = -ENODEV;
+ goto out;
+ }
+
+ bn = blkoops_read_next(c);
+ if (!bn) {
+ err = -ENOENT;
+ goto out;
+ }
+
+ bn_id = blkoops_id(bn->session, bn->file);
+
+ DBG("node at pos %lld sess %u file %u part %u len %lld nr sects %llu",
+ bn->offs, bn->session, bn->file, bn->part, bn->len,
+ (u64)bn->nr_sects);
+
+ *type = bn->type;
+ *id = bn_id;
+ *time = bn->timestamp;
+ *size = bn->tot_len;
+
+ limit = nr_free_buffer_pages() << (PAGE_SHIFT - 3);
+ limit /= c->file_cnt;
+
+ if (bn->tot_len > limit) {
+ DBG("file size %lld over limit %lu", bn->tot_len, limit);
+ err = -EFBIG;
+ goto out;
+ }
+
+ *buf = kmalloc(bn->tot_len, GFP_KERNEL | __GFP_NOWARN);
+ if (!*buf) {
+ DBG("failed to allocate %lld bytes", bn->tot_len);
+ err = -EFBIG;
+ goto out;
+ }
+
+ err = blkoops_fill_buf(c, *buf, bn);
+ if (err) {
+ pr_err("blkoops: read failed, file id %lld, error %d\n",
+ bn_id, err);
+ err = 0;
+ }
+out:
+ mutex_unlock(&blkoops_mutex);
+ return err;
+}
+
+static int blkoops_write(enum pstore_type_id type, enum kmsg_dump_reason reason,
+ u64 *id, unsigned int part, size_t size,
+ struct pstore_info *psi)
+{
+ struct blkoops *c = psi->data;
+ struct blkoops_header *hdr;
+ size_t nr, sz, rsz, len;
+ u32 partno;
+ int err;
+
+ /* If blkoops_lock is locked then there is no back end, so give up */
+ if (!spin_trylock(&blkoops_lock))
+ return -ENODEV;
+
+ if (!c->present) {
+ err = -ENODEV;
+ goto out_unlock;
+ }
+
+ if (reason != KMSG_DUMP_OOPS &&
+ reason != KMSG_DUMP_PANIC) {
+ err = -EINVAL;
+ goto out_unlock;
+ }
+
+ if (reason == KMSG_DUMP_OOPS && !dump_oops) {
+ err = -EINVAL;
+ goto out_unlock;
+ }
+
+ if (c->next_sect + c->sects_per_blk > c->nr_sects) {
+ err = -ENOSPC;
+ goto out_unlock;
+ }
+
+ if (part == 1)
+ c->next_file += 1;
+
+ /*
+ * Special case: dmesg is written backwards so reverse the order of the
+ * part numbers.
+ */
+ if (type == PSTORE_TYPE_DMESG)
+ partno = -part;
+ else
+ partno = part;
+
+ *id = blkoops_id(c->next_session, c->next_file);
+
+ /* Round up the size to block size and pad with zeroes */
+ sz = size + BLKOOPS_HDR_SZ;
+ rsz = roundup(sz, c->blksize);
+ nr = rsz >> 9;
+ memset(c->psi.buf + size, 0, rsz - sz);
+
+ /*
+ * Truncate the node to fit the remaining space. Note, we have
+ * already checked that there is enough space for at least 1 block.
+ */
+ len = size;
+ while (c->next_sect + nr > c->nr_sects) {
+ nr -= c->sects_per_blk;
+ len = (nr << 9) - BLKOOPS_HDR_SZ;
+ }
+
+ hdr = (void *)c->buf;
+ memset(hdr, 0, BLKOOPS_HDR_SZ);
+ hdr->magic = __cpu_to_le32(BLKOOPS_MAGIC);
+ hdr->version = __cpu_to_le32(BLKOOPS_VERSION);
+ hdr->session = __cpu_to_le32(c->next_session);
+ hdr->file = __cpu_to_le32(c->next_file);
+ hdr->part = __cpu_to_le32(partno);
+ hdr->type = __cpu_to_le32(type);
+ hdr->timestamp = __cpu_to_le64(get_seconds());
+ hdr->len = __cpu_to_le64(len);
+ hdr->nr_sects = __cpu_to_le64(nr);
+
+ c->cache_invalid = 1;
+ c->flush_needed = 1;
+
+ err = blk_panic_write(c->bdev, c->next_sect, c->buf, nr << 9);
+ if (err)
+ goto out_unlock;
+
+ c->next_sect += nr;
+
+out_unlock:
+ spin_unlock(&blkoops_lock);
+ return err;
+}
+
+struct blkoops_bio_batch {
+ atomic_t done;
+ unsigned long flags;
+ struct completion *wait;
+};
+
+static void blkoops_end_io(struct bio *bio, int err)
+{
+ struct blkoops_bio_batch *bb = bio->bi_private;
+
+ if (err)
+ clear_bit(BIO_UPTODATE, &bb->flags);
+ if (atomic_dec_and_test(&bb->done))
+ complete(bb->wait);
+ bio_put(bio);
+}
+
+static int blkoops_direct_io(int type, struct block_device *bdev, sector_t sect,
+ unsigned long nr, void *buf)
+{
+ DECLARE_COMPLETION_ONSTACK(wait);
+ struct blkoops_bio_batch bb;
+ struct bio *bio;
+ int ret = 0;
+ unsigned long len = nr << 9;
+
+ DBG("type %#x sect %llu nr %lu", type, (u64)sect, nr);
+
+ atomic_set(&bb.done, 1);
+ bb.flags = 1 << BIO_UPTODATE;
+ bb.wait = &wait;
+
+ while (len) {
+ bio = bio_alloc(GFP_KERNEL, 1);
+ if (!bio) {
+ ret = -ENOMEM;
+ break;
+ }
+
+ bio->bi_sector = sect;
+ bio->bi_end_io = blkoops_end_io;
+ bio->bi_bdev = bdev;
+ bio->bi_private = &bb;
+
+ while (len) {
+ unsigned int offs = offset_in_page(buf);
+ unsigned int n = PAGE_SIZE - offs;
+ int bytes;
+
+ if (n > len)
+ n = len;
+ bytes = bio_add_page(bio, virt_to_page(buf), n, offs);
+ if (bytes <= 0)
+ break;
+ len -= bytes;
+ buf += bytes;
+ }
+ sect += bio->bi_size >> 9;
+
+ atomic_inc(&bb.done);
+ submit_bio(type, bio);
+ }
+
+ if (!atomic_dec_and_test(&bb.done))
+ wait_for_completion(&wait);
+
+ if (!test_bit(BIO_UPTODATE, &bb.flags))
+ ret = -EIO;
+
+ if (ret)
+ DBG("I/O error %d", ret);
+ return ret;
+}
+
+static void blkoops_invalidate_range(struct block_device *bdev, sector_t sect,
+ unsigned int nr)
+{
+ pgoff_t start, end;
+
+ start = sect >> (PAGE_CACHE_SHIFT - 9);
+ end = (sect + nr - 1) >> (PAGE_CACHE_SHIFT - 9);
+
+ invalidate_mapping_pages(bdev->bd_inode->i_mapping, start, end);
+}
+
+static int blkoops_write_meta(struct block_device *bdev, sector_t sect,
+ unsigned long nr, void *buf)
+{
+ blkoops_invalidate_range(bdev, sect, nr);
+
+ return blkoops_direct_io(REQ_WRITE | REQ_META, bdev, sect, nr, buf);
+}
+
+static int blkoops_mark_erased(struct blkoops *c)
+{
+ struct blkoops_header *hdr;
+ int err;
+
+ DBG("session %u file %u sects %llu",
+ c->erased_session, c->erased_file, (u64)c->erased_sects);
+
+ hdr = kzalloc(c->blksize, GFP_KERNEL);
+ if (!hdr)
+ return -ENOMEM;
+
+ hdr->magic = __cpu_to_le32(BLKOOPS_MAGIC);
+ hdr->version = __cpu_to_le32(BLKOOPS_VERSION);
+ hdr->session = __cpu_to_le32(c->erased_session);
+ hdr->file = __cpu_to_le32(c->erased_file);
+ hdr->timestamp = __cpu_to_le64(get_seconds());
+ hdr->nr_sects = __cpu_to_le64(c->erased_sects);
+
+ err = blkoops_write_meta(c->bdev, 0, c->sects_per_blk, hdr);
+
+ kfree(hdr);
+
+ return err;
+}
+
+static int blkoops_erase(enum pstore_type_id type, u64 id,
+ struct pstore_info *psi)
+{
+ struct blkoops *c = psi->data;
+ int err = 0;
+
+ mutex_lock(&blkoops_mutex);
+ if (!c->present) {
+ err = -ENODEV;
+ goto out;
+ }
+ DBG("type %d id %lld", type, id);
+ /*
+ * Do nothing until all files are erased and then mark the range as
+ * erased.
+ */
+ if (c->file_cnt && !--c->file_cnt && !c->cache_invalid) {
+ c->erased_session = c->last_session;
+ c->erased_file = c->max_file;
+ c->erased_sects = c->used_sects;
+ err = blkoops_mark_erased(c);
+ }
+out:
+ mutex_unlock(&blkoops_mutex);
+ return err;
+}
+
+static int blkoops_flush(struct pstore_info *psi)
+{
+ struct blkoops *c = psi->data;
+ int err;
+
+ /* If blkoops_lock is locked then there is no back end, so give up */
+ if (!spin_trylock(&blkoops_lock))
+ return -ENODEV;
+
+ if (!c->present) {
+ err = -ENODEV;
+ goto out_unlock;
+ }
+
+ if (!c->flush_needed) {
+ err = 0;
+ goto out_unlock;
+ }
+
+ err = blk_panic_flush(c->bdev);
+
+out_unlock:
+ spin_unlock(&blkoops_lock);
+ return err;
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static int blkoops_dbg_write_buf(struct blkoops *c, void *buf, size_t len)
+{
+ unsigned long flags;
+ size_t n;
+ int ret;
+ u64 id;
+
+ while (len) {
+ n = min(len, c->psi.bufsize);
+ memcpy(c->psi.buf, buf, n);
+ spin_lock_irqsave(&c->dbg_lock, flags);
+ ret = blkoops_write(c->dbg_type, c->dbg_reason, &id,
+ c->dbg_part++, n, &c->psi);
+ spin_unlock_irqrestore(&c->dbg_lock, flags);
+ if (ret) {
+ pr_err("blkoops: debug write failed, error %d\n", ret);
+ return ret;
+ }
+ buf += n;
+ len -= n;
+ }
+ return 0;
+}
+
+static int blkoops_dbg_flush_buf(struct blkoops *c)
+{
+ int err;
+
+ err = blkoops_dbg_write_buf(c, c->dbg_buf, c->dbg_used);
+ c->dbg_used = 0;
+ return err;
+}
+
+static int blkoops_dbg_drain_buf(struct blkoops *c)
+{
+ size_t written = 0;
+ int err = 0;
+
+ while (c->dbg_used >= c->psi.bufsize) {
+ err = blkoops_dbg_write_buf(c, c->dbg_buf + written,
+ c->psi.bufsize);
+ c->dbg_used -= c->psi.bufsize;
+ written += c->psi.bufsize;
+ }
+ memmove(c->dbg_buf, c->dbg_buf + written, c->dbg_used);
+ return err;
+}
+
+static ssize_t blkoops_dbg_fill_buf(struct blkoops *c, const char __user *buf,
+ size_t len)
+{
+ size_t remains = c->dbg_bufsize - c->dbg_used, n = min(len, remains);
+ void *addr = c->dbg_buf + c->dbg_used;
+
+ if (copy_from_user(addr, buf, n))
+ return -EFAULT;
+ c->dbg_used += n;
+ return n;
+}
+
+static ssize_t blkoops_dbg_write(struct file *file, const char __user *buf,
+ size_t len, loff_t *ppos)
+{
+ struct blkoops *c = file->private_data;
+ ssize_t n, res = len;
+
+ while (len) {
+ n = blkoops_dbg_fill_buf(c, buf, len);
+ if (n < 0)
+ return n;
+ buf += n;
+ len -= n;
+ if (c->dbg_used == c->dbg_bufsize)
+ blkoops_dbg_drain_buf(c);
+ }
+ return res;
+}
+
+static int blkoops_dbg_file_open(struct inode *inode, struct file *file)
+{
+ struct blkoops *c = inode->i_private;
+ unsigned long flags;
+ int err = 0;
+
+ spin_lock_irqsave(&c->dbg_lock, flags);
+ if (c->dbg_open)
+ err = -EBUSY;
+ else
+ c->dbg_open = 1;
+ spin_unlock_irqrestore(&c->dbg_lock, flags);
+ if (err)
+ return err;
+
+ c->dbg_bufsize = BLKOOPS_BUFSIZE;
+ c->dbg_buf = kmalloc(c->dbg_bufsize, GFP_KERNEL);
+ if (!c->dbg_buf) {
+ err = -ENOMEM;
+ goto out_err;
+ }
+
+ err = nonseekable_open(inode, file);
+ if (err)
+ goto out_err;
+
+ file->private_data = c;
+
+ c->dbg_part = 1;
+ c->dbg_used = 0;
+
+ return 0;
+
+out_err:
+ spin_lock_irqsave(&c->dbg_lock, flags);
+ c->dbg_open = 0;
+ spin_unlock_irqrestore(&c->dbg_lock, flags);
+ return err;
+}
+
+static int blkoops_dbg_file_release(struct inode *inode, struct file *file)
+{
+ struct blkoops *c = inode->i_private;
+ unsigned long flags;
+ int err, err2;
+
+ err = blkoops_dbg_flush_buf(c);
+
+ spin_lock_irqsave(&c->dbg_lock, flags);
+ err2 = blkoops_flush(&c->psi);
+ spin_unlock_irqrestore(&c->dbg_lock, flags);
+ if (err2 && !err)
+ err = err2;
+
+ kfree(c->dbg_buf);
+
+ spin_lock_irqsave(&c->dbg_lock, flags);
+ c->dbg_open = 0;
+ spin_unlock_irqrestore(&c->dbg_lock, flags);
+
+ return err;
+}
+
+static const struct file_operations dbg_data_fops = {
+ .owner = THIS_MODULE,
+ .open = blkoops_dbg_file_open,
+ .release = blkoops_dbg_file_release,
+ .write = blkoops_dbg_write,
+ .llseek = no_llseek,
+};
+
+static void blkoops_init_debugfs(struct blkoops *c)
+{
+ umode_t rw = S_IRUSR | S_IWUSR, wo = S_IWUSR;
+
+ c->dbg_root = debugfs_create_dir("blkoops", NULL);
+
+ debugfs_create_u32("type", rw, c->dbg_root, &c->dbg_type);
+ debugfs_create_u32("reason", rw, c->dbg_root, &c->dbg_reason);
+ debugfs_create_file("data", wo, c->dbg_root, c, &dbg_data_fops);
+}
+
+static void blkoops_remove_debugfs(struct blkoops *c)
+{
+ debugfs_remove_recursive(c->dbg_root);
+}
+
+#else
+
+static inline void blkoops_init_debugfs(struct blkoops *c)
+{
+}
+
+static void blkoops_remove_debugfs(struct blkoops *c)
+{
+}
+
+#endif
+
+static void *blkoops_alloc_buf(unsigned int blksize, loff_t max_size,
+ unsigned int *rsz)
+{
+ unsigned int size;
+ void *addr;
+ gfp_t flgs;
+
+ size = BLKOOPS_BUFSIZE;
+ if (size > max_size)
+ size = max_size;
+
+ while (1) {
+ if (size < blksize)
+ *rsz = blksize;
+ else
+ *rsz = roundup(size, blksize);
+ flgs = *rsz == blksize ? GFP_KERNEL : GFP_KERNEL | __GFP_NOWARN;
+ addr = kzalloc(*rsz, flgs);
+ if (addr || *rsz == blksize)
+ break;
+ size >>= 1;
+ }
+ return addr;
+}
+
+static int blkoops_read_session(struct blkoops *c)
+{
+ struct blkoops_node *bn;
+
+ bn = blkoops_read_node(c, 0);
+ if (IS_ERR(bn)) {
+ if (PTR_ERR(bn) == -EINVAL)
+ pr_err("blkoops: %s: bad magic\n", c->bdev_name);
+ return PTR_ERR(bn);
+ }
+
+ c->last_session = bn->session;
+ c->next_session = c->last_session + 1;
+ c->next_file = 0;
+
+ c->erased_session = bn->session;
+ c->erased_file = bn->file;
+ c->erased_sects = bn->nr_sects;
+
+ kfree(bn);
+
+ bn = blkoops_read_node(c, blkoops_scan_start(c));
+ if (IS_ERR(bn))
+ goto out;
+
+ if (!blkoops_validate_node(c, bn)) {
+ c->last_session = bn->session;
+ c->next_session = c->last_session + 1;
+ }
+
+ kfree(bn);
+out:
+ DBG("sess %u size %lld blksz %u", c->last_session, c->size, c->blksize);
+ if (c->erased_file) {
+ DBG("erased sess %u file %u sects %llu",
+ c->erased_session, c->erased_file, (u64)c->erased_sects);
+ }
+
+ return 0;
+}
+
+static int blkoops_get_bdev_size(struct blkoops *c, struct block_device *bdev)
+{
+ unsigned int blksize;
+ loff_t size;
+
+ blksize = bdev_logical_block_size(bdev);
+ if (blksize < 512 || blksize & 511)
+ return -EINVAL;
+
+ size = i_size_read(bdev->bd_inode);
+ if (size < 2 * blksize)
+ return -EINVAL;
+
+ c->blksize = blksize;
+ c->sects_per_blk = blksize >> 9;
+ c->size = size;
+ c->nr_sects = size >> 9;
+
+ return 0;
+}
+
+static struct blkoops *blkoops_alloc(void)
+{
+ struct blkoops *c;
+
+ c = kzalloc(sizeof(struct blkoops), GFP_KERNEL);
+ if (!c)
+ return NULL;
+
+ c->psi.owner = THIS_MODULE,
+ c->psi.name = "blkoops",
+ c->psi.flags = PSTORE_NO_HEADINGS | PSTORE_MAX_KMSG_BYTES,
+ c->psi.open = blkoops_open,
+ c->psi.read = blkoops_read,
+ c->psi.file_read = blkoops_file_read,
+ c->psi.write = blkoops_write,
+ c->psi.erase = blkoops_erase,
+ c->psi.flush = blkoops_flush,
+ c->psi.data = c;
+
+ spin_lock_init(&c->psi.buf_lock);
+#ifdef CONFIG_DEBUG_FS
+ spin_lock_init(&c->dbg_lock);
+#endif
+ return c;
+}
+
+static struct blkoops *blkoops;
+
+static int blkoops_do_add(struct blkoops *c)
+{
+ int err;
+
+ if (c->present)
+ return -EINVAL;
+
+ if (!*devname)
+ return -EINVAL;
+
+ *c->bdev_name = '\0';
+
+ c->devid = name_to_dev_t(devname);
+ if (!c->devid) {
+ err = -ENODEV;
+ goto out_err;
+ }
+
+ c->bdev = blkdev_get_by_dev(c->devid, BLKOOPS_MODE, blkoops_do_add);
+ if (IS_ERR(c->bdev)) {
+ err = PTR_ERR(c->bdev);
+ goto out_err;
+ }
+
+ bdevname(c->bdev, c->bdev_name);
+
+ err = blk_panic_init(c->bdev);
+ if (err)
+ goto out_put;
+
+ err = blkoops_get_bdev_size(c, c->bdev);
+ if (err)
+ goto out_cleanup;
+
+ err = blkoops_read_session(c);
+ if (err)
+ goto out_cleanup;
+
+ if (!c->buf) {
+ unsigned int rsz;
+ void *addr;
+
+ addr = blkoops_alloc_buf(c->blksize, c->size, &rsz);
+ if (!addr) {
+ err = -ENOMEM;
+ goto out_cleanup;
+ }
+ c->buf = addr;
+ c->bufsize = rsz;
+ c->root = RB_ROOT;
+ }
+
+ c->next_sect = blkoops_scan_start(c) >> 9;
+
+ spin_lock(&blkoops_lock);
+ c->present = 1;
+ spin_unlock(&blkoops_lock);
+
+ if (!c->psi.buf) {
+ c->psi.buf = c->buf + BLKOOPS_HDR_SZ;
+ c->psi.bufsize = c->bufsize - BLKOOPS_HDR_SZ;
+ err = pstore_register(&c->psi);
+ if (err)
+ goto out_no_pstore;
+ }
+
+ blkoops_init_debugfs(c);
+
+ pr_info("blkoops initialized on %s\n", c->bdev_name);
+
+ return 0;
+
+out_no_pstore:
+ c->psi.buf = NULL;
+ c->present = 0;
+ kfree(c->buf);
+ c->buf = NULL;
+out_cleanup:
+ blk_panic_cleanup(c->bdev);
+out_put:
+ blkdev_put(c->bdev, BLKOOPS_MODE);
+out_err:
+ pr_err("blkoops initialization failed on %s, error %d\n",
+ *c->bdev_name ? c->bdev_name : devname, err);
+ return err;
+}
+
+static void blkoops_do_remove(struct blkoops *c)
+{
+ if (!c->present)
+ return;
+
+ blkoops_remove_debugfs(c);
+
+ spin_lock(&blkoops_lock);
+ c->present = 0;
+ spin_unlock(&blkoops_lock);
+
+ blkoops_free_tree(c);
+
+ blk_panic_cleanup(c->bdev);
+
+ blkdev_put(c->bdev, BLKOOPS_MODE);
+
+ pr_info("blkoops detached from %s\n", c->bdev_name);
+}
+
+static int blkoops_add(void)
+{
+ int err;
+
+ /*
+ * Headers are sector aligned and less than 1 sector in size so that
+ * only whole headers are read.
+ */
+ BUILD_BUG_ON(BLKOOPS_HDR_SZ > 512);
+
+ if (!blkoops)
+ blkoops = blkoops_alloc();
+ if (!blkoops)
+ return -ENOMEM;
+
+ err = blkoops_do_add(blkoops);
+
+ if (!blkoops->psi.buf) {
+ /*
+ * 'blkoops' can be freed if the registration with pstore
+ * failed, otherwise 'blkoops' is never freed.
+ */
+ kfree(blkoops);
+ blkoops = NULL;
+ }
+
+ return err;
+}
+
+static void blkoops_remove(void)
+{
+ if (blkoops)
+ blkoops_do_remove(blkoops);
+}
+
+static int __init blkoops_init(void)
+{
+ int err = 0;
+ dev_t devid;
+
+ mutex_lock(&blkoops_mutex);
+ init_done = 1;
+ if (!*devname)
+ goto out;
+ devid = name_to_dev_t(devname);
+ if (!devid)
+ wait_for_device_probe();
+ err = blkoops_add();
+out:
+ mutex_unlock(&blkoops_mutex);
+ return err;
+}
+
+late_initcall(blkoops_init);
+
+static int param_set_devname(const char *val, const struct kernel_param *kp)
+{
+ int err = 0;
+
+ if (strlen(val) >= BLKOOPS_DEVNAME_SZ) {
+ pr_err("blkoops: devname parameter too long\n");
+ return -ENOSPC;
+ }
+
+ mutex_lock(&blkoops_mutex);
+ if (init_done)
+ blkoops_remove();
+ if (sscanf(val, "%s", devname) != 1)
+ *devname = '\0';
+ if (init_done && *devname)
+ err = blkoops_add();
+ mutex_unlock(&blkoops_mutex);
+
+ return err;
+}
+
+static int param_get_devname(char *buffer, const struct kernel_param *kp)
+{
+ return snprintf(buffer, BLKOOPS_DEVNAME_SZ, "%s", devname);
+}
+
+static struct kernel_param_ops param_ops_devname = {
+ .set = param_set_devname,
+ .get = param_get_devname,
+};
+
+module_param_cb(devname, ¶m_ops_devname, &devname, S_IRUSR | S_IWUSR);
+MODULE_PARM_DESC(devname, "Canonical block device name or number");
+
+module_param(dump_oops, int, S_IRUSR | S_IWUSR);
+MODULE_PARM_DESC(dump_oops,
+ "set to 1 to dump oopses, 0 to dump only panics (default 0)");
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Adrian Hunter");
+MODULE_DESCRIPTION("Block Oops / Panic Logger");
--
1.7.9.5
--
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