![Kees Cook](/assets/img/avatar_default.png)
In order to use arbitrary block devices as a pstore backend, provide a new module param named "best_effort", which will allow using any block device, even if it has not provided a panic_write callback. Link: https://lore.kernel.org/lkml/20200511233229.27745-12-keescook@chromium.org/ Signed-off-by: Kees Cook <keescook@chromium.org>
518 lines
14 KiB
C
518 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Implements pstore backend driver that write to block (or non-block) storage
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* devices, using the pstore/zone API.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include "../../block/blk.h"
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#include <linux/blkdev.h>
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#include <linux/string.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/platform_device.h>
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#include <linux/pstore_blk.h>
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#include <linux/mount.h>
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#include <linux/uio.h>
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static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE;
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module_param(kmsg_size, long, 0400);
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MODULE_PARM_DESC(kmsg_size, "kmsg dump record size in kbytes");
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static int max_reason = CONFIG_PSTORE_BLK_MAX_REASON;
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module_param(max_reason, int, 0400);
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MODULE_PARM_DESC(max_reason,
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"maximum reason for kmsg dump (default 2: Oops and Panic)");
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#if IS_ENABLED(CONFIG_PSTORE_PMSG)
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static long pmsg_size = CONFIG_PSTORE_BLK_PMSG_SIZE;
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#else
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static long pmsg_size = -1;
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#endif
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module_param(pmsg_size, long, 0400);
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MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
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#if IS_ENABLED(CONFIG_PSTORE_CONSOLE)
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static long console_size = CONFIG_PSTORE_BLK_CONSOLE_SIZE;
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#else
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static long console_size = -1;
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#endif
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module_param(console_size, long, 0400);
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MODULE_PARM_DESC(console_size, "console size in kbytes");
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#if IS_ENABLED(CONFIG_PSTORE_FTRACE)
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static long ftrace_size = CONFIG_PSTORE_BLK_FTRACE_SIZE;
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#else
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static long ftrace_size = -1;
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#endif
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module_param(ftrace_size, long, 0400);
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MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes");
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static bool best_effort;
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module_param(best_effort, bool, 0400);
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MODULE_PARM_DESC(best_effort, "use best effort to write (i.e. do not require storage driver pstore support, default: off)");
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/*
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* blkdev - the block device to use for pstore storage
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*
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* Usually, this will be a partition of a block device.
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*
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* blkdev accepts the following variants:
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* 1) <hex_major><hex_minor> device number in hexadecimal representation,
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* with no leading 0x, for example b302.
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* 2) /dev/<disk_name> represents the device number of disk
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* 3) /dev/<disk_name><decimal> represents the device number
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* of partition - device number of disk plus the partition number
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* 4) /dev/<disk_name>p<decimal> - same as the above, that form is
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* used when disk name of partitioned disk ends on a digit.
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* 5) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
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* unique id of a partition if the partition table provides it.
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* The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
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* partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
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* filled hex representation of the 32-bit "NT disk signature", and PP
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* is a zero-filled hex representation of the 1-based partition number.
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* 6) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
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* a partition with a known unique id.
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* 7) <major>:<minor> major and minor number of the device separated by
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* a colon.
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*/
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static char blkdev[80] = CONFIG_PSTORE_BLK_BLKDEV;
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module_param_string(blkdev, blkdev, 80, 0400);
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MODULE_PARM_DESC(blkdev, "block device for pstore storage");
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/*
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* All globals must only be accessed under the pstore_blk_lock
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* during the register/unregister functions.
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*/
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static DEFINE_MUTEX(pstore_blk_lock);
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static struct block_device *psblk_bdev;
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static struct pstore_zone_info *pstore_zone_info;
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static pstore_blk_panic_write_op blkdev_panic_write;
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struct bdev_info {
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dev_t devt;
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sector_t nr_sects;
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sector_t start_sect;
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};
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#define check_size(name, alignsize) ({ \
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long _##name_ = (name); \
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_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024); \
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if (_##name_ & ((alignsize) - 1)) { \
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pr_info(#name " must align to %d\n", \
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(alignsize)); \
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_##name_ = ALIGN(name, (alignsize)); \
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} \
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_##name_; \
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})
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static int __register_pstore_device(struct pstore_device_info *dev)
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{
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int ret;
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lockdep_assert_held(&pstore_blk_lock);
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if (!dev || !dev->total_size || !dev->read || !dev->write)
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return -EINVAL;
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/* someone already registered before */
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if (pstore_zone_info)
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return -EBUSY;
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pstore_zone_info = kzalloc(sizeof(struct pstore_zone_info), GFP_KERNEL);
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if (!pstore_zone_info)
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return -ENOMEM;
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/* zero means not limit on which backends to attempt to store. */
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if (!dev->flags)
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dev->flags = UINT_MAX;
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#define verify_size(name, alignsize, enabled) { \
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long _##name_; \
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if (enabled) \
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_##name_ = check_size(name, alignsize); \
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else \
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_##name_ = 0; \
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name = _##name_ / 1024; \
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pstore_zone_info->name = _##name_; \
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}
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verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
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verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG);
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verify_size(console_size, 4096, dev->flags & PSTORE_FLAGS_CONSOLE);
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verify_size(ftrace_size, 4096, dev->flags & PSTORE_FLAGS_FTRACE);
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#undef verify_size
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pstore_zone_info->total_size = dev->total_size;
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pstore_zone_info->max_reason = max_reason;
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pstore_zone_info->read = dev->read;
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pstore_zone_info->write = dev->write;
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pstore_zone_info->erase = dev->erase;
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pstore_zone_info->panic_write = dev->panic_write;
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pstore_zone_info->name = KBUILD_MODNAME;
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pstore_zone_info->owner = THIS_MODULE;
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ret = register_pstore_zone(pstore_zone_info);
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if (ret) {
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kfree(pstore_zone_info);
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pstore_zone_info = NULL;
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}
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return ret;
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}
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/**
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* register_pstore_device() - register non-block device to pstore/blk
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*
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* @dev: non-block device information
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*
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* Return:
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* * 0 - OK
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* * Others - something error.
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*/
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int register_pstore_device(struct pstore_device_info *dev)
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{
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int ret;
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mutex_lock(&pstore_blk_lock);
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ret = __register_pstore_device(dev);
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mutex_unlock(&pstore_blk_lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(register_pstore_device);
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static void __unregister_pstore_device(struct pstore_device_info *dev)
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{
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lockdep_assert_held(&pstore_blk_lock);
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if (pstore_zone_info && pstore_zone_info->read == dev->read) {
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unregister_pstore_zone(pstore_zone_info);
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kfree(pstore_zone_info);
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pstore_zone_info = NULL;
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}
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}
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/**
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* unregister_pstore_device() - unregister non-block device from pstore/blk
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*
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* @dev: non-block device information
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*/
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void unregister_pstore_device(struct pstore_device_info *dev)
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{
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mutex_lock(&pstore_blk_lock);
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__unregister_pstore_device(dev);
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mutex_unlock(&pstore_blk_lock);
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}
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EXPORT_SYMBOL_GPL(unregister_pstore_device);
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/**
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* psblk_get_bdev() - open block device
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*
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* @holder: Exclusive holder identifier
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* @info: Information about bdev to fill in
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*
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* Return: pointer to block device on success and others on error.
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*
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* On success, the returned block_device has reference count of one.
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*/
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static struct block_device *psblk_get_bdev(void *holder,
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struct bdev_info *info)
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{
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struct block_device *bdev = ERR_PTR(-ENODEV);
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fmode_t mode = FMODE_READ | FMODE_WRITE;
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sector_t nr_sects;
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lockdep_assert_held(&pstore_blk_lock);
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if (pstore_zone_info)
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return ERR_PTR(-EBUSY);
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if (!blkdev[0])
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return ERR_PTR(-ENODEV);
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if (holder)
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mode |= FMODE_EXCL;
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bdev = blkdev_get_by_path(blkdev, mode, holder);
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if (IS_ERR(bdev)) {
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dev_t devt;
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devt = name_to_dev_t(blkdev);
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if (devt == 0)
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return ERR_PTR(-ENODEV);
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bdev = blkdev_get_by_dev(devt, mode, holder);
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if (IS_ERR(bdev))
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return bdev;
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}
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nr_sects = part_nr_sects_read(bdev->bd_part);
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if (!nr_sects) {
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pr_err("not enough space for '%s'\n", blkdev);
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blkdev_put(bdev, mode);
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return ERR_PTR(-ENOSPC);
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}
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if (info) {
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info->devt = bdev->bd_dev;
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info->nr_sects = nr_sects;
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info->start_sect = get_start_sect(bdev);
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}
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return bdev;
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}
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static void psblk_put_bdev(struct block_device *bdev, void *holder)
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{
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fmode_t mode = FMODE_READ | FMODE_WRITE;
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lockdep_assert_held(&pstore_blk_lock);
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if (!bdev)
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return;
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if (holder)
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mode |= FMODE_EXCL;
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blkdev_put(bdev, mode);
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}
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static ssize_t psblk_generic_blk_read(char *buf, size_t bytes, loff_t pos)
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{
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struct block_device *bdev = psblk_bdev;
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struct file file;
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struct kiocb kiocb;
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struct iov_iter iter;
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struct kvec iov = {.iov_base = buf, .iov_len = bytes};
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if (!bdev)
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return -ENODEV;
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memset(&file, 0, sizeof(struct file));
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file.f_mapping = bdev->bd_inode->i_mapping;
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file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
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file.f_inode = bdev->bd_inode;
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file_ra_state_init(&file.f_ra, file.f_mapping);
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init_sync_kiocb(&kiocb, &file);
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kiocb.ki_pos = pos;
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iov_iter_kvec(&iter, READ, &iov, 1, bytes);
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return generic_file_read_iter(&kiocb, &iter);
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}
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static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes,
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loff_t pos)
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{
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struct block_device *bdev = psblk_bdev;
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struct iov_iter iter;
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struct kiocb kiocb;
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struct file file;
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ssize_t ret;
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struct kvec iov = {.iov_base = (void *)buf, .iov_len = bytes};
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if (!bdev)
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return -ENODEV;
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/* Console/Ftrace backend may handle buffer until flush dirty zones */
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if (in_interrupt() || irqs_disabled())
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return -EBUSY;
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memset(&file, 0, sizeof(struct file));
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file.f_mapping = bdev->bd_inode->i_mapping;
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file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
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file.f_inode = bdev->bd_inode;
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init_sync_kiocb(&kiocb, &file);
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kiocb.ki_pos = pos;
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iov_iter_kvec(&iter, WRITE, &iov, 1, bytes);
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inode_lock(bdev->bd_inode);
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ret = generic_write_checks(&kiocb, &iter);
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if (ret > 0)
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ret = generic_perform_write(&file, &iter, pos);
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inode_unlock(bdev->bd_inode);
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if (likely(ret > 0)) {
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const struct file_operations f_op = {.fsync = blkdev_fsync};
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file.f_op = &f_op;
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kiocb.ki_pos += ret;
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ret = generic_write_sync(&kiocb, ret);
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}
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return ret;
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}
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static ssize_t psblk_blk_panic_write(const char *buf, size_t size,
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loff_t off)
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{
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int ret;
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if (!blkdev_panic_write)
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return -EOPNOTSUPP;
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/* size and off must align to SECTOR_SIZE for block device */
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ret = blkdev_panic_write(buf, off >> SECTOR_SHIFT,
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size >> SECTOR_SHIFT);
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/* try next zone */
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if (ret == -ENOMSG)
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return ret;
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return ret ? -EIO : size;
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}
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static int __register_pstore_blk(struct pstore_blk_info *info)
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{
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char bdev_name[BDEVNAME_SIZE];
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struct block_device *bdev;
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struct pstore_device_info dev;
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struct bdev_info binfo;
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void *holder = blkdev;
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int ret = -ENODEV;
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lockdep_assert_held(&pstore_blk_lock);
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/* hold bdev exclusively */
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memset(&binfo, 0, sizeof(binfo));
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bdev = psblk_get_bdev(holder, &binfo);
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if (IS_ERR(bdev)) {
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pr_err("failed to open '%s'!\n", blkdev);
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return PTR_ERR(bdev);
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}
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/* only allow driver matching the @blkdev */
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if (!binfo.devt || (!best_effort &&
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MAJOR(binfo.devt) != info->major)) {
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pr_debug("invalid major %u (expect %u)\n",
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info->major, MAJOR(binfo.devt));
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ret = -ENODEV;
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goto err_put_bdev;
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}
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/* psblk_bdev must be assigned before register to pstore/blk */
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psblk_bdev = bdev;
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blkdev_panic_write = info->panic_write;
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/* Copy back block device details. */
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info->devt = binfo.devt;
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info->nr_sects = binfo.nr_sects;
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info->start_sect = binfo.start_sect;
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memset(&dev, 0, sizeof(dev));
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dev.total_size = info->nr_sects << SECTOR_SHIFT;
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dev.flags = info->flags;
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dev.read = psblk_generic_blk_read;
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dev.write = psblk_generic_blk_write;
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dev.erase = NULL;
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dev.panic_write = info->panic_write ? psblk_blk_panic_write : NULL;
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ret = __register_pstore_device(&dev);
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if (ret)
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goto err_put_bdev;
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bdevname(bdev, bdev_name);
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pr_info("attached %s%s\n", bdev_name,
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info->panic_write ? "" : " (no dedicated panic_write!)");
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return 0;
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err_put_bdev:
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psblk_bdev = NULL;
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blkdev_panic_write = NULL;
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psblk_put_bdev(bdev, holder);
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return ret;
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}
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/**
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* register_pstore_blk() - register block device to pstore/blk
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*
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* @info: details on the desired block device interface
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*
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* Return:
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* * 0 - OK
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* * Others - something error.
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*/
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int register_pstore_blk(struct pstore_blk_info *info)
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{
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int ret;
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mutex_lock(&pstore_blk_lock);
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ret = __register_pstore_blk(info);
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mutex_unlock(&pstore_blk_lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(register_pstore_blk);
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static void __unregister_pstore_blk(unsigned int major)
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{
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struct pstore_device_info dev = { .read = psblk_generic_blk_read };
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void *holder = blkdev;
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lockdep_assert_held(&pstore_blk_lock);
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if (psblk_bdev && MAJOR(psblk_bdev->bd_dev) == major) {
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__unregister_pstore_device(&dev);
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psblk_put_bdev(psblk_bdev, holder);
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blkdev_panic_write = NULL;
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psblk_bdev = NULL;
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}
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}
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/**
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* unregister_pstore_blk() - unregister block device from pstore/blk
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*
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* @major: the major device number of device
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*/
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void unregister_pstore_blk(unsigned int major)
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{
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mutex_lock(&pstore_blk_lock);
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__unregister_pstore_blk(major);
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mutex_unlock(&pstore_blk_lock);
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}
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EXPORT_SYMBOL_GPL(unregister_pstore_blk);
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/* get information of pstore/blk */
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int pstore_blk_get_config(struct pstore_blk_config *info)
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{
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strncpy(info->device, blkdev, 80);
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info->max_reason = max_reason;
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info->kmsg_size = check_size(kmsg_size, 4096);
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info->pmsg_size = check_size(pmsg_size, 4096);
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info->ftrace_size = check_size(ftrace_size, 4096);
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info->console_size = check_size(console_size, 4096);
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return 0;
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}
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EXPORT_SYMBOL_GPL(pstore_blk_get_config);
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static int __init pstore_blk_init(void)
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{
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struct pstore_blk_info info = { };
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int ret = 0;
|
|
|
|
mutex_lock(&pstore_blk_lock);
|
|
if (!pstore_zone_info && best_effort && blkdev[0])
|
|
ret = __register_pstore_blk(&info);
|
|
mutex_unlock(&pstore_blk_lock);
|
|
|
|
return ret;
|
|
}
|
|
late_initcall(pstore_blk_init);
|
|
|
|
static void __exit pstore_blk_exit(void)
|
|
{
|
|
mutex_lock(&pstore_blk_lock);
|
|
if (psblk_bdev)
|
|
__unregister_pstore_blk(MAJOR(psblk_bdev->bd_dev));
|
|
else {
|
|
struct pstore_device_info dev = { };
|
|
|
|
if (pstore_zone_info)
|
|
dev.read = pstore_zone_info->read;
|
|
__unregister_pstore_device(&dev);
|
|
}
|
|
mutex_unlock(&pstore_blk_lock);
|
|
}
|
|
module_exit(pstore_blk_exit);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>");
|
|
MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
|
|
MODULE_DESCRIPTION("pstore backend for block devices");
|