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linux/drivers/nvdimm/btt.h
Vishal Verma d9b83c7569 libnvdimm, btt: rework error clearing 
Clearing errors or badblocks during a BTT write requires sending an ACPI
DSM, which means potentially sleeping. Since a BTT IO happens in atomic
context (preemption disabled, spinlocks may be held), we cannot perform
error clearing in the course of an IO. Due to this error clearing for
BTT IOs has hitherto been disabled.

In this patch we move error clearing out of the atomic section, and thus
re-enable error clearing with BTTs. When we are about to add a block to
the free list, we check if it was previously marked as an error, and if
it was, we add it to the freelist, but also set a flag that says error
clearing will be required. We then drop the lane (ending the atomic
context), and send a zero buffer so that the error can be cleared. The
error flag in the free list is protected by the nd 'lane', and is set
only be a thread while it holds that lane. When the error is cleared,
the flag is cleared, but while holding a mutex for that freelist index.

When writing, we check for two things -
1/ If the freelist mutex is held or if the error flag is set. If so,
this is an error block that is being (or about to be) cleared.
2/ If the block is a known badblock based on nsio->bb

The second check is required because the BTT map error flag for a map
entry only gets set when an error LBA is read. If we write to a new
location that may not have the map error flag set, but still might be in
the region's badblock list, we can trigger an EIO on the write, which is
undesirable and completely avoidable.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-08-31 15:05:10 -07:00

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/*
* Block Translation Table library
* Copyright (c) 2014-2015, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*/
#ifndef _LINUX_BTT_H
#define _LINUX_BTT_H
#include <linux/badblocks.h>
#include <linux/types.h>
#define BTT_SIG_LEN 16
#define BTT_SIG "BTT_ARENA_INFO\0"
#define MAP_ENT_SIZE 4
#define MAP_TRIM_SHIFT 31
#define MAP_TRIM_MASK (1 << MAP_TRIM_SHIFT)
#define MAP_ERR_SHIFT 30
#define MAP_ERR_MASK (1 << MAP_ERR_SHIFT)
#define MAP_LBA_MASK (~((1 << MAP_TRIM_SHIFT) | (1 << MAP_ERR_SHIFT)))
#define MAP_ENT_NORMAL 0xC0000000
#define LOG_ENT_SIZE sizeof(struct log_entry)
#define ARENA_MIN_SIZE (1UL << 24) /* 16 MB */
#define ARENA_MAX_SIZE (1ULL << 39) /* 512 GB */
#define RTT_VALID (1UL << 31)
#define RTT_INVALID 0
#define BTT_PG_SIZE 4096
#define BTT_DEFAULT_NFREE ND_MAX_LANES
#define LOG_SEQ_INIT 1
#define IB_FLAG_ERROR 0x00000001
#define IB_FLAG_ERROR_MASK 0x00000001
#define ent_lba(ent) (ent & MAP_LBA_MASK)
#define ent_e_flag(ent) (!!(ent & MAP_ERR_MASK))
#define ent_z_flag(ent) (!!(ent & MAP_TRIM_MASK))
#define set_e_flag(ent) (ent |= MAP_ERR_MASK)
enum btt_init_state {
INIT_UNCHECKED = 0,
INIT_NOTFOUND,
INIT_READY
};
struct log_entry {
__le32 lba;
__le32 old_map;
__le32 new_map;
__le32 seq;
__le64 padding[2];
};
struct btt_sb {
u8 signature[BTT_SIG_LEN];
u8 uuid[16];
u8 parent_uuid[16];
__le32 flags;
__le16 version_major;
__le16 version_minor;
__le32 external_lbasize;
__le32 external_nlba;
__le32 internal_lbasize;
__le32 internal_nlba;
__le32 nfree;
__le32 infosize;
__le64 nextoff;
__le64 dataoff;
__le64 mapoff;
__le64 logoff;
__le64 info2off;
u8 padding[3968];
__le64 checksum;
};
struct free_entry {
u32 block;
u8 sub;
u8 seq;
u8 has_err;
};
struct aligned_lock {
union {
spinlock_t lock;
u8 cacheline_padding[L1_CACHE_BYTES];
};
};
/**
* struct arena_info - handle for an arena
* @size: Size in bytes this arena occupies on the raw device.
* This includes arena metadata.
* @external_lba_start: The first external LBA in this arena.
* @internal_nlba: Number of internal blocks available in the arena
* including nfree reserved blocks
* @internal_lbasize: Internal and external lba sizes may be different as
* we can round up 'odd' external lbasizes such as 520B
* to be aligned.
* @external_nlba: Number of blocks contributed by the arena to the number
* reported to upper layers. (internal_nlba - nfree)
* @external_lbasize: LBA size as exposed to upper layers.
* @nfree: A reserve number of 'free' blocks that is used to
* handle incoming writes.
* @version_major: Metadata layout version major.
* @version_minor: Metadata layout version minor.
* @sector_size: The Linux sector size - 512 or 4096
* @nextoff: Offset in bytes to the start of the next arena.
* @infooff: Offset in bytes to the info block of this arena.
* @dataoff: Offset in bytes to the data area of this arena.
* @mapoff: Offset in bytes to the map area of this arena.
* @logoff: Offset in bytes to the log area of this arena.
* @info2off: Offset in bytes to the backup info block of this arena.
* @freelist: Pointer to in-memory list of free blocks
* @rtt: Pointer to in-memory "Read Tracking Table"
* @map_locks: Spinlocks protecting concurrent map writes
* @nd_btt: Pointer to parent nd_btt structure.
* @list: List head for list of arenas
* @debugfs_dir: Debugfs dentry
* @flags: Arena flags - may signify error states.
*
* arena_info is a per-arena handle. Once an arena is narrowed down for an
* IO, this struct is passed around for the duration of the IO.
*/
struct arena_info {
u64 size; /* Total bytes for this arena */
u64 external_lba_start;
u32 internal_nlba;
u32 internal_lbasize;
u32 external_nlba;
u32 external_lbasize;
u32 nfree;
u16 version_major;
u16 version_minor;
u32 sector_size;
/* Byte offsets to the different on-media structures */
u64 nextoff;
u64 infooff;
u64 dataoff;
u64 mapoff;
u64 logoff;
u64 info2off;
/* Pointers to other in-memory structures for this arena */
struct free_entry *freelist;
u32 *rtt;
struct aligned_lock *map_locks;
struct nd_btt *nd_btt;
struct list_head list;
struct dentry *debugfs_dir;
/* Arena flags */
u32 flags;
struct mutex err_lock;
};
/**
* struct btt - handle for a BTT instance
* @btt_disk: Pointer to the gendisk for BTT device
* @btt_queue: Pointer to the request queue for the BTT device
* @arena_list: Head of the list of arenas
* @debugfs_dir: Debugfs dentry
* @nd_btt: Parent nd_btt struct
* @nlba: Number of logical blocks exposed to the upper layers
* after removing the amount of space needed by metadata
* @rawsize: Total size in bytes of the available backing device
* @lbasize: LBA size as requested and presented to upper layers.
* This is sector_size + size of any metadata.
* @sector_size: The Linux sector size - 512 or 4096
* @lanes: Per-lane spinlocks
* @init_lock: Mutex used for the BTT initialization
* @init_state: Flag describing the initialization state for the BTT
* @num_arenas: Number of arenas in the BTT instance
*/
struct btt {
struct gendisk *btt_disk;
struct request_queue *btt_queue;
struct list_head arena_list;
struct dentry *debugfs_dir;
struct nd_btt *nd_btt;
u64 nlba;
unsigned long long rawsize;
u32 lbasize;
u32 sector_size;
struct nd_region *nd_region;
struct mutex init_lock;
int init_state;
int num_arenas;
struct badblocks *phys_bb;
};
bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super);
int nd_btt_version(struct nd_btt *nd_btt, struct nd_namespace_common *ndns,
struct btt_sb *btt_sb);
#endif
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