lightnvm: physical block device (pblk) target

This patch introduces pblk, a host-side translation layer for
Open-Channel SSDs to expose them like block devices. The translation
layer allows data placement decisions, and I/O scheduling to be
managed by the host, enabling users to optimize the SSD for their
specific workloads.

An open-channel SSD has a set of LUNs (parallel units) and a
collection of blocks. Each block can be read in any order, but
writes must be sequential. Writes may also fail, and if a block
requires it, must also be reset before new writes can be
applied.

To manage the constraints, pblk maintains a logical to
physical address (L2P) table,  write cache, garbage
collection logic, recovery scheme, and logic to rate-limit
user I/Os versus garbage collection I/Os.

The L2P table is fully-associative and manages sectors at a
4KB granularity. Pblk stores the L2P table in two places, in
the out-of-band area of the media and on the last page of a
line. In the cause of a power failure, pblk will perform a
scan to recover the L2P table.

The user data is organized into lines. A line is data
striped across blocks and LUNs. The lines enable the host to
reduce the amount of metadata to maintain besides the user
data and makes it easier to implement RAID or erasure coding
in the future.

pblk implements multi-tenant support and can be instantiated
multiple times on the same drive. Each instance owns a
portion of the SSD - both regarding I/O bandwidth and
capacity - providing I/O isolation for each case.

Finally, pblk also exposes a sysfs interface that allows
user-space to peek into the internals of pblk. The interface
is available at /dev/block/*/pblk/ where * is the block
device name exposed.

This work also contains contributions from:
  Matias Bjørling <matias@cnexlabs.com>
  Simon A. F. Lund <slund@cnexlabs.com>
  Young Tack Jin <youngtack.jin@gmail.com>
  Huaicheng Li <huaicheng@cs.uchicago.edu>

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <matias@cnexlabs.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 1121 insertions, 0 deletions

diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
new file mode 100644
index 000000000000..c82120ce3be5
--- /dev/null
+++ b/drivers/lightnvm/pblk.h
@@ -0,0 +1,1121 @@
+/*
+ * Copyright (C) 2015 IT University of Copenhagen (rrpc.h)
+ * Copyright (C) 2016 CNEX Labs
+ * Initial release: Matias Bjorling <matias@cnexlabs.com>
+ * Write buffering: Javier Gonzalez <javier@cnexlabs.com>
+ *
+ * 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.
+ *
+ * Implementation of a Physical Block-device target for Open-channel SSDs.
+ *
+ */
+
+#ifndef PBLK_H_
+#define PBLK_H_
+
+#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/vmalloc.h>
+#include <linux/crc32.h>
+#include <linux/uuid.h>
+
+#include <linux/lightnvm.h>
+
+/* Run only GC if less than 1/X blocks are free */
+#define GC_LIMIT_INVERSE 5
+#define GC_TIME_MSECS 1000
+
+#define PBLK_SECTOR (512)
+#define PBLK_EXPOSED_PAGE_SIZE (4096)
+#define PBLK_MAX_REQ_ADDRS (64)
+#define PBLK_MAX_REQ_ADDRS_PW (6)
+
+#define PBLK_CACHE_NAME_LEN (DISK_NAME_LEN + 16)
+
+#define PBLK_COMMAND_TIMEOUT_MS 30000
+
+/* Max 512 LUNs per device */
+#define PBLK_MAX_LUNS_BITMAP (4)
+
+#define NR_PHY_IN_LOG (PBLK_EXPOSED_PAGE_SIZE / PBLK_SECTOR)
+
+#define pblk_for_each_lun(pblk, rlun, i) \
+		for ((i) = 0, rlun = &(pblk)->luns[0]; \
+			(i) < (pblk)->nr_luns; (i)++, rlun = &(pblk)->luns[(i)])
+
+#define ERASE 2 /* READ = 0, WRITE = 1 */
+
+enum {
+	/* IO Types */
+	PBLK_IOTYPE_USER	= 1 << 0,
+	PBLK_IOTYPE_GC		= 1 << 1,
+
+	/* Write buffer flags */
+	PBLK_FLUSH_ENTRY	= 1 << 2,
+	PBLK_WRITTEN_DATA	= 1 << 3,
+	PBLK_SUBMITTED_ENTRY	= 1 << 4,
+	PBLK_WRITABLE_ENTRY	= 1 << 5,
+};
+
+enum {
+	PBLK_BLK_ST_OPEN =	0x1,
+	PBLK_BLK_ST_CLOSED =	0x2,
+};
+
+/* The number of GC lists and the rate-limiter states go together. This way the
+ * rate-limiter can dictate how much GC is needed based on resource utilization.
+ */
+#define PBLK_NR_GC_LISTS 3
+#define PBLK_MAX_GC_JOBS 32
+
+enum {
+	PBLK_RL_HIGH = 1,
+	PBLK_RL_MID = 2,
+	PBLK_RL_LOW = 3,
+};
+
+struct pblk_sec_meta {
+	u64 reserved;
+	__le64 lba;
+};
+
+#define pblk_dma_meta_size (sizeof(struct pblk_sec_meta) * PBLK_MAX_REQ_ADDRS)
+
+/* write completion context */
+struct pblk_c_ctx {
+	struct list_head list;		/* Head for out-of-order completion */
+
+	unsigned long *lun_bitmap;	/* Luns used on current request */
+	unsigned int sentry;
+	unsigned int nr_valid;
+	unsigned int nr_padded;
+};
+
+/* Read context */
+struct pblk_r_ctx {
+	struct bio *orig_bio;
+};
+
+/* Recovery context */
+struct pblk_rec_ctx {
+	struct pblk *pblk;
+	struct nvm_rq *rqd;
+	struct list_head failed;
+	struct work_struct ws_rec;
+};
+
+/* Write context */
+struct pblk_w_ctx {
+	struct bio_list bios;		/* Original bios - used for completion
+					 * in REQ_FUA, REQ_FLUSH case
+					 */
+	sector_t lba;			/* Logic addr. associated with entry */
+	struct ppa_addr ppa;		/* Physic addr. associated with entry */
+	int flags;			/* Write context flags */
+};
+
+struct pblk_rb_entry {
+	struct ppa_addr cacheline;	/* Cacheline for this entry */
+	void *data;			/* Pointer to data on this entry */
+	struct pblk_w_ctx w_ctx;	/* Context for this entry */
+	struct list_head index;		/* List head to enable indexes */
+};
+
+#define EMPTY_ENTRY (~0U)
+
+struct pblk_rb_pages {
+	struct page *pages;
+	int order;
+	struct list_head list;
+};
+
+struct pblk_rb {
+	struct pblk_rb_entry *entries;	/* Ring buffer entries */
+	unsigned int mem;		/* Write offset - points to next
+					 * writable entry in memory
+					 */
+	unsigned int subm;		/* Read offset - points to last entry
+					 * that has been submitted to the media
+					 * to be persisted
+					 */
+	unsigned int sync;		/* Synced - backpointer that signals
+					 * the last submitted entry that has
+					 * been successfully persisted to media
+					 */
+	unsigned int sync_point;	/* Sync point - last entry that must be
+					 * flushed to the media. Used with
+					 * REQ_FLUSH and REQ_FUA
+					 */
+	unsigned int l2p_update;	/* l2p update point - next entry for
+					 * which l2p mapping will be updated to
+					 * contain a device ppa address (instead
+					 * of a cacheline
+					 */
+	unsigned int nr_entries;	/* Number of entries in write buffer -
+					 * must be a power of two
+					 */
+	unsigned int seg_size;		/* Size of the data segments being
+					 * stored on each entry. Typically this
+					 * will be 4KB
+					 */
+
+	struct list_head pages;		/* List of data pages */
+
+	spinlock_t w_lock;		/* Write lock */
+	spinlock_t s_lock;		/* Sync lock */
+
+#ifdef CONFIG_NVM_DEBUG
+	atomic_t inflight_sync_point;	/* Not served REQ_FLUSH | REQ_FUA */
+#endif
+};
+
+#define PBLK_RECOVERY_SECTORS 16
+
+struct pblk_lun {
+	struct ppa_addr bppa;
+
+	u8 *bb_list;			/* Bad block list for LUN. Only used on
+					 * bring up. Bad blocks are managed
+					 * within lines on run-time.
+					 */
+
+	struct semaphore wr_sem;
+};
+
+struct pblk_gc_rq {
+	struct pblk_line *line;
+	void *data;
+	u64 *lba_list;
+	int nr_secs;
+	int secs_to_gc;
+	struct list_head list;
+};
+
+struct pblk_gc {
+	int gc_active;
+	int gc_enabled;
+	int gc_forced;
+	int gc_jobs_active;
+	atomic_t inflight_gc;
+
+	struct task_struct *gc_ts;
+	struct task_struct *gc_writer_ts;
+	struct workqueue_struct *gc_reader_wq;
+	struct timer_list gc_timer;
+
+	int w_entries;
+	struct list_head w_list;
+
+	spinlock_t lock;
+	spinlock_t w_lock;
+};
+
+struct pblk_rl {
+	unsigned int high;	/* Upper threshold for rate limiter (free run -
+				 * user I/O rate limiter
+				 */
+	unsigned int low;	/* Lower threshold for rate limiter (user I/O
+				 * rate limiter - stall)
+				 */
+	unsigned int high_pw;	/* High rounded up as a power of 2 */
+
+#define PBLK_USER_HIGH_THRS 2	/* Begin write limit at 50 percent
+				 * available blks
+				 */
+#define PBLK_USER_LOW_THRS 20	/* Aggressive GC at 5% available blocks */
+
+	int rb_windows_pw;	/* Number of rate windows in the write buffer
+				 * given as a power-of-2. This guarantees that
+				 * when user I/O is being rate limited, there
+				 * will be reserved enough space for the GC to
+				 * place its payload. A window is of
+				 * pblk->max_write_pgs size, which in NVMe is
+				 * 64, i.e., 256kb.
+				 */
+	int rb_budget;		/* Total number of entries available for I/O */
+	int rb_user_max;	/* Max buffer entries available for user I/O */
+	atomic_t rb_user_cnt;	/* User I/O buffer counter */
+	int rb_gc_max;		/* Max buffer entries available for GC I/O */
+	int rb_gc_rsv;		/* Reserved buffer entries for GC I/O */
+	int rb_state;		/* Rate-limiter current state */
+	atomic_t rb_gc_cnt;	/* GC I/O buffer counter */
+
+	int rb_user_active;
+	struct timer_list u_timer;
+
+	unsigned long long nr_secs;
+	unsigned long total_blocks;
+	atomic_t free_blocks;
+};
+
+#define PBLK_LINE_NR_LUN_BITMAP 2
+#define PBLK_LINE_NR_SEC_BITMAP 2
+#define PBLK_LINE_EMPTY (~0U)
+
+enum {
+	/* Line Types */
+	PBLK_LINETYPE_FREE = 0,
+	PBLK_LINETYPE_LOG = 1,
+	PBLK_LINETYPE_DATA = 2,
+
+	/* Line state */
+	PBLK_LINESTATE_FREE = 10,
+	PBLK_LINESTATE_OPEN = 11,
+	PBLK_LINESTATE_CLOSED = 12,
+	PBLK_LINESTATE_GC = 13,
+	PBLK_LINESTATE_BAD = 14,
+	PBLK_LINESTATE_CORRUPT = 15,
+
+	/* GC group */
+	PBLK_LINEGC_NONE = 20,
+	PBLK_LINEGC_EMPTY = 21,
+	PBLK_LINEGC_LOW = 22,
+	PBLK_LINEGC_MID = 23,
+	PBLK_LINEGC_HIGH = 24,
+	PBLK_LINEGC_FULL = 25,
+};
+
+#define PBLK_MAGIC 0x70626c6b /*pblk*/
+
+struct line_header {
+	__le32 crc;
+	__le32 identifier;	/* pblk identifier */
+	__u8 uuid[16];		/* instance uuid */
+	__le16 type;		/* line type */
+	__le16 version;		/* type version */
+	__le32 id;		/* line id for current line */
+};
+
+struct line_smeta {
+	struct line_header header;
+
+	__le32 crc;		/* Full structure including struct crc */
+	/* Previous line metadata */
+	__le32 prev_id;		/* Line id for previous line */
+
+	/* Current line metadata */
+	__le64 seq_nr;		/* Sequence number for current line */
+
+	/* Active writers */
+	__le32 window_wr_lun;	/* Number of parallel LUNs to write */
+
+	__le32 rsvd[2];
+};
+
+/*
+ * Metadata Layout:
+ *	1. struct pblk_emeta
+ *	2. nr_lbas u64 forming lba list
+ *	3. nr_lines (all) u32 valid sector count (vsc) (~0U: non-alloc line)
+ *	4. nr_luns bits (u64 format) forming line bad block bitmap
+ *
+ *	3. and 4. will be part of FTL log
+ */
+struct line_emeta {
+	struct line_header header;
+
+	__le32 crc;		/* Full structure including struct crc */
+
+	/* Previous line metadata */
+	__le32 prev_id;		/* Line id for prev line */
+
+	/* Current line metadata */
+	__le64 seq_nr;		/* Sequence number for current line */
+
+	/* Active writers */
+	__le32 window_wr_lun;	/* Number of parallel LUNs to write */
+
+	/* Bookkeeping for recovery */
+	__le32 next_id;		/* Line id for next line */
+	__le64 nr_lbas;		/* Number of lbas mapped in line */
+	__le64 nr_valid_lbas;	/* Number of valid lbas mapped in line */
+};
+
+struct pblk_line {
+	struct pblk *pblk;
+	unsigned int id;		/* Line number corresponds to the
+					 * block line
+					 */
+	unsigned int seq_nr;		/* Unique line sequence number */
+
+	int state;			/* PBLK_LINESTATE_X */
+	int type;			/* PBLK_LINETYPE_X */
+	int gc_group;			/* PBLK_LINEGC_X */
+	struct list_head list;		/* Free, GC lists */
+
+	unsigned long *lun_bitmap;	/* Bitmap for LUNs mapped in line */
+
+	struct line_smeta *smeta;	/* Start metadata */
+	struct line_emeta *emeta;	/* End metadata */
+	int meta_line;			/* Metadata line id */
+	u64 smeta_ssec;			/* Sector where smeta starts */
+	u64 emeta_ssec;			/* Sector where emeta starts */
+
+	unsigned int sec_in_line;	/* Number of usable secs in line */
+
+	unsigned int blk_in_line;	/* Number of good blocks in line */
+	unsigned long *blk_bitmap;	/* Bitmap for valid/invalid blocks */
+	unsigned long *erase_bitmap;	/* Bitmap for erased blocks */
+
+	unsigned long *map_bitmap;	/* Bitmap for mapped sectors in line */
+	unsigned long *invalid_bitmap;	/* Bitmap for invalid sectors in line */
+
+	int left_eblks;			/* Blocks left for erasing */
+	atomic_t left_seblks;		/* Blocks left for sync erasing */
+
+	int left_msecs;			/* Sectors left for mapping */
+	int left_ssecs;			/* Sectors left to sync */
+	unsigned int cur_sec;		/* Sector map pointer */
+	unsigned int vsc;		/* Valid sector count in line */
+
+	struct kref ref;		/* Write buffer L2P references */
+
+	spinlock_t lock;		/* Necessary for invalid_bitmap only */
+};
+
+#define PBLK_DATA_LINES 2
+
+enum{
+	PBLK_KMALLOC_META = 1,
+	PBLK_VMALLOC_META = 2,
+};
+
+struct pblk_line_metadata {
+	void *meta;
+};
+
+struct pblk_line_mgmt {
+	int nr_lines;			/* Total number of full lines */
+	int nr_free_lines;		/* Number of full lines in free list */
+
+	/* Free lists - use free_lock */
+	struct list_head free_list;	/* Full lines ready to use */
+	struct list_head corrupt_list;	/* Full lines corrupted */
+	struct list_head bad_list;	/* Full lines bad */
+
+	/* GC lists - use gc_lock */
+	struct list_head *gc_lists[PBLK_NR_GC_LISTS];
+	struct list_head gc_high_list;	/* Full lines ready to GC, high isc */
+	struct list_head gc_mid_list;	/* Full lines ready to GC, mid isc */
+	struct list_head gc_low_list;	/* Full lines ready to GC, low isc */
+
+	struct list_head gc_full_list;	/* Full lines ready to GC, no valid */
+	struct list_head gc_empty_list;	/* Full lines close, all valid */
+
+	struct pblk_line *log_line;	/* Current FTL log line */
+	struct pblk_line *data_line;	/* Current data line */
+	struct pblk_line *log_next;	/* Next FTL log line */
+	struct pblk_line *data_next;	/* Next data line */
+
+	/* Metadata allocation type: VMALLOC | KMALLOC */
+	int smeta_alloc_type;
+	int emeta_alloc_type;
+
+	/* Pre-allocated metadata for data lines */
+	struct pblk_line_metadata sline_meta[PBLK_DATA_LINES];
+	struct pblk_line_metadata eline_meta[PBLK_DATA_LINES];
+	unsigned long meta_bitmap;
+
+	/* Helpers for fast bitmap calculations */
+	unsigned long *bb_template;
+	unsigned long *bb_aux;
+
+	unsigned long d_seq_nr;		/* Data line unique sequence number */
+	unsigned long l_seq_nr;		/* Log line unique sequence number */
+
+	spinlock_t free_lock;
+	spinlock_t gc_lock;
+};
+
+struct pblk_line_meta {
+	unsigned int smeta_len;		/* Total length for smeta */
+	unsigned int smeta_sec;		/* Sectors needed for smeta*/
+	unsigned int emeta_len;		/* Total length for emeta */
+	unsigned int emeta_sec;		/* Sectors needed for emeta*/
+	unsigned int emeta_bb;		/* Boundary for bb that affects emeta */
+	unsigned int sec_bitmap_len;	/* Length for sector bitmap in line */
+	unsigned int blk_bitmap_len;	/* Length for block bitmap in line */
+	unsigned int lun_bitmap_len;	/* Length for lun bitmap in line */
+
+	unsigned int blk_per_line;	/* Number of blocks in a full line */
+	unsigned int sec_per_line;	/* Number of sectors in a line */
+	unsigned int min_blk_line;	/* Min. number of good blocks in line */
+
+	unsigned int mid_thrs;		/* Threshold for GC mid list */
+	unsigned int high_thrs;		/* Threshold for GC high list */
+};
+
+struct pblk_addr_format {
+	u64	ch_mask;
+	u64	lun_mask;
+	u64	pln_mask;
+	u64	blk_mask;
+	u64	pg_mask;
+	u64	sec_mask;
+	u8	ch_offset;
+	u8	lun_offset;
+	u8	pln_offset;
+	u8	blk_offset;
+	u8	pg_offset;
+	u8	sec_offset;
+};
+
+struct pblk {
+	struct nvm_tgt_dev *dev;
+	struct gendisk *disk;
+
+	struct kobject kobj;
+
+	struct pblk_lun *luns;
+
+	struct pblk_line *lines;		/* Line array */
+	struct pblk_line_mgmt l_mg;		/* Line management */
+	struct pblk_line_meta lm;		/* Line metadata */
+
+	int ppaf_bitsize;
+	struct pblk_addr_format ppaf;
+
+	struct pblk_rb rwb;
+
+	int min_write_pgs; /* Minimum amount of pages required by controller */
+	int max_write_pgs; /* Maximum amount of pages supported by controller */
+	int pgs_in_buffer; /* Number of pages that need to be held in buffer to
+			    * guarantee successful reads.
+			    */
+
+	sector_t capacity; /* Device capacity when bad blocks are subtracted */
+	int over_pct;      /* Percentage of device used for over-provisioning */
+
+	/* pblk provisioning values. Used by rate limiter */
+	struct pblk_rl rl;
+
+	struct semaphore erase_sem;
+
+	unsigned char instance_uuid[16];
+#ifdef CONFIG_NVM_DEBUG
+	/* All debug counters apply to 4kb sector I/Os */
+	atomic_long_t inflight_writes;	/* Inflight writes (user and gc) */
+	atomic_long_t padded_writes;	/* Sectors padded due to flush/fua */
+	atomic_long_t padded_wb;	/* Sectors padded in write buffer */
+	atomic_long_t nr_flush;		/* Number of flush/fua I/O */
+	atomic_long_t req_writes;	/* Sectors stored on write buffer */
+	atomic_long_t sub_writes;	/* Sectors submitted from buffer */
+	atomic_long_t sync_writes;	/* Sectors synced to media */
+	atomic_long_t compl_writes;	/* Sectors completed in write bio */
+	atomic_long_t inflight_reads;	/* Inflight sector read requests */
+	atomic_long_t sync_reads;	/* Completed sector read requests */
+	atomic_long_t recov_writes;	/* Sectors submitted from recovery */
+	atomic_long_t recov_gc_writes;	/* Sectors submitted from write GC */
+	atomic_long_t recov_gc_reads;	/* Sectors submitted from read GC */
+#endif
+
+	spinlock_t lock;
+
+	atomic_long_t read_failed;
+	atomic_long_t read_empty;
+	atomic_long_t read_high_ecc;
+	atomic_long_t read_failed_gc;
+	atomic_long_t write_failed;
+	atomic_long_t erase_failed;
+
+	struct task_struct *writer_ts;
+
+	/* Simple translation map of logical addresses to physical addresses.
+	 * The logical addresses is known by the host system, while the physical
+	 * addresses are used when writing to the disk block device.
+	 */
+	unsigned char *trans_map;
+	spinlock_t trans_lock;
+
+	struct list_head compl_list;
+
+	mempool_t *page_pool;
+	mempool_t *line_ws_pool;
+	mempool_t *rec_pool;
+	mempool_t *r_rq_pool;
+	mempool_t *w_rq_pool;
+	mempool_t *line_meta_pool;
+
+	struct workqueue_struct *kw_wq;
+	struct timer_list wtimer;
+
+	struct pblk_gc gc;
+};
+
+struct pblk_line_ws {
+	struct pblk *pblk;
+	struct pblk_line *line;
+	void *priv;
+	struct work_struct ws;
+};
+
+#define pblk_r_rq_size (sizeof(struct nvm_rq) + sizeof(struct pblk_r_ctx))
+#define pblk_w_rq_size (sizeof(struct nvm_rq) + sizeof(struct pblk_c_ctx))
+
+/*
+ * pblk ring buffer operations
+ */
+int pblk_rb_init(struct pblk_rb *rb, struct pblk_rb_entry *rb_entry_base,
+		 unsigned int power_size, unsigned int power_seg_sz);
+unsigned int pblk_rb_calculate_size(unsigned int nr_entries);
+void *pblk_rb_entries_ref(struct pblk_rb *rb);
+int pblk_rb_may_write_user(struct pblk_rb *rb, struct bio *bio,
+			   unsigned int nr_entries, unsigned int *pos);
+int pblk_rb_may_write_gc(struct pblk_rb *rb, unsigned int nr_entries,
+			 unsigned int *pos);
+void pblk_rb_write_entry_user(struct pblk_rb *rb, void *data,
+			      struct pblk_w_ctx w_ctx, unsigned int pos);
+void pblk_rb_write_entry_gc(struct pblk_rb *rb, void *data,
+			    struct pblk_w_ctx w_ctx, struct pblk_line *gc_line,
+			    unsigned int pos);
+struct pblk_w_ctx *pblk_rb_w_ctx(struct pblk_rb *rb, unsigned int pos);
+
+void pblk_rb_sync_l2p(struct pblk_rb *rb);
+unsigned int pblk_rb_read_to_bio(struct pblk_rb *rb, struct bio *bio,
+				 struct pblk_c_ctx *c_ctx,
+				 unsigned int pos,
+				 unsigned int nr_entries,
+				 unsigned int count);
+unsigned int pblk_rb_read_to_bio_list(struct pblk_rb *rb, struct bio *bio,
+				      struct list_head *list,
+				      unsigned int max);
+int pblk_rb_copy_to_bio(struct pblk_rb *rb, struct bio *bio, sector_t lba,
+			u64 pos, int bio_iter);
+unsigned int pblk_rb_read_commit(struct pblk_rb *rb, unsigned int entries);
+
+unsigned int pblk_rb_sync_init(struct pblk_rb *rb, unsigned long *flags);
+unsigned int pblk_rb_sync_advance(struct pblk_rb *rb, unsigned int nr_entries);
+struct pblk_rb_entry *pblk_rb_sync_scan_entry(struct pblk_rb *rb,
+					      struct ppa_addr *ppa);
+void pblk_rb_sync_end(struct pblk_rb *rb, unsigned long *flags);
+unsigned int pblk_rb_sync_point_count(struct pblk_rb *rb);
+
+unsigned int pblk_rb_read_count(struct pblk_rb *rb);
+unsigned int pblk_rb_wrap_pos(struct pblk_rb *rb, unsigned int pos);
+
+int pblk_rb_tear_down_check(struct pblk_rb *rb);
+int pblk_rb_pos_oob(struct pblk_rb *rb, u64 pos);
+void pblk_rb_data_free(struct pblk_rb *rb);
+ssize_t pblk_rb_sysfs(struct pblk_rb *rb, char *buf);
+
+/*
+ * pblk core
+ */
+struct nvm_rq *pblk_alloc_rqd(struct pblk *pblk, int rw);
+int pblk_setup_w_rec_rq(struct pblk *pblk, struct nvm_rq *rqd,
+			struct pblk_c_ctx *c_ctx);
+void pblk_free_rqd(struct pblk *pblk, struct nvm_rq *rqd, int rw);
+void pblk_flush_writer(struct pblk *pblk);
+struct ppa_addr pblk_get_lba_map(struct pblk *pblk, sector_t lba);
+void pblk_discard(struct pblk *pblk, struct bio *bio);
+void pblk_log_write_err(struct pblk *pblk, struct nvm_rq *rqd);
+void pblk_log_read_err(struct pblk *pblk, struct nvm_rq *rqd);
+int pblk_submit_io(struct pblk *pblk, struct nvm_rq *rqd);
+struct bio *pblk_bio_map_addr(struct pblk *pblk, void *data,
+			      unsigned int nr_secs, unsigned int len,
+			      gfp_t gfp_mask);
+struct pblk_line *pblk_line_get(struct pblk *pblk);
+struct pblk_line *pblk_line_get_first_data(struct pblk *pblk);
+struct pblk_line *pblk_line_replace_data(struct pblk *pblk);
+int pblk_line_recov_alloc(struct pblk *pblk, struct pblk_line *line);
+void pblk_line_recov_close(struct pblk *pblk, struct pblk_line *line);
+struct pblk_line *pblk_line_get_data(struct pblk *pblk);
+struct pblk_line *pblk_line_get_data_next(struct pblk *pblk);
+int pblk_line_erase(struct pblk *pblk, struct pblk_line *line);
+int pblk_line_is_full(struct pblk_line *line);
+void pblk_line_free(struct pblk *pblk, struct pblk_line *line);
+void pblk_line_close_ws(struct work_struct *work);
+void pblk_line_close(struct pblk *pblk, struct pblk_line *line);
+void pblk_line_mark_bb(struct work_struct *work);
+void pblk_line_run_ws(struct pblk *pblk, struct pblk_line *line, void *priv,
+		      void (*work)(struct work_struct *));
+u64 pblk_line_smeta_start(struct pblk *pblk, struct pblk_line *line);
+int pblk_line_read_smeta(struct pblk *pblk, struct pblk_line *line);
+int pblk_line_read_emeta(struct pblk *pblk, struct pblk_line *line);
+int pblk_blk_erase_async(struct pblk *pblk, struct ppa_addr erase_ppa);
+void pblk_line_put(struct kref *ref);
+struct list_head *pblk_line_gc_list(struct pblk *pblk, struct pblk_line *line);
+u64 pblk_alloc_page(struct pblk *pblk, struct pblk_line *line, int nr_secs);
+int pblk_calc_secs(struct pblk *pblk, unsigned long secs_avail,
+		   unsigned long secs_to_flush);
+void pblk_down_rq(struct pblk *pblk, struct ppa_addr *ppa_list, int nr_ppas,
+		  unsigned long *lun_bitmap);
+void pblk_up_rq(struct pblk *pblk, struct ppa_addr *ppa_list, int nr_ppas,
+		unsigned long *lun_bitmap);
+void pblk_end_bio_sync(struct bio *bio);
+void pblk_end_io_sync(struct nvm_rq *rqd);
+int pblk_bio_add_pages(struct pblk *pblk, struct bio *bio, gfp_t flags,
+		       int nr_pages);
+void pblk_map_pad_invalidate(struct pblk *pblk, struct pblk_line *line,
+			     u64 paddr);
+void pblk_bio_free_pages(struct pblk *pblk, struct bio *bio, int off,
+			 int nr_pages);
+void pblk_map_invalidate(struct pblk *pblk, struct ppa_addr ppa);
+void pblk_update_map(struct pblk *pblk, sector_t lba, struct ppa_addr ppa);
+void pblk_update_map_cache(struct pblk *pblk, sector_t lba,
+			   struct ppa_addr ppa);
+void pblk_update_map_dev(struct pblk *pblk, sector_t lba,
+			 struct ppa_addr ppa, struct ppa_addr entry_line);
+int pblk_update_map_gc(struct pblk *pblk, sector_t lba, struct ppa_addr ppa,
+		       struct pblk_line *gc_line);
+void pblk_lookup_l2p_rand(struct pblk *pblk, struct ppa_addr *ppas,
+			  u64 *lba_list, int nr_secs);
+void pblk_lookup_l2p_seq(struct pblk *pblk, struct ppa_addr *ppas,
+			 sector_t blba, int nr_secs);
+
+/*
+ * pblk user I/O write path
+ */
+int pblk_write_to_cache(struct pblk *pblk, struct bio *bio,
+			unsigned long flags);
+int pblk_write_gc_to_cache(struct pblk *pblk, void *data, u64 *lba_list,
+			   unsigned int nr_entries, unsigned int nr_rec_entries,
+			   struct pblk_line *gc_line, unsigned long flags);
+
+/*
+ * pblk map
+ */
+void pblk_map_erase_rq(struct pblk *pblk, struct nvm_rq *rqd,
+		       unsigned int sentry, unsigned long *lun_bitmap,
+		       unsigned int valid_secs, struct ppa_addr *erase_ppa);
+void pblk_map_rq(struct pblk *pblk, struct nvm_rq *rqd, unsigned int sentry,
+		 unsigned long *lun_bitmap, unsigned int valid_secs,
+		 unsigned int off);
+
+/*
+ * pblk write thread
+ */
+int pblk_write_ts(void *data);
+void pblk_write_timer_fn(unsigned long data);
+void pblk_write_should_kick(struct pblk *pblk);
+
+/*
+ * pblk read path
+ */
+int pblk_submit_read(struct pblk *pblk, struct bio *bio);
+int pblk_submit_read_gc(struct pblk *pblk, u64 *lba_list, void *data,
+			unsigned int nr_secs, unsigned int *secs_to_gc,
+			struct pblk_line *line);
+/*
+ * pblk recovery
+ */
+void pblk_submit_rec(struct work_struct *work);
+struct pblk_line *pblk_recov_l2p(struct pblk *pblk);
+void pblk_recov_pad(struct pblk *pblk);
+__le64 *pblk_recov_get_lba_list(struct pblk *pblk, struct line_emeta *emeta);
+int pblk_recov_setup_rq(struct pblk *pblk, struct pblk_c_ctx *c_ctx,
+			struct pblk_rec_ctx *recovery, u64 *comp_bits,
+			unsigned int comp);
+
+/*
+ * pblk gc
+ */
+#define PBLK_GC_TRIES 3
+
+int pblk_gc_init(struct pblk *pblk);
+void pblk_gc_exit(struct pblk *pblk);
+void pblk_gc_should_start(struct pblk *pblk);
+void pblk_gc_should_stop(struct pblk *pblk);
+int pblk_gc_status(struct pblk *pblk);
+void pblk_gc_sysfs_state_show(struct pblk *pblk, int *gc_enabled,
+			      int *gc_active);
+void pblk_gc_sysfs_force(struct pblk *pblk, int force);
+
+/*
+ * pblk rate limiter
+ */
+void pblk_rl_init(struct pblk_rl *rl, int budget);
+void pblk_rl_free(struct pblk_rl *rl);
+int pblk_rl_gc_thrs(struct pblk_rl *rl);
+unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl);
+int pblk_rl_user_may_insert(struct pblk_rl *rl, int nr_entries);
+void pblk_rl_user_in(struct pblk_rl *rl, int nr_entries);
+int pblk_rl_gc_may_insert(struct pblk_rl *rl, int nr_entries);
+void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries);
+void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc);
+void pblk_rl_set_gc_rsc(struct pblk_rl *rl, int rsv);
+int pblk_rl_sysfs_rate_show(struct pblk_rl *rl);
+void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line);
+void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line);
+
+/*
+ * pblk sysfs
+ */
+int pblk_sysfs_init(struct gendisk *tdisk);
+void pblk_sysfs_exit(struct gendisk *tdisk);
+
+static inline void *pblk_malloc(size_t size, int type, gfp_t flags)
+{
+	if (type == PBLK_KMALLOC_META)
+		return kmalloc(size, flags);
+	return vmalloc(size);
+}
+
+static inline void pblk_mfree(void *ptr, int type)
+{
+	if (type == PBLK_KMALLOC_META)
+		kfree(ptr);
+	else
+		vfree(ptr);
+}
+
+static inline struct nvm_rq *nvm_rq_from_c_ctx(void *c_ctx)
+{
+	return c_ctx - sizeof(struct nvm_rq);
+}
+
+static inline void *pblk_line_emeta_to_lbas(struct line_emeta *emeta)
+{
+	return (emeta) + 1;
+}
+
+#define NVM_MEM_PAGE_WRITE (8)
+
+static inline int pblk_pad_distance(struct pblk *pblk)
+{
+	struct nvm_tgt_dev *dev = pblk->dev;
+	struct nvm_geo *geo = &dev->geo;
+
+	return NVM_MEM_PAGE_WRITE * geo->nr_luns * geo->sec_per_pl;
+}
+
+static inline int pblk_dev_ppa_to_line(struct ppa_addr p)
+{
+	return p.g.blk;
+}
+
+static inline int pblk_tgt_ppa_to_line(struct ppa_addr p)
+{
+	return p.g.blk;
+}
+
+static inline int pblk_ppa_to_pos(struct nvm_geo *geo, struct ppa_addr p)
+{
+	return p.g.lun * geo->nr_chnls + p.g.ch;
+}
+
+/* A block within a line corresponds to the lun */
+static inline int pblk_dev_ppa_to_pos(struct nvm_geo *geo, struct ppa_addr p)
+{
+	return p.g.lun * geo->nr_chnls + p.g.ch;
+}
+
+static inline struct ppa_addr pblk_ppa32_to_ppa64(struct pblk *pblk, u32 ppa32)
+{
+	struct ppa_addr ppa64;
+
+	ppa64.ppa = 0;
+
+	if (ppa32 == -1) {
+		ppa64.ppa = ADDR_EMPTY;
+	} else if (ppa32 & (1U << 31)) {
+		ppa64.c.line = ppa32 & ((~0U) >> 1);
+		ppa64.c.is_cached = 1;
+	} else {
+		ppa64.g.blk = (ppa32 & pblk->ppaf.blk_mask) >>
+							pblk->ppaf.blk_offset;
+		ppa64.g.pg = (ppa32 & pblk->ppaf.pg_mask) >>
+							pblk->ppaf.pg_offset;
+		ppa64.g.lun = (ppa32 & pblk->ppaf.lun_mask) >>
+							pblk->ppaf.lun_offset;
+		ppa64.g.ch = (ppa32 & pblk->ppaf.ch_mask) >>
+							pblk->ppaf.ch_offset;
+		ppa64.g.pl = (ppa32 & pblk->ppaf.pln_mask) >>
+							pblk->ppaf.pln_offset;
+		ppa64.g.sec = (ppa32 & pblk->ppaf.sec_mask) >>
+							pblk->ppaf.sec_offset;
+	}
+
+	return ppa64;
+}
+
+static inline struct ppa_addr pblk_trans_map_get(struct pblk *pblk,
+								sector_t lba)
+{
+	struct ppa_addr ppa;
+
+	if (pblk->ppaf_bitsize < 32) {
+		u32 *map = (u32 *)pblk->trans_map;
+
+		ppa = pblk_ppa32_to_ppa64(pblk, map[lba]);
+	} else {
+		struct ppa_addr *map = (struct ppa_addr *)pblk->trans_map;
+
+		ppa = map[lba];
+	}
+
+	return ppa;
+}
+
+static inline u32 pblk_ppa64_to_ppa32(struct pblk *pblk, struct ppa_addr ppa64)
+{
+	u32 ppa32 = 0;
+
+	if (ppa64.ppa == ADDR_EMPTY) {
+		ppa32 = ~0U;
+	} else if (ppa64.c.is_cached) {
+		ppa32 |= ppa64.c.line;
+		ppa32 |= 1U << 31;
+	} else {
+		ppa32 |= ppa64.g.blk << pblk->ppaf.blk_offset;
+		ppa32 |= ppa64.g.pg << pblk->ppaf.pg_offset;
+		ppa32 |= ppa64.g.lun << pblk->ppaf.lun_offset;
+		ppa32 |= ppa64.g.ch << pblk->ppaf.ch_offset;
+		ppa32 |= ppa64.g.pl << pblk->ppaf.pln_offset;
+		ppa32 |= ppa64.g.sec << pblk->ppaf.sec_offset;
+	}
+
+	return ppa32;
+}
+
+static inline void pblk_trans_map_set(struct pblk *pblk, sector_t lba,
+						struct ppa_addr ppa)
+{
+	if (pblk->ppaf_bitsize < 32) {
+		u32 *map = (u32 *)pblk->trans_map;
+
+		map[lba] = pblk_ppa64_to_ppa32(pblk, ppa);
+	} else {
+		u64 *map = (u64 *)pblk->trans_map;
+
+		map[lba] = ppa.ppa;
+	}
+}
+
+static inline u64 pblk_dev_ppa_to_line_addr(struct pblk *pblk,
+							struct ppa_addr p)
+{
+	u64 paddr;
+
+	paddr = 0;
+	paddr |= (u64)p.g.pg << pblk->ppaf.pg_offset;
+	paddr |= (u64)p.g.lun << pblk->ppaf.lun_offset;
+	paddr |= (u64)p.g.ch << pblk->ppaf.ch_offset;
+	paddr |= (u64)p.g.pl << pblk->ppaf.pln_offset;
+	paddr |= (u64)p.g.sec << pblk->ppaf.sec_offset;
+
+	return paddr;
+}
+
+static inline int pblk_ppa_empty(struct ppa_addr ppa_addr)
+{
+	return (ppa_addr.ppa == ADDR_EMPTY);
+}
+
+static inline void pblk_ppa_set_empty(struct ppa_addr *ppa_addr)
+{
+	ppa_addr->ppa = ADDR_EMPTY;
+}
+
+static inline int pblk_addr_in_cache(struct ppa_addr ppa)
+{
+	return (ppa.ppa != ADDR_EMPTY && ppa.c.is_cached);
+}
+
+static inline int pblk_addr_to_cacheline(struct ppa_addr ppa)
+{
+	return ppa.c.line;
+}
+
+static inline struct ppa_addr pblk_cacheline_to_addr(int addr)
+{
+	struct ppa_addr p;
+
+	p.c.line = addr;
+	p.c.is_cached = 1;
+
+	return p;
+}
+
+static inline struct ppa_addr addr_to_gen_ppa(struct pblk *pblk, u64 paddr,
+					      u64 line_id)
+{
+	struct ppa_addr ppa;
+
+	ppa.ppa = 0;
+	ppa.g.blk = line_id;
+	ppa.g.pg = (paddr & pblk->ppaf.pg_mask) >> pblk->ppaf.pg_offset;
+	ppa.g.lun = (paddr & pblk->ppaf.lun_mask) >> pblk->ppaf.lun_offset;
+	ppa.g.ch = (paddr & pblk->ppaf.ch_mask) >> pblk->ppaf.ch_offset;
+	ppa.g.pl = (paddr & pblk->ppaf.pln_mask) >> pblk->ppaf.pln_offset;
+	ppa.g.sec = (paddr & pblk->ppaf.sec_mask) >> pblk->ppaf.sec_offset;
+
+	return ppa;
+}
+
+static inline struct ppa_addr addr_to_pblk_ppa(struct pblk *pblk, u64 paddr,
+					 u64 line_id)
+{
+	struct ppa_addr ppa;
+
+	ppa = addr_to_gen_ppa(pblk, paddr, line_id);
+
+	return ppa;
+}
+
+static inline u32 pblk_calc_meta_header_crc(struct pblk *pblk,
+					    struct line_smeta *smeta)
+{
+	u32 crc = ~(u32)0;
+
+	crc = crc32_le(crc, (unsigned char *)smeta + sizeof(crc),
+				sizeof(struct line_header) - sizeof(crc));
+
+	return crc;
+}
+
+static inline u32 pblk_calc_smeta_crc(struct pblk *pblk,
+				      struct line_smeta *smeta)
+{
+	struct pblk_line_meta *lm = &pblk->lm;
+	u32 crc = ~(u32)0;
+
+	crc = crc32_le(crc, (unsigned char *)smeta +
+				sizeof(struct line_header) + sizeof(crc),
+				lm->smeta_len -
+				sizeof(struct line_header) - sizeof(crc));
+
+	return crc;
+}
+
+static inline u32 pblk_calc_emeta_crc(struct pblk *pblk,
+				      struct line_emeta *emeta)
+{
+	struct pblk_line_meta *lm = &pblk->lm;
+	u32 crc = ~(u32)0;
+
+	crc = crc32_le(crc, (unsigned char *)emeta +
+				sizeof(struct line_header) + sizeof(crc),
+				lm->emeta_len -
+				sizeof(struct line_header) - sizeof(crc));
+
+	return crc;
+}
+
+static inline int pblk_set_progr_mode(struct pblk *pblk, int type)
+{
+	struct nvm_tgt_dev *dev = pblk->dev;
+	struct nvm_geo *geo = &dev->geo;
+	int flags;
+
+	flags = geo->plane_mode >> 1;
+
+	if (type == WRITE)
+		flags |= NVM_IO_SCRAMBLE_ENABLE;
+
+	return flags;
+}
+
+static inline int pblk_set_read_mode(struct pblk *pblk)
+{
+	return NVM_IO_SNGL_ACCESS | NVM_IO_SUSPEND | NVM_IO_SCRAMBLE_ENABLE;
+}
+
+#ifdef CONFIG_NVM_DEBUG
+static inline void print_ppa(struct ppa_addr *p, char *msg, int error)
+{
+	if (p->c.is_cached) {
+		pr_err("ppa: (%s: %x) cache line: %llu\n",
+				msg, error, (u64)p->c.line);
+	} else {
+		pr_err("ppa: (%s: %x):ch:%d,lun:%d,blk:%d,pg:%d,pl:%d,sec:%d\n",
+			msg, error,
+			p->g.ch, p->g.lun, p->g.blk,
+			p->g.pg, p->g.pl, p->g.sec);
+	}
+}
+
+static inline void pblk_print_failed_rqd(struct pblk *pblk, struct nvm_rq *rqd,
+					 int error)
+{
+	int bit = -1;
+
+	if (rqd->nr_ppas ==  1) {
+		print_ppa(&rqd->ppa_addr, "rqd", error);
+		return;
+	}
+
+	while ((bit = find_next_bit((void *)&rqd->ppa_status, rqd->nr_ppas,
+						bit + 1)) < rqd->nr_ppas) {
+		print_ppa(&rqd->ppa_list[bit], "rqd", error);
+	}
+
+	pr_err("error:%d, ppa_status:%llx\n", error, rqd->ppa_status);
+}
+#endif
+
+static inline int pblk_boundary_ppa_checks(struct nvm_tgt_dev *tgt_dev,
+				       struct ppa_addr *ppas, int nr_ppas)
+{
+	struct nvm_geo *geo = &tgt_dev->geo;
+	struct ppa_addr *ppa;
+	int i;
+
+	for (i = 0; i < nr_ppas; i++) {
+		ppa = &ppas[i];
+
+		if (!ppa->c.is_cached &&
+				ppa->g.ch < geo->nr_chnls &&
+				ppa->g.lun < geo->luns_per_chnl &&
+				ppa->g.pl < geo->nr_planes &&
+				ppa->g.blk < geo->blks_per_lun &&
+				ppa->g.pg < geo->pgs_per_blk &&
+				ppa->g.sec < geo->sec_per_pg)
+			continue;
+
+#ifdef CONFIG_NVM_DEBUG
+		print_ppa(ppa, "boundary", i);
+#endif
+		return 1;
+	}
+	return 0;
+}
+
+static inline int pblk_boundary_paddr_checks(struct pblk *pblk, u64 paddr)
+{
+	struct pblk_line_meta *lm = &pblk->lm;
+
+	if (paddr > lm->sec_per_line)
+		return 1;
+
+	return 0;
+}
+
+static inline unsigned int pblk_get_bi_idx(struct bio *bio)
+{
+	return bio->bi_iter.bi_idx;
+}
+
+static inline sector_t pblk_get_lba(struct bio *bio)
+{
+	return bio->bi_iter.bi_sector / NR_PHY_IN_LOG;
+}
+
+static inline unsigned int pblk_get_secs(struct bio *bio)
+{
+	return  bio->bi_iter.bi_size / PBLK_EXPOSED_PAGE_SIZE;
+}
+
+static inline sector_t pblk_get_sector(sector_t lba)
+{
+	return lba * NR_PHY_IN_LOG;
+}
+
+static inline void pblk_setup_uuid(struct pblk *pblk)
+{
+	uuid_le uuid;
+
+	uuid_le_gen(&uuid);
+	memcpy(pblk->instance_uuid, uuid.b, 16);
+}
+#endif /* PBLK_H_ */