lightnvm: pblk: fail gracefully on irrec. error

Due to user writes being decoupled from media writes because of the need
of an intermediate write buffer, irrecoverable media write errors lead
to pblk stalling; user writes fill up the buffer and end up in an
infinite retry loop.

In order to let user writes fail gracefully, it is necessary for pblk to
keep track of its own internal state and prevent further writes from
being placed into the write buffer.

This patch implements a state machine to keep track of internal errors
and, in case of failure, fail further user writes in an standard way.
Depending on the type of error, pblk will do its best to persist
buffered writes (which are already acknowledged) and close down on a
graceful manner. This way, data might be recovered by re-instantiating
pblk. Such state machine paves out the way for a state-based FTL log.

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

1 files changed, 23 insertions, 4 deletions

diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 573b5b8f789b..36c5f5999324 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -257,11 +257,13 @@ struct pblk_rl {
 				 */
 	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_user_cnt;	/* User I/O buffer counter */
 	atomic_t rb_gc_cnt;	/* GC I/O buffer counter */
+	atomic_t rb_space;	/* Space limit in case of reaching capacity */
 
 	int rsv_blocks;		/* Reserved blocks for GC */
 
@@ -529,6 +531,13 @@ struct pblk_addr_format {
 	u8	sec_offset;
 };
 
+enum {
+	PBLK_STATE_RUNNING = 0,
+	PBLK_STATE_STOPPING = 1,
+	PBLK_STATE_RECOVERING = 2,
+	PBLK_STATE_STOPPED = 3,
+};
+
 struct pblk {
 	struct nvm_tgt_dev *dev;
 	struct gendisk *disk;
@@ -546,6 +555,8 @@ struct pblk {
 
 	struct pblk_rb rwb;
 
+	int state;			/* pblk line state */
+
 	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
@@ -587,6 +598,8 @@ struct pblk {
 	atomic_long_t write_failed;
 	atomic_long_t erase_failed;
 
+	atomic_t inflight_io;		/* General inflight I/O counter */
+
 	struct task_struct *writer_ts;
 
 	/* Simple translation map of logical addresses to physical addresses.
@@ -640,6 +653,7 @@ 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_flush(struct pblk_rb *rb);
 
 void pblk_rb_sync_l2p(struct pblk_rb *rb);
 unsigned int pblk_rb_read_to_bio(struct pblk_rb *rb, struct nvm_rq *rqd,
@@ -675,7 +689,7 @@ void pblk_set_sec_per_write(struct pblk *pblk, int sec_per_write);
 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);
+void pblk_wait_for_meta(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);
@@ -687,7 +701,7 @@ struct bio *pblk_bio_map_addr(struct pblk *pblk, void *data,
 			      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);
+void 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);
@@ -697,7 +711,9 @@ int pblk_line_is_full(struct pblk_line *line);
 void pblk_line_free(struct pblk *pblk, struct pblk_line *line);
 void pblk_line_close_meta(struct pblk *pblk, struct pblk_line *line);
 void pblk_line_close(struct pblk *pblk, struct pblk_line *line);
+void pblk_line_close_meta_sync(struct pblk *pblk);
 void pblk_line_close_ws(struct work_struct *work);
+void pblk_pipeline_stop(struct pblk *pblk);
 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 *),
@@ -779,7 +795,7 @@ int pblk_submit_read_gc(struct pblk *pblk, u64 *lba_list, void *data,
  */
 void pblk_submit_rec(struct work_struct *work);
 struct pblk_line *pblk_recov_l2p(struct pblk *pblk);
-void pblk_recov_pad(struct pblk *pblk);
+int 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,
@@ -812,6 +828,7 @@ int pblk_rl_high_thrs(struct pblk_rl *rl);
 int pblk_rl_low_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_inserted(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);
@@ -819,6 +836,8 @@ void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc);
 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);
+void pblk_rl_set_space_limit(struct pblk_rl *rl, int entries_left);
+int pblk_rl_is_limit(struct pblk_rl *rl);
 
 /*
  * pblk sysfs