lightnvm: pblk: garbage collect lines with failed writes

Write failures should not happen under normal circumstances,
so in order to bring the chunk back into a known state as soon
as possible, evacuate all the valid data out of the line and let the
fw judge if the block can be written to in the next reset cycle.

Do this by introducing a new gc list for lines with failed writes,
and ensure that the rate limiter allocates a small portion of
the write bandwidth to get the job done.

The lba list is saved in memory for use during gc as we
cannot gurantee that the emeta data is readable if a write
error occurred.

Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 21 insertions, 4 deletions

diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 043a851a8e6c..725bc1bfa849 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -89,12 +89,14 @@ struct pblk_sec_meta {
 /* 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_GC_NR_LISTS 3
+#define PBLK_GC_NR_LISTS 4
 
 enum {
-	PBLK_RL_HIGH = 1,
-	PBLK_RL_MID = 2,
-	PBLK_RL_LOW = 3,
+	PBLK_RL_OFF = 0,
+	PBLK_RL_WERR = 1,
+	PBLK_RL_HIGH = 2,
+	PBLK_RL_MID = 3,
+	PBLK_RL_LOW = 4
 };
 
 #define pblk_dma_meta_size (sizeof(struct pblk_sec_meta) * PBLK_MAX_REQ_ADDRS)
@@ -278,6 +280,8 @@ struct pblk_rl {
 	int rb_user_active;
 	int rb_gc_active;
 
+	atomic_t werr_lines;	/* Number of write error lines that needs gc */
+
 	struct timer_list u_timer;
 
 	unsigned long long nr_secs;
@@ -311,6 +315,7 @@ enum {
 	PBLK_LINEGC_MID = 23,
 	PBLK_LINEGC_HIGH = 24,
 	PBLK_LINEGC_FULL = 25,
+	PBLK_LINEGC_WERR = 26
 };
 
 #define PBLK_MAGIC 0x70626c6b /*pblk*/
@@ -412,6 +417,11 @@ struct pblk_smeta {
 	struct line_smeta *buf;		/* smeta buffer in persistent format */
 };
 
+struct pblk_w_err_gc {
+	int has_write_err;
+	__le64 *lba_list;
+};
+
 struct pblk_line {
 	struct pblk *pblk;
 	unsigned int id;		/* Line number corresponds to the
@@ -457,6 +467,8 @@ struct pblk_line {
 
 	struct kref ref;		/* Write buffer L2P references */
 
+	struct pblk_w_err_gc *w_err_gc;	/* Write error gc recovery metadata */
+
 	spinlock_t lock;		/* Necessary for invalid_bitmap only */
 };
 
@@ -488,6 +500,8 @@ struct pblk_line_mgmt {
 	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_werr_list;  /* Write err recovery list */
+
 	struct list_head gc_full_list;	/* Full lines ready to GC, no valid */
 	struct list_head gc_empty_list;	/* Full lines close, all valid */
 
@@ -890,6 +904,9 @@ void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line,
 			    bool used);
 int pblk_rl_is_limit(struct pblk_rl *rl);
 
+void pblk_rl_werr_line_in(struct pblk_rl *rl);
+void pblk_rl_werr_line_out(struct pblk_rl *rl);
+
 /*
  * pblk sysfs
  */