lightnvm: pblk: avoid deadlock on low LUN config

On low LUN configurations, make sure not to send bios that are bigger
than the buffer size.

Fixes: a4bd217b4326 ("lightnvm: physical block device (pblk) target")
Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 9 insertions, 1 deletions

diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index 83445115a922..eee4eeb47d07 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -46,7 +46,7 @@ static int pblk_rw_io(struct request_queue *q, struct pblk *pblk,
          * user I/Os. Unless stalled, the rate limiter leaves at least 256KB
          * available for user I/O.
          */
-        if (unlikely(pblk_get_secs(bio) >= pblk_rl_sysfs_rate_show(&pblk->rl)))
+        if (pblk_get_secs(bio) > pblk_rl_max_io(&pblk->rl))
                 blk_queue_split(q, &bio);
 
         return pblk_write_to_cache(pblk, bio, PBLK_IOTYPE_USER);
diff --git a/drivers/lightnvm/pblk-rl.c b/drivers/lightnvm/pblk-rl.c
index 9565c3bc4d0b..0896439a91b0 100644
--- a/drivers/lightnvm/pblk-rl.c
+++ b/drivers/lightnvm/pblk-rl.c
@@ -163,6 +163,11 @@ int pblk_rl_sysfs_rate_show(struct pblk_rl *rl)
         return rl->rb_user_max;
 }
 
+int pblk_rl_max_io(struct pblk_rl *rl)
+{
+        return rl->rb_max_io;
+}
+
 static void pblk_rl_u_timer(unsigned long data)
 {
         struct pblk_rl *rl = (struct pblk_rl *)data;
@@ -199,6 +204,7 @@ void pblk_rl_init(struct pblk_rl *rl, int budget)
         /* To start with, all buffer is available to user I/O writers */
         rl->rb_budget = budget;
         rl->rb_user_max = budget;
+        rl->rb_max_io = budget >> 1;
         rl->rb_gc_max = 0;
         rl->rb_state = PBLK_RL_HIGH;
 
diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 3a07c5b61a0c..b592e5194b0f 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -267,6 +267,7 @@ struct pblk_rl {
         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 */
+        int rb_max_io;          /* Maximum size for an I/O giving the config */
 
         atomic_t rb_user_cnt;   /* User I/O buffer counter */
         atomic_t rb_gc_cnt;     /* GC I/O buffer counter */
@@ -844,6 +845,7 @@ 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);
 int pblk_rl_sysfs_rate_show(struct pblk_rl *rl);
+int pblk_rl_max_io(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);