bcache: fix misleading error message in bch_count_io_errors()

Bcache only does recoverable I/O for read operations by calling
cached_dev_read_error(). For write opertions there is no I/O recovery for
failed requests.

But in bch_count_io_errors() no matter read or write I/Os, before errors
counter reaches io error limit, pr_err() always prints "IO error on %,
recoverying". For write requests this information is misleading, because
there is no I/O recovery at all.

This patch adds a parameter 'is_read' to bch_count_io_errors(), and only
prints "recovering" by pr_err() when the bio direction is READ.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Reviewed-by: Tang Junhui <tang.junhui@zte.com.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/bcache/bcache.h

@@ -862,7 +862,7 @@ static inline void wake_up_allocators(struct cache_set *c)
 
 /* Forward declarations */
 
-void bch_count_io_errors(struct cache *, blk_status_t, const char *);
+void bch_count_io_errors(struct cache *, blk_status_t, int, const char *);
 void bch_bbio_count_io_errors(struct cache_set *, struct bio *,
 			      blk_status_t, const char *);
 void bch_bbio_endio(struct cache_set *, struct bio *, blk_status_t,

drivers/md/bcache/io.c

@@ -51,7 +51,10 @@ void bch_submit_bbio(struct bio *bio, struct cache_set *c,
 
 /* IO errors */
 
-void bch_count_io_errors(struct cache *ca, blk_status_t error, const char *m)
+void bch_count_io_errors(struct cache *ca,
+			 blk_status_t error,
+			 int is_read,
+			 const char *m)
 {
 	/*
 	 * The halflife of an error is:
@@ -94,8 +97,9 @@ void bch_count_io_errors(struct cache *ca, blk_status_t error, const char *m)
 		errors >>= IO_ERROR_SHIFT;
 
 		if (errors < ca->set->error_limit)
-			pr_err("%s: IO error on %s, recovering",
-			       bdevname(ca->bdev, buf), m);
+			pr_err("%s: IO error on %s%s",
+			       bdevname(ca->bdev, buf), m,
+			       is_read ? ", recovering." : ".");
 		else
 			bch_cache_set_error(ca->set,
 					    "%s: too many IO errors %s",
@@ -108,6 +112,7 @@ void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 {
 	struct bbio *b = container_of(bio, struct bbio, bio);
 	struct cache *ca = PTR_CACHE(c, &b->key, 0);
+	int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
 
 	unsigned threshold = op_is_write(bio_op(bio))
 		? c->congested_write_threshold_us
@@ -129,7 +134,7 @@ void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 			atomic_inc(&c->congested);
 	}
 
-	bch_count_io_errors(ca, error, m);
+	bch_count_io_errors(ca, error, is_read, m);
 }
 
 void bch_bbio_endio(struct cache_set *c, struct bio *bio,

drivers/md/bcache/super.c

@@ -274,7 +274,9 @@ static void write_super_endio(struct bio *bio)
 {
 	struct cache *ca = bio->bi_private;
 
-	bch_count_io_errors(ca, bio->bi_status, "writing superblock");
+	/* is_read = 0 */
+	bch_count_io_errors(ca, bio->bi_status, 0,
+			    "writing superblock");
 	closure_put(&ca->set->sb_write);
 }
 

drivers/md/bcache/writeback.c

@@ -244,8 +244,10 @@ static void read_dirty_endio(struct bio *bio)
 	struct keybuf_key *w = bio->bi_private;
 	struct dirty_io *io = w->private;
 
+	/* is_read = 1 */
 	bch_count_io_errors(PTR_CACHE(io->dc->disk.c, &w->key, 0),
-			    bio->bi_status, "reading dirty data from cache");
+			    bio->bi_status, 1,
+			    "reading dirty data from cache");
 
 	dirty_endio(bio);
 }