Merge tag 'dm-3.12-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device-mapper fixes from Mike Snitzer:
 "A few fixes for dm-snapshot, a 32 bit fix for dm-stats, a couple error
  handling fixes for dm-multipath.  A fix for the thin provisioning
  target to not expose non-zero discard limits if discards are disabled.

  Lastly, add two DM module parameters which allow users to tune the
  emergency memory reserves that DM mainatins per device -- this helps
  fix a long-standing issue for dm-multipath.  The conservative default
  reserve for request-based dm-multipath devices (256) has proven
  problematic for users with many multipathed SCSI devices but
  relatively little memory.  To responsibly select a smaller value users
  should use the new nr_bios tracepoint info (via commit 75afb352
  "block: Add nr_bios to block_rq_remap tracepoint") to determine the
  peak number of bios their workloads create"

* tag 'dm-3.12-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: add reserved_bio_based_ios module parameter
  dm: add reserved_rq_based_ios module parameter
  dm: lower bio-based mempool reservation
  dm thin: do not expose non-zero discard limits if discards disabled
  dm mpath: disable WRITE SAME if it fails
  dm-snapshot: fix performance degradation due to small hash size
  dm snapshot: workaround for a false positive lockdep warning
  dm stats: fix possible counter corruption on 32-bit systems
  dm mpath: do not fail path on -ENOSPC

8 files changed, 118 insertions, 25 deletions

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index ea49834377c8..2a20986a2fec 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -19,8 +19,6 @@
 #define DM_MSG_PREFIX "io"
 
 #define DM_IO_MAX_REGIONS       BITS_PER_LONG
-#define MIN_IOS         16
-#define MIN_BIOS        16
 
 struct dm_io_client {
         mempool_t *pool;
@@ -50,16 +48,17 @@ static struct kmem_cache *_dm_io_cache;
 struct dm_io_client *dm_io_client_create(void)
 {
         struct dm_io_client *client;
+        unsigned min_ios = dm_get_reserved_bio_based_ios();
 
         client = kmalloc(sizeof(*client), GFP_KERNEL);
         if (!client)
                 return ERR_PTR(-ENOMEM);
 
-        client->pool = mempool_create_slab_pool(MIN_IOS, _dm_io_cache);
+        client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache);
         if (!client->pool)
                 goto bad;
 
-        client->bios = bioset_create(MIN_BIOS, 0);
+        client->bios = bioset_create(min_ios, 0);
         if (!client->bios)
                 goto bad;
 
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index b759a127f9c3..de570a558764 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -7,6 +7,7 @@
 
 #include <linux/device-mapper.h>
 
+#include "dm.h"
 #include "dm-path-selector.h"
 #include "dm-uevent.h"
 
@@ -116,8 +117,6 @@ struct dm_mpath_io {
 
 typedef int (*action_fn) (struct pgpath *pgpath);
 
-#define MIN_IOS 256     /* Mempool size */
-
 static struct kmem_cache *_mpio_cache;
 
 static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
@@ -190,6 +189,7 @@ static void free_priority_group(struct priority_group *pg,
 static struct multipath *alloc_multipath(struct dm_target *ti)
 {
         struct multipath *m;
+        unsigned min_ios = dm_get_reserved_rq_based_ios();
 
         m = kzalloc(sizeof(*m), GFP_KERNEL);
         if (m) {
@@ -202,7 +202,7 @@ static struct multipath *alloc_multipath(struct dm_target *ti)
                 INIT_WORK(&m->trigger_event, trigger_event);
                 init_waitqueue_head(&m->pg_init_wait);
                 mutex_init(&m->work_mutex);
-                m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
+                m->mpio_pool = mempool_create_slab_pool(min_ios, _mpio_cache);
                 if (!m->mpio_pool) {
                         kfree(m);
                         return NULL;
@@ -1268,6 +1268,7 @@ static int noretry_error(int error)
         case -EREMOTEIO:
         case -EILSEQ:
         case -ENODATA:
+        case -ENOSPC:
                 return 1;
         }
 
@@ -1298,8 +1299,17 @@ static int do_end_io(struct multipath *m, struct request *clone,
         if (!error && !clone->errors)
                 return 0;       /* I/O complete */
 
-        if (noretry_error(error))
+        if (noretry_error(error)) {
+                if ((clone->cmd_flags & REQ_WRITE_SAME) &&
+                    !clone->q->limits.max_write_same_sectors) {
+                        struct queue_limits *limits;
+
+                        /* device doesn't really support WRITE SAME, disable it */
+                        limits = dm_get_queue_limits(dm_table_get_md(m->ti->table));
+                        limits->max_write_same_sectors = 0;
+                }
                 return error;
+        }
 
         if (mpio->pgpath)
                 fail_path(mpio->pgpath);
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 3ac415675b6c..4caa8e6d59d7 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -256,7 +256,7 @@ static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw,
          */
         INIT_WORK_ONSTACK(&req.work, do_metadata);
         queue_work(ps->metadata_wq, &req.work);
-        flush_work(&req.work);
+        flush_workqueue(ps->metadata_wq);
 
         return req.result;
 }
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index c434e5aab2df..aec57d76db5d 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -725,17 +725,16 @@ static int calc_max_buckets(void)
  */
 static int init_hash_tables(struct dm_snapshot *s)
 {
-        sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets;
+        sector_t hash_size, cow_dev_size, max_buckets;
 
         /*
          * Calculate based on the size of the original volume or
          * the COW volume...
          */
         cow_dev_size = get_dev_size(s->cow->bdev);
-        origin_dev_size = get_dev_size(s->origin->bdev);
         max_buckets = calc_max_buckets();
 
-        hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift;
+        hash_size = cow_dev_size >> s->store->chunk_shift;
         hash_size = min(hash_size, max_buckets);
 
         if (hash_size < 64)
diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 8ae31e8d3d64..3d404c1371ed 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -451,19 +451,26 @@ static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
         struct dm_stat_percpu *p;
 
         /*
-         * For strict correctness we should use local_irq_disable/enable
+         * For strict correctness we should use local_irq_save/restore
          * instead of preempt_disable/enable.
          *
-         * This is racy if the driver finishes bios from non-interrupt
-         * context as well as from interrupt context or from more different
-         * interrupts.
+         * preempt_disable/enable is racy if the driver finishes bios
+         * from non-interrupt context as well as from interrupt context
+         * or from more different interrupts.
          *
-         * However, the race only results in not counting some events,
-         * so it is acceptable.
+         * On 64-bit architectures the race only results in not counting some
+         * events, so it is acceptable.  On 32-bit architectures the race could
+         * cause the counter going off by 2^32, so we need to do proper locking
+         * there.
          *
          * part_stat_lock()/part_stat_unlock() have this race too.
          */
+#if BITS_PER_LONG == 32
+        unsigned long flags;
+        local_irq_save(flags);
+#else
         preempt_disable();
+#endif
         p = &s->stat_percpu[smp_processor_id()][entry];
 
         if (!end) {
@@ -478,7 +485,11 @@ static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
                 p->ticks[idx] += duration;
         }
 
+#if BITS_PER_LONG == 32
+        local_irq_restore(flags);
+#else
         preempt_enable();
+#endif
 }
 
 static void __dm_stat_bio(struct dm_stat *s, unsigned long bi_rw,
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index ed063427d676..2c0cf511ec23 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2095,6 +2095,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
          * them down to the data device.  The thin device's discard
          * processing will cause mappings to be removed from the btree.
          */
+        ti->discard_zeroes_data_unsupported = true;
         if (pf.discard_enabled && pf.discard_passdown) {
                 ti->num_discard_bios = 1;
 
@@ -2104,7 +2105,6 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
                  * thin devices' discard limits consistent).
                  */
                 ti->discards_supported = true;
-                ti->discard_zeroes_data_unsupported = true;
         }
         ti->private = pt;
 
@@ -2689,8 +2689,16 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
          * They get transferred to the live pool in bind_control_target()
          * called from pool_preresume().
          */
-        if (!pt->adjusted_pf.discard_enabled)
+        if (!pt->adjusted_pf.discard_enabled) {
+                /*
+                 * Must explicitly disallow stacking discard limits otherwise the
+                 * block layer will stack them if pool's data device has support.
+                 * QUEUE_FLAG_DISCARD wouldn't be set but there is no way for the
+                 * user to see that, so make sure to set all discard limits to 0.
+                 */
+                limits->discard_granularity = 0;
                 return;
+        }
 
         disable_passdown_if_not_supported(pt);
 
@@ -2826,10 +2834,10 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
         ti->per_bio_data_size = sizeof(struct dm_thin_endio_hook);
 
         /* In case the pool supports discards, pass them on. */
+        ti->discard_zeroes_data_unsupported = true;
         if (tc->pool->pf.discard_enabled) {
                 ti->discards_supported = true;
                 ti->num_discard_bios = 1;
-                ti->discard_zeroes_data_unsupported = true;
                 /* Discard bios must be split on a block boundary */
                 ti->split_discard_bios = true;
         }
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 6a5e9ed2fcc3..b3e26c7d1417 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -211,10 +211,55 @@ struct dm_md_mempools {
         struct bio_set *bs;
 };
 
-#define MIN_IOS 256
+#define RESERVED_BIO_BASED_IOS          16
+#define RESERVED_REQUEST_BASED_IOS      256
+#define RESERVED_MAX_IOS                1024
 static struct kmem_cache *_io_cache;
 static struct kmem_cache *_rq_tio_cache;
 
+/*
+ * Bio-based DM's mempools' reserved IOs set by the user.
+ */
+static unsigned reserved_bio_based_ios = RESERVED_BIO_BASED_IOS;
+
+/*
+ * Request-based DM's mempools' reserved IOs set by the user.
+ */
+static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
+
+static unsigned __dm_get_reserved_ios(unsigned *reserved_ios,
+                                      unsigned def, unsigned max)
+{
+        unsigned ios = ACCESS_ONCE(*reserved_ios);
+        unsigned modified_ios = 0;
+
+        if (!ios)
+                modified_ios = def;
+        else if (ios > max)
+                modified_ios = max;
+
+        if (modified_ios) {
+                (void)cmpxchg(reserved_ios, ios, modified_ios);
+                ios = modified_ios;
+        }
+
+        return ios;
+}
+
+unsigned dm_get_reserved_bio_based_ios(void)
+{
+        return __dm_get_reserved_ios(&reserved_bio_based_ios,
+                                     RESERVED_BIO_BASED_IOS, RESERVED_MAX_IOS);
+}
+EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios);
+
+unsigned dm_get_reserved_rq_based_ios(void)
+{
+        return __dm_get_reserved_ios(&reserved_rq_based_ios,
+                                     RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS);
+}
+EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
+
 static int __init local_init(void)
 {
         int r = -ENOMEM;
@@ -2278,6 +2323,17 @@ struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
 }
 
 /*
+ * The queue_limits are only valid as long as you have a reference
+ * count on 'md'.
+ */
+struct queue_limits *dm_get_queue_limits(struct mapped_device *md)
+{
+        BUG_ON(!atomic_read(&md->holders));
+        return &md->queue->limits;
+}
+EXPORT_SYMBOL_GPL(dm_get_queue_limits);
+
+/*
  * Fully initialize a request-based queue (->elevator, ->request_fn, etc).
  */
 static int dm_init_request_based_queue(struct mapped_device *md)
@@ -2862,18 +2918,18 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
 
         if (type == DM_TYPE_BIO_BASED) {
                 cachep = _io_cache;
-                pool_size = 16;
+                pool_size = dm_get_reserved_bio_based_ios();
                 front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
         } else if (type == DM_TYPE_REQUEST_BASED) {
                 cachep = _rq_tio_cache;
-                pool_size = MIN_IOS;
+                pool_size = dm_get_reserved_rq_based_ios();
                 front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
                 /* per_bio_data_size is not used. See __bind_mempools(). */
                 WARN_ON(per_bio_data_size != 0);
         } else
                 goto out;
 
-        pools->io_pool = mempool_create_slab_pool(MIN_IOS, cachep);
+        pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
         if (!pools->io_pool)
                 goto out;
 
@@ -2924,6 +2980,13 @@ module_exit(dm_exit);
 
 module_param(major, uint, 0);
 MODULE_PARM_DESC(major, "The major number of the device mapper");
+
+module_param(reserved_bio_based_ios, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools");
+
+module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
+
 MODULE_DESCRIPTION(DM_NAME " driver");
 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 MODULE_LICENSE("GPL");
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 5e604cc7b4aa..1d1ad7b7e527 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -184,6 +184,9 @@ void dm_free_md_mempools(struct dm_md_mempools *pools);
 /*
  * Helpers that are used by DM core
  */
+unsigned dm_get_reserved_bio_based_ios(void);
+unsigned dm_get_reserved_rq_based_ios(void);
+
 static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
 {
         return !maxlen || strlen(result) + 1 >= maxlen;