dm snapshot: move ctr parsing to exception store

First step of having the exception stores parse their own arguments -
generalizing the interface.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

3 files changed, 132 insertions, 129 deletions

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 2078b92470a1..a2e26c242141 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -7,6 +7,7 @@
 
 #include "dm-exception-store.h"
 
+#include <linux/ctype.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 #include <linux/vmalloc.h>
@@ -137,49 +138,129 @@ int dm_exception_store_type_unregister(struct dm_exception_store_type *type)
 }
 EXPORT_SYMBOL(dm_exception_store_type_unregister);
 
-int dm_exception_store_create(const char *type_name, struct dm_target *ti,
-                              chunk_t chunk_size, chunk_t chunk_mask,
-                              chunk_t chunk_shift, struct dm_dev *cow,
+/*
+ * Round a number up to the nearest 'size' boundary.  size must
+ * be a power of 2.
+ */
+static ulong round_up(ulong n, ulong size)
+{
+        size--;
+        return (n + size) & ~size;
+}
+
+static int set_chunk_size(struct dm_exception_store *store,
+                          const char *chunk_size_arg, char **error)
+{
+        unsigned long chunk_size_ulong;
+        char *value;
+
+        chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
+        if (*chunk_size_arg == '\0' || *value != '\0') {
+                *error = "Invalid chunk size";
+                return -EINVAL;
+        }
+
+        if (!chunk_size_ulong) {
+                store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
+                return 0;
+        }
+
+        /*
+         * Chunk size must be multiple of page size.  Silently
+         * round up if it's not.
+         */
+        chunk_size_ulong = round_up(chunk_size_ulong, PAGE_SIZE >> 9);
+
+        /* Check chunk_size is a power of 2 */
+        if (!is_power_of_2(chunk_size_ulong)) {
+                *error = "Chunk size is not a power of 2";
+                return -EINVAL;
+        }
+
+        /* Validate the chunk size against the device block size */
+        if (chunk_size_ulong % (bdev_hardsect_size(store->cow->bdev) >> 9)) {
+                *error = "Chunk size is not a multiple of device blocksize";
+                return -EINVAL;
+        }
+
+        store->chunk_size = chunk_size_ulong;
+        store->chunk_mask = chunk_size_ulong - 1;
+        store->chunk_shift = ffs(chunk_size_ulong) - 1;
+
+        return 0;
+}
+
+int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
+                              unsigned *args_used,
                               struct dm_exception_store **store)
 {
         int r = 0;
         struct dm_exception_store_type *type;
         struct dm_exception_store *tmp_store;
+        char persistent;
+
+        if (argc < 3) {
+                ti->error = "Insufficient exception store arguments";
+                return -EINVAL;
+        }
 
         tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
-        if (!tmp_store)
+        if (!tmp_store) {
+                ti->error = "Exception store allocation failed";
                 return -ENOMEM;
+        }
 
-        type = get_type(type_name);
-        if (!type) {
-                kfree(tmp_store);
+        persistent = toupper(*argv[1]);
+        if (persistent != 'P' && persistent != 'N') {
+                ti->error = "Persistent flag is not P or N";
                 return -EINVAL;
         }
 
+        type = get_type(argv[1]);
+        if (!type) {
+                ti->error = "Exception store type not recognised";
+                r = -EINVAL;
+                goto bad_type;
+        }
+
         tmp_store->type = type;
         tmp_store->ti = ti;
 
-        tmp_store->chunk_size = chunk_size;
-        tmp_store->chunk_mask = chunk_mask;
-        tmp_store->chunk_shift = chunk_shift;
+        r = dm_get_device(ti, argv[0], 0, 0,
+                          FMODE_READ | FMODE_WRITE, &tmp_store->cow);
+        if (r) {
+                ti->error = "Cannot get COW device";
+                goto bad_cow;
+        }
 
-        tmp_store->cow = cow;
+        r = set_chunk_size(tmp_store, argv[2], &ti->error);
+        if (r)
+                goto bad_cow;
 
         r = type->ctr(tmp_store, 0, NULL);
         if (r) {
-                put_type(type);
-                kfree(tmp_store);
-                return r;
+                ti->error = "Exception store type constructor failed";
+                goto bad_ctr;
         }
 
+        *args_used = 3;
         *store = tmp_store;
         return 0;
+
+bad_ctr:
+        dm_put_device(ti, tmp_store->cow);
+bad_cow:
+        put_type(type);
+bad_type:
+        kfree(tmp_store);
+        return r;
 }
 EXPORT_SYMBOL(dm_exception_store_create);
 
 void dm_exception_store_destroy(struct dm_exception_store *store)
 {
         store->type->dtr(store);
+        dm_put_device(store->ti, store->cow);
         put_type(store->type);
         kfree(store);
 }
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index 835f402d9470..023a707503c4 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -167,9 +167,8 @@ static inline chunk_t sector_to_chunk(struct dm_exception_store *store,
 int dm_exception_store_type_register(struct dm_exception_store_type *type);
 int dm_exception_store_type_unregister(struct dm_exception_store_type *type);
 
-int dm_exception_store_create(const char *type_name, struct dm_target *ti,
-                              chunk_t chunk_size, chunk_t chunk_mask,
-                              chunk_t chunk_shift, struct dm_dev *cow,
+int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
+                              unsigned *args_used,
                               struct dm_exception_store **store);
 void dm_exception_store_destroy(struct dm_exception_store *store);
 
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index fcb1ac12119f..974916b9ea21 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -7,7 +7,6 @@
  */
 
 #include <linux/blkdev.h>
-#include <linux/ctype.h>
 #include <linux/device-mapper.h>
 #include <linux/delay.h>
 #include <linux/fs.h>
@@ -538,8 +537,7 @@ static int calc_max_buckets(void)
 /*
  * Allocate room for a suitable hash table.
  */
-static int init_hash_tables(struct dm_snapshot *s, chunk_t chunk_shift,
-                            struct dm_dev *cow)
+static int init_hash_tables(struct dm_snapshot *s)
 {
         sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets;
 
@@ -547,11 +545,11 @@ static int init_hash_tables(struct dm_snapshot *s, chunk_t chunk_shift,
          * Calculate based on the size of the original volume or
          * the COW volume...
          */
-        cow_dev_size = get_dev_size(cow->bdev);
+        cow_dev_size = get_dev_size(s->store->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) >> chunk_shift;
+        hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift;
         hash_size = min(hash_size, max_buckets);
 
         hash_size = rounddown_pow_of_two(hash_size);
@@ -576,60 +574,6 @@ static int init_hash_tables(struct dm_snapshot *s, chunk_t chunk_shift,
 }
 
 /*
- * Round a number up to the nearest 'size' boundary.  size must
- * be a power of 2.
- */
-static ulong round_up(ulong n, ulong size)
-{
-        size--;
-        return (n + size) & ~size;
-}
-
-static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
-                          chunk_t *chunk_size, chunk_t *chunk_mask,
-                          chunk_t *chunk_shift, struct dm_dev *cow,
-                          char **error)
-{
-        unsigned long chunk_size_ulong;
-        char *value;
-
-        chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
-        if (*chunk_size_arg == '\0' || *value != '\0') {
-                *error = "Invalid chunk size";
-                return -EINVAL;
-        }
-
-        if (!chunk_size_ulong) {
-                *chunk_size = *chunk_mask = *chunk_shift = 0;
-                return 0;
-        }
-
-        /*
-         * Chunk size must be multiple of page size.  Silently
-         * round up if it's not.
-         */
-        chunk_size_ulong = round_up(chunk_size_ulong, PAGE_SIZE >> 9);
-
-        /* Check chunk_size is a power of 2 */
-        if (!is_power_of_2(chunk_size_ulong)) {
-                *error = "Chunk size is not a power of 2";
-                return -EINVAL;
-        }
-
-        /* Validate the chunk size against the device block size */
-        if (chunk_size_ulong % (bdev_hardsect_size(cow->bdev) >> 9)) {
-                *error = "Chunk size is not a multiple of device blocksize";
-                return -EINVAL;
-        }
-
-        *chunk_size = chunk_size_ulong;
-        *chunk_mask = chunk_size_ulong - 1;
-        *chunk_shift = ffs(chunk_size_ulong) - 1;
-
-        return 0;
-}
-
-/*
  * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size>
  */
 static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
@@ -637,55 +581,45 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         struct dm_snapshot *s;
         int i;
         int r = -EINVAL;
-        char persistent;
         char *origin_path;
-        char *cow_path;
-        chunk_t chunk_size, chunk_mask, chunk_shift;
-        struct dm_dev *cow;
+        struct dm_exception_store *store;
+        unsigned args_used;
 
         if (argc != 4) {
                 ti->error = "requires exactly 4 arguments";
                 r = -EINVAL;
-                goto bad1;
+                goto bad_args;
         }
 
         origin_path = argv[0];
-        cow_path = argv[1];
-        persistent = toupper(*argv[2]);
+        argv++;
+        argc--;
 
-        if (persistent != 'P' && persistent != 'N') {
-                ti->error = "Persistent flag is not P or N";
+        r = dm_exception_store_create(ti, argc, argv, &args_used, &store);
+        if (r) {
+                ti->error = "Couldn't create exception store";
                 r = -EINVAL;
-                goto bad1;
+                goto bad_args;
         }
 
+        argv += args_used;
+        argc -= args_used;
+
         s = kmalloc(sizeof(*s), GFP_KERNEL);
-        if (s == NULL) {
+        if (!s) {
                 ti->error = "Cannot allocate snapshot context private "
                     "structure";
                 r = -ENOMEM;
-                goto bad1;
+                goto bad_snap;
         }
 
         r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin);
         if (r) {
                 ti->error = "Cannot get origin device";
-                goto bad2;
+                goto bad_origin;
         }
 
-        r = dm_get_device(ti, cow_path, 0, 0,
-                          FMODE_READ | FMODE_WRITE, &cow);
-        if (r) {
-                dm_put_device(ti, s->origin);
-                ti->error = "Cannot get COW device";
-                goto bad2;
-        }
-
-        r = set_chunk_size(s, argv[3], &chunk_size, &chunk_mask, &chunk_shift,
-                           cow, &ti->error);
-        if (r)
-                goto bad3;
-
+        s->store = store;
         s->valid = 1;
         s->active = 0;
         atomic_set(&s->pending_exceptions_count, 0);
@@ -693,30 +627,22 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         spin_lock_init(&s->pe_lock);
 
         /* Allocate hash table for COW data */
-        if (init_hash_tables(s, chunk_shift, cow)) {
+        if (init_hash_tables(s)) {
                 ti->error = "Unable to allocate hash table space";
                 r = -ENOMEM;
-                goto bad3;
-        }
-
-        r = dm_exception_store_create(argv[2], ti, chunk_size, chunk_mask,
-                                      chunk_shift, cow, &s->store);
-        if (r) {
-                ti->error = "Couldn't create exception store";
-                r = -EINVAL;
-                goto bad4;
+                goto bad_hash_tables;
         }
 
         r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client);
         if (r) {
                 ti->error = "Could not create kcopyd client";
-                goto bad5;
+                goto bad_kcopyd;
         }
 
         s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache);
         if (!s->pending_pool) {
                 ti->error = "Could not allocate mempool for pending exceptions";
-                goto bad6;
+                goto bad_pending_pool;
         }
 
         s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS,
@@ -759,30 +685,29 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
         return 0;
 
- bad_load_and_register:
+bad_load_and_register:
         mempool_destroy(s->tracked_chunk_pool);
 
- bad_tracked_chunk_pool:
+bad_tracked_chunk_pool:
         mempool_destroy(s->pending_pool);
 
- bad6:
+bad_pending_pool:
         dm_kcopyd_client_destroy(s->kcopyd_client);
 
- bad5:
-        s->store->type->dtr(s->store);
-
- bad4:
+bad_kcopyd:
         exit_exception_table(&s->pending, pending_cache);
         exit_exception_table(&s->complete, exception_cache);
 
- bad3:
-        dm_put_device(ti, cow);
+bad_hash_tables:
         dm_put_device(ti, s->origin);
 
- bad2:
+bad_origin:
         kfree(s);
 
- bad1:
+bad_snap:
+        dm_exception_store_destroy(store);
+
+bad_args:
         return r;
 }
 
@@ -793,8 +718,6 @@ static void __free_exceptions(struct dm_snapshot *s)
 
         exit_exception_table(&s->pending, pending_cache);
         exit_exception_table(&s->complete, exception_cache);
-
-        s->store->type->dtr(s->store);
 }
 
 static void snapshot_dtr(struct dm_target *ti)
@@ -803,7 +726,6 @@ static void snapshot_dtr(struct dm_target *ti)
         int i;
 #endif
         struct dm_snapshot *s = ti->private;
-        struct dm_dev *cow = s->store->cow;
 
         flush_workqueue(ksnapd);
 
@@ -831,7 +753,8 @@ static void snapshot_dtr(struct dm_target *ti)
         mempool_destroy(s->pending_pool);
 
         dm_put_device(ti, s->origin);
-        dm_put_device(ti, cow);
+
+        dm_exception_store_destroy(s->store);
 
         kfree(s);
 }