*/
#include <linux/blkdev.h>
-#include <linux/ctype.h>
#include <linux/device-mapper.h>
+#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kdev_t.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
+#include <linux/log2.h>
+#include <linux/dm-kcopyd.h>
+#include <linux/workqueue.h>
-#include "dm-snap.h"
-#include "dm-bio-list.h"
-#include "kcopyd.h"
+#include "dm-exception-store.h"
#define DM_MSG_PREFIX "snapshots"
#define SNAPSHOT_COPY_PRIORITY 2
/*
- * Each snapshot reserves this many pages for io
+ * Reserve 1MB for each snapshot initially (with minimum of 1 page).
*/
-#define SNAPSHOT_PAGES 256
+#define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1)
+
+/*
+ * The size of the mempool used to track chunks in use.
+ */
+#define MIN_IOS 256
+
+#define DM_TRACKED_CHUNK_HASH_SIZE 16
+#define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \
+ (DM_TRACKED_CHUNK_HASH_SIZE - 1))
+
+struct dm_exception_table {
+ uint32_t hash_mask;
+ unsigned hash_shift;
+ struct list_head *table;
+};
+
+struct dm_snapshot {
+ struct rw_semaphore lock;
+
+ struct dm_dev *origin;
+ struct dm_dev *cow;
+
+ struct dm_target *ti;
+
+ /* List of snapshots per Origin */
+ struct list_head list;
+
+ /* You can't use a snapshot if this is 0 (e.g. if full) */
+ int valid;
+
+ /* Origin writes don't trigger exceptions until this is set */
+ int active;
+
+ /* Whether or not owning mapped_device is suspended */
+ int suspended;
+
+ mempool_t *pending_pool;
+
+ atomic_t pending_exceptions_count;
+
+ struct dm_exception_table pending;
+ struct dm_exception_table complete;
+
+ /*
+ * pe_lock protects all pending_exception operations and access
+ * as well as the snapshot_bios list.
+ */
+ spinlock_t pe_lock;
+
+ /* The on disk metadata handler */
+ struct dm_exception_store *store;
+
+ struct dm_kcopyd_client *kcopyd_client;
+
+ /* Queue of snapshot writes for ksnapd to flush */
+ struct bio_list queued_bios;
+ struct work_struct queued_bios_work;
+
+ /* Chunks with outstanding reads */
+ mempool_t *tracked_chunk_pool;
+ spinlock_t tracked_chunk_lock;
+ struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
+};
+
+struct dm_dev *dm_snap_cow(struct dm_snapshot *s)
+{
+ return s->cow;
+}
+EXPORT_SYMBOL(dm_snap_cow);
static struct workqueue_struct *ksnapd;
static void flush_queued_bios(struct work_struct *work);
+static sector_t chunk_to_sector(struct dm_exception_store *store,
+ chunk_t chunk)
+{
+ return chunk << store->chunk_shift;
+}
+
+static int bdev_equal(struct block_device *lhs, struct block_device *rhs)
+{
+ /*
+ * There is only ever one instance of a particular block
+ * device so we can compare pointers safely.
+ */
+ return lhs == rhs;
+}
+
struct dm_snap_pending_exception {
- struct dm_snap_exception e;
+ struct dm_exception e;
/*
* Origin buffers waiting for this to complete are held
*/
static struct kmem_cache *exception_cache;
static struct kmem_cache *pending_cache;
-static mempool_t *pending_pool;
+
+struct dm_snap_tracked_chunk {
+ struct hlist_node node;
+ chunk_t chunk;
+};
+
+static struct kmem_cache *tracked_chunk_cache;
+
+static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,
+ chunk_t chunk)
+{
+ struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool,
+ GFP_NOIO);
+ unsigned long flags;
+
+ c->chunk = chunk;
+
+ spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+ hlist_add_head(&c->node,
+ &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);
+ spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+ return c;
+}
+
+static void stop_tracking_chunk(struct dm_snapshot *s,
+ struct dm_snap_tracked_chunk *c)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+ hlist_del(&c->node);
+ spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+ mempool_free(c, s->tracked_chunk_pool);
+}
+
+static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk)
+{
+ struct dm_snap_tracked_chunk *c;
+ struct hlist_node *hn;
+ int found = 0;
+
+ spin_lock_irq(&s->tracked_chunk_lock);
+
+ hlist_for_each_entry(c, hn,
+ &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) {
+ if (c->chunk == chunk) {
+ found = 1;
+ break;
+ }
+ }
+
+ spin_unlock_irq(&s->tracked_chunk_lock);
+
+ return found;
+}
/*
* One of these per registered origin, held in the snapshot_origins hash
*/
static int register_snapshot(struct dm_snapshot *snap)
{
- struct origin *o;
+ struct dm_snapshot *l;
+ struct origin *o, *new_o;
struct block_device *bdev = snap->origin->bdev;
+ new_o = kmalloc(sizeof(*new_o), GFP_KERNEL);
+ if (!new_o)
+ return -ENOMEM;
+
down_write(&_origins_lock);
o = __lookup_origin(bdev);
- if (!o) {
+ if (o)
+ kfree(new_o);
+ else {
/* New origin */
- o = kmalloc(sizeof(*o), GFP_KERNEL);
- if (!o) {
- up_write(&_origins_lock);
- return -ENOMEM;
- }
+ o = new_o;
/* Initialise the struct */
INIT_LIST_HEAD(&o->snapshots);
__insert_origin(o);
}
- list_add_tail(&snap->list, &o->snapshots);
+ /* Sort the list according to chunk size, largest-first smallest-last */
+ list_for_each_entry(l, &o->snapshots, list)
+ if (l->store->chunk_size < snap->store->chunk_size)
+ break;
+ list_add_tail(&snap->list, &l->list);
up_write(&_origins_lock);
return 0;
/*
* Implementation of the exception hash tables.
+ * The lowest hash_shift bits of the chunk number are ignored, allowing
+ * some consecutive chunks to be grouped together.
*/
-static int init_exception_table(struct exception_table *et, uint32_t size)
+static int dm_exception_table_init(struct dm_exception_table *et,
+ uint32_t size, unsigned hash_shift)
{
unsigned int i;
+ et->hash_shift = hash_shift;
et->hash_mask = size - 1;
et->table = dm_vcalloc(size, sizeof(struct list_head));
if (!et->table)
return 0;
}
-static void exit_exception_table(struct exception_table *et, struct kmem_cache *mem)
+static void dm_exception_table_exit(struct dm_exception_table *et,
+ struct kmem_cache *mem)
{
struct list_head *slot;
- struct dm_snap_exception *ex, *next;
+ struct dm_exception *ex, *next;
int i, size;
size = et->hash_mask + 1;
vfree(et->table);
}
-static uint32_t exception_hash(struct exception_table *et, chunk_t chunk)
+static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk)
{
- return chunk & et->hash_mask;
+ return (chunk >> et->hash_shift) & et->hash_mask;
}
-static void insert_exception(struct exception_table *eh,
- struct dm_snap_exception *e)
-{
- struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)];
- list_add(&e->hash_list, l);
-}
-
-static void remove_exception(struct dm_snap_exception *e)
+static void dm_remove_exception(struct dm_exception *e)
{
list_del(&e->hash_list);
}
* Return the exception data for a sector, or NULL if not
* remapped.
*/
-static struct dm_snap_exception *lookup_exception(struct exception_table *et,
- chunk_t chunk)
+static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et,
+ chunk_t chunk)
{
struct list_head *slot;
- struct dm_snap_exception *e;
+ struct dm_exception *e;
slot = &et->table[exception_hash(et, chunk)];
list_for_each_entry (e, slot, hash_list)
- if (e->old_chunk == chunk)
+ if (chunk >= e->old_chunk &&
+ chunk <= e->old_chunk + dm_consecutive_chunk_count(e))
return e;
return NULL;
}
-static struct dm_snap_exception *alloc_exception(void)
+static struct dm_exception *alloc_completed_exception(void)
{
- struct dm_snap_exception *e;
+ struct dm_exception *e;
e = kmem_cache_alloc(exception_cache, GFP_NOIO);
if (!e)
return e;
}
-static void free_exception(struct dm_snap_exception *e)
+static void free_completed_exception(struct dm_exception *e)
{
kmem_cache_free(exception_cache, e);
}
-static struct dm_snap_pending_exception *alloc_pending_exception(void)
+static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s)
{
- return mempool_alloc(pending_pool, GFP_NOIO);
+ struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool,
+ GFP_NOIO);
+
+ atomic_inc(&s->pending_exceptions_count);
+ pe->snap = s;
+
+ return pe;
}
static void free_pending_exception(struct dm_snap_pending_exception *pe)
{
- mempool_free(pe, pending_pool);
+ struct dm_snapshot *s = pe->snap;
+
+ mempool_free(pe, s->pending_pool);
+ smp_mb__before_atomic_dec();
+ atomic_dec(&s->pending_exceptions_count);
+}
+
+static void dm_insert_exception(struct dm_exception_table *eh,
+ struct dm_exception *new_e)
+{
+ struct list_head *l;
+ struct dm_exception *e = NULL;
+
+ l = &eh->table[exception_hash(eh, new_e->old_chunk)];
+
+ /* Add immediately if this table doesn't support consecutive chunks */
+ if (!eh->hash_shift)
+ goto out;
+
+ /* List is ordered by old_chunk */
+ list_for_each_entry_reverse(e, l, hash_list) {
+ /* Insert after an existing chunk? */
+ if (new_e->old_chunk == (e->old_chunk +
+ dm_consecutive_chunk_count(e) + 1) &&
+ new_e->new_chunk == (dm_chunk_number(e->new_chunk) +
+ dm_consecutive_chunk_count(e) + 1)) {
+ dm_consecutive_chunk_count_inc(e);
+ free_completed_exception(new_e);
+ return;
+ }
+
+ /* Insert before an existing chunk? */
+ if (new_e->old_chunk == (e->old_chunk - 1) &&
+ new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) {
+ dm_consecutive_chunk_count_inc(e);
+ e->old_chunk--;
+ e->new_chunk--;
+ free_completed_exception(new_e);
+ return;
+ }
+
+ if (new_e->old_chunk > e->old_chunk)
+ break;
+ }
+
+out:
+ list_add(&new_e->hash_list, e ? &e->hash_list : l);
}
-int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new)
+/*
+ * Callback used by the exception stores to load exceptions when
+ * initialising.
+ */
+static int dm_add_exception(void *context, chunk_t old, chunk_t new)
{
- struct dm_snap_exception *e;
+ struct dm_snapshot *s = context;
+ struct dm_exception *e;
- e = alloc_exception();
+ e = alloc_completed_exception();
if (!e)
return -ENOMEM;
e->old_chunk = old;
+
+ /* Consecutive_count is implicitly initialised to zero */
e->new_chunk = new;
- insert_exception(&s->complete, e);
+
+ dm_insert_exception(&s->complete, e);
+
return 0;
}
+#define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r)))
+
+/*
+ * Return a minimum chunk size of all snapshots that have the specified origin.
+ * Return zero if the origin has no snapshots.
+ */
+static sector_t __minimum_chunk_size(struct origin *o)
+{
+ struct dm_snapshot *snap;
+ unsigned chunk_size = 0;
+
+ if (o)
+ list_for_each_entry(snap, &o->snapshots, list)
+ chunk_size = min_not_zero(chunk_size,
+ snap->store->chunk_size);
+
+ return chunk_size;
+}
+
/*
* Hard coded magic.
*/
}
/*
- * Rounds a number down to a power of 2.
- */
-static uint32_t round_down(uint32_t n)
-{
- while (n & (n - 1))
- n &= (n - 1);
- return n;
-}
-
-/*
* Allocate room for a suitable hash table.
*/
static int init_hash_tables(struct dm_snapshot *s)
origin_dev_size = get_dev_size(s->origin->bdev);
max_buckets = calc_max_buckets();
- hash_size = min(origin_dev_size, cow_dev_size) >> s->chunk_shift;
+ hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift;
hash_size = min(hash_size, max_buckets);
- /* Round it down to a power of 2 */
- hash_size = round_down(hash_size);
- if (init_exception_table(&s->complete, hash_size))
+ if (hash_size < 64)
+ hash_size = 64;
+ hash_size = rounddown_pow_of_two(hash_size);
+ if (dm_exception_table_init(&s->complete, hash_size,
+ DM_CHUNK_CONSECUTIVE_BITS))
return -ENOMEM;
/*
if (hash_size < 64)
hash_size = 64;
- if (init_exception_table(&s->pending, hash_size)) {
- exit_exception_table(&s->complete, exception_cache);
+ if (dm_exception_table_init(&s->pending, hash_size, 0)) {
+ dm_exception_table_exit(&s->complete, exception_cache);
return -ENOMEM;
}
}
/*
- * 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,
- char **error)
-{
- unsigned long chunk_size;
- char *value;
-
- chunk_size = simple_strtoul(chunk_size_arg, &value, 10);
- if (*chunk_size_arg == '\0' || *value != '\0') {
- *error = "Invalid chunk size";
- return -EINVAL;
- }
-
- if (!chunk_size) {
- s->chunk_size = s->chunk_mask = s->chunk_shift = 0;
- return 0;
- }
-
- /*
- * Chunk size must be multiple of page size. Silently
- * round up if it's not.
- */
- chunk_size = round_up(chunk_size, PAGE_SIZE >> 9);
-
- /* Check chunk_size is a power of 2 */
- if (chunk_size & (chunk_size - 1)) {
- *error = "Chunk size is not a power of 2";
- return -EINVAL;
- }
-
- /* Validate the chunk size against the device block size */
- if (chunk_size % (bdev_hardsect_size(s->cow->bdev) >> 9)) {
- *error = "Chunk size is not a multiple of device blocksize";
- return -EINVAL;
- }
-
- s->chunk_size = chunk_size;
- s->chunk_mask = chunk_size - 1;
- s->chunk_shift = ffs(chunk_size) - 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)
{
struct dm_snapshot *s;
+ int i;
int r = -EINVAL;
- char persistent;
- char *origin_path;
- char *cow_path;
+ char *origin_path, *cow_path;
+ unsigned args_used;
if (argc != 4) {
ti->error = "requires exactly 4 arguments";
r = -EINVAL;
- goto bad1;
+ goto bad;
}
origin_path = argv[0];
- cow_path = argv[1];
- persistent = toupper(*argv[2]);
-
- if (persistent != 'P' && persistent != 'N') {
- ti->error = "Persistent flag is not P or N";
- r = -EINVAL;
- goto bad1;
- }
+ argv++;
+ argc--;
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;
}
- r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin);
- if (r) {
- ti->error = "Cannot get origin device";
- goto bad2;
- }
+ cow_path = argv[0];
+ argv++;
+ argc--;
r = dm_get_device(ti, cow_path, 0, 0,
FMODE_READ | FMODE_WRITE, &s->cow);
if (r) {
- dm_put_device(ti, s->origin);
ti->error = "Cannot get COW device";
- goto bad2;
+ goto bad_cow;
}
- r = set_chunk_size(s, argv[3], &ti->error);
- if (r)
- goto bad3;
+ r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store);
+ if (r) {
+ ti->error = "Couldn't create exception store";
+ r = -EINVAL;
+ goto bad_store;
+ }
+
+ argv += args_used;
+ argc -= args_used;
- s->type = persistent;
+ r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin);
+ if (r) {
+ ti->error = "Cannot get origin device";
+ goto bad_origin;
+ }
+ s->ti = ti;
s->valid = 1;
s->active = 0;
- s->last_percent = 0;
+ s->suspended = 0;
+ atomic_set(&s->pending_exceptions_count, 0);
init_rwsem(&s->lock);
spin_lock_init(&s->pe_lock);
- s->table = ti->table;
/* Allocate hash table for COW data */
if (init_hash_tables(s)) {
ti->error = "Unable to allocate hash table space";
r = -ENOMEM;
- goto bad3;
+ goto bad_hash_tables;
}
- s->store.snap = s;
-
- if (persistent == 'P')
- r = dm_create_persistent(&s->store);
- else
- r = dm_create_transient(&s->store);
-
+ r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client);
if (r) {
- ti->error = "Couldn't create exception store";
- r = -EINVAL;
- goto bad4;
+ ti->error = "Could not create kcopyd client";
+ goto bad_kcopyd;
}
- r = kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client);
- if (r) {
- ti->error = "Could not create kcopyd client";
- goto bad5;
+ 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 bad_pending_pool;
+ }
+
+ s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS,
+ tracked_chunk_cache);
+ if (!s->tracked_chunk_pool) {
+ ti->error = "Could not allocate tracked_chunk mempool for "
+ "tracking reads";
+ goto bad_tracked_chunk_pool;
}
+ for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
+ INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]);
+
+ spin_lock_init(&s->tracked_chunk_lock);
+
/* Metadata must only be loaded into one table at once */
- r = s->store.read_metadata(&s->store);
+ r = s->store->type->read_metadata(s->store, dm_add_exception,
+ (void *)s);
if (r < 0) {
ti->error = "Failed to read snapshot metadata";
- goto bad6;
+ goto bad_load_and_register;
} else if (r > 0) {
s->valid = 0;
DMWARN("Snapshot is marked invalid.");
bio_list_init(&s->queued_bios);
INIT_WORK(&s->queued_bios_work, flush_queued_bios);
+ if (!s->store->chunk_size) {
+ ti->error = "Chunk size not set";
+ goto bad_load_and_register;
+ }
+
/* Add snapshot to the list of snapshots for this origin */
/* Exceptions aren't triggered till snapshot_resume() is called */
if (register_snapshot(s)) {
r = -EINVAL;
ti->error = "Cannot register snapshot origin";
- goto bad6;
+ goto bad_load_and_register;
}
ti->private = s;
- ti->split_io = s->chunk_size;
+ ti->split_io = s->store->chunk_size;
+ ti->num_flush_requests = 1;
return 0;
- bad6:
- kcopyd_client_destroy(s->kcopyd_client);
+bad_load_and_register:
+ mempool_destroy(s->tracked_chunk_pool);
- bad5:
- s->store.destroy(&s->store);
+bad_tracked_chunk_pool:
+ mempool_destroy(s->pending_pool);
- bad4:
- exit_exception_table(&s->pending, pending_cache);
- exit_exception_table(&s->complete, exception_cache);
+bad_pending_pool:
+ dm_kcopyd_client_destroy(s->kcopyd_client);
- bad3:
- dm_put_device(ti, s->cow);
+bad_kcopyd:
+ dm_exception_table_exit(&s->pending, pending_cache);
+ dm_exception_table_exit(&s->complete, exception_cache);
+
+bad_hash_tables:
dm_put_device(ti, s->origin);
- bad2:
+bad_origin:
+ dm_exception_store_destroy(s->store);
+
+bad_store:
+ dm_put_device(ti, s->cow);
+
+bad_cow:
kfree(s);
- bad1:
+bad:
return r;
}
static void __free_exceptions(struct dm_snapshot *s)
{
- kcopyd_client_destroy(s->kcopyd_client);
+ dm_kcopyd_client_destroy(s->kcopyd_client);
s->kcopyd_client = NULL;
- exit_exception_table(&s->pending, pending_cache);
- exit_exception_table(&s->complete, exception_cache);
-
- s->store.destroy(&s->store);
+ dm_exception_table_exit(&s->pending, pending_cache);
+ dm_exception_table_exit(&s->complete, exception_cache);
}
static void snapshot_dtr(struct dm_target *ti)
{
+#ifdef CONFIG_DM_DEBUG
+ int i;
+#endif
struct dm_snapshot *s = ti->private;
flush_workqueue(ksnapd);
/* After this returns there can be no new kcopyd jobs. */
unregister_snapshot(s);
+ while (atomic_read(&s->pending_exceptions_count))
+ msleep(1);
+ /*
+ * Ensure instructions in mempool_destroy aren't reordered
+ * before atomic_read.
+ */
+ smp_mb();
+
+#ifdef CONFIG_DM_DEBUG
+ for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
+ BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i]));
+#endif
+
+ mempool_destroy(s->tracked_chunk_pool);
+
__free_exceptions(s);
+ mempool_destroy(s->pending_pool);
+
dm_put_device(ti, s->origin);
+
+ dm_exception_store_destroy(s->store);
+
dm_put_device(ti, s->cow);
kfree(s);
while (bio) {
n = bio->bi_next;
bio->bi_next = NULL;
- bio_io_error(bio, bio->bi_size);
+ bio_io_error(bio);
bio = n;
}
}
else if (err == -ENOMEM)
DMERR("Invalidating snapshot: Unable to allocate exception.");
- if (s->store.drop_snapshot)
- s->store.drop_snapshot(&s->store);
+ if (s->store->type->drop_snapshot)
+ s->store->type->drop_snapshot(s->store);
s->valid = 0;
- dm_table_event(s->table);
+ dm_table_event(s->ti->table);
}
static void get_pending_exception(struct dm_snap_pending_exception *pe)
* the bios for the original write to the origin.
*/
if (primary_pe &&
- atomic_dec_and_test(&primary_pe->ref_count))
+ atomic_dec_and_test(&primary_pe->ref_count)) {
origin_bios = bio_list_get(&primary_pe->origin_bios);
+ free_pending_exception(primary_pe);
+ }
/*
* Free the pe if it's not linked to an origin write or if
if (!primary_pe || primary_pe != pe)
free_pending_exception(pe);
- /*
- * Free the primary pe if nothing references it.
- */
- if (primary_pe && !atomic_read(&primary_pe->ref_count))
- free_pending_exception(primary_pe);
-
return origin_bios;
}
static void pending_complete(struct dm_snap_pending_exception *pe, int success)
{
- struct dm_snap_exception *e;
+ struct dm_exception *e;
struct dm_snapshot *s = pe->snap;
struct bio *origin_bios = NULL;
struct bio *snapshot_bios = NULL;
goto out;
}
- e = alloc_exception();
+ e = alloc_completed_exception();
if (!e) {
down_write(&s->lock);
__invalidate_snapshot(s, -ENOMEM);
down_write(&s->lock);
if (!s->valid) {
- free_exception(e);
+ free_completed_exception(e);
error = 1;
goto out;
}
/*
+ * Check for conflicting reads. This is extremely improbable,
+ * so msleep(1) is sufficient and there is no need for a wait queue.
+ */
+ while (__chunk_is_tracked(s, pe->e.old_chunk))
+ msleep(1);
+
+ /*
* Add a proper exception, and remove the
* in-flight exception from the list.
*/
- insert_exception(&s->complete, e);
+ dm_insert_exception(&s->complete, e);
out:
- remove_exception(&pe->e);
+ dm_remove_exception(&pe->e);
snapshot_bios = bio_list_get(&pe->snapshot_bios);
origin_bios = put_pending_exception(pe);
* Called when the copy I/O has finished. kcopyd actually runs
* this code so don't block.
*/
-static void copy_callback(int read_err, unsigned int write_err, void *context)
+static void copy_callback(int read_err, unsigned long write_err, void *context)
{
struct dm_snap_pending_exception *pe = context;
struct dm_snapshot *s = pe->snap;
else
/* Update the metadata if we are persistent */
- s->store.commit_exception(&s->store, &pe->e, commit_callback,
- pe);
+ s->store->type->commit_exception(s->store, &pe->e,
+ commit_callback, pe);
}
/*
static void start_copy(struct dm_snap_pending_exception *pe)
{
struct dm_snapshot *s = pe->snap;
- struct io_region src, dest;
+ struct dm_io_region src, dest;
struct block_device *bdev = s->origin->bdev;
sector_t dev_size;
dev_size = get_dev_size(bdev);
src.bdev = bdev;
- src.sector = chunk_to_sector(s, pe->e.old_chunk);
- src.count = min(s->chunk_size, dev_size - src.sector);
+ src.sector = chunk_to_sector(s->store, pe->e.old_chunk);
+ src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector);
dest.bdev = s->cow->bdev;
- dest.sector = chunk_to_sector(s, pe->e.new_chunk);
+ dest.sector = chunk_to_sector(s->store, pe->e.new_chunk);
dest.count = src.count;
/* Hand over to kcopyd */
- kcopyd_copy(s->kcopyd_client,
+ dm_kcopyd_copy(s->kcopyd_client,
&src, 1, &dest, 0, copy_callback, pe);
}
+static struct dm_snap_pending_exception *
+__lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk)
+{
+ struct dm_exception *e = dm_lookup_exception(&s->pending, chunk);
+
+ if (!e)
+ return NULL;
+
+ return container_of(e, struct dm_snap_pending_exception, e);
+}
+
/*
* Looks to see if this snapshot already has a pending exception
* for this chunk, otherwise it allocates a new one and inserts
* this.
*/
static struct dm_snap_pending_exception *
-__find_pending_exception(struct dm_snapshot *s, struct bio *bio)
+__find_pending_exception(struct dm_snapshot *s,
+ struct dm_snap_pending_exception *pe, chunk_t chunk)
{
- struct dm_snap_exception *e;
- struct dm_snap_pending_exception *pe;
- chunk_t chunk = sector_to_chunk(s, bio->bi_sector);
-
- /*
- * Is there a pending exception for this already ?
- */
- e = lookup_exception(&s->pending, chunk);
- if (e) {
- /* cast the exception to a pending exception */
- pe = container_of(e, struct dm_snap_pending_exception, e);
- goto out;
- }
-
- /*
- * Create a new pending exception, we don't want
- * to hold the lock while we do this.
- */
- up_write(&s->lock);
- pe = alloc_pending_exception();
- down_write(&s->lock);
+ struct dm_snap_pending_exception *pe2;
- if (!s->valid) {
+ pe2 = __lookup_pending_exception(s, chunk);
+ if (pe2) {
free_pending_exception(pe);
- return NULL;
- }
-
- e = lookup_exception(&s->pending, chunk);
- if (e) {
- free_pending_exception(pe);
- pe = container_of(e, struct dm_snap_pending_exception, e);
- goto out;
+ return pe2;
}
pe->e.old_chunk = chunk;
bio_list_init(&pe->snapshot_bios);
pe->primary_pe = NULL;
atomic_set(&pe->ref_count, 0);
- pe->snap = s;
pe->started = 0;
- if (s->store.prepare_exception(&s->store, &pe->e)) {
+ if (s->store->type->prepare_exception(s->store, &pe->e)) {
free_pending_exception(pe);
return NULL;
}
get_pending_exception(pe);
- insert_exception(&s->pending, &pe->e);
+ dm_insert_exception(&s->pending, &pe->e);
- out:
return pe;
}
-static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e,
- struct bio *bio)
+static void remap_exception(struct dm_snapshot *s, struct dm_exception *e,
+ struct bio *bio, chunk_t chunk)
{
bio->bi_bdev = s->cow->bdev;
- bio->bi_sector = chunk_to_sector(s, e->new_chunk) +
- (bio->bi_sector & s->chunk_mask);
+ bio->bi_sector = chunk_to_sector(s->store,
+ dm_chunk_number(e->new_chunk) +
+ (chunk - e->old_chunk)) +
+ (bio->bi_sector &
+ s->store->chunk_mask);
}
static int snapshot_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
- struct dm_snap_exception *e;
+ struct dm_exception *e;
struct dm_snapshot *s = ti->private;
int r = DM_MAPIO_REMAPPED;
chunk_t chunk;
struct dm_snap_pending_exception *pe = NULL;
- chunk = sector_to_chunk(s, bio->bi_sector);
+ if (unlikely(bio_empty_barrier(bio))) {
+ bio->bi_bdev = s->cow->bdev;
+ return DM_MAPIO_REMAPPED;
+ }
+
+ chunk = sector_to_chunk(s->store, bio->bi_sector);
/* Full snapshots are not usable */
/* To get here the table must be live so s->active is always set. */
if (!s->valid)
return -EIO;
- if (unlikely(bio_barrier(bio)))
- return -EOPNOTSUPP;
-
/* FIXME: should only take write lock if we need
* to copy an exception */
down_write(&s->lock);
}
/* If the block is already remapped - use that, else remap it */
- e = lookup_exception(&s->complete, chunk);
+ e = dm_lookup_exception(&s->complete, chunk);
if (e) {
- remap_exception(s, e, bio);
+ remap_exception(s, e, bio, chunk);
goto out_unlock;
}
* writeable.
*/
if (bio_rw(bio) == WRITE) {
- pe = __find_pending_exception(s, bio);
+ pe = __lookup_pending_exception(s, chunk);
if (!pe) {
- __invalidate_snapshot(s, -ENOMEM);
- r = -EIO;
- goto out_unlock;
+ up_write(&s->lock);
+ pe = alloc_pending_exception(s);
+ down_write(&s->lock);
+
+ if (!s->valid) {
+ free_pending_exception(pe);
+ r = -EIO;
+ goto out_unlock;
+ }
+
+ e = dm_lookup_exception(&s->complete, chunk);
+ if (e) {
+ free_pending_exception(pe);
+ remap_exception(s, e, bio, chunk);
+ goto out_unlock;
+ }
+
+ pe = __find_pending_exception(s, pe, chunk);
+ if (!pe) {
+ __invalidate_snapshot(s, -ENOMEM);
+ r = -EIO;
+ goto out_unlock;
+ }
}
- remap_exception(s, &pe->e, bio);
+ remap_exception(s, &pe->e, bio, chunk);
bio_list_add(&pe->snapshot_bios, bio);
r = DM_MAPIO_SUBMITTED;
start_copy(pe);
goto out;
}
- } else
- /*
- * FIXME: this read path scares me because we
- * always use the origin when we have a pending
- * exception. However I can't think of a
- * situation where this is wrong - ejt.
- */
+ } else {
bio->bi_bdev = s->origin->bdev;
+ map_context->ptr = track_chunk(s, chunk);
+ }
out_unlock:
up_write(&s->lock);
return r;
}
+static int snapshot_end_io(struct dm_target *ti, struct bio *bio,
+ int error, union map_info *map_context)
+{
+ struct dm_snapshot *s = ti->private;
+ struct dm_snap_tracked_chunk *c = map_context->ptr;
+
+ if (c)
+ stop_tracking_chunk(s, c);
+
+ return 0;
+}
+
+static void snapshot_postsuspend(struct dm_target *ti)
+{
+ struct dm_snapshot *s = ti->private;
+
+ down_write(&s->lock);
+ s->suspended = 1;
+ up_write(&s->lock);
+}
+
static void snapshot_resume(struct dm_target *ti)
{
struct dm_snapshot *s = ti->private;
down_write(&s->lock);
s->active = 1;
+ s->suspended = 0;
up_write(&s->lock);
}
static int snapshot_status(struct dm_target *ti, status_type_t type,
char *result, unsigned int maxlen)
{
+ unsigned sz = 0;
struct dm_snapshot *snap = ti->private;
switch (type) {
case STATUSTYPE_INFO:
+
+ down_write(&snap->lock);
+
if (!snap->valid)
- snprintf(result, maxlen, "Invalid");
+ DMEMIT("Invalid");
else {
- if (snap->store.fraction_full) {
- sector_t numerator, denominator;
- snap->store.fraction_full(&snap->store,
- &numerator,
- &denominator);
- snprintf(result, maxlen, "%llu/%llu",
- (unsigned long long)numerator,
- (unsigned long long)denominator);
+ if (snap->store->type->usage) {
+ sector_t total_sectors, sectors_allocated,
+ metadata_sectors;
+ snap->store->type->usage(snap->store,
+ &total_sectors,
+ §ors_allocated,
+ &metadata_sectors);
+ DMEMIT("%llu/%llu %llu",
+ (unsigned long long)sectors_allocated,
+ (unsigned long long)total_sectors,
+ (unsigned long long)metadata_sectors);
}
else
- snprintf(result, maxlen, "Unknown");
+ DMEMIT("Unknown");
}
+
+ up_write(&snap->lock);
+
break;
case STATUSTYPE_TABLE:
* to make private copies if the output is to
* make sense.
*/
- snprintf(result, maxlen, "%s %s %c %llu",
- snap->origin->name, snap->cow->name,
- snap->type,
- (unsigned long long)snap->chunk_size);
+ DMEMIT("%s %s", snap->origin->name, snap->cow->name);
+ snap->store->type->status(snap->store, type, result + sz,
+ maxlen - sz);
break;
}
return 0;
}
+static int snapshot_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct dm_snapshot *snap = ti->private;
+
+ return fn(ti, snap->origin, 0, ti->len, data);
+}
+
+
/*-----------------------------------------------------------------
* Origin methods
*---------------------------------------------------------------*/
{
int r = DM_MAPIO_REMAPPED, first = 0;
struct dm_snapshot *snap;
- struct dm_snap_exception *e;
+ struct dm_exception *e;
struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL;
chunk_t chunk;
LIST_HEAD(pe_queue);
goto next_snapshot;
/* Nothing to do if writing beyond end of snapshot */
- if (bio->bi_sector >= dm_table_get_size(snap->table))
+ if (bio->bi_sector >= dm_table_get_size(snap->ti->table))
goto next_snapshot;
/*
* Remember, different snapshots can have
* different chunk sizes.
*/
- chunk = sector_to_chunk(snap, bio->bi_sector);
+ chunk = sector_to_chunk(snap->store, bio->bi_sector);
/*
* Check exception table to see if block
* ref_count is initialised to 1 so pending_complete()
* won't destroy the primary_pe while we're inside this loop.
*/
- e = lookup_exception(&snap->complete, chunk);
+ e = dm_lookup_exception(&snap->complete, chunk);
if (e)
goto next_snapshot;
- pe = __find_pending_exception(snap, bio);
+ pe = __lookup_pending_exception(snap, chunk);
if (!pe) {
- __invalidate_snapshot(snap, -ENOMEM);
- goto next_snapshot;
+ up_write(&snap->lock);
+ pe = alloc_pending_exception(snap);
+ down_write(&snap->lock);
+
+ if (!snap->valid) {
+ free_pending_exception(pe);
+ goto next_snapshot;
+ }
+
+ e = dm_lookup_exception(&snap->complete, chunk);
+ if (e) {
+ free_pending_exception(pe);
+ goto next_snapshot;
+ }
+
+ pe = __find_pending_exception(snap, pe, chunk);
+ if (!pe) {
+ __invalidate_snapshot(snap, -ENOMEM);
+ goto next_snapshot;
+ }
}
if (!primary_pe) {
}
ti->private = dev;
+ ti->num_flush_requests = 1;
+
return 0;
}
struct dm_dev *dev = ti->private;
bio->bi_bdev = dev->bdev;
- if (unlikely(bio_barrier(bio)))
- return -EOPNOTSUPP;
+ if (unlikely(bio_empty_barrier(bio)))
+ return DM_MAPIO_REMAPPED;
/* Only tell snapshots if this is a write */
return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
}
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
/*
* Set the target "split_io" field to the minimum of all the snapshots'
* chunk sizes.
static void origin_resume(struct dm_target *ti)
{
struct dm_dev *dev = ti->private;
- struct dm_snapshot *snap;
- struct origin *o;
- chunk_t chunk_size = 0;
down_read(&_origins_lock);
- o = __lookup_origin(dev->bdev);
- if (o)
- list_for_each_entry (snap, &o->snapshots, list)
- chunk_size = min_not_zero(chunk_size, snap->chunk_size);
- up_read(&_origins_lock);
- ti->split_io = chunk_size;
+ ti->split_io = __minimum_chunk_size(__lookup_origin(dev->bdev));
+
+ up_read(&_origins_lock);
}
static int origin_status(struct dm_target *ti, status_type_t type, char *result,
return 0;
}
+static int origin_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct dm_dev *dev = ti->private;
+
+ return fn(ti, dev, 0, ti->len, data);
+}
+
static struct target_type origin_target = {
.name = "snapshot-origin",
- .version = {1, 5, 0},
+ .version = {1, 7, 0},
.module = THIS_MODULE,
.ctr = origin_ctr,
.dtr = origin_dtr,
.map = origin_map,
.resume = origin_resume,
.status = origin_status,
+ .iterate_devices = origin_iterate_devices,
};
static struct target_type snapshot_target = {
.name = "snapshot",
- .version = {1, 5, 0},
+ .version = {1, 9, 0},
.module = THIS_MODULE,
.ctr = snapshot_ctr,
.dtr = snapshot_dtr,
.map = snapshot_map,
+ .end_io = snapshot_end_io,
+ .postsuspend = snapshot_postsuspend,
.resume = snapshot_resume,
.status = snapshot_status,
+ .iterate_devices = snapshot_iterate_devices,
};
static int __init dm_snapshot_init(void)
{
int r;
+ r = dm_exception_store_init();
+ if (r) {
+ DMERR("Failed to initialize exception stores");
+ return r;
+ }
+
r = dm_register_target(&snapshot_target);
if (r) {
DMERR("snapshot target register failed %d", r);
- return r;
+ goto bad_register_snapshot_target;
}
r = dm_register_target(&origin_target);
goto bad2;
}
- exception_cache = KMEM_CACHE(dm_snap_exception, 0);
+ exception_cache = KMEM_CACHE(dm_exception, 0);
if (!exception_cache) {
DMERR("Couldn't create exception cache.");
r = -ENOMEM;
goto bad4;
}
- pending_pool = mempool_create_slab_pool(128, pending_cache);
- if (!pending_pool) {
- DMERR("Couldn't create pending pool.");
+ tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0);
+ if (!tracked_chunk_cache) {
+ DMERR("Couldn't create cache to track chunks in use.");
r = -ENOMEM;
goto bad5;
}
if (!ksnapd) {
DMERR("Failed to create ksnapd workqueue.");
r = -ENOMEM;
- goto bad6;
+ goto bad_pending_pool;
}
return 0;
- bad6:
- mempool_destroy(pending_pool);
- bad5:
+bad_pending_pool:
+ kmem_cache_destroy(tracked_chunk_cache);
+bad5:
kmem_cache_destroy(pending_cache);
- bad4:
+bad4:
kmem_cache_destroy(exception_cache);
- bad3:
+bad3:
exit_origin_hash();
- bad2:
+bad2:
dm_unregister_target(&origin_target);
- bad1:
+bad1:
dm_unregister_target(&snapshot_target);
+
+bad_register_snapshot_target:
+ dm_exception_store_exit();
return r;
}
static void __exit dm_snapshot_exit(void)
{
- int r;
-
destroy_workqueue(ksnapd);
- r = dm_unregister_target(&snapshot_target);
- if (r)
- DMERR("snapshot unregister failed %d", r);
-
- r = dm_unregister_target(&origin_target);
- if (r)
- DMERR("origin unregister failed %d", r);
+ dm_unregister_target(&snapshot_target);
+ dm_unregister_target(&origin_target);
exit_origin_hash();
- mempool_destroy(pending_pool);
kmem_cache_destroy(pending_cache);
kmem_cache_destroy(exception_cache);
+ kmem_cache_destroy(tracked_chunk_cache);
+
+ dm_exception_store_exit();
}
/* Module hooks */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff