Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm (53365383) · Commits · 戴 / test

Documentation/device-mapper/snapshot.txt

+55 −5

Original line number	Diff line number	Diff line
		@@ -8,13 +8,19 @@ the block device which are also writable without interfering with the
		original content;
		*) To create device "forks", i.e. multiple different versions of the
		same data stream.
		*) To merge a snapshot of a block device back into the snapshot's origin
		device.

		In the first two cases, dm copies only the chunks of data that get
		changed and uses a separate copy-on-write (COW) block device for
		storage.

		In both cases, dm copies only the chunks of data that get changed and
		uses a separate copy-on-write (COW) block device for storage.
		For snapshot merge the contents of the COW storage are merged back into
		the origin device.


		There are two dm targets available: snapshot and snapshot-origin.
		There are three dm targets available:
		snapshot, snapshot-origin, and snapshot-merge.

		*) snapshot-origin <origin>

		@@ -40,8 +46,25 @@ The difference is that for transient snapshots less metadata must be
		saved on disk - they can be kept in memory by the kernel.


		How this is used by LVM2
		========================
		* snapshot-merge <origin> <COW device> <persistent> <chunksize>

		takes the same table arguments as the snapshot target except it only
		works with persistent snapshots. This target assumes the role of the
		"snapshot-origin" target and must not be loaded if the "snapshot-origin"
		is still present for <origin>.

		Creates a merging snapshot that takes control of the changed chunks
		stored in the <COW device> of an existing snapshot, through a handover
		procedure, and merges these chunks back into the <origin>. Once merging
		has started (in the background) the <origin> may be opened and the merge
		will continue while I/O is flowing to it. Changes to the <origin> are
		deferred until the merging snapshot's corresponding chunk(s) have been
		merged. Once merging has started the snapshot device, associated with
		the "snapshot" target, will return -EIO when accessed.


		How snapshot is used by LVM2
		============================
		When you create the first LVM2 snapshot of a volume, four dm devices are used:

		1) a device containing the original mapping table of the source volume;
		@@ -72,3 +95,30 @@ brw------- 1 root root 254, 12 29 ago 18:15 /dev/mapper/volumeGroup-snap-cow
		brw------- 1 root root 254, 13 29 ago 18:15 /dev/mapper/volumeGroup-snap
		brw------- 1 root root 254, 10 29 ago 18:14 /dev/mapper/volumeGroup-base


		How snapshot-merge is used by LVM2
		==================================
		A merging snapshot assumes the role of the "snapshot-origin" while
		merging. As such the "snapshot-origin" is replaced with
		"snapshot-merge". The "-real" device is not changed and the "-cow"
		device is renamed to <origin name>-cow to aid LVM2's cleanup of the
		merging snapshot after it completes. The "snapshot" that hands over its
		COW device to the "snapshot-merge" is deactivated (unless using lvchange
		--refresh); but if it is left active it will simply return I/O errors.

		A snapshot will merge into its origin with the following command:

		lvconvert --merge volumeGroup/snap

		we'll now have this situation:

		# dmsetup table\|grep volumeGroup

		volumeGroup-base-real: 0 2097152 linear 8:19 384
		volumeGroup-base-cow: 0 204800 linear 8:19 2097536
		volumeGroup-base: 0 2097152 snapshot-merge 254:11 254:12 P 16

		# ls -lL /dev/mapper/volumeGroup-*
		brw------- 1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
		brw------- 1 root root 254, 12 29 ago 18:16 /dev/mapper/volumeGroup-base-cow
		brw------- 1 root root 254, 10 29 ago 18:16 /dev/mapper/volumeGroup-base

drivers/md/dm-crypt.c

+139 −68

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2003 Christophe Saout <christophe@saout.de>
		* Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
		* Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved.
		* Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.
		*
		* This file is released under the GPL.
		*/
		@@ -71,10 +71,21 @@ struct crypt_iv_operations {
		int (ctr)(struct crypt_config cc, struct dm_target *ti,
		const char *opts);
		void (dtr)(struct crypt_config cc);
		const char (status)(struct crypt_config *cc);
		int (init)(struct crypt_config cc);
		int (wipe)(struct crypt_config cc);
		int (generator)(struct crypt_config cc, u8 *iv, sector_t sector);
		};

		struct iv_essiv_private {
		struct crypto_cipher *tfm;
		struct crypto_hash *hash_tfm;
		u8 *salt;
		};

		struct iv_benbi_private {
		int shift;
		};

		/*
		* Crypt: maps a linear range of a block device
		* and encrypts / decrypts at the same time.
		@@ -102,8 +113,8 @@ struct crypt_config {
		struct crypt_iv_operations *iv_gen_ops;
		char *iv_mode;
		union {
		struct crypto_cipher *essiv_tfm;
		int benbi_shift;
		struct iv_essiv_private essiv;
		struct iv_benbi_private benbi;
		} iv_gen_private;
		sector_t iv_offset;
		unsigned int iv_size;
		@@ -147,6 +158,9 @@ static void kcryptd_queue_crypt(struct dm_crypt_io *io);
		* plain: the initial vector is the 32-bit little-endian version of the sector
		* number, padded with zeros if necessary.
		*
		* plain64: the initial vector is the 64-bit little-endian version of the sector
		* number, padded with zeros if necessary.
		*
		* essiv: "encrypted sector\|salt initial vector", the sector number is
		* encrypted with the bulk cipher using a salt as key. The salt
		* should be derived from the bulk cipher's key via hashing.
		@@ -169,88 +183,123 @@ static int crypt_iv_plain_gen(struct crypt_config cc, u8 iv, sector_t sector)
		return 0;
		}

		static int crypt_iv_essiv_ctr(struct crypt_config cc, struct dm_target ti,
		const char *opts)
		static int crypt_iv_plain64_gen(struct crypt_config cc, u8 iv,
		sector_t sector)
		{
		struct crypto_cipher *essiv_tfm;
		struct crypto_hash *hash_tfm;
		memset(iv, 0, cc->iv_size);
		(u64 )iv = cpu_to_le64(sector);

		return 0;
		}

		/* Initialise ESSIV - compute salt but no local memory allocations */
		static int crypt_iv_essiv_init(struct crypt_config *cc)
		{
		struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
		struct hash_desc desc;
		struct scatterlist sg;
		unsigned int saltsize;
		u8 *salt;
		int err;

		if (opts == NULL) {
		sg_init_one(&sg, cc->key, cc->key_size);
		desc.tfm = essiv->hash_tfm;
		desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;

		err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt);
		if (err)
		return err;

		return crypto_cipher_setkey(essiv->tfm, essiv->salt,
		crypto_hash_digestsize(essiv->hash_tfm));
		}

		/* Wipe salt and reset key derived from volume key */
		static int crypt_iv_essiv_wipe(struct crypt_config *cc)
		{
		struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
		unsigned salt_size = crypto_hash_digestsize(essiv->hash_tfm);

		memset(essiv->salt, 0, salt_size);

		return crypto_cipher_setkey(essiv->tfm, essiv->salt, salt_size);
		}

		static void crypt_iv_essiv_dtr(struct crypt_config *cc)
		{
		struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;

		crypto_free_cipher(essiv->tfm);
		essiv->tfm = NULL;

		crypto_free_hash(essiv->hash_tfm);
		essiv->hash_tfm = NULL;

		kzfree(essiv->salt);
		essiv->salt = NULL;
		}

		static int crypt_iv_essiv_ctr(struct crypt_config cc, struct dm_target ti,
		const char *opts)
		{
		struct crypto_cipher *essiv_tfm = NULL;
		struct crypto_hash *hash_tfm = NULL;
		u8 *salt = NULL;
		int err;

		if (!opts) {
		ti->error = "Digest algorithm missing for ESSIV mode";
		return -EINVAL;
		}

		/* Hash the cipher key with the given hash algorithm */
		/* Allocate hash algorithm */
		hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
		if (IS_ERR(hash_tfm)) {
		ti->error = "Error initializing ESSIV hash";
		return PTR_ERR(hash_tfm);
		err = PTR_ERR(hash_tfm);
		goto bad;
		}

		saltsize = crypto_hash_digestsize(hash_tfm);
		salt = kmalloc(saltsize, GFP_KERNEL);
		if (salt == NULL) {
		salt = kzalloc(crypto_hash_digestsize(hash_tfm), GFP_KERNEL);
		if (!salt) {
		ti->error = "Error kmallocing salt storage in ESSIV";
		crypto_free_hash(hash_tfm);
		return -ENOMEM;
		}

		sg_init_one(&sg, cc->key, cc->key_size);
		desc.tfm = hash_tfm;
		desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
		err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
		crypto_free_hash(hash_tfm);

		if (err) {
		ti->error = "Error calculating hash in ESSIV";
		kfree(salt);
		return err;
		err = -ENOMEM;
		goto bad;
		}

		/* Setup the essiv_tfm with the given salt */
		/* Allocate essiv_tfm */
		essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
		if (IS_ERR(essiv_tfm)) {
		ti->error = "Error allocating crypto tfm for ESSIV";
		kfree(salt);
		return PTR_ERR(essiv_tfm);
		err = PTR_ERR(essiv_tfm);
		goto bad;
		}
		if (crypto_cipher_blocksize(essiv_tfm) !=
		crypto_ablkcipher_ivsize(cc->tfm)) {
		ti->error = "Block size of ESSIV cipher does "
		"not match IV size of block cipher";
		crypto_free_cipher(essiv_tfm);
		kfree(salt);
		return -EINVAL;
		}
		err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
		if (err) {
		ti->error = "Failed to set key for ESSIV cipher";
		crypto_free_cipher(essiv_tfm);
		kfree(salt);
		return err;
		err = -EINVAL;
		goto bad;
		}
		kfree(salt);

		cc->iv_gen_private.essiv_tfm = essiv_tfm;
		cc->iv_gen_private.essiv.salt = salt;
		cc->iv_gen_private.essiv.tfm = essiv_tfm;
		cc->iv_gen_private.essiv.hash_tfm = hash_tfm;

		return 0;
		}

		static void crypt_iv_essiv_dtr(struct crypt_config *cc)
		{
		crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
		cc->iv_gen_private.essiv_tfm = NULL;
		bad:
		if (essiv_tfm && !IS_ERR(essiv_tfm))
		crypto_free_cipher(essiv_tfm);
		if (hash_tfm && !IS_ERR(hash_tfm))
		crypto_free_hash(hash_tfm);
		kfree(salt);
		return err;
		}

		static int crypt_iv_essiv_gen(struct crypt_config cc, u8 iv, sector_t sector)
		{
		memset(iv, 0, cc->iv_size);
		(u64 )iv = cpu_to_le64(sector);
		crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
		crypto_cipher_encrypt_one(cc->iv_gen_private.essiv.tfm, iv, iv);
		return 0;
		}

		@@ -273,7 +322,7 @@ static int crypt_iv_benbi_ctr(struct crypt_config cc, struct dm_target ti,
		return -EINVAL;
		}

		cc->iv_gen_private.benbi_shift = 9 - log;
		cc->iv_gen_private.benbi.shift = 9 - log;

		return 0;
		}
		@@ -288,7 +337,7 @@ static int crypt_iv_benbi_gen(struct crypt_config cc, u8 iv, sector_t sector)

		memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */

		val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi_shift) + 1);
		val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi.shift) + 1);
		put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));

		return 0;
		@@ -305,9 +354,15 @@ static struct crypt_iv_operations crypt_iv_plain_ops = {
		.generator = crypt_iv_plain_gen
		};

		static struct crypt_iv_operations crypt_iv_plain64_ops = {
		.generator = crypt_iv_plain64_gen
		};

		static struct crypt_iv_operations crypt_iv_essiv_ops = {
		.ctr = crypt_iv_essiv_ctr,
		.dtr = crypt_iv_essiv_dtr,
		.init = crypt_iv_essiv_init,
		.wipe = crypt_iv_essiv_wipe,
		.generator = crypt_iv_essiv_gen
		};

		@@ -934,14 +989,14 @@ static int crypt_set_key(struct crypt_config cc, char key)

		set_bit(DM_CRYPT_KEY_VALID, &cc->flags);

		return 0;
		return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
		}

		static int crypt_wipe_key(struct crypt_config *cc)
		{
		clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
		memset(&cc->key, 0, cc->key_size * sizeof(u8));
		return 0;
		return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
		}

		/*
		@@ -983,11 +1038,6 @@ static int crypt_ctr(struct dm_target ti, unsigned int argc, char *argv)
		return -ENOMEM;
		}

		if (crypt_set_key(cc, argv[1])) {
		ti->error = "Error decoding key";
		goto bad_cipher;
		}

		/* Compatibility mode for old dm-crypt cipher strings */
		if (!chainmode \|\| (strcmp(chainmode, "plain") == 0 && !ivmode)) {
		chainmode = "cbc";
		@@ -1015,6 +1065,11 @@ static int crypt_ctr(struct dm_target ti, unsigned int argc, char *argv)
		strcpy(cc->chainmode, chainmode);
		cc->tfm = tfm;

		if (crypt_set_key(cc, argv[1]) < 0) {
		ti->error = "Error decoding and setting key";
		goto bad_ivmode;
		}

		/*
		* Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
		* See comments at iv code
		@@ -1024,6 +1079,8 @@ static int crypt_ctr(struct dm_target ti, unsigned int argc, char *argv)
		cc->iv_gen_ops = NULL;
		else if (strcmp(ivmode, "plain") == 0)
		cc->iv_gen_ops = &crypt_iv_plain_ops;
		else if (strcmp(ivmode, "plain64") == 0)
		cc->iv_gen_ops = &crypt_iv_plain64_ops;
		else if (strcmp(ivmode, "essiv") == 0)
		cc->iv_gen_ops = &crypt_iv_essiv_ops;
		else if (strcmp(ivmode, "benbi") == 0)
		@@ -1039,6 +1096,12 @@ static int crypt_ctr(struct dm_target ti, unsigned int argc, char *argv)
		cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
		goto bad_ivmode;

		if (cc->iv_gen_ops && cc->iv_gen_ops->init &&
		cc->iv_gen_ops->init(cc) < 0) {
		ti->error = "Error initialising IV";
		goto bad_slab_pool;
		}

		cc->iv_size = crypto_ablkcipher_ivsize(tfm);
		if (cc->iv_size)
		/* at least a 64 bit sector number should fit in our buffer */
		@@ -1085,11 +1148,6 @@ static int crypt_ctr(struct dm_target ti, unsigned int argc, char *argv)
		goto bad_bs;
		}

		if (crypto_ablkcipher_setkey(tfm, cc->key, key_size) < 0) {
		ti->error = "Error setting key";
		goto bad_device;
		}

		if (sscanf(argv[2], "%llu", &tmpll) != 1) {
		ti->error = "Invalid iv_offset sector";
		goto bad_device;
		@@ -1278,6 +1336,7 @@ static void crypt_resume(struct dm_target *ti)
		static int crypt_message(struct dm_target ti, unsigned argc, char *argv)
		{
		struct crypt_config *cc = ti->private;
		int ret = -EINVAL;

		if (argc < 2)
		goto error;
		@@ -1287,11 +1346,23 @@ static int crypt_message(struct dm_target ti, unsigned argc, char *argv)
		DMWARN("not suspended during key manipulation.");
		return -EINVAL;
		}
		if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
		return crypt_set_key(cc, argv[2]);
		if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
		if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) {
		ret = crypt_set_key(cc, argv[2]);
		if (ret)
		return ret;
		if (cc->iv_gen_ops && cc->iv_gen_ops->init)
		ret = cc->iv_gen_ops->init(cc);
		return ret;
		}
		if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) {
		if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
		ret = cc->iv_gen_ops->wipe(cc);
		if (ret)
		return ret;
		}
		return crypt_wipe_key(cc);
		}
		}

		error:
		DMWARN("unrecognised message received.");

drivers/md/dm-exception-store.c

+13 −20

Original line number	Diff line number	Diff line
		@@ -172,7 +172,8 @@ int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
		}

		/* Validate the chunk size against the device block size */
		if (chunk_size % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
		if (chunk_size %
		(bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9)) {
		*error = "Chunk size is not a multiple of device blocksize";
		return -EINVAL;
		}
		@@ -190,6 +191,7 @@ int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
		}

		int dm_exception_store_create(struct dm_target ti, int argc, char *argv,
		struct dm_snapshot *snap,
		unsigned *args_used,
		struct dm_exception_store **store)
		{
		@@ -198,7 +200,7 @@ int dm_exception_store_create(struct dm_target ti, int argc, char *argv,
		struct dm_exception_store *tmp_store;
		char persistent;

		if (argc < 3) {
		if (argc < 2) {
		ti->error = "Insufficient exception store arguments";
		return -EINVAL;
		}
		@@ -209,14 +211,15 @@ int dm_exception_store_create(struct dm_target ti, int argc, char *argv,
		return -ENOMEM;
		}

		persistent = toupper(*argv[1]);
		persistent = toupper(*argv[0]);
		if (persistent == 'P')
		type = get_type("P");
		else if (persistent == 'N')
		type = get_type("N");
		else {
		ti->error = "Persistent flag is not P or N";
		return -EINVAL;
		r = -EINVAL;
		goto bad_type;
		}

		if (!type) {
		@@ -226,32 +229,23 @@ int dm_exception_store_create(struct dm_target ti, int argc, char *argv,
		}

		tmp_store->type = type;
		tmp_store->ti = ti;

		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->snap = snap;

		r = set_chunk_size(tmp_store, argv[2], &ti->error);
		r = set_chunk_size(tmp_store, argv[1], &ti->error);
		if (r)
		goto bad_ctr;
		goto bad;

		r = type->ctr(tmp_store, 0, NULL);
		if (r) {
		ti->error = "Exception store type constructor failed";
		goto bad_ctr;
		goto bad;
		}

		*args_used = 3;
		*args_used = 2;
		*store = tmp_store;
		return 0;

		bad_ctr:
		dm_put_device(ti, tmp_store->cow);
		bad_cow:
		bad:
		put_type(type);
		bad_type:
		kfree(tmp_store);
		@@ -262,7 +256,6 @@ 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);
		}

drivers/md/dm-exception-store.h

+48 −14

Original line number	Diff line number	Diff line
		@@ -26,7 +26,7 @@ typedef sector_t chunk_t;
		* of chunks that follow contiguously. Remaining bits hold the number of the
		* chunk within the device.
		*/
		struct dm_snap_exception {
		struct dm_exception {
		struct list_head hash_list;

		chunk_t old_chunk;
		@@ -64,16 +64,33 @@ struct dm_exception_store_type {
		* Find somewhere to store the next exception.
		*/
		int (prepare_exception) (struct dm_exception_store store,
		struct dm_snap_exception *e);
		struct dm_exception *e);

		/*
		* Update the metadata with this exception.
		*/
		void (commit_exception) (struct dm_exception_store store,
		struct dm_snap_exception *e,
		struct dm_exception *e,
		void (callback) (void , int success),
		void *callback_context);

		/*
		* Returns 0 if the exception store is empty.
		*
		* If there are exceptions still to be merged, sets
		* last_old_chunk and last_new_chunk to the most recent
		* still-to-be-merged chunk and returns the number of
		* consecutive previous ones.
		*/
		int (prepare_merge) (struct dm_exception_store store,
		chunk_t last_old_chunk, chunk_t last_new_chunk);

		/*
		* Clear the last n exceptions.
		* nr_merged must be <= the value returned by prepare_merge.
		*/
		int (commit_merge) (struct dm_exception_store store, int nr_merged);

		/*
		* The snapshot is invalid, note this in the metadata.
		*/
		@@ -86,19 +103,19 @@ struct dm_exception_store_type {
		/*
		* Return how full the snapshot is.
		*/
		void (fraction_full) (struct dm_exception_store store,
		sector_t *numerator,
		sector_t *denominator);
		void (usage) (struct dm_exception_store store,
		sector_t total_sectors, sector_t sectors_allocated,
		sector_t *metadata_sectors);

		/* For internal device-mapper use only. */
		struct list_head list;
		};

		struct dm_snapshot;

		struct dm_exception_store {
		struct dm_exception_store_type *type;
		struct dm_target *ti;

		struct dm_dev *cow;
		struct dm_snapshot *snap;

		/* Size of data blocks saved - must be a power of 2 */
		unsigned chunk_size;
		@@ -108,6 +125,11 @@ struct dm_exception_store {
		void *context;
		};

		/*
		* Obtain the cow device used by a given snapshot.
		*/
		struct dm_dev dm_snap_cow(struct dm_snapshot snap);

		/*
		* Funtions to manipulate consecutive chunks
		*/
		@@ -120,18 +142,25 @@ static inline chunk_t dm_chunk_number(chunk_t chunk)
		return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL);
		}

		static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
		static inline unsigned dm_consecutive_chunk_count(struct dm_exception *e)
		{
		return e->new_chunk >> DM_CHUNK_NUMBER_BITS;
		}

		static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
		static inline void dm_consecutive_chunk_count_inc(struct dm_exception *e)
		{
		e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS);

		BUG_ON(!dm_consecutive_chunk_count(e));
		}

		static inline void dm_consecutive_chunk_count_dec(struct dm_exception *e)
		{
		BUG_ON(!dm_consecutive_chunk_count(e));

		e->new_chunk -= (1ULL << DM_CHUNK_NUMBER_BITS);
		}

		# else
		# define DM_CHUNK_CONSECUTIVE_BITS 0

		@@ -140,12 +169,16 @@ static inline chunk_t dm_chunk_number(chunk_t chunk)
		return chunk;
		}

		static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
		static inline unsigned dm_consecutive_chunk_count(struct dm_exception *e)
		{
		return 0;
		}

		static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
		static inline void dm_consecutive_chunk_count_inc(struct dm_exception *e)
		{
		}

		static inline void dm_consecutive_chunk_count_dec(struct dm_exception *e)
		{
		}

		@@ -162,7 +195,7 @@ static inline sector_t get_dev_size(struct block_device *bdev)
		static inline chunk_t sector_to_chunk(struct dm_exception_store *store,
		sector_t sector)
		{
		return (sector & ~store->chunk_mask) >> store->chunk_shift;
		return sector >> store->chunk_shift;
		}

		int dm_exception_store_type_register(struct dm_exception_store_type *type);
		@@ -173,6 +206,7 @@ int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
		char **error);

		int dm_exception_store_create(struct dm_target ti, int argc, char *argv,
		struct dm_snapshot *snap,
		unsigned *args_used,
		struct dm_exception_store **store);
		void dm_exception_store_destroy(struct dm_exception_store *store);

drivers/md/dm-io.c

+82 −38

Original line number	Diff line number	Diff line
		@@ -5,6 +5,8 @@
		* This file is released under the GPL.
		*/

		#include "dm.h"

		#include <linux/device-mapper.h>

		#include <linux/bio.h>
		@@ -14,12 +16,19 @@
		#include <linux/slab.h>
		#include <linux/dm-io.h>

		#define DM_MSG_PREFIX "io"

		#define DM_IO_MAX_REGIONS BITS_PER_LONG

		struct dm_io_client {
		mempool_t *pool;
		struct bio_set *bios;
		};

		/* FIXME: can we shrink this ? */
		/*
		* Aligning 'struct io' reduces the number of bits required to store
		* its address. Refer to store_io_and_region_in_bio() below.
		*/
		struct io {
		unsigned long error_bits;
		unsigned long eopnotsupp_bits;
		@@ -28,7 +37,9 @@ struct io {
		struct dm_io_client *client;
		io_notify_fn callback;
		void *context;
		};
		} __attribute__((aligned(DM_IO_MAX_REGIONS)));

		static struct kmem_cache *_dm_io_cache;

		/*
		* io contexts are only dynamically allocated for asynchronous
		@@ -53,7 +64,7 @@ struct dm_io_client *dm_io_client_create(unsigned num_pages)
		if (!client)
		return ERR_PTR(-ENOMEM);

		client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
		client->pool = mempool_create_slab_pool(ios, _dm_io_cache);
		if (!client->pool)
		goto bad;

		@@ -88,18 +99,29 @@ EXPORT_SYMBOL(dm_io_client_destroy);

		/*-----------------------------------------------------------------
		* We need to keep track of which region a bio is doing io for.
		* In order to save a memory allocation we store this the last
		* bvec which we know is unused (blech).
		* XXX This is ugly and can OOPS with some configs... find another way.
		* To avoid a memory allocation to store just 5 or 6 bits, we
		* ensure the 'struct io' pointer is aligned so enough low bits are
		* always zero and then combine it with the region number directly in
		* bi_private.
		---------------------------------------------------------------/
		static inline void bio_set_region(struct bio *bio, unsigned region)
		static void store_io_and_region_in_bio(struct bio bio, struct io io,
		unsigned region)
		{
		bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
		if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
		DMCRIT("Unaligned struct io pointer %p", io);
		BUG();
		}

		bio->bi_private = (void *)((unsigned long)io \| region);
		}

		static inline unsigned bio_get_region(struct bio *bio)
		static void retrieve_io_and_region_from_bio(struct bio bio, struct io *io,
		unsigned *region)
		{
		return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
		unsigned long val = (unsigned long)bio->bi_private;

		io = (void )(val & -(unsigned long)DM_IO_MAX_REGIONS);
		*region = val & (DM_IO_MAX_REGIONS - 1);
		}

		/*-----------------------------------------------------------------
		@@ -140,10 +162,8 @@ static void endio(struct bio *bio, int error)
		/*
		* The bio destructor in bio_put() may use the io object.
		*/
		io = bio->bi_private;
		region = bio_get_region(bio);
		retrieve_io_and_region_from_bio(bio, &io, &region);

		bio->bi_max_vecs++;
		bio_put(bio);

		dec_count(io, region, error);
		@@ -243,7 +263,10 @@ static void vm_dp_init(struct dpages dp, void data)

		static void dm_bio_destructor(struct bio *bio)
		{
		struct io *io = bio->bi_private;
		unsigned region;
		struct io *io;

		retrieve_io_and_region_from_bio(bio, &io, &region);

		bio_free(bio, io->client->bios);
		}
		@@ -286,26 +309,23 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
		unsigned num_bvecs;
		sector_t remaining = where->count;

		while (remaining) {
		/*
		* Allocate a suitably sized-bio: we add an extra
		* bvec for bio_get/set_region() and decrement bi_max_vecs
		* to hide it from bio_add_page().
		* where->count may be zero if rw holds a write barrier and we
		* need to send a zero-sized barrier.
		*/
		do {
		/*
		* Allocate a suitably sized-bio.
		*/
		num_bvecs = dm_sector_div_up(remaining,
		(PAGE_SIZE >> SECTOR_SHIFT));
		num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev),
		num_bvecs);
		if (unlikely(num_bvecs > BIO_MAX_PAGES))
		num_bvecs = BIO_MAX_PAGES;
		num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev), num_bvecs);
		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
		bio->bi_sector = where->sector + (where->count - remaining);
		bio->bi_bdev = where->bdev;
		bio->bi_end_io = endio;
		bio->bi_private = io;
		bio->bi_destructor = dm_bio_destructor;
		bio->bi_max_vecs--;
		bio_set_region(bio, region);
		store_io_and_region_in_bio(bio, io, region);

		/*
		* Try and add as many pages as possible.
		@@ -323,7 +343,7 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,

		atomic_inc(&io->count);
		submit_bio(rw, bio);
		}
		} while (remaining);
		}

		static void dispatch_io(int rw, unsigned int num_regions,
		@@ -333,6 +353,8 @@ static void dispatch_io(int rw, unsigned int num_regions,
		int i;
		struct dpages old_pages = *dp;

		BUG_ON(num_regions > DM_IO_MAX_REGIONS);

		if (sync)
		rw \|= (1 << BIO_RW_SYNCIO) \| (1 << BIO_RW_UNPLUG);

		@@ -342,7 +364,7 @@ static void dispatch_io(int rw, unsigned int num_regions,
		*/
		for (i = 0; i < num_regions; i++) {
		*dp = old_pages;
		if (where[i].count)
		if (where[i].count \|\| (rw & (1 << BIO_RW_BARRIER)))
		do_region(rw, i, where + i, dp, io);
		}

		@@ -357,7 +379,14 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
		struct dm_io_region where, int rw, struct dpages dp,
		unsigned long *error_bits)
		{
		struct io io;
		/*
		* gcc <= 4.3 can't do the alignment for stack variables, so we must
		* align it on our own.
		* volatile prevents the optimizer from removing or reusing
		* "io_" field from the stack frame (allowed in ANSI C).
		*/
		volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
		struct io io = (struct io )PTR_ALIGN(&io_, __alignof__(struct io));

		if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
		WARN_ON(1);
		@@ -365,33 +394,33 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
		}

		retry:
		io.error_bits = 0;
		io.eopnotsupp_bits = 0;
		atomic_set(&io.count, 1); /* see dispatch_io() */
		io.sleeper = current;
		io.client = client;
		io->error_bits = 0;
		io->eopnotsupp_bits = 0;
		atomic_set(&io->count, 1); /* see dispatch_io() */
		io->sleeper = current;
		io->client = client;

		dispatch_io(rw, num_regions, where, dp, &io, 1);
		dispatch_io(rw, num_regions, where, dp, io, 1);

		while (1) {
		set_current_state(TASK_UNINTERRUPTIBLE);

		if (!atomic_read(&io.count))
		if (!atomic_read(&io->count))
		break;

		io_schedule();
		}
		set_current_state(TASK_RUNNING);

		if (io.eopnotsupp_bits && (rw & (1 << BIO_RW_BARRIER))) {
		if (io->eopnotsupp_bits && (rw & (1 << BIO_RW_BARRIER))) {
		rw &= ~(1 << BIO_RW_BARRIER);
		goto retry;
		}

		if (error_bits)
		*error_bits = io.error_bits;
		*error_bits = io->error_bits;

		return io.error_bits ? -EIO : 0;
		return io->error_bits ? -EIO : 0;
		}

		static int async_io(struct dm_io_client *client, unsigned int num_regions,
		@@ -472,3 +501,18 @@ int dm_io(struct dm_io_request *io_req, unsigned num_regions,
		&dp, io_req->notify.fn, io_req->notify.context);
		}
		EXPORT_SYMBOL(dm_io);

		int __init dm_io_init(void)
		{
		_dm_io_cache = KMEM_CACHE(io, 0);
		if (!_dm_io_cache)
		return -ENOMEM;

		return 0;
		}

		void dm_io_exit(void)
		{
		kmem_cache_destroy(_dm_io_cache);
		_dm_io_cache = NULL;
		}

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