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Subjectdm-crypt using kthread (was: Oopsing cryptoapi (or loop device?) on 2.6.*)
On Sun, Feb 15, 2004 at 07:46:33PM +0000, Christoph Hellwig wrote:
> Well, actually the above code should not enter the kernel tree at all.
> Care to rewrite dm-crypt to use Rusty's kthread code in -mm instead and
> submit a patch to Andrew? Whenever he merges the kthread stuff to mainline
> he could just include dm-crypt then.

In spite of the objections I've decided to give it a try.

It's working fine this way and it seems to work fine. The overhead is
very small.


diff -Nur linux-2.6.3-rc3-mm1.orig/drivers/md/dm-crypt.c linux-2.6.3-rc3-mm1/drivers/md/dm-crypt.c
--- linux-2.6.3-rc3-mm1.orig/drivers/md/dm-crypt.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.3-rc3-mm1/drivers/md/dm-crypt.c 2004-02-16 01:47:37.000000000 +0100
@@ -0,0 +1,815 @@
+/*
+ * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/mempool.h>
+#include <linux/slab.h>
+#include <linux/crypto.h>
+#include <linux/spinlock.h>
+#include <linux/kthread.h>
+#include <asm/scatterlist.h>
+
+#include "dm.h"
+#include "dm-bio-list.h"
+
+/*
+ * per bio private data
+ */
+struct crypt_io {
+ struct dm_target *target;
+ struct bio *bio;
+ struct bio *first_clone;
+ atomic_t pending;
+ int error;
+};
+
+/*
+ * context holding the current state of a multi-part conversion
+ */
+struct convert_context {
+ struct bio *bio_in;
+ struct bio *bio_out;
+ unsigned int offset_in;
+ unsigned int offset_out;
+ int idx_in;
+ int idx_out;
+ sector_t sector;
+ int write;
+};
+
+/*
+ * Crypt: maps a linear range of a block device
+ * and encrypts / decrypts at the same time.
+ */
+struct crypt_config {
+ struct dm_dev *dev;
+ sector_t start;
+
+ /*
+ * pool for per bio private data and
+ * for encryption buffer pages
+ */
+ mempool_t *io_pool;
+ mempool_t *page_pool;
+
+ /*
+ * crypto related data
+ */
+ struct crypto_tfm *tfm;
+ sector_t iv_offset;
+ int (*iv_generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
+ int iv_size;
+ int key_size;
+ u8 key[0];
+};
+
+#define MIN_IOS 256
+#define MIN_POOL_PAGES 32
+#define MIN_BIO_PAGES 8
+
+static kmem_cache_t *_crypt_io_pool;
+
+/*
+ * Mempool alloc and free functions for the page
+ */
+static void *mempool_alloc_page(int gfp_mask, void *data)
+{
+ return alloc_page(gfp_mask);
+}
+
+static void mempool_free_page(void *page, void *data)
+{
+ __free_page(page);
+}
+
+
+/*
+ * Different IV generation algorithms
+ */
+static int crypt_iv_plain(struct crypt_config *cc, u8 *iv, sector_t sector)
+{
+ *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
+ if (cc->iv_size > sizeof(u32) / sizeof(u8))
+ memset(iv + (sizeof(u32) / sizeof(u8)), 0,
+ cc->iv_size - (sizeof(u32) / sizeof(u8)));
+
+ return 0;
+}
+
+static inline int
+crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
+ struct scatterlist *in, unsigned int length,
+ int write, sector_t sector)
+{
+ u8 iv[cc->iv_size];
+ int r;
+
+ if (cc->iv_generator) {
+ r = cc->iv_generator(cc, iv, sector);
+ if (r < 0)
+ return r;
+
+ if (write)
+ r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv);
+ else
+ r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv);
+ } else {
+ if (write)
+ r = crypto_cipher_encrypt(cc->tfm, out, in, length);
+ else
+ r = crypto_cipher_decrypt(cc->tfm, out, in, length);
+ }
+
+ return r;
+}
+
+static void
+crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
+ struct bio *bio_out, struct bio *bio_in,
+ sector_t sector, int write)
+{
+ ctx->bio_in = bio_in;
+ ctx->bio_out = bio_out;
+ ctx->offset_in = 0;
+ ctx->offset_out = 0;
+ ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
+ ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
+ ctx->sector = sector + cc->iv_offset;
+ ctx->write = write;
+}
+
+/*
+ * Encrypt / decrypt data from one bio to another one (can be the same one)
+ */
+static int crypt_convert(struct crypt_config *cc,
+ struct convert_context *ctx)
+{
+ int r = 0;
+
+ while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
+ ctx->idx_out < ctx->bio_out->bi_vcnt) {
+ struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
+ struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
+ struct scatterlist sg_in = {
+ .page = bv_in->bv_page,
+ .offset = bv_in->bv_offset + ctx->offset_in,
+ .length = 1 << SECTOR_SHIFT
+ };
+ struct scatterlist sg_out = {
+ .page = bv_out->bv_page,
+ .offset = bv_out->bv_offset + ctx->offset_out,
+ .length = 1 << SECTOR_SHIFT
+ };
+
+ ctx->offset_in += sg_in.length;
+ if (ctx->offset_in >= bv_in->bv_len) {
+ ctx->offset_in = 0;
+ ctx->idx_in++;
+ }
+
+ ctx->offset_out += sg_out.length;
+ if (ctx->offset_out >= bv_out->bv_len) {
+ ctx->offset_out = 0;
+ ctx->idx_out++;
+ }
+
+ r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
+ ctx->write, ctx->sector);
+ if (r < 0)
+ break;
+
+ ctx->sector++;
+ }
+
+ return r;
+}
+
+/*
+ * Generate a new unfragmented bio with the given size
+ * This should never violate the device limitations
+ * May return a smaller bio when running out of pages
+ */
+static struct bio *
+crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
+ struct bio *base_bio, int *bio_vec_idx)
+{
+ struct bio *bio;
+ int nr_iovecs = dm_div_up(size, PAGE_SIZE);
+ int gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
+ int flags = current->flags;
+ int i;
+
+ /*
+ * Tell VM to act less aggressively and fail earlier.
+ * This is not necessary but increases throughput.
+ * FIXME: Is this really intelligent?
+ */
+ current->flags &= ~PF_MEMALLOC;
+
+ if (base_bio)
+ bio = bio_clone(base_bio, GFP_NOIO);
+ else
+ bio = bio_alloc(GFP_NOIO, nr_iovecs);
+ if (!bio)
+ return NULL;
+
+ /* if the last bio was not complete, continue where that one ended */
+ bio->bi_idx = *bio_vec_idx;
+ bio->bi_vcnt = *bio_vec_idx;
+ bio->bi_size = 0;
+ bio->bi_flags &= ~(1 << BIO_SEG_VALID);
+
+ /* bio->bi_idx pages have already been allocated */
+ size -= bio->bi_idx * PAGE_SIZE;
+
+ for(i = bio->bi_idx; i < nr_iovecs; i++) {
+ struct bio_vec *bv = bio_iovec_idx(bio, i);
+
+ bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
+ if (!bv->bv_page)
+ break;
+
+ /*
+ * if additional pages cannot be allocated without waiting,
+ * return a partially allocated bio, the caller will then try
+ * to allocate additional bios while submitting this partial bio
+ */
+ if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1))
+ gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
+
+ bv->bv_offset = 0;
+ if (size > PAGE_SIZE)
+ bv->bv_len = PAGE_SIZE;
+ else
+ bv->bv_len = size;
+
+ bio->bi_size += bv->bv_len;
+ bio->bi_vcnt++;
+ size -= bv->bv_len;
+ }
+
+ if (flags & PF_MEMALLOC)
+ current->flags |= PF_MEMALLOC;
+
+ if (!bio->bi_size) {
+ bio_put(bio);
+ return NULL;
+ }
+
+ /*
+ * Remember the last bio_vec allocated to be able
+ * to correctly continue after the splitting.
+ */
+ *bio_vec_idx = bio->bi_vcnt;
+
+ return bio;
+}
+
+static void crypt_free_buffer_pages(struct crypt_config *cc,
+ struct bio *bio, unsigned int bytes)
+{
+ unsigned int start, end;
+ struct bio_vec *bv;
+ int i;
+
+ /*
+ * This is ugly, but Jens Axboe thinks that using bi_idx in the
+ * endio function is too dangerous at the moment, so I calculate the
+ * correct position using bi_vcnt and bi_size.
+ * The bv_offset and bv_len fields might already be modified but we
+ * know that we always allocated whole pages.
+ * A fix to the bi_idx issue in the kernel is in the works, so
+ * we will hopefully be able to revert to the cleaner solution soon.
+ */
+ i = bio->bi_vcnt - 1;
+ bv = bio_iovec_idx(bio, i);
+ end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size;
+ start = end - bytes;
+
+ start >>= PAGE_SHIFT;
+ if (!bio->bi_size)
+ end = bio->bi_vcnt;
+ else
+ end >>= PAGE_SHIFT;
+
+ for(i = start; i < end; i++) {
+ bv = bio_iovec_idx(bio, i);
+ BUG_ON(!bv->bv_page);
+ mempool_free(bv->bv_page, cc->page_pool);
+ bv->bv_page = NULL;
+ }
+}
+
+/*
+ * One of the bios was finished. Check for completion of
+ * the whole request and correctly clean up the buffer.
+ */
+static void dec_pending(struct crypt_io *io, int error)
+{
+ struct crypt_config *cc = (struct crypt_config *) io->target->private;
+
+ if (error < 0)
+ io->error = error;
+
+ if (!atomic_dec_and_test(&io->pending))
+ return;
+
+ if (io->first_clone)
+ bio_put(io->first_clone);
+
+ if (io->bio)
+ bio_endio(io->bio, io->bio->bi_size, io->error);
+
+ mempool_free(io, cc->io_pool);
+}
+
+/*
+ * kcryptd:
+ *
+ * Needed because it would be very unwise to do decryption in an
+ * interrupt context, so bios returning from read requests get
+ * queued here.
+ */
+static spinlock_t _kcryptd_lock = SPIN_LOCK_UNLOCKED;
+static struct bio_list _kcryptd_bios;
+
+static struct task_struct *_kcryptd;
+
+/*
+ * Fetch a list of the complete bios.
+ */
+static struct bio *kcryptd_get_bios(void)
+{
+ struct bio *bio;
+
+ spin_lock_irq(&_kcryptd_lock);
+ bio = bio_list_get(&_kcryptd_bios);
+ spin_unlock_irq(&_kcryptd_lock);
+
+ return bio;
+}
+
+/*
+ * Append bio to work queue
+ */
+static void kcryptd_queue_bio(struct bio *bio)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&_kcryptd_lock, flags);
+ bio_list_add(&_kcryptd_bios, bio);
+ spin_unlock_irqrestore(&_kcryptd_lock, flags);
+}
+
+static int kcryptd_do_work(void *data)
+{
+ current->flags |= PF_IOTHREAD;
+
+ for(;;) {
+ struct bio *bio;
+
+ set_task_state(current, TASK_INTERRUPTIBLE);
+ while (!(bio = kcryptd_get_bios())) {
+ schedule();
+ if (signal_pending(current))
+ return 0;
+ }
+ set_task_state(current, TASK_RUNNING);
+
+ while (bio) {
+ struct crypt_io *io;
+ struct crypt_config *cc;
+ struct convert_context ctx;
+ struct bio *next_bio;
+ int r;
+
+ io = (struct crypt_io *) bio->bi_private;
+ cc = (struct crypt_config *) io->target->private;
+
+ crypt_convert_init(cc, &ctx, io->bio, io->bio,
+ io->bio->bi_sector - io->target->begin, 0);
+ r = crypt_convert(cc, &ctx);
+
+ next_bio = bio->bi_next;
+ bio->bi_next = NULL;
+
+ bio_put(bio);
+ dec_pending(io, r);
+
+ bio = next_bio;
+ }
+ }
+}
+
+/*
+ * Decode key from its hex representation
+ */
+static int crypt_decode_key(u8 *key, char *hex, int size)
+{
+ char buffer[3];
+ char *endp;
+ int i;
+
+ buffer[2] = '\0';
+
+ for(i = 0; i < size; i++) {
+ buffer[0] = *hex++;
+ buffer[1] = *hex++;
+
+ key[i] = (u8)simple_strtoul(buffer, &endp, 16);
+
+ if (endp != &buffer[2])
+ return -EINVAL;
+ }
+
+ if (*hex != '\0')
+ return -EINVAL;
+
+ return 0;
+}
+
+/*
+ * Encode key into its hex representation
+ */
+static void crypt_encode_key(char *hex, u8 *key, int size)
+{
+ static char hex_digits[] = "0123456789abcdef";
+ int i;
+
+ for(i = 0; i < size; i++) {
+ *hex++ = hex_digits[*key >> 4];
+ *hex++ = hex_digits[*key & 0x0f];
+ key++;
+ }
+
+ *hex++ = '\0';
+}
+
+/*
+ * Construct an encryption mapping:
+ * <cipher> <key> <iv_offset> <dev_path> <start>
+ */
+static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+ struct crypt_config *cc;
+ struct crypto_tfm *tfm;
+ char *tmp;
+ char *cipher;
+ char *mode;
+ int crypto_flags;
+ int key_size;
+
+ if (argc != 5) {
+ ti->error = "dm-crypt: Not enough arguments";
+ return -EINVAL;
+ }
+
+ tmp = argv[0];
+ cipher = strsep(&tmp, "-");
+ mode = strsep(&tmp, "-");
+
+ if (tmp)
+ DMWARN("dm-crypt: Unexpected additional cipher options");
+
+ key_size = strlen(argv[1]) >> 1;
+
+ cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
+ if (cc == NULL) {
+ ti->error =
+ "dm-crypt: Cannot allocate transparent encryption context";
+ return -ENOMEM;
+ }
+
+ if (!mode || strcmp(mode, "plain") == 0)
+ cc->iv_generator = crypt_iv_plain;
+ else if (strcmp(mode, "ecb") == 0)
+ cc->iv_generator = NULL;
+ else {
+ ti->error = "dm-crypt: Invalid chaining mode";
+ return -EINVAL;
+ }
+
+ if (cc->iv_generator)
+ crypto_flags = CRYPTO_TFM_MODE_CBC;
+ else
+ crypto_flags = CRYPTO_TFM_MODE_ECB;
+
+ tfm = crypto_alloc_tfm(cipher, crypto_flags);
+ if (!tfm) {
+ ti->error = "dm-crypt: Error allocating crypto tfm";
+ goto bad1;
+ }
+
+ if (tfm->crt_u.cipher.cit_decrypt_iv && tfm->crt_u.cipher.cit_encrypt_iv)
+ /* at least a 32 bit sector number should fit in our buffer */
+ cc->iv_size = max(crypto_tfm_alg_ivsize(tfm),
+ (unsigned int)(sizeof(u32) / sizeof(u8)));
+ else {
+ cc->iv_size = 0;
+ if (cc->iv_generator) {
+ DMWARN("dm-crypt: Selected cipher does not support IVs");
+ cc->iv_generator = NULL;
+ }
+ }
+
+ cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
+ mempool_free_slab, _crypt_io_pool);
+ if (!cc->io_pool) {
+ ti->error = "dm-crypt: Cannot allocate crypt io mempool";
+ goto bad2;
+ }
+
+ cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page,
+ mempool_free_page, NULL);
+ if (!cc->page_pool) {
+ ti->error = "dm-crypt: Cannot allocate page mempool";
+ goto bad3;
+ }
+
+ cc->tfm = tfm;
+ cc->key_size = key_size;
+ if ((key_size == 0 && strcmp(argv[1], "-") != 0)
+ || crypt_decode_key(cc->key, argv[1], key_size) < 0) {
+ ti->error = "dm-crypt: Error decoding key";
+ goto bad4;
+ }
+
+ if (tfm->crt_u.cipher.cit_setkey(tfm, cc->key, key_size) < 0) {
+ ti->error = "dm-crypt: Error setting key";
+ goto bad4;
+ }
+
+ if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) {
+ ti->error = "dm-crypt: Invalid iv_offset sector";
+ goto bad4;
+ }
+
+ if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) {
+ ti->error = "dm-crypt: Invalid device sector";
+ goto bad4;
+ }
+
+ if (dm_get_device(ti, argv[3], cc->start, ti->len,
+ dm_table_get_mode(ti->table), &cc->dev)) {
+ ti->error = "dm-crypt: Device lookup failed";
+ goto bad4;
+ }
+
+ ti->private = cc;
+ return 0;
+
+bad4:
+ mempool_destroy(cc->page_pool);
+bad3:
+ mempool_destroy(cc->io_pool);
+bad2:
+ crypto_free_tfm(tfm);
+bad1:
+ kfree(cc);
+ return -EINVAL;
+}
+
+static void crypt_dtr(struct dm_target *ti)
+{
+ struct crypt_config *cc = (struct crypt_config *) ti->private;
+
+ mempool_destroy(cc->page_pool);
+ mempool_destroy(cc->io_pool);
+
+ crypto_free_tfm(cc->tfm);
+ dm_put_device(ti, cc->dev);
+ kfree(cc);
+}
+
+static int crypt_endio(struct bio *bio, unsigned int done, int error)
+{
+ struct crypt_io *io = (struct crypt_io *) bio->bi_private;
+ struct crypt_config *cc = (struct crypt_config *) io->target->private;
+
+ if (bio_rw(bio) == WRITE) {
+ /*
+ * free the processed pages, even if
+ * it's only a partially completed write
+ */
+ crypt_free_buffer_pages(cc, bio, done);
+ }
+
+ if (bio->bi_size)
+ return 1;
+
+ /*
+ * successful reads are decrypted by the worker thread
+ */
+ if ((bio_rw(bio) == READ || bio_rw(bio) == READA)
+ && bio_flagged(bio, BIO_UPTODATE)) {
+ kcryptd_queue_bio(bio);
+ wake_up_process(_kcryptd);
+ return 0;
+ }
+
+ bio_put(bio);
+ dec_pending(io, error);
+
+ return error;
+}
+
+static int crypt_map(struct dm_target *ti, struct bio *bio,
+ union map_info *map_context)
+{
+ struct crypt_config *cc = (struct crypt_config *) ti->private;
+ struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO);
+ struct bio *clone = NULL;
+ struct convert_context ctx;
+ unsigned int remaining = bio->bi_size;
+ sector_t sector = bio->bi_sector - ti->begin;
+ int bio_vec_idx = 0;
+ int r = 0;
+
+ io->target = ti;
+ io->bio = bio;
+ io->first_clone = NULL;
+ io->error = 0;
+ atomic_set(&io->pending, 1); /* hold a reference */
+
+ if (bio_rw(bio) == WRITE)
+ crypt_convert_init(cc, &ctx, NULL, bio, sector, 1);
+
+ /*
+ * The allocated buffers can be smaller than the whole bio,
+ * so repeat the whole process until all the data can be handled.
+ */
+ while (remaining) {
+ if (bio_rw(bio) == WRITE) {
+ clone = crypt_alloc_buffer(cc, bio->bi_size,
+ io->first_clone,
+ &bio_vec_idx);
+ if (clone) {
+ ctx.bio_out = clone;
+ r = crypt_convert(cc, &ctx);
+ if (r < 0) {
+ crypt_free_buffer_pages(cc, clone,
+ clone->bi_size);
+ bio_put(clone);
+ goto cleanup;
+ }
+ }
+ } else
+ clone = bio_clone(bio, GFP_NOIO);
+
+ if (!clone) {
+ r = -ENOMEM;
+ goto cleanup;
+ }
+
+ if (!io->first_clone) {
+ /*
+ * hold a reference to the first clone, because it
+ * holds the bio_vec array and that can't be freed
+ * before all other clones are released
+ */
+ bio_get(clone);
+ io->first_clone = clone;
+ }
+ atomic_inc(&io->pending);
+
+ clone->bi_private = io;
+ clone->bi_end_io = crypt_endio;
+ clone->bi_bdev = cc->dev->bdev;
+ clone->bi_sector = cc->start + sector;
+ clone->bi_rw = bio->bi_rw;
+
+ remaining -= clone->bi_size;
+ sector += bio_sectors(clone);
+
+ generic_make_request(clone);
+ }
+
+ /* drop reference, clones could have returned before we reach this */
+ dec_pending(io, 0);
+ return 0;
+
+cleanup:
+ if (io->first_clone) {
+ dec_pending(io, r);
+ return 0;
+ }
+
+ /* if no bio has been dispatched yet, we can directly return the error */
+ mempool_free(io, cc->io_pool);
+ return r;
+}
+
+static int crypt_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned int maxlen)
+{
+ struct crypt_config *cc = (struct crypt_config *) ti->private;
+ char buffer[32];
+ const char *cipher;
+ const char *mode = NULL;
+ int offset;
+
+ switch (type) {
+ case STATUSTYPE_INFO:
+ result[0] = '\0';
+ break;
+
+ case STATUSTYPE_TABLE:
+ cipher = crypto_tfm_alg_name(cc->tfm);
+
+ switch(cc->tfm->crt_u.cipher.cit_mode) {
+ case CRYPTO_TFM_MODE_CBC:
+ mode = "plain";
+ break;
+ case CRYPTO_TFM_MODE_ECB:
+ mode = "ecb";
+ break;
+ default:
+ BUG();
+ }
+
+ snprintf(result, maxlen, "%s-%s ", cipher, mode);
+ offset = strlen(result);
+
+ if (cc->key_size > 0) {
+ if ((maxlen - offset) < ((cc->key_size << 1) + 1))
+ return -ENOMEM;
+
+ crypt_encode_key(result + offset, cc->key, cc->key_size);
+ offset += cc->key_size << 1;
+ } else {
+ if (offset >= maxlen)
+ return -ENOMEM;
+ result[offset++] = '-';
+ }
+
+ format_dev_t(buffer, cc->dev->bdev->bd_dev);
+ snprintf(result + offset, maxlen - offset, " " SECTOR_FORMAT
+ " %s " SECTOR_FORMAT, cc->iv_offset,
+ buffer, cc->start);
+ break;
+ }
+ return 0;
+}
+
+static struct target_type crypt_target = {
+ .name = "crypt",
+ .module = THIS_MODULE,
+ .ctr = crypt_ctr,
+ .dtr = crypt_dtr,
+ .map = crypt_map,
+ .status = crypt_status,
+};
+
+static int __init dm_crypt_init(void)
+{
+ int r;
+
+ _crypt_io_pool = kmem_cache_create("dm-crypt_io",
+ sizeof(struct crypt_io),
+ 0, 0, NULL, NULL);
+ if (!_crypt_io_pool)
+ return -ENOMEM;
+
+ _kcryptd = kthread_create(kcryptd_do_work, NULL, "kcryptd");
+ if (IS_ERR(_kcryptd)) {
+ r = PTR_ERR(_kcryptd);
+ DMERR("couldn't create kcryptd: %d", r);
+ kmem_cache_destroy(_crypt_io_pool);
+ return r;
+ }
+
+ r = dm_register_target(&crypt_target);
+ if (r < 0) {
+ DMERR("crypt: register failed %d", r);
+ kthread_stop(_kcryptd);
+ kmem_cache_destroy(_crypt_io_pool);
+ return r;
+ }
+
+ wake_up_process(_kcryptd);
+ return 0;
+}
+
+static void __exit dm_crypt_exit(void)
+{
+ int r = dm_unregister_target(&crypt_target);
+
+ if (r < 0)
+ DMERR("crypt: unregister failed %d", r);
+
+ kthread_stop(_kcryptd);
+ kmem_cache_destroy(_crypt_io_pool);
+}
+
+module_init(dm_crypt_init);
+module_exit(dm_crypt_exit);
+
+MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
+MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
+MODULE_LICENSE("GPL");
diff -Nur linux-2.6.3-rc3-mm1.orig/drivers/md/Kconfig linux-2.6.3-rc3-mm1/drivers/md/Kconfig
--- linux-2.6.3-rc3-mm1.orig/drivers/md/Kconfig 2004-02-10 18:06:13.000000000 +0100
+++ linux-2.6.3-rc3-mm1/drivers/md/Kconfig 2004-02-16 01:30:51.000000000 +0100
@@ -170,5 +170,17 @@
Recent tools use a new version of the ioctl interface, only
select this option if you intend using such tools.

+config DM_CRYPT
+ tristate "Crypt target support"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ select CRYPTO
+ ---help---
+ This device-mapper target allows you to create a device that
+ transparently encrypts the data on it. You'll need to activate
+ the required ciphers in the cryptoapi configuration in order to
+ be able to use it.
+
+ If unsure, say N.
+
endmenu

diff -Nur linux-2.6.3-rc3-mm1.orig/drivers/md/Makefile linux-2.6.3-rc3-mm1/drivers/md/Makefile
--- linux-2.6.3-rc3-mm1.orig/drivers/md/Makefile 2004-02-16 01:24:17.000000000 +0100
+++ linux-2.6.3-rc3-mm1/drivers/md/Makefile 2004-02-16 01:30:51.000000000 +0100
@@ -23,6 +23,7 @@
obj-$(CONFIG_MD_MULTIPATH) += multipath.o
obj-$(CONFIG_BLK_DEV_MD) += md.o
obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o
+obj-$(CONFIG_DM_CRYPT) += dm-crypt.o

quiet_cmd_unroll = UNROLL $@
cmd_unroll = $(PERL) $(srctree)/$(src)/unroll.pl $(UNROLL) \
-
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