block: Block layer data integrity support

Some block devices support verifying the integrity of requests by way
of checksums or other protection information that is submitted along
with the I/O.

This patch implements support for generating and verifying integrity
metadata, as well as correctly merging, splitting and cloning bios and
requests that have this extra information attached.

See Documentation/block/data-integrity.txt for more information.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 382 insertions, 0 deletions

diff --git a/block/blk-integrity.c b/block/blk-integrity.c
new file mode 100644
index 000000000000..65f23ef38bbe
--- /dev/null
+++ b/block/blk-integrity.c
@@ -0,0 +1,382 @@
+/*
+ * blk-integrity.c - Block layer data integrity extensions
+ *
+ * Copyright (C) 2007, 2008 Oracle Corporation
+ * Written by: Martin K. Petersen <martin.petersen@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
+ * USA.
+ *
+ */
+
+#include <linux/blkdev.h>
+#include <linux/mempool.h>
+#include <linux/bio.h>
+#include <linux/scatterlist.h>
+
+#include "blk.h"
+
+static struct kmem_cache *integrity_cachep;
+
+/**
+ * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
+ * @rq:         request with integrity metadata attached
+ *
+ * Description: Returns the number of elements required in a
+ * scatterlist corresponding to the integrity metadata in a request.
+ */
+int blk_rq_count_integrity_sg(struct request *rq)
+{
+        struct bio_vec *iv, *ivprv;
+        struct req_iterator iter;
+        unsigned int segments;
+
+        ivprv = NULL;
+        segments = 0;
+
+        rq_for_each_integrity_segment(iv, rq, iter) {
+
+                if (!ivprv || !BIOVEC_PHYS_MERGEABLE(ivprv, iv))
+                        segments++;
+
+                ivprv = iv;
+        }
+
+        return segments;
+}
+EXPORT_SYMBOL(blk_rq_count_integrity_sg);
+
+/**
+ * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
+ * @rq:         request with integrity metadata attached
+ * @sglist:     target scatterlist
+ *
+ * Description: Map the integrity vectors in request into a
+ * scatterlist.  The scatterlist must be big enough to hold all
+ * elements.  I.e. sized using blk_rq_count_integrity_sg().
+ */
+int blk_rq_map_integrity_sg(struct request *rq, struct scatterlist *sglist)
+{
+        struct bio_vec *iv, *ivprv;
+        struct req_iterator iter;
+        struct scatterlist *sg;
+        unsigned int segments;
+
+        ivprv = NULL;
+        sg = NULL;
+        segments = 0;
+
+        rq_for_each_integrity_segment(iv, rq, iter) {
+
+                if (ivprv) {
+                        if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
+                                goto new_segment;
+
+                        sg->length += iv->bv_len;
+                } else {
+new_segment:
+                        if (!sg)
+                                sg = sglist;
+                        else {
+                                sg->page_link &= ~0x02;
+                                sg = sg_next(sg);
+                        }
+
+                        sg_set_page(sg, iv->bv_page, iv->bv_len, iv->bv_offset);
+                        segments++;
+                }
+
+                ivprv = iv;
+        }
+
+        if (sg)
+                sg_mark_end(sg);
+
+        return segments;
+}
+EXPORT_SYMBOL(blk_rq_map_integrity_sg);
+
+/**
+ * blk_integrity_compare - Compare integrity profile of two block devices
+ * @b1:         Device to compare
+ * @b2:         Device to compare
+ *
+ * Description: Meta-devices like DM and MD need to verify that all
+ * sub-devices use the same integrity format before advertising to
+ * upper layers that they can send/receive integrity metadata.  This
+ * function can be used to check whether two block devices have
+ * compatible integrity formats.
+ */
+int blk_integrity_compare(struct block_device *bd1, struct block_device *bd2)
+{
+        struct blk_integrity *b1 = bd1->bd_disk->integrity;
+        struct blk_integrity *b2 = bd2->bd_disk->integrity;
+
+        BUG_ON(bd1->bd_disk == NULL);
+        BUG_ON(bd2->bd_disk == NULL);
+
+        if (!b1 || !b2)
+                return 0;
+
+        if (b1->sector_size != b2->sector_size) {
+                printk(KERN_ERR "%s: %s/%s sector sz %u != %u\n", __func__,
+                       bd1->bd_disk->disk_name, bd2->bd_disk->disk_name,
+                       b1->sector_size, b2->sector_size);
+                return -1;
+        }
+
+        if (b1->tuple_size != b2->tuple_size) {
+                printk(KERN_ERR "%s: %s/%s tuple sz %u != %u\n", __func__,
+                       bd1->bd_disk->disk_name, bd2->bd_disk->disk_name,
+                       b1->tuple_size, b2->tuple_size);
+                return -1;
+        }
+
+        if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
+                printk(KERN_ERR "%s: %s/%s tag sz %u != %u\n", __func__,
+                       bd1->bd_disk->disk_name, bd2->bd_disk->disk_name,
+                       b1->tag_size, b2->tag_size);
+                return -1;
+        }
+
+        if (strcmp(b1->name, b2->name)) {
+                printk(KERN_ERR "%s: %s/%s type %s != %s\n", __func__,
+                       bd1->bd_disk->disk_name, bd2->bd_disk->disk_name,
+                       b1->name, b2->name);
+                return -1;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL(blk_integrity_compare);
+
+struct integrity_sysfs_entry {
+        struct attribute attr;
+        ssize_t (*show)(struct blk_integrity *, char *);
+        ssize_t (*store)(struct blk_integrity *, const char *, size_t);
+};
+
+static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
+                                   char *page)
+{
+        struct blk_integrity *bi =
+                container_of(kobj, struct blk_integrity, kobj);
+        struct integrity_sysfs_entry *entry =
+                container_of(attr, struct integrity_sysfs_entry, attr);
+
+        return entry->show(bi, page);
+}
+
+static ssize_t integrity_attr_store(struct kobject *kobj, struct attribute *attr,
+                                    const char *page, size_t count)
+{
+        struct blk_integrity *bi =
+                container_of(kobj, struct blk_integrity, kobj);
+        struct integrity_sysfs_entry *entry =
+                container_of(attr, struct integrity_sysfs_entry, attr);
+        ssize_t ret = 0;
+
+        if (entry->store)
+                ret = entry->store(bi, page, count);
+
+        return ret;
+}
+
+static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
+{
+        if (bi != NULL && bi->name != NULL)
+                return sprintf(page, "%s\n", bi->name);
+        else
+                return sprintf(page, "none\n");
+}
+
+static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
+{
+        if (bi != NULL)
+                return sprintf(page, "%u\n", bi->tag_size);
+        else
+                return sprintf(page, "0\n");
+}
+
+static ssize_t integrity_read_store(struct blk_integrity *bi,
+                                    const char *page, size_t count)
+{
+        char *p = (char *) page;
+        unsigned long val = simple_strtoul(p, &p, 10);
+
+        if (val)
+                set_bit(INTEGRITY_FLAG_READ, &bi->flags);
+        else
+                clear_bit(INTEGRITY_FLAG_READ, &bi->flags);
+
+        return count;
+}
+
+static ssize_t integrity_read_show(struct blk_integrity *bi, char *page)
+{
+        return sprintf(page, "%d\n",
+                       test_bit(INTEGRITY_FLAG_READ, &bi->flags) ? 1 : 0);
+}
+
+static ssize_t integrity_write_store(struct blk_integrity *bi,
+                                     const char *page, size_t count)
+{
+        char *p = (char *) page;
+        unsigned long val = simple_strtoul(p, &p, 10);
+
+        if (val)
+                set_bit(INTEGRITY_FLAG_WRITE, &bi->flags);
+        else
+                clear_bit(INTEGRITY_FLAG_WRITE, &bi->flags);
+
+        return count;
+}
+
+static ssize_t integrity_write_show(struct blk_integrity *bi, char *page)
+{
+        return sprintf(page, "%d\n",
+                       test_bit(INTEGRITY_FLAG_WRITE, &bi->flags) ? 1 : 0);
+}
+
+static struct integrity_sysfs_entry integrity_format_entry = {
+        .attr = { .name = "format", .mode = S_IRUGO },
+        .show = integrity_format_show,
+};
+
+static struct integrity_sysfs_entry integrity_tag_size_entry = {
+        .attr = { .name = "tag_size", .mode = S_IRUGO },
+        .show = integrity_tag_size_show,
+};
+
+static struct integrity_sysfs_entry integrity_read_entry = {
+        .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
+        .show = integrity_read_show,
+        .store = integrity_read_store,
+};
+
+static struct integrity_sysfs_entry integrity_write_entry = {
+        .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
+        .show = integrity_write_show,
+        .store = integrity_write_store,
+};
+
+static struct attribute *integrity_attrs[] = {
+        &integrity_format_entry.attr,
+        &integrity_tag_size_entry.attr,
+        &integrity_read_entry.attr,
+        &integrity_write_entry.attr,
+        NULL,
+};
+
+static struct sysfs_ops integrity_ops = {
+        .show   = &integrity_attr_show,
+        .store  = &integrity_attr_store,
+};
+
+static int __init blk_dev_integrity_init(void)
+{
+        integrity_cachep = kmem_cache_create("blkdev_integrity",
+                                             sizeof(struct blk_integrity),
+                                             0, SLAB_PANIC, NULL);
+        return 0;
+}
+subsys_initcall(blk_dev_integrity_init);
+
+static void blk_integrity_release(struct kobject *kobj)
+{
+        struct blk_integrity *bi =
+                container_of(kobj, struct blk_integrity, kobj);
+
+        kmem_cache_free(integrity_cachep, bi);
+}
+
+static struct kobj_type integrity_ktype = {
+        .default_attrs  = integrity_attrs,
+        .sysfs_ops      = &integrity_ops,
+        .release        = blk_integrity_release,
+};
+
+/**
+ * blk_integrity_register - Register a gendisk as being integrity-capable
+ * @disk:       struct gendisk pointer to make integrity-aware
+ * @template:   integrity profile
+ *
+ * Description: When a device needs to advertise itself as being able
+ * to send/receive integrity metadata it must use this function to
+ * register the capability with the block layer.  The template is a
+ * blk_integrity struct with values appropriate for the underlying
+ * hardware.  See Documentation/block/data-integrity.txt.
+ */
+int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
+{
+        struct blk_integrity *bi;
+
+        BUG_ON(disk == NULL);
+        BUG_ON(template == NULL);
+
+        if (disk->integrity == NULL) {
+                bi = kmem_cache_alloc(integrity_cachep, GFP_KERNEL | __GFP_ZERO);
+                if (!bi)
+                        return -1;
+
+                if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
+                                         &disk->dev.kobj, "%s", "integrity")) {
+                        kmem_cache_free(integrity_cachep, bi);
+                        return -1;
+                }
+
+                kobject_uevent(&bi->kobj, KOBJ_ADD);
+
+                set_bit(INTEGRITY_FLAG_READ, &bi->flags);
+                set_bit(INTEGRITY_FLAG_WRITE, &bi->flags);
+                bi->sector_size = disk->queue->hardsect_size;
+                disk->integrity = bi;
+        } else
+                bi = disk->integrity;
+
+        /* Use the provided profile as template */
+        bi->name = template->name;
+        bi->generate_fn = template->generate_fn;
+        bi->verify_fn = template->verify_fn;
+        bi->tuple_size = template->tuple_size;
+        bi->set_tag_fn = template->set_tag_fn;
+        bi->get_tag_fn = template->get_tag_fn;
+        bi->tag_size = template->tag_size;
+
+        return 0;
+}
+EXPORT_SYMBOL(blk_integrity_register);
+
+/**
+ * blk_integrity_unregister - Remove block integrity profile
+ * @disk:       disk whose integrity profile to deallocate
+ *
+ * Description: This function frees all memory used by the block
+ * integrity profile.  To be called at device teardown.
+ */
+void blk_integrity_unregister(struct gendisk *disk)
+{
+        struct blk_integrity *bi;
+
+        if (!disk || !disk->integrity)
+                return;
+
+        bi = disk->integrity;
+
+        kobject_uevent(&bi->kobj, KOBJ_REMOVE);
+        kobject_del(&bi->kobj);
+        kobject_put(&disk->dev.kobj);
+        kmem_cache_free(integrity_cachep, bi);
+}
+EXPORT_SYMBOL(blk_integrity_unregister);