linux/block/bio-integrity.c
Keith Busch 492c5d4559 block: bio-integrity: directly map user buffers
Passthrough commands that utilize metadata currently need to bounce the
user space buffer through the kernel. Add support for mapping user space
directly so that we can avoid this costly overhead. This is similar to
how the normal bio data payload utilizes user addresses with
bio_map_user_iov().

If the user address can't directly be used for reason, like too many
segments or address unalignement, fallback to a copy of the user vec
while keeping the user address pinned for the IO duration so that it
can safely be copied on completion in any process context.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20231130215309.2923568-2-kbusch@meta.com
[axboe: fold in fix from Kanchan Joshi]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-12-01 18:29:00 -07:00

676 lines
18 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* bio-integrity.c - bio data integrity extensions
*
* Copyright (C) 2007, 2008, 2009 Oracle Corporation
* Written by: Martin K. Petersen <martin.petersen@oracle.com>
*/
#include <linux/blk-integrity.h>
#include <linux/mempool.h>
#include <linux/export.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include "blk.h"
static struct kmem_cache *bip_slab;
static struct workqueue_struct *kintegrityd_wq;
void blk_flush_integrity(void)
{
flush_workqueue(kintegrityd_wq);
}
static void __bio_integrity_free(struct bio_set *bs,
struct bio_integrity_payload *bip)
{
if (bs && mempool_initialized(&bs->bio_integrity_pool)) {
if (bip->bip_vec)
bvec_free(&bs->bvec_integrity_pool, bip->bip_vec,
bip->bip_max_vcnt);
mempool_free(bip, &bs->bio_integrity_pool);
} else {
kfree(bip);
}
}
/**
* bio_integrity_alloc - Allocate integrity payload and attach it to bio
* @bio: bio to attach integrity metadata to
* @gfp_mask: Memory allocation mask
* @nr_vecs: Number of integrity metadata scatter-gather elements
*
* Description: This function prepares a bio for attaching integrity
* metadata. nr_vecs specifies the maximum number of pages containing
* integrity metadata that can be attached.
*/
struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
gfp_t gfp_mask,
unsigned int nr_vecs)
{
struct bio_integrity_payload *bip;
struct bio_set *bs = bio->bi_pool;
unsigned inline_vecs;
if (WARN_ON_ONCE(bio_has_crypt_ctx(bio)))
return ERR_PTR(-EOPNOTSUPP);
if (!bs || !mempool_initialized(&bs->bio_integrity_pool)) {
bip = kmalloc(struct_size(bip, bip_inline_vecs, nr_vecs), gfp_mask);
inline_vecs = nr_vecs;
} else {
bip = mempool_alloc(&bs->bio_integrity_pool, gfp_mask);
inline_vecs = BIO_INLINE_VECS;
}
if (unlikely(!bip))
return ERR_PTR(-ENOMEM);
memset(bip, 0, sizeof(*bip));
/* always report as many vecs as asked explicitly, not inline vecs */
bip->bip_max_vcnt = nr_vecs;
if (nr_vecs > inline_vecs) {
bip->bip_vec = bvec_alloc(&bs->bvec_integrity_pool,
&bip->bip_max_vcnt, gfp_mask);
if (!bip->bip_vec)
goto err;
} else {
bip->bip_vec = bip->bip_inline_vecs;
}
bip->bip_bio = bio;
bio->bi_integrity = bip;
bio->bi_opf |= REQ_INTEGRITY;
return bip;
err:
__bio_integrity_free(bs, bip);
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(bio_integrity_alloc);
static void bio_integrity_unpin_bvec(struct bio_vec *bv, int nr_vecs,
bool dirty)
{
int i;
for (i = 0; i < nr_vecs; i++) {
if (dirty && !PageCompound(bv[i].bv_page))
set_page_dirty_lock(bv[i].bv_page);
unpin_user_page(bv[i].bv_page);
}
}
static void bio_integrity_uncopy_user(struct bio_integrity_payload *bip)
{
unsigned short nr_vecs = bip->bip_max_vcnt - 1;
struct bio_vec *copy = &bip->bip_vec[1];
size_t bytes = bip->bip_iter.bi_size;
struct iov_iter iter;
int ret;
iov_iter_bvec(&iter, ITER_DEST, copy, nr_vecs, bytes);
ret = copy_to_iter(bvec_virt(bip->bip_vec), bytes, &iter);
WARN_ON_ONCE(ret != bytes);
bio_integrity_unpin_bvec(copy, nr_vecs, true);
}
static void bio_integrity_unmap_user(struct bio_integrity_payload *bip)
{
bool dirty = bio_data_dir(bip->bip_bio) == READ;
if (bip->bip_flags & BIP_COPY_USER) {
if (dirty)
bio_integrity_uncopy_user(bip);
kfree(bvec_virt(bip->bip_vec));
return;
}
bio_integrity_unpin_bvec(bip->bip_vec, bip->bip_max_vcnt, dirty);
}
/**
* bio_integrity_free - Free bio integrity payload
* @bio: bio containing bip to be freed
*
* Description: Used to free the integrity portion of a bio. Usually
* called from bio_free().
*/
void bio_integrity_free(struct bio *bio)
{
struct bio_integrity_payload *bip = bio_integrity(bio);
struct bio_set *bs = bio->bi_pool;
if (bip->bip_flags & BIP_BLOCK_INTEGRITY)
kfree(bvec_virt(bip->bip_vec));
else if (bip->bip_flags & BIP_INTEGRITY_USER)
bio_integrity_unmap_user(bip);
__bio_integrity_free(bs, bip);
bio->bi_integrity = NULL;
bio->bi_opf &= ~REQ_INTEGRITY;
}
/**
* bio_integrity_add_page - Attach integrity metadata
* @bio: bio to update
* @page: page containing integrity metadata
* @len: number of bytes of integrity metadata in page
* @offset: start offset within page
*
* Description: Attach a page containing integrity metadata to bio.
*/
int bio_integrity_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int offset)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
struct bio_integrity_payload *bip = bio_integrity(bio);
if (((bip->bip_iter.bi_size + len) >> SECTOR_SHIFT) >
queue_max_hw_sectors(q))
return 0;
if (bip->bip_vcnt > 0) {
struct bio_vec *bv = &bip->bip_vec[bip->bip_vcnt - 1];
bool same_page = false;
if (bvec_try_merge_hw_page(q, bv, page, len, offset,
&same_page)) {
bip->bip_iter.bi_size += len;
return len;
}
if (bip->bip_vcnt >=
min(bip->bip_max_vcnt, queue_max_integrity_segments(q)))
return 0;
/*
* If the queue doesn't support SG gaps and adding this segment
* would create a gap, disallow it.
*/
if (bvec_gap_to_prev(&q->limits, bv, offset))
return 0;
}
bvec_set_page(&bip->bip_vec[bip->bip_vcnt], page, len, offset);
bip->bip_vcnt++;
bip->bip_iter.bi_size += len;
return len;
}
EXPORT_SYMBOL(bio_integrity_add_page);
static int bio_integrity_copy_user(struct bio *bio, struct bio_vec *bvec,
int nr_vecs, unsigned int len,
unsigned int direction, u32 seed)
{
bool write = direction == ITER_SOURCE;
struct bio_integrity_payload *bip;
struct iov_iter iter;
void *buf;
int ret;
buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (write) {
iov_iter_bvec(&iter, direction, bvec, nr_vecs, len);
if (!copy_from_iter_full(buf, len, &iter)) {
ret = -EFAULT;
goto free_buf;
}
bip = bio_integrity_alloc(bio, GFP_KERNEL, 1);
} else {
memset(buf, 0, len);
/*
* We need to preserve the original bvec and the number of vecs
* in it for completion handling
*/
bip = bio_integrity_alloc(bio, GFP_KERNEL, nr_vecs + 1);
}
if (IS_ERR(bip)) {
ret = PTR_ERR(bip);
goto free_buf;
}
if (write)
bio_integrity_unpin_bvec(bvec, nr_vecs, false);
else
memcpy(&bip->bip_vec[1], bvec, nr_vecs * sizeof(*bvec));
ret = bio_integrity_add_page(bio, virt_to_page(buf), len,
offset_in_page(buf));
if (ret != len) {
ret = -ENOMEM;
goto free_bip;
}
bip->bip_flags |= BIP_INTEGRITY_USER | BIP_COPY_USER;
bip->bip_iter.bi_sector = seed;
return 0;
free_bip:
bio_integrity_free(bio);
free_buf:
kfree(buf);
return ret;
}
static int bio_integrity_init_user(struct bio *bio, struct bio_vec *bvec,
int nr_vecs, unsigned int len, u32 seed)
{
struct bio_integrity_payload *bip;
bip = bio_integrity_alloc(bio, GFP_KERNEL, nr_vecs);
if (IS_ERR(bip))
return PTR_ERR(bip);
memcpy(bip->bip_vec, bvec, nr_vecs * sizeof(*bvec));
bip->bip_flags |= BIP_INTEGRITY_USER;
bip->bip_iter.bi_sector = seed;
bip->bip_iter.bi_size = len;
return 0;
}
static unsigned int bvec_from_pages(struct bio_vec *bvec, struct page **pages,
int nr_vecs, ssize_t bytes, ssize_t offset)
{
unsigned int nr_bvecs = 0;
int i, j;
for (i = 0; i < nr_vecs; i = j) {
size_t size = min_t(size_t, bytes, PAGE_SIZE - offset);
struct folio *folio = page_folio(pages[i]);
bytes -= size;
for (j = i + 1; j < nr_vecs; j++) {
size_t next = min_t(size_t, PAGE_SIZE, bytes);
if (page_folio(pages[j]) != folio ||
pages[j] != pages[j - 1] + 1)
break;
unpin_user_page(pages[j]);
size += next;
bytes -= next;
}
bvec_set_page(&bvec[nr_bvecs], pages[i], size, offset);
offset = 0;
nr_bvecs++;
}
return nr_bvecs;
}
int bio_integrity_map_user(struct bio *bio, void __user *ubuf, ssize_t bytes,
u32 seed)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
unsigned int align = q->dma_pad_mask | queue_dma_alignment(q);
struct page *stack_pages[UIO_FASTIOV], **pages = stack_pages;
struct bio_vec stack_vec[UIO_FASTIOV], *bvec = stack_vec;
unsigned int direction, nr_bvecs;
struct iov_iter iter;
int ret, nr_vecs;
size_t offset;
bool copy;
if (bio_integrity(bio))
return -EINVAL;
if (bytes >> SECTOR_SHIFT > queue_max_hw_sectors(q))
return -E2BIG;
if (bio_data_dir(bio) == READ)
direction = ITER_DEST;
else
direction = ITER_SOURCE;
iov_iter_ubuf(&iter, direction, ubuf, bytes);
nr_vecs = iov_iter_npages(&iter, BIO_MAX_VECS + 1);
if (nr_vecs > BIO_MAX_VECS)
return -E2BIG;
if (nr_vecs > UIO_FASTIOV) {
bvec = kcalloc(sizeof(*bvec), nr_vecs, GFP_KERNEL);
if (!bvec)
return -ENOMEM;
pages = NULL;
}
copy = !iov_iter_is_aligned(&iter, align, align);
ret = iov_iter_extract_pages(&iter, &pages, bytes, nr_vecs, 0, &offset);
if (unlikely(ret < 0))
goto free_bvec;
nr_bvecs = bvec_from_pages(bvec, pages, nr_vecs, bytes, offset);
if (pages != stack_pages)
kvfree(pages);
if (nr_bvecs > queue_max_integrity_segments(q))
copy = true;
if (copy)
ret = bio_integrity_copy_user(bio, bvec, nr_bvecs, bytes,
direction, seed);
else
ret = bio_integrity_init_user(bio, bvec, nr_bvecs, bytes, seed);
if (ret)
goto release_pages;
if (bvec != stack_vec)
kfree(bvec);
return 0;
release_pages:
bio_integrity_unpin_bvec(bvec, nr_bvecs, false);
free_bvec:
if (bvec != stack_vec)
kfree(bvec);
return ret;
}
EXPORT_SYMBOL_GPL(bio_integrity_map_user);
/**
* bio_integrity_process - Process integrity metadata for a bio
* @bio: bio to generate/verify integrity metadata for
* @proc_iter: iterator to process
* @proc_fn: Pointer to the relevant processing function
*/
static blk_status_t bio_integrity_process(struct bio *bio,
struct bvec_iter *proc_iter, integrity_processing_fn *proc_fn)
{
struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
struct blk_integrity_iter iter;
struct bvec_iter bviter;
struct bio_vec bv;
struct bio_integrity_payload *bip = bio_integrity(bio);
blk_status_t ret = BLK_STS_OK;
iter.disk_name = bio->bi_bdev->bd_disk->disk_name;
iter.interval = 1 << bi->interval_exp;
iter.tuple_size = bi->tuple_size;
iter.seed = proc_iter->bi_sector;
iter.prot_buf = bvec_virt(bip->bip_vec);
__bio_for_each_segment(bv, bio, bviter, *proc_iter) {
void *kaddr = bvec_kmap_local(&bv);
iter.data_buf = kaddr;
iter.data_size = bv.bv_len;
ret = proc_fn(&iter);
kunmap_local(kaddr);
if (ret)
break;
}
return ret;
}
/**
* bio_integrity_prep - Prepare bio for integrity I/O
* @bio: bio to prepare
*
* Description: Checks if the bio already has an integrity payload attached.
* If it does, the payload has been generated by another kernel subsystem,
* and we just pass it through. Otherwise allocates integrity payload.
* The bio must have data direction, target device and start sector set priot
* to calling. In the WRITE case, integrity metadata will be generated using
* the block device's integrity function. In the READ case, the buffer
* will be prepared for DMA and a suitable end_io handler set up.
*/
bool bio_integrity_prep(struct bio *bio)
{
struct bio_integrity_payload *bip;
struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
void *buf;
unsigned long start, end;
unsigned int len, nr_pages;
unsigned int bytes, offset, i;
if (!bi)
return true;
if (bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE)
return true;
if (!bio_sectors(bio))
return true;
/* Already protected? */
if (bio_integrity(bio))
return true;
if (bio_data_dir(bio) == READ) {
if (!bi->profile->verify_fn ||
!(bi->flags & BLK_INTEGRITY_VERIFY))
return true;
} else {
if (!bi->profile->generate_fn ||
!(bi->flags & BLK_INTEGRITY_GENERATE))
return true;
}
/* Allocate kernel buffer for protection data */
len = bio_integrity_bytes(bi, bio_sectors(bio));
buf = kmalloc(len, GFP_NOIO);
if (unlikely(buf == NULL)) {
printk(KERN_ERR "could not allocate integrity buffer\n");
goto err_end_io;
}
end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
start = ((unsigned long) buf) >> PAGE_SHIFT;
nr_pages = end - start;
/* Allocate bio integrity payload and integrity vectors */
bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
if (IS_ERR(bip)) {
printk(KERN_ERR "could not allocate data integrity bioset\n");
kfree(buf);
goto err_end_io;
}
bip->bip_flags |= BIP_BLOCK_INTEGRITY;
bip_set_seed(bip, bio->bi_iter.bi_sector);
if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
bip->bip_flags |= BIP_IP_CHECKSUM;
/* Map it */
offset = offset_in_page(buf);
for (i = 0; i < nr_pages && len > 0; i++) {
bytes = PAGE_SIZE - offset;
if (bytes > len)
bytes = len;
if (bio_integrity_add_page(bio, virt_to_page(buf),
bytes, offset) < bytes) {
printk(KERN_ERR "could not attach integrity payload\n");
goto err_end_io;
}
buf += bytes;
len -= bytes;
offset = 0;
}
/* Auto-generate integrity metadata if this is a write */
if (bio_data_dir(bio) == WRITE) {
bio_integrity_process(bio, &bio->bi_iter,
bi->profile->generate_fn);
} else {
bip->bio_iter = bio->bi_iter;
}
return true;
err_end_io:
bio->bi_status = BLK_STS_RESOURCE;
bio_endio(bio);
return false;
}
EXPORT_SYMBOL(bio_integrity_prep);
/**
* bio_integrity_verify_fn - Integrity I/O completion worker
* @work: Work struct stored in bio to be verified
*
* Description: This workqueue function is called to complete a READ
* request. The function verifies the transferred integrity metadata
* and then calls the original bio end_io function.
*/
static void bio_integrity_verify_fn(struct work_struct *work)
{
struct bio_integrity_payload *bip =
container_of(work, struct bio_integrity_payload, bip_work);
struct bio *bio = bip->bip_bio;
struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
/*
* At the moment verify is called bio's iterator was advanced
* during split and completion, we need to rewind iterator to
* it's original position.
*/
bio->bi_status = bio_integrity_process(bio, &bip->bio_iter,
bi->profile->verify_fn);
bio_integrity_free(bio);
bio_endio(bio);
}
/**
* __bio_integrity_endio - Integrity I/O completion function
* @bio: Protected bio
*
* Description: Completion for integrity I/O
*
* Normally I/O completion is done in interrupt context. However,
* verifying I/O integrity is a time-consuming task which must be run
* in process context. This function postpones completion
* accordingly.
*/
bool __bio_integrity_endio(struct bio *bio)
{
struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
struct bio_integrity_payload *bip = bio_integrity(bio);
if (bio_op(bio) == REQ_OP_READ && !bio->bi_status &&
(bip->bip_flags & BIP_BLOCK_INTEGRITY) && bi->profile->verify_fn) {
INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
queue_work(kintegrityd_wq, &bip->bip_work);
return false;
}
bio_integrity_free(bio);
return true;
}
/**
* bio_integrity_advance - Advance integrity vector
* @bio: bio whose integrity vector to update
* @bytes_done: number of data bytes that have been completed
*
* Description: This function calculates how many integrity bytes the
* number of completed data bytes correspond to and advances the
* integrity vector accordingly.
*/
void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
{
struct bio_integrity_payload *bip = bio_integrity(bio);
struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
bip->bip_iter.bi_sector += bio_integrity_intervals(bi, bytes_done >> 9);
bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);
}
/**
* bio_integrity_trim - Trim integrity vector
* @bio: bio whose integrity vector to update
*
* Description: Used to trim the integrity vector in a cloned bio.
*/
void bio_integrity_trim(struct bio *bio)
{
struct bio_integrity_payload *bip = bio_integrity(bio);
struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
bip->bip_iter.bi_size = bio_integrity_bytes(bi, bio_sectors(bio));
}
EXPORT_SYMBOL(bio_integrity_trim);
/**
* bio_integrity_clone - Callback for cloning bios with integrity metadata
* @bio: New bio
* @bio_src: Original bio
* @gfp_mask: Memory allocation mask
*
* Description: Called to allocate a bip when cloning a bio
*/
int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
gfp_t gfp_mask)
{
struct bio_integrity_payload *bip_src = bio_integrity(bio_src);
struct bio_integrity_payload *bip;
BUG_ON(bip_src == NULL);
bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
if (IS_ERR(bip))
return PTR_ERR(bip);
memcpy(bip->bip_vec, bip_src->bip_vec,
bip_src->bip_vcnt * sizeof(struct bio_vec));
bip->bip_vcnt = bip_src->bip_vcnt;
bip->bip_iter = bip_src->bip_iter;
bip->bip_flags = bip_src->bip_flags & ~BIP_BLOCK_INTEGRITY;
return 0;
}
int bioset_integrity_create(struct bio_set *bs, int pool_size)
{
if (mempool_initialized(&bs->bio_integrity_pool))
return 0;
if (mempool_init_slab_pool(&bs->bio_integrity_pool,
pool_size, bip_slab))
return -1;
if (biovec_init_pool(&bs->bvec_integrity_pool, pool_size)) {
mempool_exit(&bs->bio_integrity_pool);
return -1;
}
return 0;
}
EXPORT_SYMBOL(bioset_integrity_create);
void bioset_integrity_free(struct bio_set *bs)
{
mempool_exit(&bs->bio_integrity_pool);
mempool_exit(&bs->bvec_integrity_pool);
}
void __init bio_integrity_init(void)
{
/*
* kintegrityd won't block much but may burn a lot of CPU cycles.
* Make it highpri CPU intensive wq with max concurrency of 1.
*/
kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
if (!kintegrityd_wq)
panic("Failed to create kintegrityd\n");
bip_slab = kmem_cache_create("bio_integrity_payload",
sizeof(struct bio_integrity_payload) +
sizeof(struct bio_vec) * BIO_INLINE_VECS,
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
}