[dm-devel] [PATCH 6/7] dm-integrity: support discard
Mikulas Patocka
mpatocka at redhat.com
Sun Mar 22 19:42:26 UTC 2020
This patch adds an argument allow_discards that enables discard processing
on dm-integrity device. Only devices with internal hash are allowed.
If we discard a block, we fill the integrity tag with bytes 0xf6.
Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
---
drivers/md/dm-integrity.c | 175 +++++++++++++++++++++++++++++++++++++---------
1 file changed, 143 insertions(+), 32 deletions(-)
Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c 2020-03-20 17:41:22.000000000 +0100
+++ linux-2.6/drivers/md/dm-integrity.c 2020-03-20 17:41:22.000000000 +0100
@@ -39,6 +39,7 @@
#define RECALC_WRITE_SUPER 16
#define BITMAP_BLOCK_SIZE 4096 /* don't change it */
#define BITMAP_FLUSH_INTERVAL (10 * HZ)
+#define DISCARD_FILLER 0xf6
/*
* Warning - DEBUG_PRINT prints security-sensitive data to the log,
@@ -257,6 +258,7 @@ struct dm_integrity_c {
bool just_formatted;
bool recalculate_flag;
bool fix_padding;
+ bool discard;
struct alg_spec internal_hash_alg;
struct alg_spec journal_crypt_alg;
@@ -284,7 +286,7 @@ struct dm_integrity_io {
struct work_struct work;
struct dm_integrity_c *ic;
- bool write;
+ enum req_opf op;
bool fua;
struct dm_integrity_range range;
@@ -1299,6 +1301,11 @@ static bool find_newer_committed_node(st
static int dm_integrity_rw_tag(struct dm_integrity_c *ic, unsigned char *tag, sector_t *metadata_block,
unsigned *metadata_offset, unsigned total_size, int op)
{
+#define MAY_BE_FILLER 1
+#define MAY_BE_HASH 2
+ unsigned hash_offset = 0;
+ unsigned may_be = MAY_BE_HASH | (ic->discard ? MAY_BE_FILLER : 0);
+
do {
unsigned char *data, *dp;
struct dm_buffer *b;
@@ -1320,18 +1327,35 @@ static int dm_integrity_rw_tag(struct dm
} else if (op == TAG_WRITE) {
memcpy(dp, tag, to_copy);
dm_bufio_mark_partial_buffer_dirty(b, *metadata_offset, *metadata_offset + to_copy);
- } else {
+ } else {
/* e.g.: op == TAG_CMP */
- if (unlikely(memcmp(dp, tag, to_copy))) {
- unsigned i;
- for (i = 0; i < to_copy; i++) {
- if (dp[i] != tag[i])
- break;
- total_size--;
+ if (likely(is_power_of_2(ic->tag_size))) {
+ if (unlikely(memcmp(dp, tag, to_copy)))
+ if (unlikely(!ic->discard) ||
+ unlikely(!memchr_inv(dp, DISCARD_FILLER, to_copy))) {
+ goto thorough_test;
+ }
+ } else {
+ unsigned i, ts;
+thorough_test:
+ ts = total_size;
+
+ for (i = 0; i < to_copy; i++, ts--) {
+ if (unlikely(dp[i] != tag[i]))
+ may_be &= ~MAY_BE_HASH;
+ if (likely(dp[i] != DISCARD_FILLER))
+ may_be &= ~MAY_BE_FILLER;
+ hash_offset++;
+ if (unlikely(hash_offset == ic->tag_size)) {
+ if (unlikely(!may_be)) {
+ dm_bufio_release(b);
+ return ts;
+ }
+ hash_offset = 0;
+ may_be = MAY_BE_HASH | (ic->discard ? MAY_BE_FILLER : 0);
+ }
}
- dm_bufio_release(b);
- return total_size;
}
}
dm_bufio_release(b);
@@ -1342,10 +1366,17 @@ static int dm_integrity_rw_tag(struct dm
(*metadata_block)++;
*metadata_offset = 0;
}
+
+ if (unlikely(!is_power_of_2(ic->tag_size))) {
+ hash_offset = (hash_offset + to_copy) % ic->tag_size;
+ }
+
total_size -= to_copy;
} while (unlikely(total_size));
return 0;
+#undef MAY_BE_FILLER
+#undef MAY_BE_HASH
}
static void dm_integrity_flush_buffers(struct dm_integrity_c *ic)
@@ -1428,7 +1459,7 @@ static void dec_in_flight(struct dm_inte
remove_range(ic, &dio->range);
- if (unlikely(dio->write))
+ if (dio->op == REQ_OP_WRITE || unlikely(dio->op == REQ_OP_DISCARD))
schedule_autocommit(ic);
bio = dm_bio_from_per_bio_data(dio, sizeof(struct dm_integrity_io));
@@ -1520,14 +1551,19 @@ static void integrity_metadata(struct wo
char *checksums;
unsigned extra_space = unlikely(digest_size > ic->tag_size) ? digest_size - ic->tag_size : 0;
char checksums_onstack[max((size_t)HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
- unsigned sectors_to_process = dio->range.n_sectors;
- sector_t sector = dio->range.logical_sector;
+ sector_t sector;
+ unsigned sectors_to_process;
+ sector_t save_metadata_block;
+ unsigned save_metadata_offset;
if (unlikely(ic->mode == 'R'))
goto skip_io;
- checksums = kmalloc((PAGE_SIZE >> SECTOR_SHIFT >> ic->sb->log2_sectors_per_block) * ic->tag_size + extra_space,
- GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
+ if (likely(dio->op != REQ_OP_DISCARD))
+ checksums = kmalloc((PAGE_SIZE >> SECTOR_SHIFT >> ic->sb->log2_sectors_per_block) * ic->tag_size + extra_space,
+ GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
+ else
+ checksums = kmalloc(PAGE_SIZE, GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
if (!checksums) {
checksums = checksums_onstack;
if (WARN_ON(extra_space &&
@@ -1537,6 +1573,42 @@ static void integrity_metadata(struct wo
}
}
+ if (unlikely(dio->op == REQ_OP_DISCARD)) {
+ sector_t bi_sector = dio->bio_details.bi_iter.bi_sector;
+ unsigned bi_size = dio->bio_details.bi_iter.bi_size;
+ unsigned max_size = likely(checksums != checksums_onstack) ? PAGE_SIZE : HASH_MAX_DIGESTSIZE;
+ unsigned max_blocks = max_size / ic->tag_size;
+ memset(checksums, DISCARD_FILLER, max_size);
+
+ while (bi_size) {
+ unsigned this_step_blocks = bi_size >> (SECTOR_SHIFT + ic->sb->log2_sectors_per_block);
+ this_step_blocks = min(this_step_blocks, max_blocks);
+ r = dm_integrity_rw_tag(ic, checksums, &dio->metadata_block, &dio->metadata_offset, this_step_blocks * ic->tag_size, TAG_WRITE);
+ if (unlikely(r)) {
+ if (likely(checksums != checksums_onstack))
+ kfree(checksums);
+ goto error;
+ }
+
+ /*if (bi_size < this_step_blocks << (SECTOR_SHIFT + ic->sb->log2_sectors_per_block)) {
+ printk("BUGG: bi_sector: %llx, bi_size: %u\n", bi_sector, bi_size);
+ printk("BUGG: this_step_blocks: %u\n", this_step_blocks);
+ BUG();
+ }*/
+ bi_size -= this_step_blocks << (SECTOR_SHIFT + ic->sb->log2_sectors_per_block);
+ bi_sector += this_step_blocks << ic->sb->log2_sectors_per_block;
+ }
+
+ if (likely(checksums != checksums_onstack))
+ kfree(checksums);
+ goto skip_io;
+ }
+
+ save_metadata_block = dio->metadata_block;
+ save_metadata_offset = dio->metadata_offset;
+ sector = dio->range.logical_sector;
+ sectors_to_process = dio->range.n_sectors;
+
__bio_for_each_segment(bv, bio, iter, dio->bio_details.bi_iter) {
unsigned pos;
char *mem, *checksums_ptr;
@@ -1555,7 +1627,7 @@ again:
kunmap_atomic(mem);
r = dm_integrity_rw_tag(ic, checksums, &dio->metadata_block, &dio->metadata_offset,
- checksums_ptr - checksums, !dio->write ? TAG_CMP : TAG_WRITE);
+ checksums_ptr - checksums, dio->op == REQ_OP_READ ? TAG_CMP : TAG_WRITE);
if (unlikely(r)) {
if (r > 0) {
DMERR_LIMIT("Checksum failed at sector 0x%llx",
@@ -1598,7 +1670,7 @@ again:
tag = lowmem_page_address(biv.bv_page) + biv.bv_offset;
this_len = min(biv.bv_len, data_to_process);
r = dm_integrity_rw_tag(ic, tag, &dio->metadata_block, &dio->metadata_offset,
- this_len, !dio->write ? TAG_READ : TAG_WRITE);
+ this_len, dio->op == REQ_OP_READ ? TAG_READ : TAG_WRITE);
if (unlikely(r))
goto error;
data_to_process -= this_len;
@@ -1625,6 +1697,20 @@ static int dm_integrity_map(struct dm_ta
dio->ic = ic;
dio->bi_status = 0;
+ dio->op = bio_op(bio);
+
+ if (unlikely(dio->op == REQ_OP_DISCARD)) {
+ if (ti->max_io_len) {
+ sector_t sec = dm_target_offset(ti, bio->bi_iter.bi_sector);
+ unsigned log2_max_io_len = __fls(ti->max_io_len);
+ sector_t start_boundary = sec >> log2_max_io_len;
+ sector_t end_boundary = (sec + bio_sectors(bio) - 1) >> log2_max_io_len;
+ if (start_boundary < end_boundary) {
+ sector_t len = ti->max_io_len - (sec & (ti->max_io_len - 1));
+ dm_accept_partial_bio(bio, len);
+ }
+ }
+ }
if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
submit_flush_bio(ic, dio);
@@ -1632,8 +1718,7 @@ static int dm_integrity_map(struct dm_ta
}
dio->range.logical_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
- dio->write = bio_op(bio) == REQ_OP_WRITE;
- dio->fua = dio->write && bio->bi_opf & REQ_FUA;
+ dio->fua = dio->op == REQ_OP_WRITE && bio->bi_opf & REQ_FUA;
if (unlikely(dio->fua)) {
/*
* Don't pass down the FUA flag because we have to flush
@@ -1654,7 +1739,7 @@ static int dm_integrity_map(struct dm_ta
return DM_MAPIO_KILL;
}
- if (ic->sectors_per_block > 1) {
+ if (ic->sectors_per_block > 1 && likely(dio->op != REQ_OP_DISCARD)) {
struct bvec_iter iter;
struct bio_vec bv;
bio_for_each_segment(bv, bio, iter) {
@@ -1687,7 +1772,7 @@ static int dm_integrity_map(struct dm_ta
}
}
- if (unlikely(ic->mode == 'R') && unlikely(dio->write))
+ if (unlikely(ic->mode == 'R') && unlikely(dio->op != REQ_OP_READ))
return DM_MAPIO_KILL;
get_area_and_offset(ic, dio->range.logical_sector, &area, &offset);
@@ -1717,13 +1802,13 @@ static bool __journal_read_write(struct
bio_advance_iter(bio, &bio->bi_iter, bv.bv_len);
retry_kmap:
mem = kmap_atomic(bv.bv_page);
- if (likely(dio->write))
+ if (likely(dio->op == REQ_OP_WRITE))
flush_dcache_page(bv.bv_page);
do {
struct journal_entry *je = access_journal_entry(ic, journal_section, journal_entry);
- if (unlikely(!dio->write)) {
+ if (unlikely(dio->op == REQ_OP_READ)) {
struct journal_sector *js;
char *mem_ptr;
unsigned s;
@@ -1770,7 +1855,7 @@ retry_kmap:
char *tag_addr;
BUG_ON(PageHighMem(biv.bv_page));
tag_addr = lowmem_page_address(biv.bv_page) + biv.bv_offset;
- if (likely(dio->write))
+ if (likely(dio->op == REQ_OP_WRITE))
memcpy(tag_ptr, tag_addr, tag_now);
else
memcpy(tag_addr, tag_ptr, tag_now);
@@ -1778,12 +1863,12 @@ retry_kmap:
tag_ptr += tag_now;
tag_todo -= tag_now;
} while (unlikely(tag_todo)); else {
- if (likely(dio->write))
+ if (likely(dio->op == REQ_OP_WRITE))
memset(tag_ptr, 0, tag_todo);
}
}
- if (likely(dio->write)) {
+ if (likely(dio->op == REQ_OP_WRITE)) {
struct journal_sector *js;
unsigned s;
@@ -1819,12 +1904,12 @@ retry_kmap:
bv.bv_offset += ic->sectors_per_block << SECTOR_SHIFT;
} while (bv.bv_len -= ic->sectors_per_block << SECTOR_SHIFT);
- if (unlikely(!dio->write))
+ if (unlikely(dio->op == REQ_OP_READ))
flush_dcache_page(bv.bv_page);
kunmap_atomic(mem);
} while (n_sectors);
- if (likely(dio->write)) {
+ if (likely(dio->op == REQ_OP_WRITE)) {
smp_mb();
if (unlikely(waitqueue_active(&ic->copy_to_journal_wait)))
wake_up(&ic->copy_to_journal_wait);
@@ -1856,7 +1941,9 @@ static void dm_integrity_map_continue(st
unsigned journal_section, journal_entry;
unsigned journal_read_pos;
struct completion read_comp;
- bool need_sync_io = ic->internal_hash && !dio->write;
+ bool need_sync_io = ic->internal_hash && dio->op == REQ_OP_READ;
+ if (unlikely(dio->op == REQ_OP_DISCARD) && ic->mode != 'D')
+ need_sync_io = true;
if (need_sync_io && from_map) {
INIT_WORK(&dio->work, integrity_bio_wait);
@@ -1874,8 +1961,8 @@ retry:
}
dio->range.n_sectors = bio_sectors(bio);
journal_read_pos = NOT_FOUND;
- if (likely(ic->mode == 'J')) {
- if (dio->write) {
+ if (ic->mode == 'J' && likely(dio->op != REQ_OP_DISCARD)) {
+ if (dio->op == REQ_OP_WRITE) {
unsigned next_entry, i, pos;
unsigned ws, we, range_sectors;
@@ -1978,7 +2065,7 @@ offload_to_thread:
goto journal_read_write;
}
- if (ic->mode == 'B' && dio->write) {
+ if (ic->mode == 'B' && (dio->op == REQ_OP_WRITE || unlikely(dio->op == REQ_OP_DISCARD))) {
if (!block_bitmap_op(ic, ic->may_write_bitmap, dio->range.logical_sector,
dio->range.n_sectors, BITMAP_OP_TEST_ALL_SET)) {
struct bitmap_block_status *bbs;
@@ -2007,6 +2094,18 @@ offload_to_thread:
bio->bi_end_io = integrity_end_io;
bio->bi_iter.bi_size = dio->range.n_sectors << SECTOR_SHIFT;
+ if (unlikely(dio->op == REQ_OP_DISCARD) && likely(ic->mode != 'D')) {
+ integrity_metadata(&dio->work);
+ dm_integrity_flush_buffers(ic);
+
+ dio->in_flight = (atomic_t)ATOMIC_INIT(1);
+ dio->completion = NULL;
+
+ generic_make_request(bio);
+
+ return;
+ }
+
generic_make_request(bio);
if (need_sync_io) {
@@ -2966,6 +3065,7 @@ static void dm_integrity_status(struct d
arg_count += !!ic->meta_dev;
arg_count += ic->sectors_per_block != 1;
arg_count += !!(ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING));
+ arg_count += ic->discard;
arg_count += ic->mode == 'J';
arg_count += ic->mode == 'J';
arg_count += ic->mode == 'B';
@@ -2982,6 +3082,8 @@ static void dm_integrity_status(struct d
DMEMIT(" block_size:%u", ic->sectors_per_block << SECTOR_SHIFT);
if (ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING))
DMEMIT(" recalculate");
+ if (ic->discard)
+ DMEMIT(" allow_discards");
DMEMIT(" journal_sectors:%u", ic->initial_sectors - SB_SECTORS);
DMEMIT(" interleave_sectors:%u", 1U << ic->sb->log2_interleave_sectors);
DMEMIT(" buffer_sectors:%u", 1U << ic->log2_buffer_sectors);
@@ -3768,6 +3870,8 @@ static int dm_integrity_ctr(struct dm_ta
goto bad;
} else if (!strcmp(opt_string, "recalculate")) {
ic->recalculate_flag = true;
+ } else if (!strcmp(opt_string, "allow_discards")) {
+ ic->discard = true;
} else if (!strcmp(opt_string, "fix_padding")) {
ic->fix_padding = true;
} else {
@@ -3826,6 +3930,12 @@ static int dm_integrity_ctr(struct dm_ta
goto bad;
}
+ if (ic->discard && !ic->internal_hash) {
+ r = -EINVAL;
+ ti->error = "Discard can be only used with internal hash";
+ goto bad;
+ }
+
ic->autocommit_jiffies = msecs_to_jiffies(sync_msec);
ic->autocommit_msec = sync_msec;
timer_setup(&ic->autocommit_timer, autocommit_fn, 0);
@@ -4155,6 +4265,7 @@ try_smaller_buffer:
ti->num_flush_bios = 1;
ti->flush_supported = true;
+ ti->num_discard_bios = ic->discard;
return 0;
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