If a full metadata buffer is being written, don't read it first. This prevents a read-modify-write cycle and increases performance on HDDs considerably.
To do this we now calculate the checksums for all sectors in the bio in one go in integrity_metadata and then pass the result to dm_integrity_rw_tag, which now checks if we overwrite the whole buffer. Benchmarking with a 5400RPM HDD with bitmap mode: integritysetup format --no-wipe --batch-mode --interleave-sectors $((64*1024)) -t 4 -s 512 -I crc32c -B /dev/sdc integritysetup open --buffer-sectors=1 -I crc32c -B /dev/sdc hdda_integ dd if=/dev/zero of=/dev/mapper/hdda_integ bs=64K count=$((16*1024*4)) conv=fsync oflag=direct status=progress Without patch: 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 400.326 s, 10.7 MB/s With patch: 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 41.2057 s, 104 MB/s Signed-off-by: Lukas Straub <[email protected]> --- Hello Everyone, So here is v2, now checking if we overwrite a whole metadata buffer instead of the (buggy) check if we overwrite a whole tag area before. Performance stayed the same (with --buffer-sectors=1). The only quirk now is that it advertises a very big optimal io size in the standard configuration (where buffer_sectors=128). Is this a Problem? v2: -fix dm_integrity_rw_tag to check if we overwrite a whole metadat buffer -fix optimal io size to check if we overwrite a whole metadata buffer Regards, Lukas Straub drivers/md/dm-integrity.c | 81 +++++++++++++++++++++++---------------- 1 file changed, 47 insertions(+), 34 deletions(-) diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index b225b3e445fa..a6d3cf1406df 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -1309,9 +1309,17 @@ static int dm_integrity_rw_tag(struct dm_integrity_c *ic, unsigned char *tag, se if (unlikely(r)) return r; - data = dm_bufio_read(ic->bufio, *metadata_block, &b); - if (IS_ERR(data)) - return PTR_ERR(data); + /* Don't read metadata sectors from disk if we're going to overwrite them completely */ + if (op == TAG_WRITE && *metadata_offset == 0 \ + && total_size >= (1U << SECTOR_SHIFT << ic->log2_buffer_sectors)) { + data = dm_bufio_new(ic->bufio, *metadata_block, &b); + if (IS_ERR(data)) + return PTR_ERR(data); + } else { + data = dm_bufio_read(ic->bufio, *metadata_block, &b); + if (IS_ERR(data)) + return PTR_ERR(data); + } to_copy = min((1U << SECTOR_SHIFT << ic->log2_buffer_sectors) - *metadata_offset, total_size); dp = data + *metadata_offset; @@ -1514,6 +1522,8 @@ static void integrity_metadata(struct work_struct *w) { struct dm_integrity_io *dio = container_of(w, struct dm_integrity_io, work); struct dm_integrity_c *ic = dio->ic; + unsigned sectors_to_process = dio->range.n_sectors; + sector_t sector = dio->range.logical_sector; int r; @@ -1522,16 +1532,14 @@ static void integrity_metadata(struct work_struct *w) struct bio_vec bv; unsigned digest_size = crypto_shash_digestsize(ic->internal_hash); struct bio *bio = dm_bio_from_per_bio_data(dio, sizeof(struct dm_integrity_io)); - char *checksums; + char *checksums, *checksums_ptr; unsigned extra_space = unlikely(digest_size > ic->tag_size) ? digest_size - ic->tag_size : 0; char checksums_onstack[HASH_MAX_DIGESTSIZE]; - unsigned sectors_to_process = dio->range.n_sectors; - sector_t sector = dio->range.logical_sector; 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, + checksums = kmalloc((dio->range.n_sectors >> ic->sb->log2_sectors_per_block) * ic->tag_size + extra_space, GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN); if (!checksums) { checksums = checksums_onstack; @@ -1542,49 +1550,45 @@ static void integrity_metadata(struct work_struct *w) } } + checksums_ptr = checksums; __bio_for_each_segment(bv, bio, iter, dio->orig_bi_iter) { unsigned pos; - char *mem, *checksums_ptr; - -again: + char *mem; mem = (char *)kmap_atomic(bv.bv_page) + bv.bv_offset; pos = 0; - checksums_ptr = checksums; do { integrity_sector_checksum(ic, sector, mem + pos, checksums_ptr); - checksums_ptr += ic->tag_size; - sectors_to_process -= ic->sectors_per_block; + + if (likely(checksums != checksums_onstack)) { + checksums_ptr += ic->tag_size; + } else { + r = dm_integrity_rw_tag(ic, checksums, &dio->metadata_block, &dio->metadata_offset, + ic->tag_size, !dio->write ? TAG_CMP : TAG_WRITE); + if (unlikely(r)) + goto internal_hash_error; + } + pos += ic->sectors_per_block << SECTOR_SHIFT; sector += ic->sectors_per_block; - } while (pos < bv.bv_len && sectors_to_process && checksums != checksums_onstack); + sectors_to_process -= ic->sectors_per_block; + } while (pos < bv.bv_len && sectors_to_process); 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); - if (unlikely(r)) { - if (r > 0) { - DMERR_LIMIT("Checksum failed at sector 0x%llx", - (unsigned long long)(sector - ((r + ic->tag_size - 1) / ic->tag_size))); - r = -EILSEQ; - atomic64_inc(&ic->number_of_mismatches); - } - if (likely(checksums != checksums_onstack)) - kfree(checksums); - goto error; - } - if (!sectors_to_process) break; + } - if (unlikely(pos < bv.bv_len)) { - bv.bv_offset += pos; - bv.bv_len -= pos; - goto again; + if (likely(checksums != checksums_onstack)) { + r = dm_integrity_rw_tag(ic, checksums, &dio->metadata_block, &dio->metadata_offset, + (dio->range.n_sectors >> ic->sb->log2_sectors_per_block) * ic->tag_size, + !dio->write ? TAG_CMP : TAG_WRITE); + if (unlikely(r)) { + kfree(checksums); + goto internal_hash_error; } + kfree(checksums); } - if (likely(checksums != checksums_onstack)) - kfree(checksums); } else { struct bio_integrity_payload *bip = dio->orig_bi_integrity; @@ -1615,6 +1619,13 @@ static void integrity_metadata(struct work_struct *w) skip_io: dec_in_flight(dio); return; +internal_hash_error: + if (r > 0) { + DMERR_LIMIT("Checksum failed at sector 0x%llx", + (unsigned long long)(sector - ((r + ic->tag_size - 1) / ic->tag_size))); + r = -EILSEQ; + atomic64_inc(&ic->number_of_mismatches); + } error: dio->bi_status = errno_to_blk_status(r); dec_in_flight(dio); @@ -3019,6 +3030,8 @@ static void dm_integrity_io_hints(struct dm_target *ti, struct queue_limits *lim limits->physical_block_size = ic->sectors_per_block << SECTOR_SHIFT; blk_limits_io_min(limits, ic->sectors_per_block << SECTOR_SHIFT); } + + blk_limits_io_opt(limits, 1U << SECTOR_SHIFT << ic->log2_buffer_sectors >> ic->log2_tag_size << SECTOR_SHIFT ); } static void calculate_journal_section_size(struct dm_integrity_c *ic) -- 2.20.1 -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
