In r5cache recovery, the journal device is scanned page by page.
Currently, we use sync_page_io() to read journal device. This is
not efficient when we have to recovery many stripes from the journal.
To improve the speed of recovery, this patch introduces a read ahead
page pool (ra_pool) to recovery_ctx. With ra_pool, multiple consecutive
pages are read in one IO. Then the recovery code read the journal from
ra_pool.
Signed-off-by: Song Liu <songliubraving@xxxxxx>
---
drivers/md/raid5-cache.c | 151 +++++++++++++++++++++++++++++++++++++++++------
1 file changed, 134 insertions(+), 17 deletions(-)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 3f307be..46afea8 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1552,6 +1552,8 @@ bool r5l_log_disk_error(struct r5conf *conf)
return ret;
}
+#define R5L_RECOVERY_PAGE_POOL_SIZE 64
+
struct r5l_recovery_ctx {
struct page *meta_page; /* current meta */
sector_t meta_total_blocks; /* total size of current meta and data */
@@ -1560,18 +1562,130 @@ struct r5l_recovery_ctx {
int data_parity_stripes; /* number of data_parity stripes */
int data_only_stripes; /* number of data_only stripes */
struct list_head cached_list;
+
+ /*
+ * read ahead page pool (ra_pool)
+ * in recovery, log is read sequentially. It is not efficient to
+ * read every page with sync_page_io(). The read ahead page pool
+ * reads multiple pages with one IO, so further log read can
+ * just copy data from the pool.
+ */
+ struct page *ra_pool[R5L_RECOVERY_PAGE_POOL_SIZE];
+ sector_t pool_offset; /* offset of first page in the pool */
+ int total_pages; /* total allocated pages */
+ int valid_pages; /* pages with valid data */
+ struct bio *ra_bio; /* bio to do the read ahead*/
};
+static int r5l_recovery_allocate_ra_pool(struct r5l_log *log,
+ struct r5l_recovery_ctx *ctx)
+{
+ struct page *page;
+
+ ctx->ra_bio = bio_alloc_bioset(GFP_KERNEL, BIO_MAX_PAGES, log->bs);
+ if (!ctx->ra_bio)
+ return -ENOMEM;
+
+ ctx->valid_pages = 0;
+ ctx->total_pages = 0;
+ while (ctx->total_pages < R5L_RECOVERY_PAGE_POOL_SIZE) {
+ page = alloc_page(GFP_KERNEL);
+
+ if (!page)
+ break;
+ ctx->ra_pool[ctx->total_pages] = page;
+ ctx->total_pages += 1;
+ }
+
+ if (ctx->total_pages == 0) {
+ bio_put(ctx->ra_bio);
+ return -ENOMEM;
+ }
+
+ ctx->pool_offset = 0;
+ return 0;
+}
+
+static void r5l_recovery_free_ra_pool(struct r5l_log *log,
+ struct r5l_recovery_ctx *ctx)
+{
+ int i;
+
+ for (i = 0; i < ctx->total_pages; ++i)
+ put_page(ctx->ra_pool[i]);
+ bio_put(ctx->ra_bio);
+}
+
+/*
+ * fetch ctx->valid_pages pages from offset
+ * In normal cases, ctx->valid_pages == ctx->total_pages after the call.
+ * However, if the offset is close to the end of the journal device,
+ * ctx->valid_pages could be smaller than ctx->total_pages
+ */
+static int r5l_recovery_fetch_ra_pool(struct r5l_log *log,
+ struct r5l_recovery_ctx *ctx,
+ sector_t offset)
+{
+ bio_reset(ctx->ra_bio);
+ ctx->ra_bio->bi_bdev = log->rdev->bdev;
+ bio_set_op_attrs(ctx->ra_bio, REQ_OP_READ, 0);
+ ctx->ra_bio->bi_iter.bi_sector = log->rdev->data_offset + offset;
+
+ ctx->valid_pages = 0;
+ ctx->pool_offset = offset;
+
+ while (ctx->valid_pages < ctx->total_pages) {
+ bio_add_page(ctx->ra_bio,
+ ctx->ra_pool[ctx->valid_pages], PAGE_SIZE, 0);
+ ctx->valid_pages += 1;
+
+ offset = r5l_ring_add(log, offset, BLOCK_SECTORS);
+
+ if (offset == 0) /* reached end of the device */
+ break;
+ }
+
+ return submit_bio_wait(ctx->ra_bio);
+}
+
+/*
+ * try read a page from the read ahead page pool, if the page is not in the
+ * pool, call r5l_recovery_fetch_ra_pool
+ */
+static int r5l_recovery_read_page(struct r5l_log *log,
+ struct r5l_recovery_ctx *ctx,
+ struct page *page,
+ sector_t offset)
+{
+ int ret;
+
+ if (offset < ctx->pool_offset ||
+ offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS) {
+ ret = r5l_recovery_fetch_ra_pool(log, ctx, offset);
+ if (ret)
+ return ret;
+ }
+
+ BUG_ON(offset < ctx->pool_offset ||
+ offset >= ctx->pool_offset + ctx->valid_pages * BLOCK_SECTORS);
+
+ memcpy(page_address(page),
+ page_address(ctx->ra_pool[(offset - ctx->pool_offset) / BLOCK_SECTORS]),
+ PAGE_SIZE);
+ return 0;
+}
+
static int r5l_recovery_read_meta_block(struct r5l_log *log,
struct r5l_recovery_ctx *ctx)
{
struct page *page = ctx->meta_page;
struct r5l_meta_block *mb;
u32 crc, stored_crc;
+ int ret;
- if (!sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page, REQ_OP_READ, 0,
- false))
- return -EIO;
+ ret = r5l_recovery_read_page(log, ctx, page, ctx->pos);
+ if (ret != 0)
+ return ret;
mb = page_address(page);
stored_crc = le32_to_cpu(mb->checksum);
@@ -1653,8 +1767,7 @@ static void r5l_recovery_load_data(struct r5l_log *log,
raid5_compute_sector(conf,
le64_to_cpu(payload->location), 0,
&dd_idx, sh);
- sync_page_io(log->rdev, log_offset, PAGE_SIZE,
- sh->dev[dd_idx].page, REQ_OP_READ, 0, false);
+ r5l_recovery_read_page(log, ctx, sh->dev[dd_idx].page, log_offset);
sh->dev[dd_idx].log_checksum =
le32_to_cpu(payload->checksum[0]);
ctx->meta_total_blocks += BLOCK_SECTORS;
@@ -1673,17 +1786,13 @@ static void r5l_recovery_load_parity(struct r5l_log *log,
struct r5conf *conf = mddev->private;
ctx->meta_total_blocks += BLOCK_SECTORS * conf->max_degraded;
- sync_page_io(log->rdev, log_offset, PAGE_SIZE,
- sh->dev[sh->pd_idx].page, REQ_OP_READ, 0, false);
+ r5l_recovery_read_page(log, ctx, sh->dev[sh->pd_idx].page, log_offset);
sh->dev[sh->pd_idx].log_checksum =
le32_to_cpu(payload->checksum[0]);
set_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags);
if (sh->qd_idx >= 0) {
- sync_page_io(log->rdev,
- r5l_ring_add(log, log_offset, BLOCK_SECTORS),
- PAGE_SIZE, sh->dev[sh->qd_idx].page,
- REQ_OP_READ, 0, false);
+ r5l_recovery_read_page(log, ctx, sh->dev[sh->qd_idx].page, log_offset);
sh->dev[sh->qd_idx].log_checksum =
le32_to_cpu(payload->checksum[1]);
set_bit(R5_Wantwrite, &sh->dev[sh->qd_idx].flags);
@@ -1814,14 +1923,15 @@ r5c_recovery_replay_stripes(struct list_head *cached_stripe_list,
/* if matches return 0; otherwise return -EINVAL */
static int
-r5l_recovery_verify_data_checksum(struct r5l_log *log, struct page *page,
+r5l_recovery_verify_data_checksum(struct r5l_log *log,
+ struct r5l_recovery_ctx *ctx,
+ struct page *page,
sector_t log_offset, __le32 log_checksum)
{
void *addr;
u32 checksum;
- sync_page_io(log->rdev, log_offset, PAGE_SIZE,
- page, REQ_OP_READ, 0, false);
+ r5l_recovery_read_page(log, ctx, page, log_offset);
addr = kmap_atomic(page);
checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);
kunmap_atomic(addr);
@@ -1853,17 +1963,17 @@ r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log,
if (payload->header.type == R5LOG_PAYLOAD_DATA) {
if (r5l_recovery_verify_data_checksum(
- log, page, log_offset,
+ log, ctx, page, log_offset,
payload->checksum[0]) < 0)
goto mismatch;
} else if (payload->header.type == R5LOG_PAYLOAD_PARITY) {
if (r5l_recovery_verify_data_checksum(
- log, page, log_offset,
+ log, ctx, page, log_offset,
payload->checksum[0]) < 0)
goto mismatch;
if (conf->max_degraded == 2 && /* q for RAID 6 */
r5l_recovery_verify_data_checksum(
- log, page,
+ log, ctx, page,
r5l_ring_add(log, log_offset,
BLOCK_SECTORS),
payload->checksum[1]) < 0)
@@ -2255,9 +2365,16 @@ static int r5l_recovery_log(struct r5l_log *log)
if (!ctx.meta_page)
return -ENOMEM;
+ if (r5l_recovery_allocate_ra_pool(log, &ctx) != 0) {
+ __free_page(ctx.meta_page);
+ return -ENOMEM;
+ }
+
ret = r5c_recovery_flush_log(log, &ctx);
+ r5l_recovery_free_ra_pool(log, &ctx);
__free_page(ctx.meta_page);
+
if (ret)
return ret;
--
2.9.3
--
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