If we write a superblock in writecache_flush, we don't need to set bit and scan the bitmap for it - we can just write the superblock directly. Also, we can set the flag REQ_FUA on the write bio, so that we don't need to submit a flush bio afterwards.
Signed-off-by: Mikulas Patocka <[email protected]> --- drivers/md/dm-writecache.c | 34 ++++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) Index: linux-2.6/drivers/md/dm-writecache.c =================================================================== --- linux-2.6.orig/drivers/md/dm-writecache.c 2020-02-24 10:19:14.000000000 +0100 +++ linux-2.6/drivers/md/dm-writecache.c 2020-02-24 10:19:14.000000000 +0100 @@ -508,6 +508,34 @@ static void ssd_commit_flushed(struct dm memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size); } +static void ssd_commit_superblock(struct dm_writecache *wc) +{ + int r; + struct dm_io_region region; + struct dm_io_request req; + + region.bdev = wc->ssd_dev->bdev; + region.sector = 0; + region.count = PAGE_SIZE; + + if (unlikely(region.sector + region.count > wc->metadata_sectors)) + region.count = wc->metadata_sectors - region.sector; + + region.sector += wc->start_sector; + + req.bi_op = REQ_OP_WRITE; + req.bi_op_flags = REQ_SYNC | REQ_FUA; + req.mem.type = DM_IO_VMA; + req.mem.ptr.vma = (char *)wc->memory_map; + req.client = wc->dm_io; + req.notify.fn = NULL; + req.notify.context = NULL; + + r = dm_io(&req, 1, ®ion, NULL); + if (unlikely(r)) + writecache_error(wc, r, "error writing superblock"); +} + static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios) { if (WC_MODE_PMEM(wc)) @@ -757,8 +785,10 @@ static void writecache_flush(struct dm_w wc->seq_count++; pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count)); - writecache_flush_region(wc, &sb(wc)->seq_count, sizeof sb(wc)->seq_count); - writecache_commit_flushed(wc, false); + if (WC_MODE_PMEM(wc)) + writecache_commit_flushed(wc, false); + else + ssd_commit_superblock(wc); wc->overwrote_committed = false; -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
