On Fri, Mar 22, 2013 at 06:34:28PM -0400, Mike Snitzer wrote: > On Fri, Mar 22 2013 at 4:11pm -0400, > Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > > > The new writethrough strategy for dm-cache issues a bio to the origin device, > > remaps the bio to the cache device, and issues the bio to the cache device. > > However, the block layer modifies bi_sector and bi_size, so we need to preserve > > these or else nothing gets written to the cache (bi_size == 0). This fixes the > > problem where someone writes a block through the cache, but a subsequent reread > > (from the cache) returns old contents. > > Your writethrough blkid test results are certainly strange. But I'm not > aware of where the block layer would modify bi_size and bi_sector; > please elaborate. > > I cannot reproduce your original report. I developed > 'test_writethrough_ext4_uuids_match', apologies for the ruby code: Hmm... I'm building my kernels off 0a7e453103b9718d357688b83bb968ee108cc874 in Linus' tree (post 3.9-rc3). This is the full output of dmsetup table: moocache-blocks: 0 1039360 linear 8:16 9088 moocache-metadata: 0 8704 linear 8:16 384 moocache: 0 67108864 cache 253:0 253:1 8:0 512 1 writethrough default 4 random_threshold 4 sequential_threshold 32768 253:0 -> moocache-metadata and 253:1 -> moocache-blocks. I'm curious what your setup is... --D > > def test_writethrough_ext4_uuids_match > size = meg(10) > > # wipe the origin to ensure we don't accidentally have the same > # data on it. > with_standard_linear(:data_size => size) do |origin| > wipe_device(origin) > end > > uuid = "deadbeef-cafe-dead-beef-cafedeadbeef" > > # format the cache device with a specific uuid > with_standard_cache(:format => true, > :io_mode => :writethrough, > :data_size => size) do |cache| > fs = FS::file_system(:ext4, cache) > fs.format(:uuid => uuid) > FS::assert_fs_uuid(uuid, cache) > end > > # origin should have the same uuid as the cache > with_standard_linear(:data_size => size) do |origin| > FS::assert_fs_uuid(uuid, origin) > end > end > > This test was committed to the 'devel' branch of my thinp-test-suite > tree: git://github.com/snitm/thinp-test-suite.git > > Also the existing 'test_writethrough' test works fine. > > So for now: > > Nacked-by: Mike Snitzer <snitzer@xxxxxxxxxx> > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
