On 2021/06/04 7:16, Mike Snitzer wrote: > On Thu, Jun 03 2021 at 1:46P -0400, > Jens Axboe <axboe@xxxxxxxxx> wrote: > >> On 6/2/21 12:32 PM, Mike Snitzer wrote: >>> On Tue, Jun 01 2021 at 6:57P -0400, >>> Damien Le Moal <Damien.LeMoal@xxxxxxx> wrote: >>> >>>> On 2021/05/26 6:25, Damien Le Moal wrote: >>>>> This series improve device mapper support for zoned block devices and >>>>> of targets exposing a zoned device. >>>> >>>> Mike, Jens, >>>> >>>> Any feedback regarding this series ? >>>> >>>>> >>>>> The first patch improve support for user requests to reset all zones of >>>>> the target device. With the fix, such operation behave similarly to >>>>> physical block devices implementation based on the single zone reset >>>>> command with the ALL bit set. >>>>> >>>>> The following 2 patches are preparatory block layer patches. >>>>> >>>>> Patch 4 and 5 are 2 small fixes to DM core zoned block device support. >>>>> >>>>> Patch 6 reorganizes DM core code, moving conditionally defined zoned >>>>> block device code into the new dm-zone.c file. This avoids sprinkly DM >>>>> with zone related code defined under an #ifdef CONFIG_BLK_DEV_ZONED. >>>>> >>>>> Patch 7 improves DM zone report helper functions for target drivers. >>>>> >>>>> Patch 8 fixes a potential problem with BIO requeue on zoned target. >>>>> >>>>> Finally, patch 9 to 11 implement zone append emulation using regular >>>>> writes for target drivers that cannot natively support this BIO type. >>>>> The only target currently needing this emulation is dm-crypt. With this >>>>> change, a zoned dm-crypt device behaves exactly like a regular zoned >>>>> block device, correctly executing user zone append BIOs. >>>>> >>>>> This series passes the following tests: >>>>> 1) zonefs tests on top of dm-crypt with a zoned nullblk device >>>>> 2) zonefs tests on top of dm-crypt+dm-linear with an SMR HDD >>>>> 3) btrfs fstests on top of dm-crypt with zoned nullblk devices. >>>>> >>>>> Comments are as always welcome. >>> >>> I've picked up DM patches 4-8 because they didn't depend on the first >>> 3 block patches. >>> >>> But I'm fine with picking up 1-3 if Jens provides his Acked-by. >>> And then I can pickup the remaining DM patches 9-11. >> >> I'm fine with 1-3, you can add my Acked-by to those. > > Thanks, did so. > > Damien: I've staged this patchset in linux-next via the dm-5.14 branch of linux-dm.git Thanks ! > Might look at optimizing the fast-path of __map_bio further, e.g. this > leaves something to be desired considering how niche this all is: > > /* > * Check if the IO needs a special mapping due to zone append emulation > * on zoned target. In this case, dm_zone_map_bio() calls the target > * map operation. > */ > if (dm_emulate_zone_append(io->md)) > r = dm_zone_map_bio(tio); > else > r = ti->type->map(ti, clone); > > Does it make sense to split out a new CONFIG_ that encapsulates legacy > zoned devices? Well, the problem is that there are no "legacy" zoned devices: they all support zone append commands, either natively (for zns and nullblk) or emulated in their respective drivers (scsi sd for SMR drives). So I do not think that a new CONFIG_XXX can be used. What we could do is have this conditional on either: (1) the DM targets that need it: dm-crypt only for now (CONFIG_DM_CRYPT) (2) Zone append command users: btrfs and zonefs only for now (CONFIG_FS_BTRFS and CONFIG_FS_ZONEFS) (1) would be the nicest as we can keep this contained in DM and define something in KConfig. However, given that most distros (if not all) enable dm-crypt, I am not convinced this will do any good. Note that for the !CONFIG_BLK_DEV_ZONED case, the "if (dm_emulate_zone_append(io->md))" is compiled out, resulting in the same code as without the emulation. -- Damien Le Moal Western Digital Research -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
