Thank you Toomas for patch and Andrey for reviews. On 03.05.2015 17:15, Andrei Borzenkov wrote: > В Sun, 19 Apr 2015 17:57:04 +0300 > Toomas Soome <tso...@me.com> пишет: > >> >>> On 19.04.2015, at 17:51, Andrei Borzenkov <arvidj...@gmail.com> wrote: >>> >>> В Sun, 19 Apr 2015 17:40:16 +0300 >>> Toomas Soome <tso...@me.com> пишет: >>> >>>> >>>> the features in openzfs have different effects, some affect only writes >>>> and are therefore read only compatible - such feature does not need any >>>> changes for reads, this feature is not read only compatible and therefore, >>>> once this feature is enabled, reader code must be changed accordingly. >>>> >>>> so, what they did with hole_birth was they started to insert block birth >>>> timestamps for blocks being released to make it possible to track such >>>> blocks while doing zfs send (when block has birth time, you know its place >>>> on timeline of snapshots). as old reader code was relying on blk_birth == >>>> 0 to detect an hole, after hole_birth is enabled, hole blk_birth is not 0 >>>> any more, so the solution is to check if DVA pointers are zero instead. >>>> and thats exactly what its about. >>> >>> And if hole_birth is *not* enabled on a filesystem we are reading? >>> Should not old code be used in this case? >> >> >> not really, as for holes, DVA pointers are zero anyhow. I guess the >> original implementation used blk_birth to save extra compare - so the new >> read code is compatible with old data. > > Committed with explanatory text for non-insiders. > >> >> >>> >>>> >>>> reference: >>>> https://github.com/illumos/illumos-gate/commit/43466aae47bfcd2ad9bf501faec8e75c08095e4f >>>> >>>> >>>> >>>> >>>>> On 19.04.2015, at 17:11, Andrei Borzenkov <arvidj...@gmail.com> wrote: >>>>> >>>>> В Thu, 16 Apr 2015 08:22:08 +0300 >>>>> Toomas Soome <tso...@me.com> пишет: >>>>> >>>>> This really needs better explanation. Otherwise this looks like either >>>>> old code was broken to start with and it is a bug fix or new code needs >>>>> some conditionals on new feature. >>>>> >>>>>> >>>>>> --- >>>>>> grub-core/fs/zfs/zfs.c | 6 ++++-- >>>>>> include/grub/zfs/spa.h | 4 +++- >>>>>> 2 files changed, 7 insertions(+), 3 deletions(-) >>>>>> >>>>>> diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c >>>>>> index 2689986..a731c3d 100644 >>>>>> --- a/grub-core/fs/zfs/zfs.c >>>>>> +++ b/grub-core/fs/zfs/zfs.c >>>>>> @@ -280,7 +280,9 @@ grub_crypto_cipher_handle_t (*grub_zfs_load_key) >>>>>> (const struct grub_zfs_key *key >>>>>> */ >>>>>> #define MAX_SUPPORTED_FEATURE_STRLEN 50 >>>>>> static const char *spa_feature_names[] = { >>>>>> - "org.illumos:lz4_compress",NULL >>>>>> + "org.illumos:lz4_compress", >>>>>> + "com.delphix:hole_birth", >>>>>> + NULL >>>>>> }; >>>>>> >>>>>> static int >>>>>> @@ -1751,7 +1753,7 @@ zio_read_gang (blkptr_t * bp, grub_zfs_endian_t >>>>>> endian, dva_t * dva, void *buf, >>>>>> >>>>>> for (i = 0; i < SPA_GBH_NBLKPTRS; i++) >>>>>> { >>>>>> - if (zio_gb->zg_blkptr[i].blk_birth == 0) >>>>>> + if (BP_IS_HOLE(&zio_gb->zg_blkptr[i])) >>>>>> continue; >>>>>> >>>>>> err = zio_read_data (&zio_gb->zg_blkptr[i], endian, buf, data); >>>>>> diff --git a/include/grub/zfs/spa.h b/include/grub/zfs/spa.h >>>>>> index 7edb8ab..df43b6b 100644 >>>>>> --- a/include/grub/zfs/spa.h >>>>>> +++ b/include/grub/zfs/spa.h >>>>>> @@ -279,7 +279,9 @@ typedef struct blkptr { >>>>>> >>>>>> #define BP_IDENTITY(bp) (&(bp)->blk_dva[0]) >>>>>> #define BP_IS_GANG(bp) DVA_GET_GANG(BP_IDENTITY(bp)) >>>>>> -#define BP_IS_HOLE(bp) ((bp)->blk_birth == 0) >>>>>> +#define DVA_IS_EMPTY(dva) ((dva)->dva_word[0] == 0ULL && \ >>>>>> + (dva)->dva_word[1] == 0ULL) >>>>>> +#define BP_IS_HOLE(bp) DVA_IS_EMPTY(BP_IDENTITY(bp)) >>>>>> >>>>>> /* BP_IS_RAIDZ(bp) assumes no block compression */ >>>>>> #define BP_IS_RAIDZ(bp) (DVA_GET_ASIZE(&(bp)->blk_dva[0]) > \ >>>>> >>>>> >>>>> _______________________________________________ >>>>> Grub-devel mailing list >>>>> Grub-devel@gnu.org >>>>> https://lists.gnu.org/mailman/listinfo/grub-devel >>>> >>>> >>>> _______________________________________________ >>>> Grub-devel mailing list >>>> Grub-devel@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/grub-devel >> > > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel >
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