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? > > 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
