From d2734cce68cf740e015312314415f9034c67851c Mon Sep 17 00:00:00 2001 From: Serapheim Dimitropoulos Date: Fri, 16 Dec 2016 14:11:29 -0800 Subject: OpenZFS 9166 - zfs storage pool checkpoint Details about the motivation of this feature and its usage can be found in this blogpost: https://sdimitro.github.io/post/zpool-checkpoint/ A lightning talk of this feature can be found here: https://www.youtube.com/watch?v=fPQA8K40jAM Implementation details can be found in big block comment of spa_checkpoint.c Side-changes that are relevant to this commit but not explained elsewhere: * renames members of "struct metaslab trees to be shorter without losing meaning * space_map_{alloc,truncate}() accept a block size as a parameter. The reason is that in the current state all space maps that we allocate through the DMU use a global tunable (space_map_blksz) which defauls to 4KB. This is ok for metaslab space maps in terms of bandwirdth since they are scattered all over the disk. But for other space maps this default is probably not what we want. Examples are device removal's vdev_obsolete_sm or vdev_chedkpoint_sm from this review. Both of these have a 1:1 relationship with each vdev and could benefit from a bigger block size. Porting notes: * The part of dsl_scan_sync() which handles async destroys has been moved into the new dsl_process_async_destroys() function. * Remove "VERIFY(!(flags & FWRITE))" in "kernel.c" so zhack can write to block device backed pools. * ZTS: * Fix get_txg() in zpool_sync_001_pos due to "checkpoint_txg". * Don't use large dd block sizes on /dev/urandom under Linux in checkpoint_capacity. * Adopt Delphix-OS's setting of 4 (spa_asize_inflation = SPA_DVAS_PER_BP + 1) for the checkpoint_capacity test to speed its attempts to fill the pool * Create the base and nested pools with sync=disabled to speed up the "setup" phase. * Clear labels in test pool between checkpoint tests to avoid duplicate pool issues. * The import_rewind_device_replaced test has been marked as "known to fail" for the reasons listed in its DISCLAIMER. * New module parameters: zfs_spa_discard_memory_limit, zfs_remove_max_bytes_pause (not documented - debugging only) vdev_max_ms_count (formerly metaslabs_per_vdev) vdev_min_ms_count Authored by: Serapheim Dimitropoulos Reviewed by: Matthew Ahrens Reviewed by: John Kennedy Reviewed by: Dan Kimmel Reviewed by: Brian Behlendorf Approved by: Richard Lowe Ported-by: Tim Chase Signed-off-by: Tim Chase OpenZFS-issue: https://illumos.org/issues/9166 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7159fdb8 Closes #7570 --- include/sys/uberblock_impl.h | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) (limited to 'include/sys/uberblock_impl.h') diff --git a/include/sys/uberblock_impl.h b/include/sys/uberblock_impl.h index 08eeabdda..113df7c61 100644 --- a/include/sys/uberblock_impl.h +++ b/include/sys/uberblock_impl.h @@ -20,7 +20,7 @@ */ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. - * Copyright (c) 2017 by Delphix. All rights reserved. + * Copyright (c) 2016, 2017 by Delphix. All rights reserved. */ #ifndef _SYS_UBERBLOCK_IMPL_H @@ -61,6 +61,28 @@ struct uberblock { uint64_t ub_mmp_magic; /* MMP_MAGIC */ uint64_t ub_mmp_delay; /* nanosec since last MMP write */ uint64_t ub_mmp_seq; /* reserved for sequence number */ + + /* + * ub_checkpoint_txg indicates two things about the current uberblock: + * + * 1] If it is not zero then this uberblock is a checkpoint. If it is + * zero, then this uberblock is not a checkpoint. + * + * 2] On checkpointed uberblocks, the value of ub_checkpoint_txg is + * the ub_txg that the uberblock had at the time we moved it to + * the MOS config. + * + * The field is set when we checkpoint the uberblock and continues to + * hold that value even after we've rewound (unlike the ub_txg that + * is reset to a higher value). + * + * Besides checks used to determine whether we are reopening the + * pool from a checkpointed uberblock [see spa_ld_select_uberblock()], + * the value of the field is used to determine which ZIL blocks have + * been allocated according to the ms_sm when we are rewinding to a + * checkpoint. Specifically, if blk_birth > ub_checkpoint_txg, then + * the ZIL block is not allocated [see uses of spa_min_claim_txg()]. + */ uint64_t ub_checkpoint_txg; }; -- cgit v1.2.3