OpenZFS 7614, 9064 - zfs device evacuation/removal

OpenZFS 7614 - zfs device evacuation/removal
OpenZFS 9064 - remove_mirror should wait for device removal to complete

This project allows top-level vdevs to be removed from the storage pool
with "zpool remove", reducing the total amount of storage in the pool.
This operation copies all allocated regions of the device to be removed
onto other devices, recording the mapping from old to new location.
After the removal is complete, read and free operations to the removed
(now "indirect") vdev must be remapped and performed at the new location
on disk.  The indirect mapping table is kept in memory whenever the pool
is loaded, so there is minimal performance overhead when doing operations
on the indirect vdev.

The size of the in-memory mapping table will be reduced when its entries
become "obsolete" because they are no longer used by any block pointers
in the pool.  An entry becomes obsolete when all the blocks that use
it are freed.  An entry can also become obsolete when all the snapshots
that reference it are deleted, and the block pointers that reference it
have been "remapped" in all filesystems/zvols (and clones).  Whenever an
indirect block is written, all the block pointers in it will be "remapped"
to their new (concrete) locations if possible.  This process can be
accelerated by using the "zfs remap" command to proactively rewrite all
indirect blocks that reference indirect (removed) vdevs.

Note that when a device is removed, we do not verify the checksum of
the data that is copied.  This makes the process much faster, but if it
were used on redundant vdevs (i.e. mirror or raidz vdevs), it would be
possible to copy the wrong data, when we have the correct data on e.g.
the other side of the mirror.

At the moment, only mirrors and simple top-level vdevs can be removed
and no removal is allowed if any of the top-level vdevs are raidz.

Porting Notes:

* Avoid zero-sized kmem_alloc() in vdev_compact_children().

    The device evacuation code adds a dependency that
    vdev_compact_children() be able to properly empty the vdev_child
    array by setting it to NULL and zeroing vdev_children.  Under Linux,
    kmem_alloc() and related functions return a sentinel pointer rather
    than NULL for zero-sized allocations.

* Remove comment regarding "mpt" driver where zfs_remove_max_segment
  is initialized to SPA_MAXBLOCKSIZE.

  Change zfs_condense_indirect_commit_entry_delay_ticks to
  zfs_condense_indirect_commit_entry_delay_ms for consistency with
  most other tunables in which delays are specified in ms.

* ZTS changes:

    Use set_tunable rather than mdb
    Use zpool sync as appropriate
    Use sync_pool instead of sync
    Kill jobs during test_removal_with_operation to allow unmount/export
    Don't add non-disk names such as "mirror" or "raidz" to $DISKS
    Use $TEST_BASE_DIR instead of /tmp
    Increase HZ from 100 to 1000 which is more common on Linux

    removal_multiple_indirection.ksh
        Reduce iterations in order to not time out on the code
        coverage builders.

    removal_resume_export:
        Functionally, the test case is correct but there exists a race
        where the kernel thread hasn't been fully started yet and is
        not visible.  Wait for up to 1 second for the removal thread
        to be started before giving up on it.  Also, increase the
        amount of data copied in order that the removal not finish
        before the export has a chance to fail.

* MMP compatibility, the concept of concrete versus non-concrete devices
  has slightly changed the semantics of vdev_writeable().  Update
  mmp_random_leaf_impl() accordingly.

* Updated dbuf_remap() to handle the org.zfsonlinux:large_dnode pool
  feature which is not supported by OpenZFS.

* Added support for new vdev removal tracepoints.

* Test cases removal_with_zdb and removal_condense_export have been
  intentionally disabled.  When run manually they pass as intended,
  but when running in the automated test environment they produce
  unreliable results on the latest Fedora release.

  They may work better once the upstream pool import refectoring is
  merged into ZoL at which point they will be re-enabled.

Authored by: Matthew Ahrens <[email protected]>
Reviewed-by: Alex Reece <[email protected]>
Reviewed-by: George Wilson <[email protected]>
Reviewed-by: John Kennedy <[email protected]>
Reviewed-by: Prakash Surya <[email protected]>
Reviewed by: Richard Laager <[email protected]>
Reviewed by: Tim Chase <[email protected]>
Reviewed by: Brian Behlendorf <[email protected]>
Approved by: Garrett D'Amore <[email protected]>
Ported-by: Tim Chase <[email protected]>
Signed-off-by: Tim Chase <[email protected]>

OpenZFS-issue: https://www.illumos.org/issues/7614
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/f539f1eb
Closes #6900

1 files changed, 73 insertions, 1 deletions

diff --git a/include/sys/spa_impl.h b/include/sys/spa_impl.h
index 77625d4b0..1741eb9e5 100644
--- a/include/sys/spa_impl.h
+++ b/include/sys/spa_impl.h
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  * Copyright 2013 Saso Kiselkov. All rights reserved.
@@ -33,6 +33,7 @@
 
 #include <sys/spa.h>
 #include <sys/vdev.h>
+#include <sys/vdev_removal.h>
 #include <sys/metaslab.h>
 #include <sys/dmu.h>
 #include <sys/dsl_pool.h>
@@ -64,6 +65,62 @@ typedef struct spa_history_phys {
 	uint64_t sh_records_lost;	/* num of records overwritten */
 } spa_history_phys_t;
 
+/*
+ * All members must be uint64_t, for byteswap purposes.
+ */
+typedef struct spa_removing_phys {
+	uint64_t sr_state; /* dsl_scan_state_t */
+
+	/*
+	 * The vdev ID that we most recently attempted to remove,
+	 * or -1 if no removal has been attempted.
+	 */
+	uint64_t sr_removing_vdev;
+
+	/*
+	 * The vdev ID that we most recently successfully removed,
+	 * or -1 if no devices have been removed.
+	 */
+	uint64_t sr_prev_indirect_vdev;
+
+	uint64_t sr_start_time;
+	uint64_t sr_end_time;
+
+	/*
+	 * Note that we can not use the space map's or indirect mapping's
+	 * accounting as a substitute for these values, because we need to
+	 * count frees of not-yet-copied data as though it did the copy.
+	 * Otherwise, we could get into a situation where copied > to_copy,
+	 * or we complete before copied == to_copy.
+	 */
+	uint64_t sr_to_copy; /* bytes that need to be copied */
+	uint64_t sr_copied; /* bytes that have been copied or freed */
+} spa_removing_phys_t;
+
+/*
+ * This struct is stored as an entry in the DMU_POOL_DIRECTORY_OBJECT
+ * (with key DMU_POOL_CONDENSING_INDIRECT).  It is present if a condense
+ * of an indirect vdev's mapping object is in progress.
+ */
+typedef struct spa_condensing_indirect_phys {
+	/*
+	 * The vdev ID of the indirect vdev whose indirect mapping is
+	 * being condensed.
+	 */
+	uint64_t	scip_vdev;
+
+	/*
+	 * The vdev's old obsolete spacemap.  This spacemap's contents are
+	 * being integrated into the new mapping.
+	 */
+	uint64_t	scip_prev_obsolete_sm_object;
+
+	/*
+	 * The new mapping object that is being created.
+	 */
+	uint64_t	scip_next_mapping_object;
+} spa_condensing_indirect_phys_t;
+
 struct spa_aux_vdev {
 	uint64_t	sav_object;		/* MOS object for device list */
 	nvlist_t	*sav_config;		/* cached device config */
@@ -143,6 +200,7 @@ struct spa {
 	int		spa_inject_ref;		/* injection references */
 	uint8_t		spa_sync_on;		/* sync threads are running */
 	spa_load_state_t spa_load_state;	/* current load operation */
+	boolean_t	spa_indirect_vdevs_loaded; /* mappings loaded? */
 	uint64_t	spa_import_flags;	/* import specific flags */
 	spa_taskqs_t	spa_zio_taskq[ZIO_TYPES][ZIO_TASKQ_TYPES];
 	dsl_pool_t	*spa_dsl_pool;
@@ -204,6 +262,14 @@ struct spa {
 	int		spa_async_suspended;	/* async tasks suspended */
 	kcondvar_t	spa_async_cv;		/* wait for thread_exit() */
 	uint16_t	spa_async_tasks;	/* async task mask */
+
+	spa_removing_phys_t spa_removing_phys;
+	spa_vdev_removal_t *spa_vdev_removal;
+
+	spa_condensing_indirect_phys_t	spa_condensing_indirect_phys;
+	spa_condensing_indirect_t	*spa_condensing_indirect;
+	kthread_t	*spa_condense_thread;	/* thread doing condense. */
+
 	char		*spa_root;		/* alternate root directory */
 	uint64_t	spa_ena;		/* spa-wide ereport ENA */
 	int		spa_last_open_failed;	/* error if last open failed */
@@ -234,6 +300,7 @@ struct spa {
 	/* per-CPU array of root of async I/O: */
 	zio_t		**spa_async_zio_root;
 	zio_t		*spa_suspend_zio_root;	/* root of all suspended I/O */
+	zio_t		*spa_txg_zio[TXG_SIZE]; /* spa_sync() waits for this */
 	kmutex_t	spa_suspend_lock;	/* protects suspend_zio_root */
 	kcondvar_t	spa_suspend_cv;		/* notification of resume */
 	zio_suspend_reason_t	spa_suspended;	/* pool is suspended */
@@ -302,6 +369,11 @@ extern void spa_taskq_dispatch_ent(spa_t *spa, zio_type_t t, zio_taskq_type_t q,
     task_func_t *func, void *arg, uint_t flags, taskq_ent_t *ent);
 extern void spa_taskq_dispatch_sync(spa_t *, zio_type_t t, zio_taskq_type_t q,
     task_func_t *func, void *arg, uint_t flags);
+extern void spa_load_spares(spa_t *spa);
+extern void spa_load_l2cache(spa_t *spa);
+extern sysevent_t *spa_event_create(spa_t *spa, vdev_t *vd, nvlist_t *hist_nvl,
+    const char *name);
+extern void spa_event_post(sysevent_t *ev);
 
 
 #ifdef	__cplusplus