spa_misc.c revision 0125049cd6136d1d2ca9e982382a915b6d7916ce
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include <sys/zfs_context.h>
#include <sys/spa_impl.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <sys/vdev_impl.h>
#include <sys/metaslab.h>
#include <sys/uberblock_impl.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_prop.h>
/*
* SPA locking
*
* There are four basic locks for managing spa_t structures:
*
* spa_namespace_lock (global mutex)
*
* This lock must be acquired to do any of the following:
*
* - Lookup a spa_t by name
* - Add or remove a spa_t from the namespace
* - Increase spa_refcount from non-zero
* - Check if spa_refcount is zero
* - Rename a spa_t
*
* It does not need to handle recursion. A create or destroy may
* reference objects (files or zvols) in other pools, but by
* definition they must have an existing reference, and will never need
* to lookup a spa_t by name.
*
* spa_refcount (per-spa refcount_t protected by mutex)
*
* This reference count keep track of any active users of the spa_t. The
* spa_t cannot be destroyed or freed while this is non-zero. Internally,
* the refcount is never really 'zero' - opening a pool implicitly keeps
* some references in the DMU. Internally we check against SPA_MINREF, but
*
* spa_config_lock (per-spa crazy rwlock)
*
* This SPA special is a recursive rwlock, capable of being acquired from
* asynchronous threads. It has protects the spa_t from config changes,
* and must be held in the following circumstances:
*
* - RW_READER to perform I/O to the spa
* - RW_WRITER to change the vdev config
*
* spa_config_cache_lock (per-spa mutex)
*
* This mutex prevents the spa_config nvlist from being updated. No
* other locks are required to obtain this lock, although implicitly you
* must have the namespace lock or non-zero refcount to have any kind
* of spa_t pointer at all.
*
* The locking order is fairly straightforward:
*
* spa_namespace_lock -> spa_refcount
*
* The namespace lock must be acquired to increase the refcount from 0
* or to check if it is zero.
*
* spa_refcount -> spa_config_lock
*
* There must be at least one valid reference on the spa_t to acquire
* the config lock.
*
* spa_namespace_lock -> spa_config_lock
*
* The namespace lock must always be taken before the config lock.
*
*
* The spa_namespace_lock and spa_config_cache_lock can be acquired directly and
* are globally visible.
*
* The namespace is manipulated using the following functions, all which require
* the spa_namespace_lock to be held.
*
* spa_lookup() Lookup a spa_t by name.
*
* spa_add() Create a new spa_t in the namespace.
*
* spa_remove() Remove a spa_t from the namespace. This also
* frees up any memory associated with the spa_t.
*
* spa_next() Returns the next spa_t in the system, or the
* first if NULL is passed.
*
* spa_evict_all() Shutdown and remove all spa_t structures in
* the system.
*
*
* The spa_refcount is manipulated using the following functions:
*
* spa_open_ref() Adds a reference to the given spa_t. Must be
* called with spa_namespace_lock held if the
* refcount is currently zero.
*
* spa_close() Remove a reference from the spa_t. This will
* not free the spa_t or remove it from the
* namespace. No locking is required.
*
* spa_refcount_zero() Returns true if the refcount is currently
* zero. Must be called with spa_namespace_lock
* held.
*
* The spa_config_lock is manipulated using the following functions:
*
* spa_config_enter() Acquire the config lock as RW_READER or
* RW_WRITER. At least one reference on the spa_t
* must exist.
*
* spa_config_exit() Release the config lock.
*
* spa_config_held() Returns true if the config lock is currently
* held in the given state.
*
* The vdev configuration is protected by spa_vdev_enter() / spa_vdev_exit().
*
* spa_vdev_enter() Acquire the namespace lock and the config lock
* for writing.
*
* spa_vdev_exit() Release the config lock, wait for all I/O
* to complete, sync the updated configs to the
* cache, and release the namespace lock.
*
* The spa_name() function also requires either the spa_namespace_lock
* or the spa_config_lock, as both are needed to do a rename. spa_rename() is
* also implemented within this file since is requires manipulation of the
* namespace.
*/
static avl_tree_t spa_namespace_avl;
static kcondvar_t spa_namespace_cv;
static int spa_active_count;
static kmutex_t spa_spare_lock;
static avl_tree_t spa_spare_avl;
int spa_mode;
#ifdef ZFS_DEBUG
int zfs_flags = ~0;
#else
int zfs_flags = 0;
#endif
/*
* zfs_recover can be set to nonzero to attempt to recover from
* otherwise-fatal errors, typically caused by on-disk corruption. When
* set, calls to zfs_panic_recover() will turn into warning messages.
*/
int zfs_recover = 0;
/*
* ==========================================================================
* SPA namespace functions
* ==========================================================================
*/
/*
* Lookup the named spa_t in the AVL tree. The spa_namespace_lock must be held.
* Returns NULL if no matching spa_t is found.
*/
spa_t *
spa_lookup(const char *name)
{
return (spa);
}
/*
* Create an uninitialized spa_t with the given name. Requires
* spa_namespace_lock. The caller must ensure that the spa_t doesn't already
* exist by calling spa_lookup() first.
*/
spa_t *
{
/*
* Set the alternate root, if there is one.
*/
if (altroot) {
}
return (spa);
}
/*
* Removes a spa_t from the namespace, freeing up any memory used. Requires
* spa_namespace_lock. This is called only after the spa_t has been closed and
* deactivated.
*/
void
{
}
}
/*
* Given a pool, return the next pool in the namespace, or NULL if there is
* none. If 'prev' is NULL, return the first pool.
*/
spa_t *
{
if (prev)
else
return (avl_first(&spa_namespace_avl));
}
/*
* ==========================================================================
* SPA refcount functions
* ==========================================================================
*/
/*
* Add a reference to the given spa_t. Must have at least one reference, or
* have the namespace lock held.
*/
void
{
}
/*
* Remove a reference to the given spa_t. Must have at least one reference, or
* have the namespace lock held.
*/
void
{
}
/*
* Check to see if the spa refcount is zero. Must be called with
* spa_namespace_lock held. We really compare against SPA_MINREF, which is the
* number of references acquired when opening a pool
*/
{
}
/*
* ==========================================================================
* SPA spare tracking
* ==========================================================================
*/
/*
* Spares are tracked globally due to the following constraints:
*
* - A spare may be part of multiple pools.
* - A spare may be added to a pool even if it's actively in use within
* another pool.
* - A spare in use in any pool can only be the source of a replacement if
* the target is a spare in the same pool.
*
* We keep track of all spares on the system through the use of a reference
* counted AVL tree. When a vdev is added as a spare, or used as a replacement
* spare, then we bump the reference count in the AVL tree. In addition, we set
* the 'vdev_isspare' member to indicate that the device is a spare (active or
* inactive). When a spare is made active (used to replace a device in the
* pool), we also keep track of which pool its been made a part of.
*
* The 'spa_spare_lock' protects the AVL tree. These functions are normally
* called under the spa_namespace lock as part of vdev reconfiguration. The
* separate spare lock exists for the status query path, which does not need to
* be completely consistent with respect to other vdev configuration changes.
*/
typedef struct spa_spare {
int spare_count;
} spa_spare_t;
static int
spa_spare_compare(const void *a, const void *b)
{
const spa_spare_t *sa = a;
const spa_spare_t *sb = b;
return (-1);
return (1);
else
return (0);
}
void
{
spare->spare_count++;
} else {
}
}
void
{
if (--spare->spare_count == 0) {
}
}
{
if (pool) {
if (found)
else
}
}
void
{
}
/*
* ==========================================================================
* SPA config locking
* ==========================================================================
*/
/*
* Acquire the config lock. The config lock is a special rwlock that allows for
* recursive enters. Because these enters come from the same thread as well as
* asynchronous threads working on behalf of the owner, we must unilaterally
* allow all reads access as long at least one reader is held (even if a write
* is requested). This has the side effect of write starvation, but write locks
* are extremely rare, and a solution to this problem would be significantly
* more complex (if even possible).
*
* We would like to assert that the namespace lock isn't held, but this is a
* valid use during create.
*/
void
{
} else {
}
}
}
/*
* Release the spa config lock, notifying any waiters in the process.
*/
void
{
}
}
/*
* Returns true if the config lock is held in the given manner.
*/
{
else
return (held);
}
/*
* ==========================================================================
* SPA vdev locking
* ==========================================================================
*/
/*
* Lock the given spa_t for the purpose of adding or removing a vdev.
* Grabs the global spa_namespace_lock plus the spa config lock for writing.
* It returns the next transaction group for the spa_t.
*/
{
/*
* Suspend scrub activity while we mess with the config.
*/
}
/*
* Unlock the spa_t after adding or removing a vdev. Besides undoing the
* locking of spa_vdev_enter(), we also want make sure the transactions have
* synced to disk, and then update the global configuration cache with the new
* information.
*/
int
{
int config_changed = B_FALSE;
/*
* Reassess the DTLs.
*/
/*
* If the config changed, notify the scrub thread that it must restart.
*/
}
/*
* Allow scrubbing to resume.
*/
/*
* Note: this txg_wait_synced() is important because it ensures
* that there won't be more than one config change per txg.
* This allows us to use the txg as the generation number.
*/
if (error == 0)
}
/*
* If the config changed, update the config cache.
*/
if (config_changed)
return (error);
}
/*
* ==========================================================================
* Miscellaneous functions
* ==========================================================================
*/
/*
* Rename a spa_t.
*/
int
{
int err;
/*
* Lookup the spa_t and grab the config lock for writing. We need to
* actually open the pool so that we can sync out the necessary labels.
* It's OK to call spa_open() with the namespace lock held because we
* allow recursive calls for other reasons.
*/
return (err);
}
/*
* Sync all labels to disk with the new names by marking the root vdev
* dirty and waiting for it to sync. It will pick up the new pool name
* during the sync.
*/
/*
* Sync the updated config cache.
*/
return (0);
}
/*
* Determine whether a pool with given pool_guid exists. If device_guid is
* non-zero, determine whether the pool exists *and* contains a device with the
* specified device_guid.
*/
{
avl_tree_t *t = &spa_namespace_avl;
continue;
continue;
if (device_guid == 0)
break;
device_guid) != NULL)
break;
/*
* Check any devices we may in the process of adding.
*/
if (spa->spa_pending_vdev) {
device_guid) != NULL)
break;
}
}
}
}
char *
spa_strdup(const char *s)
{
char *new;
return (new);
}
void
spa_strfree(char *s)
{
}
{
uint64_t r;
(void) random_get_pseudo_bytes((void *)&r, sizeof (uint64_t));
return (r % range);
}
void
{
int d;
return;
}
if (BP_IS_HOLE(bp)) {
return;
}
for (d = 0; d < BP_GET_NDVAS(bp); d++) {
"DVA[%d]=<%llu:%llx:%llx> ", d,
}
"%s %s %s %s birth=%llu fill=%llu cksum=%llx:%llx:%llx:%llx",
}
void
{
uint64_t freeze_txg = 0;
}
if (freeze_txg != 0)
}
void
zfs_panic_recover(const char *fmt, ...)
{
}
/*
* ==========================================================================
* Accessor functions
* ==========================================================================
*/
{
return (&spa->spa_traverse_lock);
}
int
{
return (spa->spa_traverse_wanted);
}
{
return (spa->spa_dsl_pool);
}
blkptr_t *
{
}
void
{
}
void
{
buf[0] = '\0';
else
}
int
{
return (spa->spa_sync_pass);
}
char *
{
/*
* Accessing the name requires holding either the namespace lock or the
* config lock, both of which are required to do a rename.
*/
}
{
/*
* If we fail to parse the config during spa_load(), we can go through
* the error path (which posts an ereport) and end up here with no root
* vdev. We stash the original pool guid in 'spa_load_guid' to handle
* this case.
*/
else
return (spa->spa_load_guid);
}
{
}
{
return (spa->spa_first_txg);
}
int
{
}
{
return (spa->spa_freeze_txg);
}
/*
* In the future, this may select among different metaslab classes
* depending on the zdp. For now, there's no such distinction.
*/
{
return (spa->spa_normal_class);
}
/*
* Return how much space is allocated in the pool (ie. sum of all asize)
*/
{
}
/*
* Return how much (raid-z inflated) space there is in the pool.
*/
{
}
/*
* Return the amount of raid-z-deflated space in the pool.
*/
{
if (spa->spa_deflate)
else
}
/* ARGSUSED */
{
/*
* For now, the worst case is 512-byte RAID-Z blocks, in which
* case the space requirement is exactly 2x; so just assume that.
* Add to this the fact that we can have up to 3 DVAs per bp, and
* we have to multiply by a total of 6x.
*/
return (lsize * 6);
}
{
}
int
{
/*
* As of ZFS_VERSION == ZFS_VERSION_DITTO_BLOCKS, we are able to
* handle BPs with more than one DVA allocated. Set our max
* replication level accordingly.
*/
return (1);
}
{
int sz = 0, i;
if (!spa->spa_deflate)
return (BP_GET_ASIZE(bp));
for (i = 0; i < SPA_DVAS_PER_BP; i++) {
}
return (sz);
}
/*
* ==========================================================================
* Initialization and Termination
* ==========================================================================
*/
static int
{
int s;
if (s > 0)
return (1);
if (s < 0)
return (-1);
return (0);
}
int
spa_busy(void)
{
return (spa_active_count);
}
void
{
unique_init();
zio_init();
dmu_init();
zil_init();
}
void
spa_fini(void)
{
zil_fini();
dmu_fini();
zio_fini();
}