zfs-builds-mm/zfs-0.8.3/module/zfs/dsl_userhold.c

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2020-03-01 19:43:35 +01:00
/*
* 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
* or http://www.opensolaris.org/os/licensing.
* 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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2017 by Delphix. All rights reserved.
* Copyright (c) 2013 Steven Hartland. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/dsl_userhold.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_destroy.h>
#include <sys/dsl_synctask.h>
#include <sys/dmu_tx.h>
#include <sys/zfs_onexit.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_dir.h>
#include <sys/zfs_ioctl.h>
#include <sys/zap.h>
typedef struct dsl_dataset_user_hold_arg {
nvlist_t *dduha_holds;
nvlist_t *dduha_chkholds;
nvlist_t *dduha_errlist;
minor_t dduha_minor;
} dsl_dataset_user_hold_arg_t;
/*
* If you add new checks here, you may need to add additional checks to the
* "temporary" case in snapshot_check() in dmu_objset.c.
*/
int
dsl_dataset_user_hold_check_one(dsl_dataset_t *ds, const char *htag,
boolean_t temphold, dmu_tx_t *tx)
{
dsl_pool_t *dp = dmu_tx_pool(tx);
objset_t *mos = dp->dp_meta_objset;
int error = 0;
ASSERT(dsl_pool_config_held(dp));
if (strlen(htag) > MAXNAMELEN)
return (SET_ERROR(E2BIG));
/* Tempholds have a more restricted length */
if (temphold && strlen(htag) + MAX_TAG_PREFIX_LEN >= MAXNAMELEN)
return (SET_ERROR(E2BIG));
/* tags must be unique (if ds already exists) */
if (ds != NULL && dsl_dataset_phys(ds)->ds_userrefs_obj != 0) {
uint64_t value;
error = zap_lookup(mos, dsl_dataset_phys(ds)->ds_userrefs_obj,
htag, 8, 1, &value);
if (error == 0)
error = SET_ERROR(EEXIST);
else if (error == ENOENT)
error = 0;
}
return (error);
}
static int
dsl_dataset_user_hold_check(void *arg, dmu_tx_t *tx)
{
dsl_dataset_user_hold_arg_t *dduha = arg;
dsl_pool_t *dp = dmu_tx_pool(tx);
nvlist_t *tmp_holds;
if (spa_version(dp->dp_spa) < SPA_VERSION_USERREFS)
return (SET_ERROR(ENOTSUP));
if (!dmu_tx_is_syncing(tx))
return (0);
/*
* Ensure the list has no duplicates by copying name/values from
* non-unique dduha_holds to unique tmp_holds, and comparing counts.
*/
tmp_holds = fnvlist_alloc();
for (nvpair_t *pair = nvlist_next_nvpair(dduha->dduha_holds, NULL);
pair != NULL; pair = nvlist_next_nvpair(dduha->dduha_holds, pair)) {
size_t len = strlen(nvpair_name(pair)) +
strlen(fnvpair_value_string(pair));
char *nameval = kmem_zalloc(len + 2, KM_SLEEP);
(void) strcpy(nameval, nvpair_name(pair));
(void) strcat(nameval, "@");
(void) strcat(nameval, fnvpair_value_string(pair));
fnvlist_add_string(tmp_holds, nameval, "");
kmem_free(nameval, len + 2);
}
size_t tmp_count = fnvlist_num_pairs(tmp_holds);
fnvlist_free(tmp_holds);
if (tmp_count != fnvlist_num_pairs(dduha->dduha_holds))
return (SET_ERROR(EEXIST));
for (nvpair_t *pair = nvlist_next_nvpair(dduha->dduha_holds, NULL);
pair != NULL; pair = nvlist_next_nvpair(dduha->dduha_holds, pair)) {
dsl_dataset_t *ds;
int error = 0;
char *htag, *name;
/* must be a snapshot */
name = nvpair_name(pair);
if (strchr(name, '@') == NULL)
error = SET_ERROR(EINVAL);
if (error == 0)
error = nvpair_value_string(pair, &htag);
if (error == 0)
error = dsl_dataset_hold(dp, name, FTAG, &ds);
if (error == 0) {
error = dsl_dataset_user_hold_check_one(ds, htag,
dduha->dduha_minor != 0, tx);
dsl_dataset_rele(ds, FTAG);
}
if (error == 0) {
fnvlist_add_string(dduha->dduha_chkholds, name, htag);
} else {
/*
* We register ENOENT errors so they can be correctly
* reported if needed, such as when all holds fail.
*/
fnvlist_add_int32(dduha->dduha_errlist, name, error);
if (error != ENOENT)
return (error);
}
}
return (0);
}
static void
dsl_dataset_user_hold_sync_one_impl(nvlist_t *tmpholds, dsl_dataset_t *ds,
const char *htag, minor_t minor, uint64_t now, dmu_tx_t *tx)
{
dsl_pool_t *dp = ds->ds_dir->dd_pool;
objset_t *mos = dp->dp_meta_objset;
uint64_t zapobj;
ASSERT(RRW_WRITE_HELD(&dp->dp_config_rwlock));
if (dsl_dataset_phys(ds)->ds_userrefs_obj == 0) {
/*
* This is the first user hold for this dataset. Create
* the userrefs zap object.
*/
dmu_buf_will_dirty(ds->ds_dbuf, tx);
zapobj = dsl_dataset_phys(ds)->ds_userrefs_obj =
zap_create(mos, DMU_OT_USERREFS, DMU_OT_NONE, 0, tx);
} else {
zapobj = dsl_dataset_phys(ds)->ds_userrefs_obj;
}
ds->ds_userrefs++;
VERIFY0(zap_add(mos, zapobj, htag, 8, 1, &now, tx));
if (minor != 0) {
char name[MAXNAMELEN];
nvlist_t *tags;
VERIFY0(dsl_pool_user_hold(dp, ds->ds_object,
htag, now, tx));
(void) snprintf(name, sizeof (name), "%llx",
(u_longlong_t)ds->ds_object);
if (nvlist_lookup_nvlist(tmpholds, name, &tags) != 0) {
tags = fnvlist_alloc();
fnvlist_add_boolean(tags, htag);
fnvlist_add_nvlist(tmpholds, name, tags);
fnvlist_free(tags);
} else {
fnvlist_add_boolean(tags, htag);
}
}
spa_history_log_internal_ds(ds, "hold", tx,
"tag=%s temp=%d refs=%llu",
htag, minor != 0, ds->ds_userrefs);
}
typedef struct zfs_hold_cleanup_arg {
char zhca_spaname[ZFS_MAX_DATASET_NAME_LEN];
uint64_t zhca_spa_load_guid;
nvlist_t *zhca_holds;
} zfs_hold_cleanup_arg_t;
static void
dsl_dataset_user_release_onexit(void *arg)
{
zfs_hold_cleanup_arg_t *ca = arg;
spa_t *spa;
int error;
error = spa_open(ca->zhca_spaname, &spa, FTAG);
if (error != 0) {
zfs_dbgmsg("couldn't release holds on pool=%s "
"because pool is no longer loaded",
ca->zhca_spaname);
return;
}
if (spa_load_guid(spa) != ca->zhca_spa_load_guid) {
zfs_dbgmsg("couldn't release holds on pool=%s "
"because pool is no longer loaded (guid doesn't match)",
ca->zhca_spaname);
spa_close(spa, FTAG);
return;
}
(void) dsl_dataset_user_release_tmp(spa_get_dsl(spa), ca->zhca_holds);
fnvlist_free(ca->zhca_holds);
kmem_free(ca, sizeof (zfs_hold_cleanup_arg_t));
spa_close(spa, FTAG);
}
static void
dsl_onexit_hold_cleanup(spa_t *spa, nvlist_t *holds, minor_t minor)
{
zfs_hold_cleanup_arg_t *ca;
if (minor == 0 || nvlist_empty(holds)) {
fnvlist_free(holds);
return;
}
ASSERT(spa != NULL);
ca = kmem_alloc(sizeof (*ca), KM_SLEEP);
(void) strlcpy(ca->zhca_spaname, spa_name(spa),
sizeof (ca->zhca_spaname));
ca->zhca_spa_load_guid = spa_load_guid(spa);
ca->zhca_holds = holds;
VERIFY0(zfs_onexit_add_cb(minor,
dsl_dataset_user_release_onexit, ca, NULL));
}
void
dsl_dataset_user_hold_sync_one(dsl_dataset_t *ds, const char *htag,
minor_t minor, uint64_t now, dmu_tx_t *tx)
{
nvlist_t *tmpholds;
if (minor != 0)
tmpholds = fnvlist_alloc();
else
tmpholds = NULL;
dsl_dataset_user_hold_sync_one_impl(tmpholds, ds, htag, minor, now, tx);
dsl_onexit_hold_cleanup(dsl_dataset_get_spa(ds), tmpholds, minor);
}
static void
dsl_dataset_user_hold_sync(void *arg, dmu_tx_t *tx)
{
dsl_dataset_user_hold_arg_t *dduha = arg;
dsl_pool_t *dp = dmu_tx_pool(tx);
nvlist_t *tmpholds;
uint64_t now = gethrestime_sec();
if (dduha->dduha_minor != 0)
tmpholds = fnvlist_alloc();
else
tmpholds = NULL;
for (nvpair_t *pair = nvlist_next_nvpair(dduha->dduha_chkholds, NULL);
pair != NULL;
pair = nvlist_next_nvpair(dduha->dduha_chkholds, pair)) {
dsl_dataset_t *ds;
VERIFY0(dsl_dataset_hold(dp, nvpair_name(pair), FTAG, &ds));
dsl_dataset_user_hold_sync_one_impl(tmpholds, ds,
fnvpair_value_string(pair), dduha->dduha_minor, now, tx);
dsl_dataset_rele(ds, FTAG);
}
dsl_onexit_hold_cleanup(dp->dp_spa, tmpholds, dduha->dduha_minor);
}
/*
* The full semantics of this function are described in the comment above
* lzc_hold().
*
* To summarize:
* holds is nvl of snapname -> holdname
* errlist will be filled in with snapname -> error
*
* The snapshots must all be in the same pool.
*
* Holds for snapshots that don't exist will be skipped.
*
* If none of the snapshots for requested holds exist then ENOENT will be
* returned.
*
* If cleanup_minor is not 0, the holds will be temporary, which will be cleaned
* up when the process exits.
*
* On success all the holds, for snapshots that existed, will be created and 0
* will be returned.
*
* On failure no holds will be created, the errlist will be filled in,
* and an errno will returned.
*
* In all cases the errlist will contain entries for holds where the snapshot
* didn't exist.
*/
int
dsl_dataset_user_hold(nvlist_t *holds, minor_t cleanup_minor, nvlist_t *errlist)
{
dsl_dataset_user_hold_arg_t dduha;
nvpair_t *pair;
int ret;
pair = nvlist_next_nvpair(holds, NULL);
if (pair == NULL)
return (0);
dduha.dduha_holds = holds;
/* chkholds can have non-unique name */
VERIFY(0 == nvlist_alloc(&dduha.dduha_chkholds, 0, KM_SLEEP));
dduha.dduha_errlist = errlist;
dduha.dduha_minor = cleanup_minor;
ret = dsl_sync_task(nvpair_name(pair), dsl_dataset_user_hold_check,
dsl_dataset_user_hold_sync, &dduha,
fnvlist_num_pairs(holds), ZFS_SPACE_CHECK_RESERVED);
fnvlist_free(dduha.dduha_chkholds);
return (ret);
}
typedef int (dsl_holdfunc_t)(dsl_pool_t *dp, const char *name, void *tag,
dsl_dataset_t **dsp);
typedef struct dsl_dataset_user_release_arg {
dsl_holdfunc_t *ddura_holdfunc;
nvlist_t *ddura_holds;
nvlist_t *ddura_todelete;
nvlist_t *ddura_errlist;
nvlist_t *ddura_chkholds;
} dsl_dataset_user_release_arg_t;
/* Place a dataset hold on the snapshot identified by passed dsobj string */
static int
dsl_dataset_hold_obj_string(dsl_pool_t *dp, const char *dsobj, void *tag,
dsl_dataset_t **dsp)
{
return (dsl_dataset_hold_obj(dp, zfs_strtonum(dsobj, NULL), tag, dsp));
}
static int
dsl_dataset_user_release_check_one(dsl_dataset_user_release_arg_t *ddura,
dsl_dataset_t *ds, nvlist_t *holds, const char *snapname)
{
uint64_t zapobj;
nvlist_t *holds_found;
objset_t *mos;
int numholds;
if (!ds->ds_is_snapshot)
return (SET_ERROR(EINVAL));
if (nvlist_empty(holds))
return (0);
numholds = 0;
mos = ds->ds_dir->dd_pool->dp_meta_objset;
zapobj = dsl_dataset_phys(ds)->ds_userrefs_obj;
VERIFY0(nvlist_alloc(&holds_found, NV_UNIQUE_NAME, KM_SLEEP));
for (nvpair_t *pair = nvlist_next_nvpair(holds, NULL); pair != NULL;
pair = nvlist_next_nvpair(holds, pair)) {
uint64_t tmp;
int error;
const char *holdname = nvpair_name(pair);
if (zapobj != 0)
error = zap_lookup(mos, zapobj, holdname, 8, 1, &tmp);
else
error = SET_ERROR(ENOENT);
/*
* Non-existent holds are put on the errlist, but don't
* cause an overall failure.
*/
if (error == ENOENT) {
if (ddura->ddura_errlist != NULL) {
char *errtag = kmem_asprintf("%s#%s",
snapname, holdname);
fnvlist_add_int32(ddura->ddura_errlist, errtag,
ENOENT);
strfree(errtag);
}
continue;
}
if (error != 0) {
fnvlist_free(holds_found);
return (error);
}
fnvlist_add_boolean(holds_found, holdname);
numholds++;
}
if (DS_IS_DEFER_DESTROY(ds) &&
dsl_dataset_phys(ds)->ds_num_children == 1 &&
ds->ds_userrefs == numholds) {
/* we need to destroy the snapshot as well */
if (dsl_dataset_long_held(ds)) {
fnvlist_free(holds_found);
return (SET_ERROR(EBUSY));
}
fnvlist_add_boolean(ddura->ddura_todelete, snapname);
}
if (numholds != 0) {
fnvlist_add_nvlist(ddura->ddura_chkholds, snapname,
holds_found);
}
fnvlist_free(holds_found);
return (0);
}
static int
dsl_dataset_user_release_check(void *arg, dmu_tx_t *tx)
{
dsl_dataset_user_release_arg_t *ddura;
dsl_holdfunc_t *holdfunc;
dsl_pool_t *dp;
if (!dmu_tx_is_syncing(tx))
return (0);
dp = dmu_tx_pool(tx);
ASSERT(RRW_WRITE_HELD(&dp->dp_config_rwlock));
ddura = arg;
holdfunc = ddura->ddura_holdfunc;
for (nvpair_t *pair = nvlist_next_nvpair(ddura->ddura_holds, NULL);
pair != NULL; pair = nvlist_next_nvpair(ddura->ddura_holds, pair)) {
int error;
dsl_dataset_t *ds;
nvlist_t *holds;
const char *snapname = nvpair_name(pair);
error = nvpair_value_nvlist(pair, &holds);
if (error != 0)
error = (SET_ERROR(EINVAL));
else
error = holdfunc(dp, snapname, FTAG, &ds);
if (error == 0) {
error = dsl_dataset_user_release_check_one(ddura, ds,
holds, snapname);
dsl_dataset_rele(ds, FTAG);
}
if (error != 0) {
if (ddura->ddura_errlist != NULL) {
fnvlist_add_int32(ddura->ddura_errlist,
snapname, error);
}
/*
* Non-existent snapshots are put on the errlist,
* but don't cause an overall failure.
*/
if (error != ENOENT)
return (error);
}
}
return (0);
}
static void
dsl_dataset_user_release_sync_one(dsl_dataset_t *ds, nvlist_t *holds,
dmu_tx_t *tx)
{
dsl_pool_t *dp = ds->ds_dir->dd_pool;
objset_t *mos = dp->dp_meta_objset;
for (nvpair_t *pair = nvlist_next_nvpair(holds, NULL); pair != NULL;
pair = nvlist_next_nvpair(holds, pair)) {
int error;
const char *holdname = nvpair_name(pair);
/* Remove temporary hold if one exists. */
error = dsl_pool_user_release(dp, ds->ds_object, holdname, tx);
VERIFY(error == 0 || error == ENOENT);
VERIFY0(zap_remove(mos, dsl_dataset_phys(ds)->ds_userrefs_obj,
holdname, tx));
ds->ds_userrefs--;
spa_history_log_internal_ds(ds, "release", tx,
"tag=%s refs=%lld", holdname, (longlong_t)ds->ds_userrefs);
}
}
static void
dsl_dataset_user_release_sync(void *arg, dmu_tx_t *tx)
{
dsl_dataset_user_release_arg_t *ddura = arg;
dsl_holdfunc_t *holdfunc = ddura->ddura_holdfunc;
dsl_pool_t *dp = dmu_tx_pool(tx);
ASSERT(RRW_WRITE_HELD(&dp->dp_config_rwlock));
for (nvpair_t *pair = nvlist_next_nvpair(ddura->ddura_chkholds, NULL);
pair != NULL; pair = nvlist_next_nvpair(ddura->ddura_chkholds,
pair)) {
dsl_dataset_t *ds;
const char *name = nvpair_name(pair);
VERIFY0(holdfunc(dp, name, FTAG, &ds));
dsl_dataset_user_release_sync_one(ds,
fnvpair_value_nvlist(pair), tx);
if (nvlist_exists(ddura->ddura_todelete, name)) {
ASSERT(ds->ds_userrefs == 0 &&
dsl_dataset_phys(ds)->ds_num_children == 1 &&
DS_IS_DEFER_DESTROY(ds));
dsl_destroy_snapshot_sync_impl(ds, B_FALSE, tx);
}
dsl_dataset_rele(ds, FTAG);
}
}
/*
* The full semantics of this function are described in the comment above
* lzc_release().
*
* To summarize:
* Releases holds specified in the nvl holds.
*
* holds is nvl of snapname -> { holdname, ... }
* errlist will be filled in with snapname -> error
*
* If tmpdp is not NULL the names for holds should be the dsobj's of snapshots,
* otherwise they should be the names of snapshots.
*
* As a release may cause snapshots to be destroyed this tries to ensure they
* aren't mounted.
*
* The release of non-existent holds are skipped.
*
* At least one hold must have been released for the this function to succeed
* and return 0.
*/
static int
dsl_dataset_user_release_impl(nvlist_t *holds, nvlist_t *errlist,
dsl_pool_t *tmpdp)
{
dsl_dataset_user_release_arg_t ddura;
nvpair_t *pair;
char *pool;
int error;
pair = nvlist_next_nvpair(holds, NULL);
if (pair == NULL)
return (0);
/*
* The release may cause snapshots to be destroyed; make sure they
* are not mounted.
*/
if (tmpdp != NULL) {
/* Temporary holds are specified by dsobj string. */
ddura.ddura_holdfunc = dsl_dataset_hold_obj_string;
pool = spa_name(tmpdp->dp_spa);
#ifdef _KERNEL
for (pair = nvlist_next_nvpair(holds, NULL); pair != NULL;
pair = nvlist_next_nvpair(holds, pair)) {
dsl_dataset_t *ds;
dsl_pool_config_enter(tmpdp, FTAG);
error = dsl_dataset_hold_obj_string(tmpdp,
nvpair_name(pair), FTAG, &ds);
if (error == 0) {
char name[ZFS_MAX_DATASET_NAME_LEN];
dsl_dataset_name(ds, name);
dsl_pool_config_exit(tmpdp, FTAG);
dsl_dataset_rele(ds, FTAG);
(void) zfs_unmount_snap(name);
} else {
dsl_pool_config_exit(tmpdp, FTAG);
}
}
#endif
} else {
/* Non-temporary holds are specified by name. */
ddura.ddura_holdfunc = dsl_dataset_hold;
pool = nvpair_name(pair);
#ifdef _KERNEL
for (pair = nvlist_next_nvpair(holds, NULL); pair != NULL;
pair = nvlist_next_nvpair(holds, pair)) {
(void) zfs_unmount_snap(nvpair_name(pair));
}
#endif
}
ddura.ddura_holds = holds;
ddura.ddura_errlist = errlist;
VERIFY0(nvlist_alloc(&ddura.ddura_todelete, NV_UNIQUE_NAME,
KM_SLEEP));
VERIFY0(nvlist_alloc(&ddura.ddura_chkholds, NV_UNIQUE_NAME,
KM_SLEEP));
error = dsl_sync_task(pool, dsl_dataset_user_release_check,
dsl_dataset_user_release_sync, &ddura, 0,
ZFS_SPACE_CHECK_EXTRA_RESERVED);
fnvlist_free(ddura.ddura_todelete);
fnvlist_free(ddura.ddura_chkholds);
return (error);
}
/*
* holds is nvl of snapname -> { holdname, ... }
* errlist will be filled in with snapname -> error
*/
int
dsl_dataset_user_release(nvlist_t *holds, nvlist_t *errlist)
{
return (dsl_dataset_user_release_impl(holds, errlist, NULL));
}
/*
* holds is nvl of snapdsobj -> { holdname, ... }
*/
void
dsl_dataset_user_release_tmp(struct dsl_pool *dp, nvlist_t *holds)
{
ASSERT(dp != NULL);
(void) dsl_dataset_user_release_impl(holds, NULL, dp);
}
int
dsl_dataset_get_holds(const char *dsname, nvlist_t *nvl)
{
dsl_pool_t *dp;
dsl_dataset_t *ds;
int err;
err = dsl_pool_hold(dsname, FTAG, &dp);
if (err != 0)
return (err);
err = dsl_dataset_hold(dp, dsname, FTAG, &ds);
if (err != 0) {
dsl_pool_rele(dp, FTAG);
return (err);
}
if (dsl_dataset_phys(ds)->ds_userrefs_obj != 0) {
zap_attribute_t *za;
zap_cursor_t zc;
za = kmem_alloc(sizeof (zap_attribute_t), KM_SLEEP);
for (zap_cursor_init(&zc, ds->ds_dir->dd_pool->dp_meta_objset,
dsl_dataset_phys(ds)->ds_userrefs_obj);
zap_cursor_retrieve(&zc, za) == 0;
zap_cursor_advance(&zc)) {
fnvlist_add_uint64(nvl, za->za_name,
za->za_first_integer);
}
zap_cursor_fini(&zc);
kmem_free(za, sizeof (zap_attribute_t));
}
dsl_dataset_rele(ds, FTAG);
dsl_pool_rele(dp, FTAG);
return (0);
}