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OpenZFS 9238 - ZFS Spacemap Encoding V2 

Motivation
==========

The current space map encoding has the following disadvantages:
[1] Assuming 512 sector size each entry can represent at most 16MB for a segment.
    This makes the encoding very inefficient for large regions of space.
[2] As vdev-wide space maps have started to be used by new features (i.e.
    device removal, zpool checkpoint) we've started imposing limits in the
    vdevs that can be used with them based on the maximum addressable offset
    (currently 64PB for a top-level vdev).

New encoding
============

The layout can be found at space_map.h and it remains backwards compatible with
the old one. The introduced two-word entry format, besides extending the limits
imposed by the single-entry layout, also includes a vdev field and some extra
padding after its prefix.

The extra padding after the prefix should is reserved for future usage (e.g.
new prefixes for future encodings or new fields for flags). The new vdev field
not only makes the space maps more self-descriptive, but also opens the doors
for pool-wide space maps (expected to be used in the log spacemap project).

One final important note is that the number of bits used for vdevs is reduced
to 24 bits for blkptrs. That was decided as we don't know of any setups that
use more than 16M vdevs for the time being and we wanted to fit the vdev field
in the space map. In addition that gives us some extra bits in dva_t.

Other references:
=================

The new encoding is also discussed towards the end of the Log Space Map
presentation from 2017's OpenZFS summit.
Link: https://www.youtube.com/watch?v=jj2IxRkl5bQ

Authored by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <gwilson@zfsmail.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Gordon Ross <gwr@nexenta.com>
Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>

OpenZFS-commit: https://github.com/openzfs/openzfs/commit/90a56e6d
OpenZFS-issue: https://www.illumos.org/issues/9238
Closes #7665
This commit is contained in:
Serapheim Dimitropoulos 2017-08-04 09:30:49 -07:00 committed by Brian Behlendorf
parent 4e82b4be78
commit 4d044c4c1d
15 changed files with 867 additions and 373 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

127
cmd/zdb/zdb.c
View File

@ -776,7 +776,6 @@ verify_spacemap_refcounts(spa_t *spa)
static void static void
dump_spacemap(objset_t *os, space_map_t *sm) dump_spacemap(objset_t *os, space_map_t *sm)
{ {
uint64_t alloc, offset, entry;
const char *ddata[] = { "ALLOC", "FREE", "CONDENSE", "INVALID", const char *ddata[] = { "ALLOC", "FREE", "CONDENSE", "INVALID",
"INVALID", "INVALID", "INVALID", "INVALID" }; "INVALID", "INVALID", "INVALID", "INVALID" };
@ -793,41 +792,73 @@ dump_spacemap(objset_t *os, space_map_t *sm)
/* /*
* Print out the freelist entries in both encoded and decoded form. * Print out the freelist entries in both encoded and decoded form.
*/ */
alloc = 0; uint8_t mapshift = sm->sm_shift;
for (offset = 0; offset < space_map_length(sm); int64_t alloc = 0;
offset += sizeof (entry)) { uint64_t word;
uint8_t mapshift = sm->sm_shift; for (uint64_t offset = 0; offset < space_map_length(sm);
offset += sizeof (word)) {
VERIFY0(dmu_read(os, space_map_object(sm), offset, VERIFY0(dmu_read(os, space_map_object(sm), offset,
sizeof (entry), &entry, DMU_READ_PREFETCH)); sizeof (word), &word, DMU_READ_PREFETCH));
if (SM_DEBUG_DECODE(entry)) {
if (sm_entry_is_debug(word)) {
(void) printf("\t [%6llu] %s: txg %llu, pass %llu\n", (void) printf("\t [%6llu] %s: txg %llu, pass %llu\n",
(u_longlong_t)(offset / sizeof (entry)), (u_longlong_t)(offset / sizeof (word)),
ddata[SM_DEBUG_ACTION_DECODE(entry)], ddata[SM_DEBUG_ACTION_DECODE(word)],
(u_longlong_t)SM_DEBUG_TXG_DECODE(entry), (u_longlong_t)SM_DEBUG_TXG_DECODE(word),
(u_longlong_t)SM_DEBUG_SYNCPASS_DECODE(entry)); (u_longlong_t)SM_DEBUG_SYNCPASS_DECODE(word));
} else { continue;
(void) printf("\t [%6llu] %c range:"
" %010llx-%010llx size: %06llx\n",
(u_longlong_t)(offset / sizeof (entry)),
SM_TYPE_DECODE(entry) == SM_ALLOC ? 'A' : 'F',
(u_longlong_t)((SM_OFFSET_DECODE(entry) <<
mapshift) + sm->sm_start),
(u_longlong_t)((SM_OFFSET_DECODE(entry) <<
mapshift) + sm->sm_start +
(SM_RUN_DECODE(entry) << mapshift)),
(u_longlong_t)(SM_RUN_DECODE(entry) << mapshift));
if (SM_TYPE_DECODE(entry) == SM_ALLOC)
alloc += SM_RUN_DECODE(entry) << mapshift;
else
alloc -= SM_RUN_DECODE(entry) << mapshift;
} }
uint8_t words;
char entry_type;
uint64_t entry_off, entry_run, entry_vdev = SM_NO_VDEVID;
if (sm_entry_is_single_word(word)) {
entry_type = (SM_TYPE_DECODE(word) == SM_ALLOC) ?
'A' : 'F';
entry_off = (SM_OFFSET_DECODE(word) << mapshift) +
sm->sm_start;
entry_run = SM_RUN_DECODE(word) << mapshift;
words = 1;
} else {
/* it is a two-word entry so we read another word */
ASSERT(sm_entry_is_double_word(word));
uint64_t extra_word;
offset += sizeof (extra_word);
VERIFY0(dmu_read(os, space_map_object(sm), offset,
sizeof (extra_word), &extra_word,
DMU_READ_PREFETCH));
ASSERT3U(offset, <=, space_map_length(sm));
entry_run = SM2_RUN_DECODE(word) << mapshift;
entry_vdev = SM2_VDEV_DECODE(word);
entry_type = (SM2_TYPE_DECODE(extra_word) == SM_ALLOC) ?
'A' : 'F';
entry_off = (SM2_OFFSET_DECODE(extra_word) <<
mapshift) + sm->sm_start;
words = 2;
}
(void) printf("\t [%6llu] %c range:"
" %010llx-%010llx size: %06llx vdev: %06llu words: %u\n",
(u_longlong_t)(offset / sizeof (word)),
entry_type, (u_longlong_t)entry_off,
(u_longlong_t)(entry_off + entry_run),
(u_longlong_t)entry_run,
(u_longlong_t)entry_vdev, words);
if (entry_type == 'A')
alloc += entry_run;
else
alloc -= entry_run;
} }
if (alloc != space_map_allocated(sm)) { if ((uint64_t)alloc != space_map_allocated(sm)) {
(void) printf("space_map_object alloc (%llu) INCONSISTENT " (void) printf("space_map_object alloc (%lld) INCONSISTENT "
"with space map summary (%llu)\n", "with space map summary (%lld)\n",
(u_longlong_t)space_map_allocated(sm), (u_longlong_t)alloc); (longlong_t)space_map_allocated(sm), (longlong_t)alloc);
} }
} }
@ -1158,7 +1189,7 @@ dump_ddt(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
while ((error = ddt_object_walk(ddt, type, class, &walk, &dde)) == 0) while ((error = ddt_object_walk(ddt, type, class, &walk, &dde)) == 0)
dump_dde(ddt, &dde, walk); dump_dde(ddt, &dde, walk);
ASSERT(error == ENOENT); ASSERT3U(error, ==, ENOENT);
(void) printf("\n"); (void) printf("\n");
} }
@ -3579,15 +3610,14 @@ typedef struct checkpoint_sm_exclude_entry_arg {
} checkpoint_sm_exclude_entry_arg_t; } checkpoint_sm_exclude_entry_arg_t;
static int static int
checkpoint_sm_exclude_entry_cb(maptype_t type, uint64_t offset, uint64_t size, checkpoint_sm_exclude_entry_cb(space_map_entry_t *sme, void *arg)
void *arg)
{ {
checkpoint_sm_exclude_entry_arg_t *cseea = arg; checkpoint_sm_exclude_entry_arg_t *cseea = arg;
vdev_t *vd = cseea->cseea_vd; vdev_t *vd = cseea->cseea_vd;
metaslab_t *ms = vd->vdev_ms[offset >> vd->vdev_ms_shift]; metaslab_t *ms = vd->vdev_ms[sme->sme_offset >> vd->vdev_ms_shift];
uint64_t end = offset + size; uint64_t end = sme->sme_offset + sme->sme_run;
ASSERT(type == SM_FREE); ASSERT(sme->sme_type == SM_FREE);
/* /*
* Since the vdev_checkpoint_sm exists in the vdev level * Since the vdev_checkpoint_sm exists in the vdev level
@ -3605,7 +3635,7 @@ checkpoint_sm_exclude_entry_cb(maptype_t type, uint64_t offset, uint64_t size,
* metaslab boundaries. So if needed we could add code * metaslab boundaries. So if needed we could add code
* that handles metaslab-crossing segments in the future. * that handles metaslab-crossing segments in the future.
*/ */
VERIFY3U(offset, >=, ms->ms_start); VERIFY3U(sme->sme_offset, >=, ms->ms_start);
VERIFY3U(end, <=, ms->ms_start + ms->ms_size); VERIFY3U(end, <=, ms->ms_start + ms->ms_size);
/* /*
@ -3613,10 +3643,10 @@ checkpoint_sm_exclude_entry_cb(maptype_t type, uint64_t offset, uint64_t size,
* also verify that the entry is there to begin with. * also verify that the entry is there to begin with.
*/ */
mutex_enter(&ms->ms_lock); mutex_enter(&ms->ms_lock);
range_tree_remove(ms->ms_allocatable, offset, size); range_tree_remove(ms->ms_allocatable, sme->sme_offset, sme->sme_run);
mutex_exit(&ms->ms_lock); mutex_exit(&ms->ms_lock);
cseea->cseea_checkpoint_size += size; cseea->cseea_checkpoint_size += sme->sme_run;
return (0); return (0);
} }
@ -4606,15 +4636,14 @@ typedef struct verify_checkpoint_sm_entry_cb_arg {
#define ENTRIES_PER_PROGRESS_UPDATE 10000 #define ENTRIES_PER_PROGRESS_UPDATE 10000
static int static int
verify_checkpoint_sm_entry_cb(maptype_t type, uint64_t offset, uint64_t size, verify_checkpoint_sm_entry_cb(space_map_entry_t *sme, void *arg)
void *arg)
{ {
verify_checkpoint_sm_entry_cb_arg_t *vcsec = arg; verify_checkpoint_sm_entry_cb_arg_t *vcsec = arg;
vdev_t *vd = vcsec->vcsec_vd; vdev_t *vd = vcsec->vcsec_vd;
metaslab_t *ms = vd->vdev_ms[offset >> vd->vdev_ms_shift]; metaslab_t *ms = vd->vdev_ms[sme->sme_offset >> vd->vdev_ms_shift];
uint64_t end = offset + size; uint64_t end = sme->sme_offset + sme->sme_run;
ASSERT(type == SM_FREE); ASSERT(sme->sme_type == SM_FREE);
if ((vcsec->vcsec_entryid % ENTRIES_PER_PROGRESS_UPDATE) == 0) { if ((vcsec->vcsec_entryid % ENTRIES_PER_PROGRESS_UPDATE) == 0) {
(void) fprintf(stderr, (void) fprintf(stderr,
@ -4628,7 +4657,7 @@ verify_checkpoint_sm_entry_cb(maptype_t type, uint64_t offset, uint64_t size,
/* /*
* See comment in checkpoint_sm_exclude_entry_cb() * See comment in checkpoint_sm_exclude_entry_cb()
*/ */
VERIFY3U(offset, >=, ms->ms_start); VERIFY3U(sme->sme_offset, >=, ms->ms_start);
VERIFY3U(end, <=, ms->ms_start + ms->ms_size); VERIFY3U(end, <=, ms->ms_start + ms->ms_size);
/* /*
@ -4637,7 +4666,7 @@ verify_checkpoint_sm_entry_cb(maptype_t type, uint64_t offset, uint64_t size,
* their respective ms_allocateable trees should not contain them. * their respective ms_allocateable trees should not contain them.
*/ */
mutex_enter(&ms->ms_lock); mutex_enter(&ms->ms_lock);
range_tree_verify(ms->ms_allocatable, offset, size); range_tree_verify(ms->ms_allocatable, sme->sme_offset, sme->sme_run);
mutex_exit(&ms->ms_lock); mutex_exit(&ms->ms_lock);
return (0); return (0);
@ -4883,7 +4912,7 @@ verify_checkpoint(spa_t *spa)
DMU_POOL_ZPOOL_CHECKPOINT, sizeof (uint64_t), DMU_POOL_ZPOOL_CHECKPOINT, sizeof (uint64_t),
sizeof (uberblock_t) / sizeof (uint64_t), &checkpoint); sizeof (uberblock_t) / sizeof (uint64_t), &checkpoint);
if (error == ENOENT) { if (error == ENOENT && !dump_opt['L']) {
/* /*
* If the feature is active but the uberblock is missing * If the feature is active but the uberblock is missing
* then we must be in the middle of discarding the * then we must be in the middle of discarding the
@ -4906,7 +4935,7 @@ verify_checkpoint(spa_t *spa)
error = 3; error = 3;
} }
if (error == 0) if (error == 0 && !dump_opt['L'])
verify_checkpoint_blocks(spa); verify_checkpoint_blocks(spa);
return (error); return (error);
@ -5015,7 +5044,7 @@ dump_zpool(spa_t *spa)
if (dump_opt['h']) if (dump_opt['h'])
dump_history(spa); dump_history(spa);
if (rc == 0 && !dump_opt['L']) if (rc == 0)
rc = verify_checkpoint(spa); rc = verify_checkpoint(spa);
if (rc != 0) { if (rc != 0) {

7
cmd/ztest/ztest.c
View File

@ -202,6 +202,7 @@ extern int metaslab_preload_limit;
extern boolean_t zfs_compressed_arc_enabled; extern boolean_t zfs_compressed_arc_enabled;
extern int zfs_abd_scatter_enabled; extern int zfs_abd_scatter_enabled;
extern int dmu_object_alloc_chunk_shift; extern int dmu_object_alloc_chunk_shift;
extern boolean_t zfs_force_some_double_word_sm_entries;
static ztest_shared_opts_t *ztest_shared_opts; static ztest_shared_opts_t *ztest_shared_opts;
static ztest_shared_opts_t ztest_opts; static ztest_shared_opts_t ztest_opts;
@ -7349,6 +7350,12 @@ main(int argc, char **argv)
dprintf_setup(&argc, argv); dprintf_setup(&argc, argv);
zfs_deadman_synctime_ms = 300000; zfs_deadman_synctime_ms = 300000;
/*
* As two-word space map entries may not come up often (especially
* if pool and vdev sizes are small) we want to force at least some
* of them so the feature get tested.
*/
zfs_force_some_double_word_sm_entries = B_TRUE;
action.sa_handler = sig_handler; action.sa_handler = sig_handler;
sigemptyset(&action.sa_mask); sigemptyset(&action.sa_mask);

12
include/sys/spa.h
View File

@ -153,6 +153,7 @@ _NOTE(CONSTCOND) } while (0)
#define SPA_ASIZEBITS 24 /* ASIZE up to 64 times larger */ #define SPA_ASIZEBITS 24 /* ASIZE up to 64 times larger */
#define SPA_COMPRESSBITS 7 #define SPA_COMPRESSBITS 7
#define SPA_VDEVBITS 24
/* /*
* All SPA data is represented by 128-bit data virtual addresses (DVAs). * All SPA data is represented by 128-bit data virtual addresses (DVAs).
@ -177,15 +178,15 @@ typedef struct zio_cksum_salt {
* *
* 64 56 48 40 32 24 16 8 0 * 64 56 48 40 32 24 16 8 0
* +-------+-------+-------+-------+-------+-------+-------+-------+ * +-------+-------+-------+-------+-------+-------+-------+-------+
* 0 | vdev1 | GRID | ASIZE | * 0 | pad | vdev1 | GRID | ASIZE |
* +-------+-------+-------+-------+-------+-------+-------+-------+ * +-------+-------+-------+-------+-------+-------+-------+-------+
* 1 |G| offset1 | * 1 |G| offset1 |
* +-------+-------+-------+-------+-------+-------+-------+-------+ * +-------+-------+-------+-------+-------+-------+-------+-------+
* 2 | vdev2 | GRID | ASIZE | * 2 | pad | vdev2 | GRID | ASIZE |
* +-------+-------+-------+-------+-------+-------+-------+-------+ * +-------+-------+-------+-------+-------+-------+-------+-------+
* 3 |G| offset2 | * 3 |G| offset2 |
* +-------+-------+-------+-------+-------+-------+-------+-------+ * +-------+-------+-------+-------+-------+-------+-------+-------+
* 4 | vdev3 | GRID | ASIZE | * 4 | pad | vdev3 | GRID | ASIZE |
* +-------+-------+-------+-------+-------+-------+-------+-------+ * +-------+-------+-------+-------+-------+-------+-------+-------+
* 5 |G| offset3 | * 5 |G| offset3 |
* +-------+-------+-------+-------+-------+-------+-------+-------+ * +-------+-------+-------+-------+-------+-------+-------+-------+
@ -443,8 +444,9 @@ typedef struct blkptr {
#define DVA_GET_GRID(dva) BF64_GET((dva)->dva_word[0], 24, 8) #define DVA_GET_GRID(dva) BF64_GET((dva)->dva_word[0], 24, 8)
#define DVA_SET_GRID(dva, x) BF64_SET((dva)->dva_word[0], 24, 8, x) #define DVA_SET_GRID(dva, x) BF64_SET((dva)->dva_word[0], 24, 8, x)
#define DVA_GET_VDEV(dva) BF64_GET((dva)->dva_word[0], 32, 32) #define DVA_GET_VDEV(dva) BF64_GET((dva)->dva_word[0], 32, SPA_VDEVBITS)
#define DVA_SET_VDEV(dva, x) BF64_SET((dva)->dva_word[0], 32, 32, x) #define DVA_SET_VDEV(dva, x) \
BF64_SET((dva)->dva_word[0], 32, SPA_VDEVBITS, x)
#define DVA_GET_OFFSET(dva) \ #define DVA_GET_OFFSET(dva) \
BF64_GET_SB((dva)->dva_word[1], 0, 63, SPA_MINBLOCKSHIFT, 0) BF64_GET_SB((dva)->dva_word[1], 0, 63, SPA_MINBLOCKSHIFT, 0)

118
include/sys/space_map.h
View File

@ -93,50 +93,100 @@ typedef struct space_map {
/* /*
* debug entry * debug entry
* *
* 1 3 10 50 * 2 2 10 50
* ,---+--------+------------+---------------------------------. * +-----+-----+------------+----------------------------------+
* | 1 | action | syncpass | txg (lower bits) | * | 1 0 | act | syncpass | txg (lower bits) |
* `---+--------+------------+---------------------------------' * +-----+-----+------------+----------------------------------+
* 63 62 60 59 50 49 0 * 63 62 61 60 59 50 49 0
* *
* *
* non-debug entry * one-word entry
* *
* 1 47 1 15 * 1 47 1 15
* ,-----------------------------------------------------------. * +-----------------------------------------------------------+
* | 0 | offset (sm_shift units) | type | run | * | 0 | offset (sm_shift units) | type | run |
* `-----------------------------------------------------------' * +-----------------------------------------------------------+
* 63 62 17 16 15 0 * 63 62 16 15 14 0
*
*
* two-word entry
*
* 2 2 36 24
* +-----+-----+---------------------------+-------------------+
* | 1 1 | pad | run | vdev |
* +-----+-----+---------------------------+-------------------+
* 63 62 61 60 59 24 23 0
*
* 1 63
* +------+----------------------------------------------------+
* | type | offset |
* +------+----------------------------------------------------+
* 63 62 0
*
* Note that a two-word entry will not straddle a block boundary.
* If necessary, the last word of a block will be padded with a
* debug entry (with act = syncpass = txg = 0).
*/ */
/* All this stuff takes and returns bytes */
#define SM_RUN_DECODE(x) (BF64_DECODE(x, 0, 15) + 1)
#define SM_RUN_ENCODE(x) BF64_ENCODE((x) - 1, 0, 15)
#define SM_TYPE_DECODE(x) BF64_DECODE(x, 15, 1)
#define SM_TYPE_ENCODE(x) BF64_ENCODE(x, 15, 1)
#define SM_OFFSET_DECODE(x) BF64_DECODE(x, 16, 47)
#define SM_OFFSET_ENCODE(x) BF64_ENCODE(x, 16, 47)
#define SM_DEBUG_DECODE(x) BF64_DECODE(x, 63, 1)
#define SM_DEBUG_ENCODE(x) BF64_ENCODE(x, 63, 1)
#define SM_DEBUG_ACTION_DECODE(x) BF64_DECODE(x, 60, 3)
#define SM_DEBUG_ACTION_ENCODE(x) BF64_ENCODE(x, 60, 3)
#define SM_DEBUG_SYNCPASS_DECODE(x) BF64_DECODE(x, 50, 10)
#define SM_DEBUG_SYNCPASS_ENCODE(x) BF64_ENCODE(x, 50, 10)
#define SM_DEBUG_TXG_DECODE(x) BF64_DECODE(x, 0, 50)
#define SM_DEBUG_TXG_ENCODE(x) BF64_ENCODE(x, 0, 50)
#define SM_RUN_MAX SM_RUN_DECODE(~0ULL)
typedef enum { typedef enum {
SM_ALLOC, SM_ALLOC,
SM_FREE SM_FREE
} maptype_t; } maptype_t;
typedef int (*sm_cb_t)(maptype_t type, uint64_t offset, uint64_t size, typedef struct space_map_entry {
void *arg); maptype_t sme_type;
uint32_t sme_vdev; /* max is 2^24-1; SM_NO_VDEVID if not present */
uint64_t sme_offset; /* max is 2^63-1; units of sm_shift */
uint64_t sme_run; /* max is 2^36; units of sm_shift */
} space_map_entry_t;
#define SM_NO_VDEVID (1 << SPA_VDEVBITS)
/* one-word entry constants */
#define SM_DEBUG_PREFIX 2
#define SM_OFFSET_BITS 47
#define SM_RUN_BITS 15
/* two-word entry constants */
#define SM2_PREFIX 3
#define SM2_OFFSET_BITS 63
#define SM2_RUN_BITS 36
#define SM_PREFIX_DECODE(x) BF64_DECODE(x, 62, 2)
#define SM_PREFIX_ENCODE(x) BF64_ENCODE(x, 62, 2)
#define SM_DEBUG_ACTION_DECODE(x) BF64_DECODE(x, 60, 2)
#define SM_DEBUG_ACTION_ENCODE(x) BF64_ENCODE(x, 60, 2)
#define SM_DEBUG_SYNCPASS_DECODE(x) BF64_DECODE(x, 50, 10)
#define SM_DEBUG_SYNCPASS_ENCODE(x) BF64_ENCODE(x, 50, 10)
#define SM_DEBUG_TXG_DECODE(x) BF64_DECODE(x, 0, 50)
#define SM_DEBUG_TXG_ENCODE(x) BF64_ENCODE(x, 0, 50)
#define SM_OFFSET_DECODE(x) BF64_DECODE(x, 16, SM_OFFSET_BITS)
#define SM_OFFSET_ENCODE(x) BF64_ENCODE(x, 16, SM_OFFSET_BITS)
#define SM_TYPE_DECODE(x) BF64_DECODE(x, 15, 1)
#define SM_TYPE_ENCODE(x) BF64_ENCODE(x, 15, 1)
#define SM_RUN_DECODE(x) (BF64_DECODE(x, 0, SM_RUN_BITS) + 1)
#define SM_RUN_ENCODE(x) BF64_ENCODE((x) - 1, 0, SM_RUN_BITS)
#define SM_RUN_MAX SM_RUN_DECODE(~0ULL)
#define SM_OFFSET_MAX SM_OFFSET_DECODE(~0ULL)
#define SM2_RUN_DECODE(x) (BF64_DECODE(x, SPA_VDEVBITS, SM2_RUN_BITS) + 1)
#define SM2_RUN_ENCODE(x) BF64_ENCODE((x) - 1, SPA_VDEVBITS, SM2_RUN_BITS)
#define SM2_VDEV_DECODE(x) BF64_DECODE(x, 0, SPA_VDEVBITS)
#define SM2_VDEV_ENCODE(x) BF64_ENCODE(x, 0, SPA_VDEVBITS)
#define SM2_TYPE_DECODE(x) BF64_DECODE(x, SM2_OFFSET_BITS, 1)
#define SM2_TYPE_ENCODE(x) BF64_ENCODE(x, SM2_OFFSET_BITS, 1)
#define SM2_OFFSET_DECODE(x) BF64_DECODE(x, 0, SM2_OFFSET_BITS)
#define SM2_OFFSET_ENCODE(x) BF64_ENCODE(x, 0, SM2_OFFSET_BITS)
#define SM2_RUN_MAX SM2_RUN_DECODE(~0ULL)
#define SM2_OFFSET_MAX SM2_OFFSET_DECODE(~0ULL)
boolean_t sm_entry_is_debug(uint64_t e);
boolean_t sm_entry_is_single_word(uint64_t e);
boolean_t sm_entry_is_double_word(uint64_t e);
typedef int (*sm_cb_t)(space_map_entry_t *sme, void *arg);
int space_map_load(space_map_t *sm, range_tree_t *rt, maptype_t maptype); int space_map_load(space_map_t *sm, range_tree_t *rt, maptype_t maptype);
int space_map_iterate(space_map_t *sm, sm_cb_t callback, void *arg); int space_map_iterate(space_map_t *sm, sm_cb_t callback, void *arg);
@ -154,7 +204,9 @@ uint64_t space_map_allocated(space_map_t *sm);
uint64_t space_map_length(space_map_t *sm); uint64_t space_map_length(space_map_t *sm);
void space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype, void space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
dmu_tx_t *tx); uint64_t vdev_id, dmu_tx_t *tx);
uint64_t space_map_estimate_optimal_size(space_map_t *sm, range_tree_t *rt,
uint64_t vdev_id);
void space_map_truncate(space_map_t *sm, int blocksize, dmu_tx_t *tx); void space_map_truncate(space_map_t *sm, int blocksize, dmu_tx_t *tx);
uint64_t space_map_alloc(objset_t *os, int blocksize, dmu_tx_t *tx); uint64_t space_map_alloc(objset_t *os, int blocksize, dmu_tx_t *tx);
void space_map_free(space_map_t *sm, dmu_tx_t *tx); void space_map_free(space_map_t *sm, dmu_tx_t *tx);

1
include/zfeature_common.h
View File

@ -62,6 +62,7 @@ typedef enum spa_feature {
SPA_FEATURE_DEVICE_REMOVAL, SPA_FEATURE_DEVICE_REMOVAL,
SPA_FEATURE_OBSOLETE_COUNTS, SPA_FEATURE_OBSOLETE_COUNTS,
SPA_FEATURE_POOL_CHECKPOINT, SPA_FEATURE_POOL_CHECKPOINT,
SPA_FEATURE_SPACEMAP_V2,
SPA_FEATURES SPA_FEATURES
} spa_feature_t; } spa_feature_t;

23
man/man5/zpool-features.5
View File

@ -503,6 +503,29 @@ is used to checkpoint the pool.
The feature will only return back to being \fBenabled\fR when the pool The feature will only return back to being \fBenabled\fR when the pool
is rewound or the checkpoint has been discarded. is rewound or the checkpoint has been discarded.
.RE
.sp
.ne 2
.na
\fB\fBspacemap_v2\fR\fR
.ad
.RS 4n
.TS
l l .
GUID com.delphix:spacemap_v2
READ\-ONLY COMPATIBLE yes
DEPENDENCIES none
.TE
This feature enables the use of the new space map encoding which
consists of two words (instead of one) whenever it is advantageous.
The new encoding allows space maps to represent large regions of
space more efficiently on-disk while also increasing their maximum
addressable offset.
This feature becomes \fBactive\fR once it is \fBenabled\fR, and never
returns back to being \fBenabled\fR.
.RE .RE
.sp .sp
.ne 2 .ne 2

6
module/zcommon/zfeature_common.c
View File

@ -215,6 +215,12 @@ zpool_feature_init(void)
"Pool state can be checkpointed, allowing rewind later.", "Pool state can be checkpointed, allowing rewind later.",
ZFEATURE_FLAG_READONLY_COMPAT, NULL); ZFEATURE_FLAG_READONLY_COMPAT, NULL);
zfeature_register(SPA_FEATURE_SPACEMAP_V2,
"com.delphix:spacemap_v2", "spacemap_v2",
"Space maps representing large segments are more efficient.",
ZFEATURE_FLAG_READONLY_COMPAT | ZFEATURE_FLAG_ACTIVATE_ON_ENABLE,
NULL);
zfeature_register(SPA_FEATURE_EXTENSIBLE_DATASET, zfeature_register(SPA_FEATURE_EXTENSIBLE_DATASET,
"com.delphix:extensible_dataset", "extensible_dataset", "com.delphix:extensible_dataset", "extensible_dataset",
"Enhanced dataset functionality, used by other features.", "Enhanced dataset functionality, used by other features.",

58
module/zfs/metaslab.c
View File

@ -2025,17 +2025,6 @@ metaslab_group_preload(metaslab_group_t *mg)
* *
* 3. The on-disk size of the space map should actually decrease. * 3. The on-disk size of the space map should actually decrease.
* *
* Checking the first condition is tricky since we don't want to walk
* the entire AVL tree calculating the estimated on-disk size. Instead we
* use the size-ordered range tree in the metaslab and calculate the
* size required to write out the largest segment in our free tree. If the
* size required to represent that segment on disk is larger than the space
* map object then we avoid condensing this map.
*
* To determine the second criterion we use a best-case estimate and assume
* each segment can be represented on-disk as a single 64-bit entry. We refer
* to this best-case estimate as the space map's minimal form.
*
* Unfortunately, we cannot compute the on-disk size of the space map in this * Unfortunately, we cannot compute the on-disk size of the space map in this
* context because we cannot accurately compute the effects of compression, etc. * context because we cannot accurately compute the effects of compression, etc.
* Instead, we apply the heuristic described in the block comment for * Instead, we apply the heuristic described in the block comment for
@ -2046,9 +2035,6 @@ static boolean_t
metaslab_should_condense(metaslab_t *msp) metaslab_should_condense(metaslab_t *msp)
{ {
space_map_t *sm = msp->ms_sm; space_map_t *sm = msp->ms_sm;
range_seg_t *rs;
uint64_t size, entries, segsz, object_size, optimal_size, record_size;
dmu_object_info_t doi;
vdev_t *vd = msp->ms_group->mg_vd; vdev_t *vd = msp->ms_group->mg_vd;
uint64_t vdev_blocksize = 1 << vd->vdev_ashift; uint64_t vdev_blocksize = 1 << vd->vdev_ashift;
uint64_t current_txg = spa_syncing_txg(vd->vdev_spa); uint64_t current_txg = spa_syncing_txg(vd->vdev_spa);
@ -2074,34 +2060,22 @@ metaslab_should_condense(metaslab_t *msp)
msp->ms_condense_checked_txg = current_txg; msp->ms_condense_checked_txg = current_txg;
/* /*
* Use the ms_allocatable_by_size range tree, which is ordered by * We always condense metaslabs that are empty and metaslabs for
* size, to obtain the largest segment in the free tree. We always * which a condense request has been made.
* condense metaslabs that are empty and metaslabs for which a
* condense request has been made.
*/ */
rs = avl_last(&msp->ms_allocatable_by_size); if (avl_is_empty(&msp->ms_allocatable_by_size) ||
if (rs == NULL || msp->ms_condense_wanted) msp->ms_condense_wanted)
return (B_TRUE); return (B_TRUE);
/* uint64_t object_size = space_map_length(msp->ms_sm);
* Calculate the number of 64-bit entries this segment would uint64_t optimal_size = space_map_estimate_optimal_size(sm,
* require when written to disk. If this single segment would be msp->ms_allocatable, SM_NO_VDEVID);
* larger on-disk than the entire current on-disk structure, then
* clearly condensing will increase the on-disk structure size.
*/
size = (rs->rs_end - rs->rs_start) >> sm->sm_shift;
entries = size / (MIN(size, SM_RUN_MAX));
segsz = entries * sizeof (uint64_t);
optimal_size =
sizeof (uint64_t) * avl_numnodes(&msp->ms_allocatable->rt_root);
object_size = space_map_length(msp->ms_sm);
dmu_object_info_t doi;
dmu_object_info_from_db(sm->sm_dbuf, &doi); dmu_object_info_from_db(sm->sm_dbuf, &doi);
record_size = MAX(doi.doi_data_block_size, vdev_blocksize); uint64_t record_size = MAX(doi.doi_data_block_size, vdev_blocksize);
return (segsz <= object_size && return (object_size >= (optimal_size * zfs_condense_pct / 100) &&
object_size >= (optimal_size * zfs_condense_pct / 100) &&
object_size > zfs_metaslab_condense_block_threshold * record_size); object_size > zfs_metaslab_condense_block_threshold * record_size);
} }
@ -2177,11 +2151,11 @@ metaslab_condense(metaslab_t *msp, uint64_t txg, dmu_tx_t *tx)
* optimal, this is typically close to optimal, and much cheaper to * optimal, this is typically close to optimal, and much cheaper to
* compute. * compute.
*/ */
space_map_write(sm, condense_tree, SM_ALLOC, tx); space_map_write(sm, condense_tree, SM_ALLOC, SM_NO_VDEVID, tx);
range_tree_vacate(condense_tree, NULL, NULL); range_tree_vacate(condense_tree, NULL, NULL);
range_tree_destroy(condense_tree); range_tree_destroy(condense_tree);
space_map_write(sm, msp->ms_allocatable, SM_FREE, tx); space_map_write(sm, msp->ms_allocatable, SM_FREE, SM_NO_VDEVID, tx);
mutex_enter(&msp->ms_lock); mutex_enter(&msp->ms_lock);
msp->ms_condensing = B_FALSE; msp->ms_condensing = B_FALSE;
} }
@ -2293,8 +2267,10 @@ metaslab_sync(metaslab_t *msp, uint64_t txg)
metaslab_condense(msp, txg, tx); metaslab_condense(msp, txg, tx);
} else { } else {
mutex_exit(&msp->ms_lock); mutex_exit(&msp->ms_lock);
space_map_write(msp->ms_sm, alloctree, SM_ALLOC, tx); space_map_write(msp->ms_sm, alloctree, SM_ALLOC,
space_map_write(msp->ms_sm, msp->ms_freeing, SM_FREE, tx); SM_NO_VDEVID, tx);
space_map_write(msp->ms_sm, msp->ms_freeing, SM_FREE,
SM_NO_VDEVID, tx);
mutex_enter(&msp->ms_lock); mutex_enter(&msp->ms_lock);
} }
@ -2309,7 +2285,7 @@ metaslab_sync(metaslab_t *msp, uint64_t txg)
*/ */
mutex_exit(&msp->ms_lock); mutex_exit(&msp->ms_lock);
space_map_write(vd->vdev_checkpoint_sm, space_map_write(vd->vdev_checkpoint_sm,
msp->ms_checkpointing, SM_FREE, tx); msp->ms_checkpointing, SM_FREE, SM_NO_VDEVID, tx);
mutex_enter(&msp->ms_lock); mutex_enter(&msp->ms_lock);
space_map_update(vd->vdev_checkpoint_sm); space_map_update(vd->vdev_checkpoint_sm);

50
module/zfs/spa_checkpoint.c
View File

@ -203,13 +203,12 @@ typedef struct spa_checkpoint_discard_sync_callback_arg {
} spa_checkpoint_discard_sync_callback_arg_t; } spa_checkpoint_discard_sync_callback_arg_t;
static int static int
spa_checkpoint_discard_sync_callback(maptype_t type, uint64_t offset, spa_checkpoint_discard_sync_callback(space_map_entry_t *sme, void *arg)
uint64_t size, void *arg)
{ {
spa_checkpoint_discard_sync_callback_arg_t *sdc = arg; spa_checkpoint_discard_sync_callback_arg_t *sdc = arg;
vdev_t *vd = sdc->sdc_vd; vdev_t *vd = sdc->sdc_vd;
metaslab_t *ms = vd->vdev_ms[offset >> vd->vdev_ms_shift]; metaslab_t *ms = vd->vdev_ms[sme->sme_offset >> vd->vdev_ms_shift];
uint64_t end = offset + size; uint64_t end = sme->sme_offset + sme->sme_run;
if (sdc->sdc_entry_limit == 0) if (sdc->sdc_entry_limit == 0)
return (EINTR); return (EINTR);
@ -224,8 +223,8 @@ spa_checkpoint_discard_sync_callback(maptype_t type, uint64_t offset,
* metaslab boundaries. So if needed we could add code * metaslab boundaries. So if needed we could add code
* that handles metaslab-crossing segments in the future. * that handles metaslab-crossing segments in the future.
*/ */
VERIFY3U(type, ==, SM_FREE); VERIFY3U(sme->sme_type, ==, SM_FREE);
VERIFY3U(offset, >=, ms->ms_start); VERIFY3U(sme->sme_offset, >=, ms->ms_start);
VERIFY3U(end, <=, ms->ms_start + ms->ms_size); VERIFY3U(end, <=, ms->ms_start + ms->ms_size);
/* /*
@ -237,14 +236,15 @@ spa_checkpoint_discard_sync_callback(maptype_t type, uint64_t offset,
mutex_enter(&ms->ms_lock); mutex_enter(&ms->ms_lock);
if (range_tree_is_empty(ms->ms_freeing)) if (range_tree_is_empty(ms->ms_freeing))
vdev_dirty(vd, VDD_METASLAB, ms, sdc->sdc_txg); vdev_dirty(vd, VDD_METASLAB, ms, sdc->sdc_txg);
range_tree_add(ms->ms_freeing, offset, size); range_tree_add(ms->ms_freeing, sme->sme_offset, sme->sme_run);
mutex_exit(&ms->ms_lock); mutex_exit(&ms->ms_lock);
ASSERT3U(vd->vdev_spa->spa_checkpoint_info.sci_dspace, >=, size); ASSERT3U(vd->vdev_spa->spa_checkpoint_info.sci_dspace, >=,
ASSERT3U(vd->vdev_stat.vs_checkpoint_space, >=, size); sme->sme_run);
ASSERT3U(vd->vdev_stat.vs_checkpoint_space, >=, sme->sme_run);
vd->vdev_spa->spa_checkpoint_info.sci_dspace -= size; vd->vdev_spa->spa_checkpoint_info.sci_dspace -= sme->sme_run;
vd->vdev_stat.vs_checkpoint_space -= size; vd->vdev_stat.vs_checkpoint_space -= sme->sme_run;
sdc->sdc_entry_limit--; sdc->sdc_entry_limit--;
return (0); return (0);
@ -291,12 +291,13 @@ spa_checkpoint_discard_thread_sync(void *arg, dmu_tx_t *tx)
* Thus, we set the maximum entries that the space map callback * Thus, we set the maximum entries that the space map callback
* will be applied to be half the entries that could fit in the * will be applied to be half the entries that could fit in the
* imposed memory limit. * imposed memory limit.
*
* Note that since this is a conservative estimate we also
* assume the worst case scenario in our computation where each
* entry is two-word.
*/ */
uint64_t max_entry_limit = uint64_t max_entry_limit =
(zfs_spa_discard_memory_limit / sizeof (uint64_t)) >> 1; (zfs_spa_discard_memory_limit / (2 * sizeof (uint64_t))) >> 1;
uint64_t entries_in_sm =
space_map_length(vd->vdev_checkpoint_sm) / sizeof (uint64_t);
/* /*
* Iterate from the end of the space map towards the beginning, * Iterate from the end of the space map towards the beginning,
@ -320,14 +321,15 @@ spa_checkpoint_discard_thread_sync(void *arg, dmu_tx_t *tx)
spa_checkpoint_discard_sync_callback_arg_t sdc; spa_checkpoint_discard_sync_callback_arg_t sdc;
sdc.sdc_vd = vd; sdc.sdc_vd = vd;
sdc.sdc_txg = tx->tx_txg; sdc.sdc_txg = tx->tx_txg;
sdc.sdc_entry_limit = MIN(entries_in_sm, max_entry_limit); sdc.sdc_entry_limit = max_entry_limit;
uint64_t entries_before = entries_in_sm; uint64_t words_before =
space_map_length(vd->vdev_checkpoint_sm) / sizeof (uint64_t);
error = space_map_incremental_destroy(vd->vdev_checkpoint_sm, error = space_map_incremental_destroy(vd->vdev_checkpoint_sm,
spa_checkpoint_discard_sync_callback, &sdc, tx); spa_checkpoint_discard_sync_callback, &sdc, tx);
uint64_t entries_after = uint64_t words_after =
space_map_length(vd->vdev_checkpoint_sm) / sizeof (uint64_t); space_map_length(vd->vdev_checkpoint_sm) / sizeof (uint64_t);
#ifdef ZFS_DEBUG #ifdef ZFS_DEBUG
@ -335,9 +337,9 @@ spa_checkpoint_discard_thread_sync(void *arg, dmu_tx_t *tx)
#endif #endif
zfs_dbgmsg("discarding checkpoint: txg %llu, vdev id %d, " zfs_dbgmsg("discarding checkpoint: txg %llu, vdev id %d, "
"deleted %llu entries - %llu entries are left", "deleted %llu words - %llu words are left",
tx->tx_txg, vd->vdev_id, (entries_before - entries_after), tx->tx_txg, vd->vdev_id, (words_before - words_after),
entries_after); words_after);
if (error != EINTR) { if (error != EINTR) {
if (error != 0) { if (error != 0) {
@ -346,15 +348,15 @@ spa_checkpoint_discard_thread_sync(void *arg, dmu_tx_t *tx)
"space map of vdev %llu\n", "space map of vdev %llu\n",
error, vd->vdev_id); error, vd->vdev_id);
} }
ASSERT0(entries_after); ASSERT0(words_after);
ASSERT0(vd->vdev_checkpoint_sm->sm_alloc); ASSERT0(vd->vdev_checkpoint_sm->sm_alloc);
ASSERT0(vd->vdev_checkpoint_sm->sm_length); ASSERT0(space_map_length(vd->vdev_checkpoint_sm));
space_map_free(vd->vdev_checkpoint_sm, tx); space_map_free(vd->vdev_checkpoint_sm, tx);
space_map_close(vd->vdev_checkpoint_sm); space_map_close(vd->vdev_checkpoint_sm);
vd->vdev_checkpoint_sm = NULL; vd->vdev_checkpoint_sm = NULL;
VERIFY0(zap_remove(vd->vdev_spa->spa_meta_objset, VERIFY0(zap_remove(spa_meta_objset(vd->vdev_spa),
vd->vdev_top_zap, VDEV_TOP_ZAP_POOL_CHECKPOINT_SM, tx)); vd->vdev_top_zap, VDEV_TOP_ZAP_POOL_CHECKPOINT_SM, tx));
} }
} }

818
module/zfs/space_map.c
View File

@ -41,11 +41,36 @@
* Note on space map block size: * Note on space map block size:
* *
* The data for a given space map can be kept on blocks of any size. * The data for a given space map can be kept on blocks of any size.
* Larger blocks entail fewer i/o operations, but they also cause the * Larger blocks entail fewer I/O operations, but they also cause the
* DMU to keep more data in-core, and also to waste more i/o bandwidth * DMU to keep more data in-core, and also to waste more I/O bandwidth
* when only a few blocks have changed since the last transaction group. * when only a few blocks have changed since the last transaction group.
*/ */
/*
* Enabled whenever we want to stress test the use of double-word
* space map entries.
*/
boolean_t zfs_force_some_double_word_sm_entries = B_FALSE;
boolean_t
sm_entry_is_debug(uint64_t e)
{
return (SM_PREFIX_DECODE(e) == SM_DEBUG_PREFIX);
}
boolean_t
sm_entry_is_single_word(uint64_t e)
{
uint8_t prefix = SM_PREFIX_DECODE(e);
return (prefix != SM_DEBUG_PREFIX && prefix != SM2_PREFIX);
}
boolean_t
sm_entry_is_double_word(uint64_t e)
{
return (SM_PREFIX_DECODE(e) == SM2_PREFIX);
}
/* /*
* Iterate through the space map, invoking the callback on each (non-debug) * Iterate through the space map, invoking the callback on each (non-debug)
* space map entry. * space map entry.
@ -53,56 +78,157 @@
int int
space_map_iterate(space_map_t *sm, sm_cb_t callback, void *arg) space_map_iterate(space_map_t *sm, sm_cb_t callback, void *arg)
{ {
uint64_t *entry, *entry_map, *entry_map_end; uint64_t sm_len = space_map_length(sm);
uint64_t bufsize, size, offset, end; ASSERT3U(sm->sm_blksz, !=, 0);
dmu_prefetch(sm->sm_os, space_map_object(sm), 0, 0, sm_len,
ZIO_PRIORITY_SYNC_READ);
uint64_t blksz = sm->sm_blksz;
int error = 0; int error = 0;
for (uint64_t block_base = 0; block_base < sm_len && error == 0;
end = space_map_length(sm); block_base += blksz) {
dmu_buf_t *db;
bufsize = MAX(sm->sm_blksz, SPA_MINBLOCKSIZE); error = dmu_buf_hold(sm->sm_os, space_map_object(sm),
entry_map = vmem_alloc(bufsize, KM_SLEEP); block_base, FTAG, &db, DMU_READ_PREFETCH);
if (end > bufsize) {
dmu_prefetch(sm->sm_os, space_map_object(sm), 0, bufsize,
end - bufsize, ZIO_PRIORITY_SYNC_READ);
}
for (offset = 0; offset < end && error == 0; offset += bufsize) {
size = MIN(end - offset, bufsize);
VERIFY(P2PHASE(size, sizeof (uint64_t)) == 0);
VERIFY(size != 0);
ASSERT3U(sm->sm_blksz, !=, 0);
dprintf("object=%llu offset=%llx size=%llx\n",
space_map_object(sm), offset, size);
error = dmu_read(sm->sm_os, space_map_object(sm), offset, size,
entry_map, DMU_READ_PREFETCH);
if (error != 0) if (error != 0)
break; return (error);
entry_map_end = entry_map + (size / sizeof (uint64_t)); uint64_t *block_start = db->db_data;
for (entry = entry_map; entry < entry_map_end && error == 0; uint64_t block_length = MIN(sm_len - block_base, blksz);
entry++) { uint64_t *block_end = block_start +
uint64_t e = *entry; (block_length / sizeof (uint64_t));
uint64_t offset, size;
if (SM_DEBUG_DECODE(e)) /* Skip debug entries */ VERIFY0(P2PHASE(block_length, sizeof (uint64_t)));
VERIFY3U(block_length, !=, 0);
ASSERT3U(blksz, ==, db->db_size);
for (uint64_t *block_cursor = block_start;
block_cursor < block_end && error == 0; block_cursor++) {
uint64_t e = *block_cursor;
if (sm_entry_is_debug(e)) /* Skip debug entries */
continue; continue;
offset = (SM_OFFSET_DECODE(e) << sm->sm_shift) + uint64_t raw_offset, raw_run, vdev_id;
sm->sm_start; maptype_t type;
size = SM_RUN_DECODE(e) << sm->sm_shift; if (sm_entry_is_single_word(e)) {
type = SM_TYPE_DECODE(e);
vdev_id = SM_NO_VDEVID;
raw_offset = SM_OFFSET_DECODE(e);
raw_run = SM_RUN_DECODE(e);
} else {
/* it is a two-word entry */
ASSERT(sm_entry_is_double_word(e));
raw_run = SM2_RUN_DECODE(e);
vdev_id = SM2_VDEV_DECODE(e);
VERIFY0(P2PHASE(offset, 1ULL << sm->sm_shift)); /* move on to the second word */
VERIFY0(P2PHASE(size, 1ULL << sm->sm_shift)); block_cursor++;
VERIFY3U(offset, >=, sm->sm_start); e = *block_cursor;
VERIFY3U(offset + size, <=, sm->sm_start + sm->sm_size); VERIFY3P(block_cursor, <=, block_end);
error = callback(SM_TYPE_DECODE(e), offset, size, arg);
type = SM2_TYPE_DECODE(e);
raw_offset = SM2_OFFSET_DECODE(e);
}
uint64_t entry_offset = (raw_offset << sm->sm_shift) +
sm->sm_start;
uint64_t entry_run = raw_run << sm->sm_shift;
VERIFY0(P2PHASE(entry_offset, 1ULL << sm->sm_shift));
VERIFY0(P2PHASE(entry_run, 1ULL << sm->sm_shift));
ASSERT3U(entry_offset, >=, sm->sm_start);
ASSERT3U(entry_offset, <, sm->sm_start + sm->sm_size);
ASSERT3U(entry_run, <=, sm->sm_size);
ASSERT3U(entry_offset + entry_run, <=,
sm->sm_start + sm->sm_size);
space_map_entry_t sme = {
.sme_type = type,
.sme_vdev = vdev_id,
.sme_offset = entry_offset,
.sme_run = entry_run
};
error = callback(&sme, arg);
}
dmu_buf_rele(db, FTAG);
}
return (error);
}
/*
* Reads the entries from the last block of the space map into
* buf in reverse order. Populates nwords with number of words
* in the last block.
*
* Refer to block comment within space_map_incremental_destroy()
* to understand why this function is needed.
*/
static int
space_map_reversed_last_block_entries(space_map_t *sm, uint64_t *buf,
uint64_t bufsz, uint64_t *nwords)
{
int error = 0;
dmu_buf_t *db;
/*
* Find the offset of the last word in the space map and use
* that to read the last block of the space map with
* dmu_buf_hold().
*/
uint64_t last_word_offset =
sm->sm_phys->smp_objsize - sizeof (uint64_t);
error = dmu_buf_hold(sm->sm_os, space_map_object(sm), last_word_offset,
FTAG, &db, DMU_READ_NO_PREFETCH);
if (error != 0)
return (error);
ASSERT3U(sm->sm_object, ==, db->db_object);
ASSERT3U(sm->sm_blksz, ==, db->db_size);
ASSERT3U(bufsz, >=, db->db_size);
ASSERT(nwords != NULL);
uint64_t *words = db->db_data;
*nwords =
(sm->sm_phys->smp_objsize - db->db_offset) / sizeof (uint64_t);
ASSERT3U(*nwords, <=, bufsz / sizeof (uint64_t));
uint64_t n = *nwords;
uint64_t j = n - 1;
for (uint64_t i = 0; i < n; i++) {
uint64_t entry = words[i];
if (sm_entry_is_double_word(entry)) {
/*
* Since we are populating the buffer backwards
* we have to be extra careful and add the two
* words of the double-word entry in the right
* order.
*/
ASSERT3U(j, >, 0);
buf[j - 1] = entry;
i++;
ASSERT3U(i, <, n);
entry = words[i];
buf[j] = entry;
j -= 2;
} else {
ASSERT(sm_entry_is_debug(entry) ||
sm_entry_is_single_word(entry));
buf[j] = entry;
j--;
} }
} }
vmem_free(entry_map, bufsize); /*
* Assert that we wrote backwards all the
* way to the beginning of the buffer.
*/
ASSERT3S(j, ==, -1);
dmu_buf_rele(db, FTAG);
return (error); return (error);
} }
@ -116,124 +242,122 @@ int
space_map_incremental_destroy(space_map_t *sm, sm_cb_t callback, void *arg, space_map_incremental_destroy(space_map_t *sm, sm_cb_t callback, void *arg,
dmu_tx_t *tx) dmu_tx_t *tx)
{ {
uint64_t bufsize, len; uint64_t bufsz = MAX(sm->sm_blksz, SPA_MINBLOCKSIZE);
uint64_t *entry_map; uint64_t *buf = zio_buf_alloc(bufsz);
int error = 0;
len = space_map_length(sm);
bufsize = MAX(sm->sm_blksz, SPA_MINBLOCKSIZE);
entry_map = zio_buf_alloc(bufsize);
dmu_buf_will_dirty(sm->sm_dbuf, tx); dmu_buf_will_dirty(sm->sm_dbuf, tx);
/* /*
* Since we can't move the starting offset of the space map * Ideally we would want to iterate from the beginning of the
* (e.g there are reference on-disk pointing to it), we destroy * space map to the end in incremental steps. The issue with this
* its entries incrementally starting from the end. * approach is that we don't have any field on-disk that points
* us where to start between each step. We could try zeroing out
* entries that we've destroyed, but this doesn't work either as
* an entry that is 0 is a valid one (ALLOC for range [0x0:0x200]).
* *
* The logic that follows is basically the same as the one used * As a result, we destroy its entries incrementally starting from
* in space_map_iterate() but it traverses the space map * the end after applying the callback to each of them.
* backwards:
* *
* 1] We figure out the size of the buffer that we want to use * The problem with this approach is that we cannot literally
* to read the on-disk space map entries. * iterate through the words in the space map backwards as we
* 2] We figure out the offset at the end of the space map where * can't distinguish two-word space map entries from their second
* we will start reading entries into our buffer. * word. Thus we do the following:
* 3] We read the on-disk entries into the buffer. *
* 4] We iterate over the entries from end to beginning calling * 1] We get all the entries from the last block of the space map
* the callback function on each one. As we move from entry * and put them into a buffer in reverse order. This way the
* to entry we decrease the size of the space map, deleting * last entry comes first in the buffer, the second to last is
* effectively each entry. * second, etc.
* 5] If there are no more entries in the space map or the * 2] We iterate through the entries in the buffer and we apply
* callback returns a value other than 0, we stop iterating * the callback to each one. As we move from entry to entry we
* over the space map. If there are entries remaining and * we decrease the size of the space map, deleting effectively
* the callback returned zero we go back to step [1]. * each entry.
* 3] If there are no more entries in the space map or the callback
* returns a value other than 0, we stop iterating over the
* space map. If there are entries remaining and the callback
* returned 0, we go back to step [1].
*/ */
uint64_t offset = 0, size = 0; int error = 0;
while (len > 0 && error == 0) { while (space_map_length(sm) > 0 && error == 0) {
size = MIN(bufsize, len); uint64_t nwords = 0;
error = space_map_reversed_last_block_entries(sm, buf, bufsz,
VERIFY(P2PHASE(size, sizeof (uint64_t)) == 0); &nwords);
VERIFY3U(size, >, 0);
ASSERT3U(sm->sm_blksz, !=, 0);
offset = len - size;
IMPLY(bufsize > len, offset == 0);
IMPLY(bufsize == len, offset == 0);
IMPLY(bufsize < len, offset > 0);
EQUIV(size == len, offset == 0);
IMPLY(size < len, bufsize < len);
dprintf("object=%llu offset=%llx size=%llx\n",
space_map_object(sm), offset, size);
error = dmu_read(sm->sm_os, space_map_object(sm),
offset, size, entry_map, DMU_READ_PREFETCH);
if (error != 0) if (error != 0)
break; break;
uint64_t num_entries = size / sizeof (uint64_t); ASSERT3U(nwords, <=, bufsz / sizeof (uint64_t));
ASSERT3U(num_entries, >, 0); for (uint64_t i = 0; i < nwords; i++) {
uint64_t e = buf[i];
while (num_entries > 0) { if (sm_entry_is_debug(e)) {
uint64_t e, entry_offset, entry_size;
maptype_t type;
e = entry_map[num_entries - 1];
ASSERT3U(num_entries, >, 0);
ASSERT0(error);
if (SM_DEBUG_DECODE(e)) {
sm->sm_phys->smp_objsize -= sizeof (uint64_t); sm->sm_phys->smp_objsize -= sizeof (uint64_t);
space_map_update(sm); space_map_update(sm);
len -= sizeof (uint64_t);
num_entries--;
continue; continue;
} }
type = SM_TYPE_DECODE(e); int words = 1;
entry_offset = (SM_OFFSET_DECODE(e) << sm->sm_shift) + uint64_t raw_offset, raw_run, vdev_id;
sm->sm_start; maptype_t type;
entry_size = SM_RUN_DECODE(e) << sm->sm_shift; if (sm_entry_is_single_word(e)) {
type = SM_TYPE_DECODE(e);
vdev_id = SM_NO_VDEVID;
raw_offset = SM_OFFSET_DECODE(e);
raw_run = SM_RUN_DECODE(e);
} else {
ASSERT(sm_entry_is_double_word(e));
words = 2;
raw_run = SM2_RUN_DECODE(e);
vdev_id = SM2_VDEV_DECODE(e);
/* move to the second word */
i++;
e = buf[i];
ASSERT3P(i, <=, nwords);
type = SM2_TYPE_DECODE(e);
raw_offset = SM2_OFFSET_DECODE(e);
}
uint64_t entry_offset =
(raw_offset << sm->sm_shift) + sm->sm_start;
uint64_t entry_run = raw_run << sm->sm_shift;
VERIFY0(P2PHASE(entry_offset, 1ULL << sm->sm_shift)); VERIFY0(P2PHASE(entry_offset, 1ULL << sm->sm_shift));
VERIFY0(P2PHASE(entry_size, 1ULL << sm->sm_shift)); VERIFY0(P2PHASE(entry_run, 1ULL << sm->sm_shift));
VERIFY3U(entry_offset, >=, sm->sm_start); VERIFY3U(entry_offset, >=, sm->sm_start);
VERIFY3U(entry_offset + entry_size, <=, VERIFY3U(entry_offset, <, sm->sm_start + sm->sm_size);
VERIFY3U(entry_run, <=, sm->sm_size);
VERIFY3U(entry_offset + entry_run, <=,
sm->sm_start + sm->sm_size); sm->sm_start + sm->sm_size);
error = callback(type, entry_offset, entry_size, arg); space_map_entry_t sme = {
.sme_type = type,
.sme_vdev = vdev_id,
.sme_offset = entry_offset,
.sme_run = entry_run
};
error = callback(&sme, arg);
if (error != 0) if (error != 0)
break; break;
if (type == SM_ALLOC) if (type == SM_ALLOC)
sm->sm_phys->smp_alloc -= entry_size; sm->sm_phys->smp_alloc -= entry_run;
else else
sm->sm_phys->smp_alloc += entry_size; sm->sm_phys->smp_alloc += entry_run;
sm->sm_phys->smp_objsize -= words * sizeof (uint64_t);
sm->sm_phys->smp_objsize -= sizeof (uint64_t);
space_map_update(sm); space_map_update(sm);
len -= sizeof (uint64_t);
num_entries--;
} }
IMPLY(error == 0, num_entries == 0);
EQUIV(offset == 0 && error == 0, len == 0 && num_entries == 0);
} }
if (len == 0) { if (space_map_length(sm) == 0) {
ASSERT0(error); ASSERT0(error);
ASSERT0(offset);
ASSERT0(sm->sm_length);
ASSERT0(sm->sm_phys->smp_objsize); ASSERT0(sm->sm_phys->smp_objsize);
ASSERT0(sm->sm_alloc); ASSERT0(sm->sm_alloc);
} }
zio_buf_free(entry_map, bufsize); zio_buf_free(buf, bufsz);
return (error); return (error);
} }
@ -244,16 +368,15 @@ typedef struct space_map_load_arg {
} space_map_load_arg_t; } space_map_load_arg_t;
static int static int
space_map_load_callback(maptype_t type, uint64_t offset, uint64_t size, space_map_load_callback(space_map_entry_t *sme, void *arg)
void *arg)
{ {
space_map_load_arg_t *smla = arg; space_map_load_arg_t *smla = arg;
if (type == smla->smla_type) { if (sme->sme_type == smla->smla_type) {
VERIFY3U(range_tree_space(smla->smla_rt) + size, <=, VERIFY3U(range_tree_space(smla->smla_rt) + sme->sme_run, <=,
smla->smla_sm->sm_size); smla->smla_sm->sm_size);
range_tree_add(smla->smla_rt, offset, size); range_tree_add(smla->smla_rt, sme->sme_offset, sme->sme_run);
} else { } else {
range_tree_remove(smla->smla_rt, offset, size); range_tree_remove(smla->smla_rt, sme->sme_offset, sme->sme_run);
} }
return (0); return (0);
@ -365,43 +488,237 @@ space_map_histogram_add(space_map_t *sm, range_tree_t *rt, dmu_tx_t *tx)
} }
} }
uint64_t static void
space_map_entries(space_map_t *sm, range_tree_t *rt) space_map_write_intro_debug(space_map_t *sm, maptype_t maptype, dmu_tx_t *tx)
{ {
avl_tree_t *t = &rt->rt_root; dmu_buf_will_dirty(sm->sm_dbuf, tx);
range_seg_t *rs;
uint64_t size, entries;
/* uint64_t dentry = SM_PREFIX_ENCODE(SM_DEBUG_PREFIX) |
* All space_maps always have a debug entry so account for it here. SM_DEBUG_ACTION_ENCODE(maptype) |
*/ SM_DEBUG_SYNCPASS_ENCODE(spa_sync_pass(tx->tx_pool->dp_spa)) |
entries = 1; SM_DEBUG_TXG_ENCODE(dmu_tx_get_txg(tx));
/* dmu_write(sm->sm_os, space_map_object(sm), sm->sm_phys->smp_objsize,
* Traverse the range tree and calculate the number of space map sizeof (dentry), &dentry, tx);
* entries that would be required to write out the range tree.
*/ sm->sm_phys->smp_objsize += sizeof (dentry);
for (rs = avl_first(t); rs != NULL; rs = AVL_NEXT(t, rs)) {
size = (rs->rs_end - rs->rs_start) >> sm->sm_shift;
entries += howmany(size, SM_RUN_MAX);
}
return (entries);
} }
/*
* Writes one or more entries given a segment.
*
* Note: The function may release the dbuf from the pointer initially
* passed to it, and return a different dbuf. Also, the space map's
* dbuf must be dirty for the changes in sm_phys to take effect.
*/
static void
space_map_write_seg(space_map_t *sm, range_seg_t *rs, maptype_t maptype,
uint64_t vdev_id, uint8_t words, dmu_buf_t **dbp, void *tag, dmu_tx_t *tx)
{
ASSERT3U(words, !=, 0);
ASSERT3U(words, <=, 2);
/* ensure the vdev_id can be represented by the space map */
ASSERT3U(vdev_id, <=, SM_NO_VDEVID);
/*
* if this is a single word entry, ensure that no vdev was
* specified.
*/
IMPLY(words == 1, vdev_id == SM_NO_VDEVID);
dmu_buf_t *db = *dbp;
ASSERT3U(db->db_size, ==, sm->sm_blksz);
uint64_t *block_base = db->db_data;
uint64_t *block_end = block_base + (sm->sm_blksz / sizeof (uint64_t));
uint64_t *block_cursor = block_base +
(sm->sm_phys->smp_objsize - db->db_offset) / sizeof (uint64_t);
ASSERT3P(block_cursor, <=, block_end);
uint64_t size = (rs->rs_end - rs->rs_start) >> sm->sm_shift;
uint64_t start = (rs->rs_start - sm->sm_start) >> sm->sm_shift;
uint64_t run_max = (words == 2) ? SM2_RUN_MAX : SM_RUN_MAX;
ASSERT3U(rs->rs_start, >=, sm->sm_start);
ASSERT3U(rs->rs_start, <, sm->sm_start + sm->sm_size);
ASSERT3U(rs->rs_end - rs->rs_start, <=, sm->sm_size);
ASSERT3U(rs->rs_end, <=, sm->sm_start + sm->sm_size);
while (size != 0) {
ASSERT3P(block_cursor, <=, block_end);
/*
* If we are at the end of this block, flush it and start
* writing again from the beginning.
*/
if (block_cursor == block_end) {
dmu_buf_rele(db, tag);
uint64_t next_word_offset = sm->sm_phys->smp_objsize;
VERIFY0(dmu_buf_hold(sm->sm_os,
space_map_object(sm), next_word_offset,
tag, &db, DMU_READ_PREFETCH));
dmu_buf_will_dirty(db, tx);
/* update caller's dbuf */
*dbp = db;
ASSERT3U(db->db_size, ==, sm->sm_blksz);
block_base = db->db_data;
block_cursor = block_base;
block_end = block_base +
(db->db_size / sizeof (uint64_t));
}
/*
* If we are writing a two-word entry and we only have one
* word left on this block, just pad it with an empty debug
* entry and write the two-word entry in the next block.
*/
uint64_t *next_entry = block_cursor + 1;
if (next_entry == block_end && words > 1) {
ASSERT3U(words, ==, 2);
*block_cursor = SM_PREFIX_ENCODE(SM_DEBUG_PREFIX) |
SM_DEBUG_ACTION_ENCODE(0) |
SM_DEBUG_SYNCPASS_ENCODE(0) |
SM_DEBUG_TXG_ENCODE(0);
block_cursor++;
sm->sm_phys->smp_objsize += sizeof (uint64_t);
ASSERT3P(block_cursor, ==, block_end);
continue;
}
uint64_t run_len = MIN(size, run_max);
switch (words) {
case 1:
*block_cursor = SM_OFFSET_ENCODE(start) |
SM_TYPE_ENCODE(maptype) |
SM_RUN_ENCODE(run_len);
block_cursor++;
break;
case 2:
/* write the first word of the entry */
*block_cursor = SM_PREFIX_ENCODE(SM2_PREFIX) |
SM2_RUN_ENCODE(run_len) |
SM2_VDEV_ENCODE(vdev_id);
block_cursor++;
/* move on to the second word of the entry */
ASSERT3P(block_cursor, <, block_end);
*block_cursor = SM2_TYPE_ENCODE(maptype) |
SM2_OFFSET_ENCODE(start);
block_cursor++;
break;
default:
panic("%d-word space map entries are not supported",
words);
break;
}
sm->sm_phys->smp_objsize += words * sizeof (uint64_t);
start += run_len;
size -= run_len;
}
ASSERT0(size);
}
/*
* Note: The space map's dbuf must be dirty for the changes in sm_phys to
* take effect.
*/
static void
space_map_write_impl(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
uint64_t vdev_id, dmu_tx_t *tx)
{
spa_t *spa = tx->tx_pool->dp_spa;
dmu_buf_t *db;
space_map_write_intro_debug(sm, maptype, tx);
#ifdef DEBUG
/*
* We do this right after we write the intro debug entry
* because the estimate does not take it into account.
*/
uint64_t initial_objsize = sm->sm_phys->smp_objsize;
uint64_t estimated_growth =
space_map_estimate_optimal_size(sm, rt, SM_NO_VDEVID);
uint64_t estimated_final_objsize = initial_objsize + estimated_growth;
#endif
/*
* Find the offset right after the last word in the space map
* and use that to get a hold of the last block, so we can
* start appending to it.
*/
uint64_t next_word_offset = sm->sm_phys->smp_objsize;
VERIFY0(dmu_buf_hold(sm->sm_os, space_map_object(sm),
next_word_offset, FTAG, &db, DMU_READ_PREFETCH));
ASSERT3U(db->db_size, ==, sm->sm_blksz);
dmu_buf_will_dirty(db, tx);
avl_tree_t *t = &rt->rt_root;
for (range_seg_t *rs = avl_first(t); rs != NULL; rs = AVL_NEXT(t, rs)) {
uint64_t offset = (rs->rs_start - sm->sm_start) >> sm->sm_shift;
uint64_t length = (rs->rs_end - rs->rs_start) >> sm->sm_shift;
uint8_t words = 1;
/*
* We only write two-word entries when both of the following
* are true:
*
* [1] The feature is enabled.
* [2] The offset or run is too big for a single-word entry,
* or the vdev_id is set (meaning not equal to
* SM_NO_VDEVID).
*
* Note that for purposes of testing we've added the case that
* we write two-word entries occasionally when the feature is
* enabled and zfs_force_some_double_word_sm_entries has been
* set.
*/
if (spa_feature_is_active(spa, SPA_FEATURE_SPACEMAP_V2) &&
(offset >= (1ULL << SM_OFFSET_BITS) ||
length > SM_RUN_MAX ||
vdev_id != SM_NO_VDEVID ||
(zfs_force_some_double_word_sm_entries &&
spa_get_random(100) == 0)))
words = 2;
space_map_write_seg(sm, rs, maptype, vdev_id, words,
&db, FTAG, tx);
}
dmu_buf_rele(db, FTAG);
#ifdef DEBUG
/*
* We expect our estimation to be based on the worst case
* scenario [see comment in space_map_estimate_optimal_size()].
* Therefore we expect the actual objsize to be equal or less
* than whatever we estimated it to be.
*/
ASSERT3U(estimated_final_objsize, >=, sm->sm_phys->smp_objsize);
#endif
}
/*
* Note: This function manipulates the state of the given space map but
* does not hold any locks implicitly. Thus the caller is responsible
* for synchronizing writes to the space map.
*/
void void
space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype, space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
dmu_tx_t *tx) uint64_t vdev_id, dmu_tx_t *tx)
{ {
objset_t *os = sm->sm_os; ASSERT(dsl_pool_sync_context(dmu_objset_pool(sm->sm_os)));
spa_t *spa = dmu_objset_spa(os);
avl_tree_t *t = &rt->rt_root;
range_seg_t *rs;
uint64_t size, total, rt_space, nodes;
uint64_t *entry, *entry_map, *entry_map_end;
uint64_t expected_entries, actual_entries = 1;
ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
VERIFY3U(space_map_object(sm), !=, 0); VERIFY3U(space_map_object(sm), !=, 0);
dmu_buf_will_dirty(sm->sm_dbuf, tx); dmu_buf_will_dirty(sm->sm_dbuf, tx);
/* /*
@ -421,58 +738,10 @@ space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
else else
sm->sm_phys->smp_alloc -= range_tree_space(rt); sm->sm_phys->smp_alloc -= range_tree_space(rt);
expected_entries = space_map_entries(sm, rt); uint64_t nodes = avl_numnodes(&rt->rt_root);
uint64_t rt_space = range_tree_space(rt);
entry_map = vmem_alloc(sm->sm_blksz, KM_SLEEP); space_map_write_impl(sm, rt, maptype, vdev_id, tx);
entry_map_end = entry_map + (sm->sm_blksz / sizeof (uint64_t));
entry = entry_map;
*entry++ = SM_DEBUG_ENCODE(1) |
SM_DEBUG_ACTION_ENCODE(maptype) |
SM_DEBUG_SYNCPASS_ENCODE(spa_sync_pass(spa)) |
SM_DEBUG_TXG_ENCODE(dmu_tx_get_txg(tx));
total = 0;
nodes = avl_numnodes(&rt->rt_root);
rt_space = range_tree_space(rt);
for (rs = avl_first(t); rs != NULL; rs = AVL_NEXT(t, rs)) {
uint64_t start;
size = (rs->rs_end - rs->rs_start) >> sm->sm_shift;
start = (rs->rs_start - sm->sm_start) >> sm->sm_shift;
total += size << sm->sm_shift;
while (size != 0) {
uint64_t run_len;
run_len = MIN(size, SM_RUN_MAX);
if (entry == entry_map_end) {
dmu_write(os, space_map_object(sm),
sm->sm_phys->smp_objsize, sm->sm_blksz,
entry_map, tx);
sm->sm_phys->smp_objsize += sm->sm_blksz;
entry = entry_map;
}
*entry++ = SM_OFFSET_ENCODE(start) |
SM_TYPE_ENCODE(maptype) |
SM_RUN_ENCODE(run_len);
start += run_len;
size -= run_len;
actual_entries++;
}
}
if (entry != entry_map) {
size = (entry - entry_map) * sizeof (uint64_t);
dmu_write(os, space_map_object(sm), sm->sm_phys->smp_objsize,
size, entry_map, tx);
sm->sm_phys->smp_objsize += size;
}
ASSERT3U(expected_entries, ==, actual_entries);
/* /*
* Ensure that the space_map's accounting wasn't changed * Ensure that the space_map's accounting wasn't changed
@ -480,9 +749,6 @@ space_map_write(space_map_t *sm, range_tree_t *rt, maptype_t maptype,
*/ */
VERIFY3U(nodes, ==, avl_numnodes(&rt->rt_root)); VERIFY3U(nodes, ==, avl_numnodes(&rt->rt_root));
VERIFY3U(range_tree_space(rt), ==, rt_space); VERIFY3U(range_tree_space(rt), ==, rt_space);
VERIFY3U(range_tree_space(rt), ==, total);
vmem_free(entry_map, sm->sm_blksz);
} }
static int static int
@ -529,7 +795,6 @@ space_map_open(space_map_t **smp, objset_t *os, uint64_t object,
space_map_close(sm); space_map_close(sm);
return (error); return (error);
} }
*smp = sm; *smp = sm;
return (0); return (0);
@ -661,6 +926,133 @@ space_map_free(space_map_t *sm, dmu_tx_t *tx)
sm->sm_object = 0; sm->sm_object = 0;
} }
/*
* Given a range tree, it makes a worst-case estimate of how much
* space would the tree's segments take if they were written to
* the given space map.
*/
uint64_t
space_map_estimate_optimal_size(space_map_t *sm, range_tree_t *rt,
uint64_t vdev_id)
{
spa_t *spa = dmu_objset_spa(sm->sm_os);
uint64_t shift = sm->sm_shift;
uint64_t *histogram = rt->rt_histogram;
uint64_t entries_for_seg = 0;
/*
* In order to get a quick estimate of the optimal size that this
* range tree would have on-disk as a space map, we iterate through
* its histogram buckets instead of iterating through its nodes.
*
* Note that this is a highest-bound/worst-case estimate for the
* following reasons:
*
* 1] We assume that we always add a debug padding for each block
* we write and we also assume that we start at the last word
* of a block attempting to write a two-word entry.
* 2] Rounding up errors due to the way segments are distributed
* in the buckets of the range tree's histogram.
* 3] The activation of zfs_force_some_double_word_sm_entries
* (tunable) when testing.
*
* = Math and Rounding Errors =
*
* rt_histogram[i] bucket of a range tree represents the number
* of entries in [2^i, (2^(i+1))-1] of that range_tree. Given
* that, we want to divide the buckets into groups: Buckets that
* can be represented using a single-word entry, ones that can
* be represented with a double-word entry, and ones that can
* only be represented with multiple two-word entries.
*
* [Note that if the new encoding feature is not enabled there
* are only two groups: single-word entry buckets and multiple
* single-word entry buckets. The information below assumes
* two-word entries enabled, but it can easily applied when
* the feature is not enabled]
*
* To find the highest bucket that can be represented with a
* single-word entry we look at the maximum run that such entry
* can have, which is 2^(SM_RUN_BITS + sm_shift) [remember that
* the run of a space map entry is shifted by sm_shift, thus we
* add it to the exponent]. This way, excluding the value of the
* maximum run that can be represented by a single-word entry,
* all runs that are smaller exist in buckets 0 to
* SM_RUN_BITS + shift - 1.
*
* To find the highest bucket that can be represented with a
* double-word entry, we follow the same approach. Finally, any
* bucket higher than that are represented with multiple two-word
* entries. To be more specific, if the highest bucket whose
* segments can be represented with a single two-word entry is X,
* then bucket X+1 will need 2 two-word entries for each of its
* segments, X+2 will need 4, X+3 will need 8, ...etc.
*
* With all of the above we make our estimation based on bucket
* groups. There is a rounding error though. As we mentioned in
* the example with the one-word entry, the maximum run that can
* be represented in a one-word entry 2^(SM_RUN_BITS + shift) is
* not part of bucket SM_RUN_BITS + shift - 1. Thus, segments of
* that length fall into the next bucket (and bucket group) where
* we start counting two-word entries and this is one more reason
* why the estimated size may end up being bigger than the actual
* size written.
*/
uint64_t size = 0;
uint64_t idx = 0;
if (!spa_feature_is_enabled(spa, SPA_FEATURE_SPACEMAP_V2) ||
(vdev_id == SM_NO_VDEVID && sm->sm_size < SM_OFFSET_MAX)) {
/*
* If we are trying to force some double word entries just
* assume the worst-case of every single word entry being
* written as a double word entry.
*/
uint64_t entry_size =
(spa_feature_is_enabled(spa, SPA_FEATURE_SPACEMAP_V2) &&
zfs_force_some_double_word_sm_entries) ?
(2 * sizeof (uint64_t)) : sizeof (uint64_t);
uint64_t single_entry_max_bucket = SM_RUN_BITS + shift - 1;
for (; idx <= single_entry_max_bucket; idx++)
size += histogram[idx] * entry_size;
if (!spa_feature_is_enabled(spa, SPA_FEATURE_SPACEMAP_V2)) {
for (; idx < RANGE_TREE_HISTOGRAM_SIZE; idx++) {
ASSERT3U(idx, >=, single_entry_max_bucket);
entries_for_seg =
1ULL << (idx - single_entry_max_bucket);
size += histogram[idx] *
entries_for_seg * entry_size;
}
return (size);
}
}
ASSERT(spa_feature_is_enabled(spa, SPA_FEATURE_SPACEMAP_V2));
uint64_t double_entry_max_bucket = SM2_RUN_BITS + shift - 1;
for (; idx <= double_entry_max_bucket; idx++)
size += histogram[idx] * 2 * sizeof (uint64_t);
for (; idx < RANGE_TREE_HISTOGRAM_SIZE; idx++) {
ASSERT3U(idx, >=, double_entry_max_bucket);
entries_for_seg = 1ULL << (idx - double_entry_max_bucket);
size += histogram[idx] *
entries_for_seg * 2 * sizeof (uint64_t);
}
/*
* Assume the worst case where we start with the padding at the end
* of the current block and we add an extra padding entry at the end
* of all subsequent blocks.
*/
size += ((size / sm->sm_blksz) + 1) * sizeof (uint64_t);
return (size);
}
uint64_t uint64_t
space_map_object(space_map_t *sm) space_map_object(space_map_t *sm)
{ {

2
module/zfs/vdev.c
View File

@ -2634,7 +2634,7 @@ vdev_dtl_sync(vdev_t *vd, uint64_t txg)
mutex_exit(&vd->vdev_dtl_lock); mutex_exit(&vd->vdev_dtl_lock);
space_map_truncate(vd->vdev_dtl_sm, vdev_dtl_sm_blksz, tx); space_map_truncate(vd->vdev_dtl_sm, vdev_dtl_sm_blksz, tx);
space_map_write(vd->vdev_dtl_sm, rtsync, SM_ALLOC, tx); space_map_write(vd->vdev_dtl_sm, rtsync, SM_ALLOC, SM_NO_VDEVID, tx);
range_tree_vacate(rtsync, NULL, NULL); range_tree_vacate(rtsync, NULL, NULL);
range_tree_destroy(rtsync); range_tree_destroy(rtsync);

2
module/zfs/vdev_indirect.c
View File

@ -825,7 +825,7 @@ vdev_indirect_sync_obsolete(vdev_t *vd, dmu_tx_t *tx)
space_map_object(vd->vdev_obsolete_sm)); space_map_object(vd->vdev_obsolete_sm));
space_map_write(vd->vdev_obsolete_sm, space_map_write(vd->vdev_obsolete_sm,
vd->vdev_obsolete_segments, SM_ALLOC, tx); vd->vdev_obsolete_segments, SM_ALLOC, SM_NO_VDEVID, tx);
space_map_update(vd->vdev_obsolete_sm); space_map_update(vd->vdev_obsolete_sm);
range_tree_vacate(vd->vdev_obsolete_segments, NULL, NULL); range_tree_vacate(vd->vdev_obsolete_segments, NULL, NULL);
} }

9
module/zfs/vdev_indirect_mapping.c
View File

@ -14,7 +14,7 @@
*/ */
/* /*
* Copyright (c) 2015 by Delphix. All rights reserved. * Copyright (c) 2015, 2017 by Delphix. All rights reserved.
*/ */
#include <sys/dmu_tx.h> #include <sys/dmu_tx.h>
@ -539,14 +539,13 @@ typedef struct load_obsolete_space_map_arg {
} load_obsolete_space_map_arg_t; } load_obsolete_space_map_arg_t;
static int static int
load_obsolete_sm_callback(maptype_t type, uint64_t offset, uint64_t size, load_obsolete_sm_callback(space_map_entry_t *sme, void *arg)
void *arg)
{ {
load_obsolete_space_map_arg_t *losma = arg; load_obsolete_space_map_arg_t *losma = arg;
ASSERT3S(type, ==, SM_ALLOC); ASSERT3S(sme->sme_type, ==, SM_ALLOC);
vdev_indirect_mapping_increment_obsolete_count(losma->losma_vim, vdev_indirect_mapping_increment_obsolete_count(losma->losma_vim,
offset, size, losma->losma_counts); sme->sme_offset, sme->sme_run, losma->losma_counts);
return (0); return (0);
} }

1
tests/zfs-tests/tests/functional/cli_root/zpool_get/zpool_get.cfg
View File

@ -74,6 +74,7 @@ typeset -a properties=(
"feature@device_removal" "feature@device_removal"
"feature@obsolete_counts" "feature@obsolete_counts"
"feature@zpool_checkpoint" "feature@zpool_checkpoint"
"feature@spacemap_v2"
) )
# Additional properties added for Linux. # Additional properties added for Linux.

6
tests/zfs-tests/tests/functional/pool_checkpoint/checkpoint_discard_busy.ksh
View File

@ -19,7 +19,7 @@
# #
# DESCRIPTION: # DESCRIPTION:
# Discard checkpoint on a stressed pool. Ensure that we can # Discard checkpoint on a stressed pool. Ensure that we can
# export and import the pool while discarding but not run any # export and import the pool while discarding but not run any
# operations that have to do with the checkpoint or change the # operations that have to do with the checkpoint or change the
# pool's config. # pool's config.
@ -63,6 +63,10 @@ log_onexit test_cleanup
# the current setup the checkpoint space maps should # the current setup the checkpoint space maps should
# have tens of thousands of entries. # have tens of thousands of entries.
# #
# Note: If two-words entries are used in the space
# map, we should have even more time to
# verify this.
#
set_tunable64 zfs_spa_discard_memory_limit 128 set_tunable64 zfs_spa_discard_memory_limit 128
log_must zpool checkpoint $NESTEDPOOL log_must zpool checkpoint $NESTEDPOOL