On 10/30/20 9:51 AM, Naohiro Aota wrote:
This commit implements a zoned chunk/dev_extent allocator. The zoned
allocator aligns the device extents to zone boundaries, so that a zone
reset affects only the device extent and does not change the state of
blocks in the neighbor device extents.
Also, it checks that a region allocation is not overlapping any of the
super block zones, and ensures the region is empty.
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
---
fs/btrfs/volumes.c | 131 +++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.h | 1 +
fs/btrfs/zoned.c | 126 +++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/zoned.h | 30 +++++++++++
4 files changed, 288 insertions(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index db884b96a5ea..78c62ef02e6f 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1416,6 +1416,14 @@ static bool contains_pending_extent(struct btrfs_device *device, u64 *start,
return false;
}
+static inline u64 dev_extent_search_start_zoned(struct btrfs_device *device,
+ u64 start)
+{
+ start = max_t(u64, start,
+ max_t(u64, device->zone_info->zone_size, SZ_1M));
+ return btrfs_zone_align(device, start);
+}
+
static u64 dev_extent_search_start(struct btrfs_device *device, u64 start)
{
switch (device->fs_devices->chunk_alloc_policy) {
@@ -1426,11 +1434,57 @@ static u64 dev_extent_search_start(struct btrfs_device *device, u64 start)
* make sure to start at an offset of at least 1MB.
*/
return max_t(u64, start, SZ_1M);
+ case BTRFS_CHUNK_ALLOC_ZONED:
+ return dev_extent_search_start_zoned(device, start);
default:
BUG();
}
}
+static bool dev_extent_hole_check_zoned(struct btrfs_device *device,
+ u64 *hole_start, u64 *hole_size,
+ u64 num_bytes)
+{
+ u64 zone_size = device->zone_info->zone_size;
+ u64 pos;
+ int ret;
+ int changed = 0;
+
+ ASSERT(IS_ALIGNED(*hole_start, zone_size));
+
+ while (*hole_size > 0) {
+ pos = btrfs_find_allocatable_zones(device, *hole_start,
+ *hole_start + *hole_size,
+ num_bytes);
+ if (pos != *hole_start) {
+ *hole_size = *hole_start + *hole_size - pos;
+ *hole_start = pos;
+ changed = 1;
+ if (*hole_size < num_bytes)
+ break;
+ }
+
+ ret = btrfs_ensure_empty_zones(device, pos, num_bytes);
+
+ /* range is ensured to be empty */
+ if (!ret)
+ return changed;
+
+ /* given hole range was invalid (outside of device) */
+ if (ret == -ERANGE) {
+ *hole_start += *hole_size;
+ *hole_size = 0;
+ return 1;
+ }
+
+ *hole_start += zone_size;
+ *hole_size -= zone_size;
+ changed = 1;
+ }
+
+ return changed;
+}
+
/**
* dev_extent_hole_check - check if specified hole is suitable for allocation
* @device: the device which we have the hole
@@ -1463,6 +1517,10 @@ static bool dev_extent_hole_check(struct btrfs_device *device, u64 *hole_start,
case BTRFS_CHUNK_ALLOC_REGULAR:
/* No extra check */
break;
+ case BTRFS_CHUNK_ALLOC_ZONED:
+ changed |= dev_extent_hole_check_zoned(device, hole_start,
+ hole_size, num_bytes);
I'm confused here, we check to make sure the pending stuff doesn't overlap with
non-empty zones. However we don't ever actually mark zones as non-empty except
on mount. I realize that if we allocate this zone then it appears pending and
thus we won't allocate with this zone again while the fs is mounted, but it took
me a while to realize this. Is there a reason to not mark a zone as non-empty
when we allocate from it?
+ break;
default:
BUG();
}
@@ -1517,6 +1575,9 @@ static int find_free_dev_extent_start(struct btrfs_device *device,
search_start = dev_extent_search_start(device, search_start);
+ WARN_ON(device->zone_info &&
+ !IS_ALIGNED(num_bytes, device->zone_info->zone_size));
+
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
@@ -4907,6 +4968,37 @@ static void init_alloc_chunk_ctl_policy_regular(
ctl->dev_extent_min = BTRFS_STRIPE_LEN * ctl->dev_stripes;
}
+static void
+init_alloc_chunk_ctl_policy_zoned(struct btrfs_fs_devices *fs_devices,
+ struct alloc_chunk_ctl *ctl)
+{
+ u64 zone_size = fs_devices->fs_info->zone_size;
+ u64 limit;
+ int min_num_stripes = ctl->devs_min * ctl->dev_stripes;
+ int min_data_stripes = (min_num_stripes - ctl->nparity) / ctl->ncopies;
+ u64 min_chunk_size = min_data_stripes * zone_size;
+ u64 type = ctl->type;
+
+ ctl->max_stripe_size = zone_size;
+ if (type & BTRFS_BLOCK_GROUP_DATA) {
+ ctl->max_chunk_size = round_down(BTRFS_MAX_DATA_CHUNK_SIZE,
+ zone_size);
+ } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
+ ctl->max_chunk_size = ctl->max_stripe_size;
+ } else if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
+ ctl->max_chunk_size = 2 * ctl->max_stripe_size;
+ ctl->devs_max = min_t(int, ctl->devs_max,
+ BTRFS_MAX_DEVS_SYS_CHUNK);
+ }
+
+ /* We don't want a chunk larger than 10% of writable space */
+ limit = max(round_down(div_factor(fs_devices->total_rw_bytes, 1),
+ zone_size),
+ min_chunk_size);
+ ctl->max_chunk_size = min(limit, ctl->max_chunk_size);
+ ctl->dev_extent_min = zone_size * ctl->dev_stripes;
+}
+
static void init_alloc_chunk_ctl(struct btrfs_fs_devices *fs_devices,
struct alloc_chunk_ctl *ctl)
{
@@ -4927,6 +5019,9 @@ static void init_alloc_chunk_ctl(struct btrfs_fs_devices *fs_devices,
case BTRFS_CHUNK_ALLOC_REGULAR:
init_alloc_chunk_ctl_policy_regular(fs_devices, ctl);
break;
+ case BTRFS_CHUNK_ALLOC_ZONED:
+ init_alloc_chunk_ctl_policy_zoned(fs_devices, ctl);
+ break;
default:
BUG();
}
@@ -5053,6 +5148,40 @@ static int decide_stripe_size_regular(struct alloc_chunk_ctl *ctl,
return 0;
}
+static int decide_stripe_size_zoned(struct alloc_chunk_ctl *ctl,
+ struct btrfs_device_info *devices_info)
+{
+ u64 zone_size = devices_info[0].dev->zone_info->zone_size;
+ /* number of stripes that count for block group size */
+ int data_stripes;
+
+ /*
+ * It should hold because:
+ * dev_extent_min == dev_extent_want == zone_size * dev_stripes
+ */
+ ASSERT(devices_info[ctl->ndevs - 1].max_avail == ctl->dev_extent_min);
+
+ ctl->stripe_size = zone_size;
+ ctl->num_stripes = ctl->ndevs * ctl->dev_stripes;
+ data_stripes = (ctl->num_stripes - ctl->nparity) / ctl->ncopies;
+
+ /*
+ * stripe_size is fixed in ZONED. Reduce ndevs instead.
+ */
+ if (ctl->stripe_size * data_stripes > ctl->max_chunk_size) {
+ ctl->ndevs = div_u64(div_u64(ctl->max_chunk_size * ctl->ncopies,
+ ctl->stripe_size) + ctl->nparity,
+ ctl->dev_stripes);
+ ctl->num_stripes = ctl->ndevs * ctl->dev_stripes;
+ data_stripes = (ctl->num_stripes - ctl->nparity) / ctl->ncopies;
+ ASSERT(ctl->stripe_size * data_stripes <= ctl->max_chunk_size);
+ }
+
+ ctl->chunk_size = ctl->stripe_size * data_stripes;
+
+ return 0;
+}
+
static int decide_stripe_size(struct btrfs_fs_devices *fs_devices,
struct alloc_chunk_ctl *ctl,
struct btrfs_device_info *devices_info)
@@ -5080,6 +5209,8 @@ static int decide_stripe_size(struct btrfs_fs_devices *fs_devices,
switch (fs_devices->chunk_alloc_policy) {
case BTRFS_CHUNK_ALLOC_REGULAR:
return decide_stripe_size_regular(ctl, devices_info);
+ case BTRFS_CHUNK_ALLOC_ZONED:
+ return decide_stripe_size_zoned(ctl, devices_info);
default:
BUG();
}
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 9c07b97a2260..0249aca668fb 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -213,6 +213,7 @@ BTRFS_DEVICE_GETSET_FUNCS(bytes_used);
enum btrfs_chunk_allocation_policy {
BTRFS_CHUNK_ALLOC_REGULAR,
+ BTRFS_CHUNK_ALLOC_ZONED,
};
struct btrfs_fs_devices {
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index d5487cba203b..4411d786597a 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1,11 +1,13 @@
// SPDX-License-Identifier: GPL-2.0
+#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include "ctree.h"
#include "volumes.h"
#include "zoned.h"
#include "rcu-string.h"
+#include "disk-io.h"
/* Maximum number of zones to report per blkdev_report_zones() call */
#define BTRFS_REPORT_NR_ZONES 4096
@@ -328,6 +330,7 @@ int btrfs_check_zoned_mode(struct btrfs_fs_info *fs_info)
fs_info->zone_size = zone_size;
fs_info->max_zone_append_size = max_zone_append_size;
+ fs_info->fs_devices->chunk_alloc_policy = BTRFS_CHUNK_ALLOC_ZONED;
btrfs_info(fs_info, "ZONED mode enabled, zone size %llu B",
fs_info->zone_size);
@@ -607,3 +610,126 @@ int btrfs_reset_sb_log_zones(struct block_device *bdev, int mirror)
sb_zone << zone_sectors_shift, zone_sectors * 2,
GFP_NOFS);
}
+
+/*
+ * btrfs_check_allocatable_zones - find allocatable zones within give region
+ * @device: the device to allocate a region
+ * @hole_start: the position of the hole to allocate the region
+ * @num_bytes: the size of wanted region
+ * @hole_size: the size of hole
+ *
+ * Allocatable region should not contain any superblock locations.
+ */
+u64 btrfs_find_allocatable_zones(struct btrfs_device *device, u64 hole_start,
+ u64 hole_end, u64 num_bytes)
+{
+ struct btrfs_zoned_device_info *zinfo = device->zone_info;
+ u8 shift = zinfo->zone_size_shift;
+ u64 nzones = num_bytes >> shift;
+ u64 pos = hole_start;
+ u64 begin, end;
+ u64 sb_pos;
+ bool have_sb;
+ int i;
+
+ ASSERT(IS_ALIGNED(hole_start, zinfo->zone_size));
+ ASSERT(IS_ALIGNED(num_bytes, zinfo->zone_size));
+
+ while (pos < hole_end) {
+ begin = pos >> shift;
+ end = begin + nzones;
+
+ if (end > zinfo->nr_zones)
+ return hole_end;
+
+ /* check if zones in the region are all empty */
+ if (btrfs_dev_is_sequential(device, pos) &&
+ find_next_zero_bit(zinfo->empty_zones, end, begin) != end) {
+ pos += zinfo->zone_size;
+ continue;
+ }
+
+ have_sb = false;
+ for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+ sb_pos = sb_zone_number(zinfo->zone_size, i);
+ if (!(end < sb_pos || sb_pos + 1 < begin)) {
+ have_sb = true;
+ pos = (sb_pos + 2) << shift;
+ break;
+ }
+ }
+ if (!have_sb)
+ break;
+ }
+
+ return pos;
+}
+
+int btrfs_reset_device_zone(struct btrfs_device *device, u64 physical,
+ u64 length, u64 *bytes)
+{
+ int ret;
+
+ *bytes = 0;
+ ret = blkdev_zone_mgmt(device->bdev, REQ_OP_ZONE_RESET,
+ physical >> SECTOR_SHIFT, length >> SECTOR_SHIFT,
+ GFP_NOFS);
+ if (ret)
+ return ret;
+
+ *bytes = length;
+ while (length) {
+ btrfs_dev_set_zone_empty(device, physical);
+ physical += device->zone_info->zone_size;
+ length -= device->zone_info->zone_size;
+ }
+
+ return 0;
+}
+
+int btrfs_ensure_empty_zones(struct btrfs_device *device, u64 start, u64 size)
+{
+ struct btrfs_zoned_device_info *zinfo = device->zone_info;
+ u8 shift = zinfo->zone_size_shift;
+ unsigned long begin = start >> shift;
+ unsigned long end = (start + size) >> shift;
+ u64 pos;
+ int ret;
+
+ ASSERT(IS_ALIGNED(start, zinfo->zone_size));
+ ASSERT(IS_ALIGNED(size, zinfo->zone_size));
+
+ if (end > zinfo->nr_zones)
+ return -ERANGE;
+
+ /* all the zones are conventional */
+ if (find_next_bit(zinfo->seq_zones, begin, end) == end)
+ return 0;
+
This check is duplicated below.
+ /* all the zones are sequential and empty */
+ if (find_next_zero_bit(zinfo->seq_zones, begin, end) == end &&
+ find_next_zero_bit(zinfo->empty_zones, begin, end) == end)
+ return 0;
+
+ for (pos = start; pos < start + size; pos += zinfo->zone_size) {
+ u64 reset_bytes;
+
+ if (!btrfs_dev_is_sequential(device, pos) ||
+ btrfs_dev_is_empty_zone(device, pos))
+ continue;
+
+ /* free regions should be empty */
+ btrfs_warn_in_rcu(
+ device->fs_info,
+ "resetting device %s zone %llu for allocation",
+ rcu_str_deref(device->name), pos >> shift);
+ WARN_ON_ONCE(1);
+
+ ret = btrfs_reset_device_zone(device, pos, zinfo->zone_size,
+ &reset_bytes);
+ if (ret)
+ return ret;
This seems bad, as we could just have corruption right? So we're resetting the
zone which could lose us data right? Shouldn't we just bail here? Thanks,
Josef
