Re: [PATCH v6 02/28] btrfs: Get zone information of zoned block devices

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On Fri, Dec 13, 2019 at 11:18:53AM -0500, Josef Bacik wrote:
On 12/12/19 11:08 PM, Naohiro Aota wrote:
If a zoned block device is found, get its zone information (number of zones
and zone size) using the new helper function btrfs_get_dev_zone_info().  To
avoid costly run-time zone report commands to test the device zones type
during block allocation, attach the seq_zones bitmap to the device
structure to indicate if a zone is sequential or accept random writes. Also
it attaches the empty_zones bitmap to indicate if a zone is empty or not.

This patch also introduces the helper function btrfs_dev_is_sequential() to
test if the zone storing a block is a sequential write required zone and
btrfs_dev_is_empty_zone() to test if the zone is a empty zone.

Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
---
 fs/btrfs/Makefile  |   1 +
 fs/btrfs/hmzoned.c | 168 +++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/hmzoned.h |  92 +++++++++++++++++++++++++
 fs/btrfs/volumes.c |  18 ++++-
 fs/btrfs/volumes.h |   4 ++
 5 files changed, 281 insertions(+), 2 deletions(-)
 create mode 100644 fs/btrfs/hmzoned.c
 create mode 100644 fs/btrfs/hmzoned.h

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 82200dbca5ac..64aaeed397a4 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -16,6 +16,7 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
 btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o
 btrfs-$(CONFIG_BTRFS_FS_REF_VERIFY) += ref-verify.o
+btrfs-$(CONFIG_BLK_DEV_ZONED) += hmzoned.o
 btrfs-$(CONFIG_BTRFS_FS_RUN_SANITY_TESTS) += tests/free-space-tests.o \
 	tests/extent-buffer-tests.o tests/btrfs-tests.o \
diff --git a/fs/btrfs/hmzoned.c b/fs/btrfs/hmzoned.c
new file mode 100644
index 000000000000..6a13763d2916
--- /dev/null
+++ b/fs/btrfs/hmzoned.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ * Authors:
+ *	Naohiro Aota	<naohiro.aota@xxxxxxx>
+ *	Damien Le Moal	<damien.lemoal@xxxxxxx>
+ */
+
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include "ctree.h"
+#include "volumes.h"
+#include "hmzoned.h"
+#include "rcu-string.h"
+
+/* Maximum number of zones to report per blkdev_report_zones() call */
+#define BTRFS_REPORT_NR_ZONES   4096
+
+static int btrfs_get_dev_zones(struct btrfs_device *device, u64 pos,
+			       struct blk_zone *zones, unsigned int *nr_zones)
+{
+	int ret;
+
+	ret = blkdev_report_zones(device->bdev, pos >> SECTOR_SHIFT, zones,
+				  nr_zones);
+	if (ret != 0) {
+		btrfs_err_in_rcu(device->fs_info,
+				 "get zone at %llu on %s failed %d", pos,
+				 rcu_str_deref(device->name), ret);
+		return ret;
+	}
+	if (!*nr_zones)
+		return -EIO;
+
+	return 0;
+}
+
+int btrfs_get_dev_zone_info(struct btrfs_device *device)
+{
+	struct btrfs_zoned_device_info *zone_info = NULL;
+	struct block_device *bdev = device->bdev;
+	sector_t nr_sectors = bdev->bd_part->nr_sects;
+	sector_t sector = 0;
+	struct blk_zone *zones = NULL;
+	unsigned int i, nreported = 0, nr_zones;
+	unsigned int zone_sectors;
+	int ret;
+	char devstr[sizeof(device->fs_info->sb->s_id) +
+		    sizeof(" (device )") - 1];
+
+	if (!bdev_is_zoned(bdev))
+		return 0;
+
+	zone_info = kzalloc(sizeof(*zone_info), GFP_KERNEL);
+	if (!zone_info)
+		return -ENOMEM;
+
+	zone_sectors = bdev_zone_sectors(bdev);
+	ASSERT(is_power_of_2(zone_sectors));
+	zone_info->zone_size = (u64)zone_sectors << SECTOR_SHIFT;
+	zone_info->zone_size_shift = ilog2(zone_info->zone_size);
+	zone_info->nr_zones = nr_sectors >> ilog2(bdev_zone_sectors(bdev));
+	if (!IS_ALIGNED(nr_sectors, zone_sectors))
+		zone_info->nr_zones++;
+
+	zone_info->seq_zones = bitmap_zalloc(zone_info->nr_zones, GFP_KERNEL);
+	if (!zone_info->seq_zones) {
+		ret = -ENOMEM;
+		goto free_zone_info;
+	}
+
+	zone_info->empty_zones = bitmap_zalloc(zone_info->nr_zones, GFP_KERNEL);
+	if (!zone_info->empty_zones) {
+		ret = -ENOMEM;
+		goto free_seq_zones;
+	}
+
+	zones = kcalloc(BTRFS_REPORT_NR_ZONES,
+			sizeof(struct blk_zone), GFP_KERNEL);
+	if (!zones) {
+		ret = -ENOMEM;
+		goto free_empty_zones;
+	}
+
+	/* Get zones type */
+	while (sector < nr_sectors) {
+		nr_zones = BTRFS_REPORT_NR_ZONES;
+		ret = btrfs_get_dev_zones(device, sector << SECTOR_SHIFT, zones,
+					  &nr_zones);
+		if (ret)
+			goto free_zones;
+
+		for (i = 0; i < nr_zones; i++) {
+			if (zones[i].type == BLK_ZONE_TYPE_SEQWRITE_REQ)
+				set_bit(nreported, zone_info->seq_zones);
+			if (zones[i].cond == BLK_ZONE_COND_EMPTY)
+				set_bit(nreported, zone_info->empty_zones);
+			nreported++;
+		}
+		sector = zones[nr_zones - 1].start + zones[nr_zones - 1].len;
+	}
+
+	if (nreported != zone_info->nr_zones) {
+		btrfs_err_in_rcu(device->fs_info,
+				 "inconsistent number of zones on %s (%u / %u)",
+				 rcu_str_deref(device->name), nreported,
+				 zone_info->nr_zones);
+		ret = -EIO;
+		goto free_zones;
+	}
+
+	kfree(zones);
+
+	device->zone_info = zone_info;
+
+	devstr[0] = 0;
+	if (device->fs_info)
+		snprintf(devstr, sizeof(devstr), " (device %s)",
+			 device->fs_info->sb->s_id);
+
+	rcu_read_lock();
+	pr_info(
+"BTRFS info%s: host-%s zoned block device %s, %u zones of %llu sectors",
+		devstr,
+		bdev_zoned_model(bdev) == BLK_ZONED_HM ? "managed" : "aware",
+		rcu_str_deref(device->name), zone_info->nr_zones,
+		zone_info->zone_size >> SECTOR_SHIFT);
+	rcu_read_unlock();
+
+	return 0;
+
+free_zones:
+	kfree(zones);
+free_empty_zones:
+	bitmap_free(zone_info->empty_zones);
+free_seq_zones:
+	bitmap_free(zone_info->seq_zones);
+free_zone_info:

bitmap_free is just a kfree which handles NULL pointers properly, so you only need one goto here for cleaning up the zone_info. Once that's fixed you can add

Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>

Josef

Ah, then, I think I can simplify the code to use one "out" label and
kfree/bitmap_free both zones and zone_info.

Thanks,



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