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Subject[PATCH 07/12] btrfs-progs: support discarding zoned device
Date
All zones of zoned block devices should be reset before writing. Support
this by considering zone reset as a special case of block discard and block
zeroing. Of note is that only zones accepting random writes can be zeroed.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
utils.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 88 insertions(+), 6 deletions(-)

diff --git a/utils.c b/utils.c
index a26fe7a5743c..c375b32953f7 100644
--- a/utils.c
+++ b/utils.c
@@ -123,6 +123,37 @@ static int discard_range(int fd, u64 start, u64 len)
return 0;
}

+/*
+ * Discard blocks in the zones of a zoned block device.
+ * Process this with zone size granularity so that blocks in
+ * conventional zones are discarded using discard_range and
+ * blocks in sequential zones are discarded though a zone reset.
+ */
+static int discard_zones(int fd, struct btrfs_zone_info *zinfo)
+{
+#ifdef BTRFS_ZONED
+ unsigned int i;
+
+ /* Zone size granularity */
+ for (i = 0; i < zinfo->nr_zones; i++) {
+ if (zinfo->zones[i].type == BLK_ZONE_TYPE_CONVENTIONAL) {
+ discard_range(fd, zinfo->zones[i].start << 9,
+ zinfo->zone_size);
+ } else if (zinfo->zones[i].cond != BLK_ZONE_COND_EMPTY) {
+ struct blk_zone_range range = {
+ zinfo->zones[i].start,
+ zinfo->zone_size >> 9 };
+ if (ioctl(fd, BLKRESETZONE, &range) < 0)
+ return errno;
+ }
+ }
+
+ return 0;
+#else
+ return -EIO;
+#endif
+}
+
/*
* Discard blocks in the given range in 1G chunks, the process is interruptible
*/
@@ -205,8 +236,38 @@ static int zero_blocks(int fd, off_t start, size_t len)

#define ZERO_DEV_BYTES SZ_2M

+static int zero_zone_blocks(int fd, struct btrfs_zone_info *zinfo,
+ off_t start, size_t len)
+{
+ size_t zone_len = zinfo->zone_size;
+ off_t ofst = start;
+ size_t count;
+ int ret;
+
+ /* Make sure that zero_blocks does not write sequential zones */
+ while (len > 0) {
+
+ /* Limit zero_blocks to a single zone */
+ count = min_t(size_t, len, zone_len);
+ if (count > zone_len - (ofst & (zone_len - 1)))
+ count = zone_len - (ofst & (zone_len - 1));
+
+ if (zone_is_random_write(zinfo, ofst)) {
+ ret = zero_blocks(fd, ofst, count);
+ if (ret != 0)
+ return ret;
+ }
+
+ len -= count;
+ ofst += count;
+ }
+
+ return 0;
+}
+
/* don't write outside the device by clamping the region to the device size */
-static int zero_dev_clamped(int fd, off_t start, ssize_t len, u64 dev_size)
+static int zero_dev_clamped(int fd, struct btrfs_zone_info *zinfo,
+ off_t start, ssize_t len, u64 dev_size)
{
off_t end = max(start, start + len);

@@ -219,6 +280,9 @@ static int zero_dev_clamped(int fd, off_t start, ssize_t len, u64 dev_size)
start = min_t(u64, start, dev_size);
end = min_t(u64, end, dev_size);

+ if (zinfo->model != ZONED_NONE)
+ return zero_zone_blocks(fd, zinfo, start, end - start);
+
return zero_blocks(fd, start, end - start);
}

@@ -566,6 +630,7 @@ int btrfs_get_zone_info(int fd, const char *file, int hmzoned,
int btrfs_prepare_device(int fd, const char *file, u64 *block_count_ret,
u64 max_block_count, unsigned opflags)
{
+ struct btrfs_zone_info zinfo;
u64 block_count;
struct stat st;
int i, ret;
@@ -584,13 +649,30 @@ int btrfs_prepare_device(int fd, const char *file, u64 *block_count_ret,
if (max_block_count)
block_count = min(block_count, max_block_count);

+ ret = btrfs_get_zone_info(fd, file, opflags & PREP_DEVICE_HMZONED,
+ &zinfo);
+ if (ret < 0)
+ return 1;
+
if (opflags & PREP_DEVICE_DISCARD) {
/*
* We intentionally ignore errors from the discard ioctl. It
* is not necessary for the mkfs functionality but just an
- * optimization.
+ * optimization. However, we cannot ignore zone discard (reset)
+ * errors for a zoned block device as this could result in the
+ * inability to write to non-empty sequential zones of the
+ * device.
*/
- if (discard_range(fd, 0, 0) == 0) {
+ if (zinfo.model != ZONED_NONE) {
+ printf("Resetting device zones %s (%u zones) ...\n",
+ file, zinfo.nr_zones);
+ if (discard_zones(fd, &zinfo)) {
+ fprintf(stderr,
+ "ERROR: failed to reset device '%s' zones\n",
+ file);
+ return 1;
+ }
+ } else if (discard_range(fd, 0, 0) == 0) {
if (opflags & PREP_DEVICE_VERBOSE)
printf("Performing full device TRIM %s (%s) ...\n",
file, pretty_size(block_count));
@@ -598,12 +680,12 @@ int btrfs_prepare_device(int fd, const char *file, u64 *block_count_ret,
}
}

- ret = zero_dev_clamped(fd, 0, ZERO_DEV_BYTES, block_count);
+ ret = zero_dev_clamped(fd, &zinfo, 0, ZERO_DEV_BYTES, block_count);
for (i = 0 ; !ret && i < BTRFS_SUPER_MIRROR_MAX; i++)
- ret = zero_dev_clamped(fd, btrfs_sb_offset(i),
+ ret = zero_dev_clamped(fd, &zinfo, btrfs_sb_offset(i),
BTRFS_SUPER_INFO_SIZE, block_count);
if (!ret && (opflags & PREP_DEVICE_ZERO_END))
- ret = zero_dev_clamped(fd, block_count - ZERO_DEV_BYTES,
+ ret = zero_dev_clamped(fd, &zinfo, block_count - ZERO_DEV_BYTES,
ZERO_DEV_BYTES, block_count);

if (ret < 0) {
--
2.21.0
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