zbd: fix sequential write pattern with verify= and max_open_zones=

Sequential write with max_open_zones=1 has interesting (read: buggy)
interaction with verify=.

If verify is off, then job runs correctly and IO is sequential,
and restarted from offset 0 and remains sequential.

If verify is on, then 1 full run is done and verified correctly.
At this point there is exactly 1 open zone which is the last zone.

Now IO restarts from offset 0 and pick_random_zone() picks opened zone
#0 which is the last zone because offset is 0. All IO is redirected
to the last zone, which is rewritten once triggering verify again.

IO pattern becomes: 1 full sequential rewrite followed by constant
sequential rewrites of the last zone.

	[global]
	filename=/dev/loop0
	direct=1
	zonemode=zbd
	zonesize=1M
	bs=512K
	rw=write
	verify=xxhash
	[j]
	max_open_zones=1
	io_size=3G

Fix is to close every zone given that verification acts as a barrier
between jobs.

max_open_zones=2 can restart from half of the device, etc.

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Alexey Dobriyan (SK hynix) <adobriyan@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/zbd.c b/zbd.c
index 99ac72cab71cbcbdec4c32f755367aff94a8669a..de0c5bf4fe0d425583dc9ed203b8bea6a5cd7f42 100644 (file)
--- a/zbd.c
+++ b/zbd.c
@@ -687,6 +687,22 @@ static int zbd_reset_zone(struct thread_data *td, struct fio_file *f,
        return zbd_reset_range(td, f, z->start, (z+1)->start - z->start);
 }
 
+/* The caller must hold f->zbd_info->mutex */
+static void zbd_close_zone(struct thread_data *td, const struct fio_file *f,
+                          unsigned int open_zone_idx)
+{
+       uint32_t zone_idx;
+
+       assert(open_zone_idx < f->zbd_info->num_open_zones);
+       zone_idx = f->zbd_info->open_zones[open_zone_idx];
+       memmove(f->zbd_info->open_zones + open_zone_idx,
+               f->zbd_info->open_zones + open_zone_idx + 1,
+               (ZBD_MAX_OPEN_ZONES - (open_zone_idx + 1)) *
+               sizeof(f->zbd_info->open_zones[0]));
+       f->zbd_info->num_open_zones--;
+       f->zbd_info->zone_info[zone_idx].open = 0;
+}
+
 /*
  * Reset a range of zones. Returns 0 upon success and 1 upon failure.
  * @td: fio thread data.
@@ -710,12 +726,26 @@ static int zbd_reset_zones(struct thread_data *td, struct fio_file *f,
        dprint(FD_ZBD, "%s: examining zones %u .. %u\n", f->file_name,
                zbd_zone_nr(f->zbd_info, zb), zbd_zone_nr(f->zbd_info, ze));
        for (z = zb; z < ze; z++) {
+               uint32_t nz = z - f->zbd_info->zone_info;
+
                if (!zbd_zone_swr(z))
                        continue;
                zone_lock(td, z);
-               reset_wp = all_zones ? z->wp != z->start :
-                               (td->o.td_ddir & TD_DDIR_WRITE) &&
-                               z->wp % min_bs != 0;
+               if (all_zones) {
+                       unsigned int i;
+
+                       pthread_mutex_lock(&f->zbd_info->mutex);
+                       for (i = 0; i < f->zbd_info->num_open_zones; i++) {
+                               if (f->zbd_info->open_zones[i] == nz)
+                                       zbd_close_zone(td, f, i);
+                       }
+                       pthread_mutex_unlock(&f->zbd_info->mutex);
+
+                       reset_wp = z->wp != z->start;
+               } else {
+                       reset_wp = (td->o.td_ddir & TD_DDIR_WRITE) &&
+                                       z->wp % min_bs != 0;
+               }
                if (reset_wp) {
                        dprint(FD_ZBD, "%s: resetting zone %u\n",
                               f->file_name,
@@ -905,22 +935,6 @@ out:
        return res;
 }
 
-/* The caller must hold f->zbd_info->mutex */
-static void zbd_close_zone(struct thread_data *td, const struct fio_file *f,
-                          unsigned int open_zone_idx)
-{
-       uint32_t zone_idx;
-
-       assert(open_zone_idx < f->zbd_info->num_open_zones);
-       zone_idx = f->zbd_info->open_zones[open_zone_idx];
-       memmove(f->zbd_info->open_zones + open_zone_idx,
-               f->zbd_info->open_zones + open_zone_idx + 1,
-               (ZBD_MAX_OPEN_ZONES - (open_zone_idx + 1)) *
-               sizeof(f->zbd_info->open_zones[0]));
-       f->zbd_info->num_open_zones--;
-       f->zbd_info->zone_info[zone_idx].open = 0;
-}
-
 /* Anything goes as long as it is not a constant. */
 static uint32_t pick_random_zone_idx(const struct fio_file *f,
                                     const struct io_u *io_u)