Initialize the seq_zone_bitmap and nr_zones fields of the disk request
queue on disk revalidate. As the seq_zone_bitmap allocation is
identical to the allocation of the zone write lock bitmap, introduce
the helper sd_zbc_alloc_zone_bitmap(). Using this helper, wait for the
disk capacity and number of zones to stabilize on the second
revalidation pass to allocate and initialize the bitmaps.

Signed-off-by: Damien Le Moal <damien.lem...@wdc.com>
---
 drivers/scsi/sd_zbc.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 139 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index 27793b9f54c0..cc64fada9cd9 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -586,8 +586,127 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
        return 0;
 }
 
+/**
+ * sd_zbc_alloc_zone_bitmap - Allocate a zone bitmap (one bit per zone).
+ * @sdkp: The disk of the bitmap
+ */
+static inline unsigned long *sd_zbc_alloc_zone_bitmap(struct scsi_disk *sdkp)
+{
+       struct request_queue *q = sdkp->disk->queue;
+
+       return kzalloc_node(BITS_TO_LONGS(sdkp->nr_zones)
+                           * sizeof(unsigned long),
+                           GFP_KERNEL, q->node);
+}
+
+/**
+ * sd_zbc_get_seq_zones - Parse report zones reply to identify sequential zones
+ * @sdkp: disk used
+ * @buf: report reply buffer
+ * @seq_zone_bitamp: bitmap of sequential zones to set
+ * @zno: Zone number of the first zone in the report
+ *
+ * Parse reported zone descriptors to find sequiential zones.
+ * Since read-only and offline zones cannot be written, do not
+ * mark them as sequential in the bitmap.
+ * Return the LBA after the last zone reported.
+ */
+static sector_t sd_zbc_get_seq_zones(struct scsi_disk *sdkp, unsigned char 
*buf,
+                                    unsigned int buflen,
+                                    unsigned long *seq_zone_bitmap,
+                                    unsigned int *zno)
+{
+       sector_t last_lba = sdkp->capacity;
+       unsigned int buf_len, list_length;
+       unsigned int n = *zno;
+       unsigned char *rec;
+       u8 type, cond;
+
+       list_length = get_unaligned_be32(&buf[0]) + 64;
+       buf_len = min(list_length, buflen);
+       rec = buf + 64;
+
+       while (rec < buf + buf_len) {
+               type = rec[0] & 0x0f;
+               cond = (rec[1] >> 4) & 0xf;
+               if (type != ZBC_ZONE_TYPE_CONV &&
+                   cond != ZBC_ZONE_COND_READONLY &&
+                   cond != ZBC_ZONE_COND_OFFLINE)
+                       set_bit(n, seq_zone_bitmap);
+               last_lba = get_unaligned_be64(&rec[8]) +
+                       get_unaligned_be64(&rec[16]);
+               rec += 64;
+               n++;
+       }
+
+       *zno = n;
+
+       return last_lba;
+}
+
+/**
+ * sd_zbc_setup_seq_zone_bitmap - Initialize the disk seq zone bitmap.
+ * @sdkp: target disk
+ *
+ * Allocate a zone bitmap and initialize it by identifying sequential zones.
+ */
+static int sd_zbc_setup_seq_zone_bitmap(struct scsi_disk *sdkp)
+{
+       struct request_queue *q = sdkp->disk->queue;
+       unsigned long *seq_zone_bitmap;
+       sector_t lba = 0;
+       unsigned char *buf;
+       unsigned int n = 0;
+       int ret = -ENOMEM;
+
+       seq_zone_bitmap = sd_zbc_alloc_zone_bitmap(sdkp);
+       if (!seq_zone_bitmap)
+               return -ENOMEM;
+
+       buf = kmalloc(SD_ZBC_BUF_SIZE, GFP_KERNEL);
+       if (!buf)
+               goto out;
+
+       while (lba < sdkp->capacity) {
+               ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, lba);
+               if (ret)
+                       goto out;
+               lba = sd_zbc_get_seq_zones(sdkp, buf, SD_ZBC_BUF_SIZE,
+                                          seq_zone_bitmap, &n);
+       }
+
+       if (n != sdkp->nr_zones) {
+               /* Something went wrong */
+               ret = -EIO;
+       }
+
+out:
+       kfree(buf);
+       if (ret) {
+               kfree(seq_zone_bitmap);
+               return ret;
+       }
+
+       q->seq_zone_bitmap = seq_zone_bitmap;
+
+       return 0;
+}
+
+static void sd_zbc_cleanup(struct scsi_disk *sdkp)
+{
+       struct request_queue *q = sdkp->disk->queue;
+
+       kfree(q->seq_zone_bitmap);
+       q->seq_zone_bitmap = NULL;
+
+       kfree(sdkp->zones_wlock);
+       sdkp->zones_wlock = NULL;
+}
+
 static int sd_zbc_setup(struct scsi_disk *sdkp)
 {
+       struct request_queue *q = sdkp->disk->queue;
+       int ret;
 
        /* READ16/WRITE16 is mandatory for ZBC disks */
        sdkp->device->use_16_for_rw = 1;
@@ -599,14 +718,29 @@ static int sd_zbc_setup(struct scsi_disk *sdkp)
        sdkp->nr_zones =
                round_up(sdkp->capacity, sdkp->zone_blocks) >> sdkp->zone_shift;
 
+       /*
+        * Wait for the disk capacity to stabilize before
+        * initializing zone related information.
+        */
+       if (sdkp->first_scan)
+               return 0;
+
        if (!sdkp->zones_wlock) {
-               sdkp->zones_wlock = kcalloc(BITS_TO_LONGS(sdkp->nr_zones),
-                                           sizeof(unsigned long),
-                                           GFP_KERNEL);
+               sdkp->zones_wlock = sd_zbc_alloc_zone_bitmap(sdkp);
                if (!sdkp->zones_wlock)
                        return -ENOMEM;
        }
 
+       if (!q->seq_zone_bitmap) {
+               ret = sd_zbc_setup_seq_zone_bitmap(sdkp);
+               if (ret) {
+                       sd_zbc_cleanup(sdkp);
+                       return ret;
+               }
+       }
+
+       q->nr_zones = sdkp->nr_zones;
+
        return 0;
 }
 
@@ -661,14 +795,14 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned 
char *buf)
 
 err:
        sdkp->capacity = 0;
+       sd_zbc_cleanup(sdkp);
 
        return ret;
 }
 
 void sd_zbc_remove(struct scsi_disk *sdkp)
 {
-       kfree(sdkp->zones_wlock);
-       sdkp->zones_wlock = NULL;
+       sd_zbc_cleanup(sdkp);
 }
 
 void sd_zbc_print_zones(struct scsi_disk *sdkp)
-- 
2.13.5

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