zbd: Fix zone report handling

fio may be executed concurrently with a block device revalidation by
the kernel. Device revalidation may lead to the block device capacity
to be changed to a smaller value (device changed) or to even 0 in case
of revalidation failure. In such case, the BLKREPORTZONE ioctl
executed from read_zone_info() may report a success with an empty zone
report when the start sector for the report is above the new capacity
of the device. This leads to an infinite loop inside parse_zone_info()
and the fio run never terminating.

Fix this problem by returning -EIO from read_zone_info() thus
avoiding the infinite loop in parse_zone_info(). This change does not
affect the normal case with a stable device as read_zone_info() is
always called with a valid start sector that does not result in an
empty zone report.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/zbd.c b/zbd.c
index 2da742b7212280cb5e2ab562836bd058bb156fbe..1c46b45298db18fcf2d8e36971ec1b85e790926a 100644 (file)
--- a/zbd.c
+++ b/zbd.c
@@ -186,11 +186,14 @@ static bool zbd_verify_bs(void)
  * size of @buf.
  *
  * Returns 0 upon success and a negative error code upon failure.
  * size of @buf.
  *
  * Returns 0 upon success and a negative error code upon failure.

+ * If the zone report is empty, always assume an error (device problem) and
+ * return -EIO.

  */
 static int read_zone_info(int fd, uint64_t start_sector,
                          void *buf, unsigned int bufsz)
 {
        struct blk_zone_report *hdr = buf;
  */
 static int read_zone_info(int fd, uint64_t start_sector,
                          void *buf, unsigned int bufsz)
 {
        struct blk_zone_report *hdr = buf;

+       int ret;

 
        if (bufsz < sizeof(*hdr))
                return -EINVAL;
 
        if (bufsz < sizeof(*hdr))
                return -EINVAL;


@@ -199,7 +202,12 @@ static int read_zone_info(int fd, uint64_t start_sector,
 
        hdr->nr_zones = (bufsz - sizeof(*hdr)) / sizeof(struct blk_zone);
        hdr->sector = start_sector;
 
        hdr->nr_zones = (bufsz - sizeof(*hdr)) / sizeof(struct blk_zone);
        hdr->sector = start_sector;

-       return ioctl(fd, BLKREPORTZONE, hdr) >= 0 ? 0 : -errno;
+       ret = ioctl(fd, BLKREPORTZONE, hdr);
+       if (ret)
+               return -errno;
+       if (!hdr->nr_zones)
+               return -EIO;
+       return 0;

 }
 
 /*
 }
 
 /*