> On Sep 6, 2021, at 9:06 AM, Naohiro Aota <naohiro.aota@xxxxxxx> wrote:
>
> Reporting zones on a SCSI device sometimes fail with the following error.
>
> [76248.516390] ata16.00: invalid transfer count 131328
> [76248.523618] sd 15:0:0:0: [sda] REPORT ZONES start lba 536870912 failed
>
> The error (from drivers/ata/libata-scsi.c ata_scsi_zbc_in_xlat())
> indicates that buffer size is not aligned to SECTOR_SIZE.
>
> This happens when the __vmalloc() failed. Consider we are reporting 4096
> zones, then we will have "bufsize = roundup((4096 + 1) * 64,
> SECTOR_SIZE)" = (513 * 512) = 262656. Then, __vmalloc() failure halven
> the bufsize to 131328, which is no longer aligned to SECTOR_SIZE.
>
> Use rounddown() to ensure the size is always aligned to SECTOR_SIZE and
> fix the comment as well.
>
> Fixes: 23a50861adda ("scsi: sd_zbc: Cleanup sd_zbc_alloc_report_buffer()")
> Cc: stable@xxxxxxxxxxxxxxx # 5.5+
> Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
> ---
> drivers/scsi/sd_zbc.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
> index 186b5ff52c3a..ea8b3f6ee5cd 100644
> --- a/drivers/scsi/sd_zbc.c
> +++ b/drivers/scsi/sd_zbc.c
> @@ -154,8 +154,8 @@ static void *sd_zbc_alloc_report_buffer(struct scsi_disk *sdkp,
>
> /*
> * Report zone buffer size should be at most 64B times the number of
> - * zones requested plus the 64B reply header, but should be at least
> - * SECTOR_SIZE for ATA devices.
> + * zones requested plus the 64B reply header, but should be aligned
> + * to SECTOR_SIZE for ATA devices.
> * Make sure that this size does not exceed the hardware capabilities.
> * Furthermore, since the report zone command cannot be split, make
> * sure that the allocated buffer can always be mapped by limiting the
> @@ -174,7 +174,7 @@ static void *sd_zbc_alloc_report_buffer(struct scsi_disk *sdkp,
> *buflen = bufsize;
> return buf;
> }
> - bufsize >>= 1;
> + bufsize = rounddown(bufsize >> 1, SECTOR_SIZE);
> }
>
> return NULL;
> --
> 2.33.0
>
Makes sense.
Reviewed-by: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
--
Himanshu Madhani Oracle Linux Engineering
