On Thu, May 10, 2018 at 04:49:29PM -0400, Scott Mayhew wrote:
> nfsd4_scsi_identify_device() performs a single IDENTIFY command for the
> device identification VPD page using a small buffer. If the reply is
> too large to fit in this buffer then the GETDEVICEINFO reply will not
> contain any info for the SCSI volume aside from the registration key.
> This can happen for example if the device has descriptors using long
> SCSI name strings.
>
> When the initial reply from the device indicates a larger buffer is
> needed, retry once using the page length from that reply.
>
> Signed-off-by: Scott Mayhew <smayhew@xxxxxxxxxx>
> ---
> fs/nfsd/blocklayout.c | 25 ++++++++++++++++++++-----
> 1 file changed, 20 insertions(+), 5 deletions(-)
>
> Changes since v1:
> - added comment explaining the initial and max buffer lengths
> - changed the len-to-maxlen comparison from "<" to "<="
>
> diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
> index 70b8bf7..aa1c6f9 100644
> --- a/fs/nfsd/blocklayout.c
> +++ b/fs/nfsd/blocklayout.c
> @@ -216,13 +216,21 @@ static int nfsd4_scsi_identify_device(struct block_device *bdev,
> struct request_queue *q = bdev->bd_disk->queue;
> struct request *rq;
> struct scsi_request *req;
> - size_t bufflen = 252, len, id_len;
> + /*
> + * The allocation length (passed in bytes 3 and 4 of the INQUIRY
> + * command descriptor block) specifies the number of bytes that have
> + * been allocated for the data-in buffer.
> + * 252 is the highest one-byte value that is a multiple of 4.
> + * 65532 is the highest two-byte value that is a multiple of 4.
> + */
> + size_t bufflen = 252, maxlen = 65532, len, id_len;
> u8 *buf, *d, type, assoc;
> - int error;
> + int retries = 1, error;
>
> if (WARN_ON_ONCE(!blk_queue_scsi_passthrough(q)))
> return -EINVAL;
>
> +again:
> buf = kzalloc(bufflen, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
> @@ -255,9 +263,16 @@ static int nfsd4_scsi_identify_device(struct block_device *bdev,
>
> len = (buf[2] << 8) + buf[3] + 4;
> if (len > bufflen) {
> - pr_err("pNFS: INQUIRY 0x83 response invalid (len = %zd)\n",
> - len);
> - goto out_put_request;
> + if (len <= maxlen && retries--) {
> + blk_put_request(rq);
> + kfree(buf);
> + bufflen = len;
> + goto again;
> + } else {
> + pr_err("pNFS: INQUIRY 0x83 response invalid (len = %zd)\n",
> + len);
> + goto out_put_request;
No need for an else after a goto.
Otherwise looks fine:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
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