On Mon, May 07, 2018 at 09:01:31AM -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.
Looks good, but how did you choose 65532 as the maximum? Does the scsi
layer give us any maximum?
Also, I don't know why this is bothering me, but: I'd prefer "buflen" to
"bufflen".
--b.
>
> Signed-off-by: Scott Mayhew <smayhew@xxxxxxxxxx>
> ---
> fs/nfsd/blocklayout.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
> index 70b8bf7..0cd9249 100644
> --- a/fs/nfsd/blocklayout.c
> +++ b/fs/nfsd/blocklayout.c
> @@ -216,13 +216,14 @@ 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;
> + 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 +256,16 @@ 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;
> + }
> }
>
> d = buf + 4;
> --
> 2.9.5
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