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Re: [Qemu-devel] [PATCH 1/2] iscsi: Use bs->sg for everything else than
From: |
Benoît Canet |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] iscsi: Use bs->sg for everything else than disks |
Date: |
Wed, 5 Mar 2014 16:33:23 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
The Wednesday 05 Mar 2014 à 16:00:48 (+0100), Kevin Wolf wrote :
> The current iscsi block driver code makes the rather arbitrary decision
> that TYPE_MEDIUM_CHANGER and TYPE_TAPE devices have bs->sg = 1 and all
> other device types are disks.
>
> Instead of this, check for TYPE_DISK to expose the disk interface and
> make everything else bs->sg = 1. In particular, this includes devices
> with TYPE_STORAGE_ARRAY, which is what LUN 0 of an iscsi target is.
> (See https://bugzilla.redhat.com/show_bug.cgi?id=1067784 for the exact
> scenario.)
>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> block/iscsi.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 0a15f53..b490e98 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -1231,12 +1231,11 @@ static int iscsi_open(BlockDriverState *bs, QDict
> *options, int flags,
> bs->total_sectors = sector_lun2qemu(iscsilun->num_blocks, iscsilun);
> bs->request_alignment = iscsilun->block_size;
>
> - /* Medium changer or tape. We dont have any emulation for this so this
> must
> - * be sg ioctl compatible. We force it to be sg, otherwise qemu will try
> - * to read from the device to guess the image format.
> + /* We don't have any emulation for devices other than disks and CD-ROMs,
> so
> + * this must be sg ioctl compatible. We force it to be sg, otherwise qemu
> + * will try to read from the device to guess the image format.
> */
> - if (iscsilun->type == TYPE_MEDIUM_CHANGER ||
> - iscsilun->type == TYPE_TAPE) {
> + if (iscsilun->type != TYPE_DISK && iscsilun->type != TYPE_ROM) {
I don't understand you are talking about type TYPE_STORAGE_ARRAY in the commit
message but testing against TYPE_ROM and they are not the same.
Maybe a comment explaining the role of TYPE_ROM would give a clue to non scsi
savy persons like me.
Best regards
Benoît
> bs->sg = 1;
> }
>
> --
> 1.8.1.4
>
>