On Wed, 29 Jun 2011, FUJITA Tomonori wrote:
On Thu, 23 Jun 2011 19:02:56 -0700
Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
On 06/22/2011 06:51 PM, FUJITA Tomonori wrote:
@@ -965,6 +1009,40 @@ static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
}
}
Rather than adding 'is_user' argument to everywhere, it could cleaner
to add something like 'int from_kernel' in struct bsg_command? No?
I agree it should be part of the bsg_command,
I would prefer if all these "from_kernel" or "is_user" are bool. and true/false
we don't do int for bool(s) in Kernel anymore.
Yeah.
This makes sense.
+int bsg_private_command (struct request_queue *q, struct sg_io_v4 *hdr)
A question:
I needed to do something like this for a long time. But the way I need it I actually
have user_buffers at @hdr. Because I want it as part of an OSD ioctl which is filtered
and enhanced and then chained to here. (Like block devices chain to blk_ioctl)
Could we add in the future, a bool param "is_user" to this API?
Why applications can't simply send bsg commands instead of ioctl?
+{
+ struct request *rq;
+ struct bio *bio, *bidi_bio = NULL;
+ int at_head;
+ u8 sense[SCSI_SENSE_BUFFERSIZE];
+ fmode_t has_write_perm = 0;
+ int ret;
+
+ if (!q)
+ return -ENXIO;
+
+ /* Fake that we have write permission */
+ has_write_perm |= FMODE_WRITE;
+
+ rq = bsg_map_hdr_kern(q, hdr, has_write_perm, sense);
+
+ if (IS_ERR(rq)) {
+ return PTR_ERR(rq);
+ }
+
+ bio = rq->bio;
+ if (rq->next_rq)
+ bidi_bio = rq->next_rq->bio;
+ at_head = (0 == (hdr->flags & BSG_FLAG_Q_AT_TAIL));
+
+ blk_execute_rq(q, NULL, rq, at_head);
+ ret = blk_complete_sgv4_hdr_rq(rq, hdr, bio, bidi_bio, 0);
+
+ return ret;
+}
+EXPORT_SYMBOL(bsg_private_command);
EXPORT_SYMBOL_GPL, please.
I have a question about this API:
From user mode we open a filehandle on the device and it is pinned down till
we close the handle. A kernel user API might need to take the device reference
somewhere. Is that true?
Yeah, as I wrote at the previous submission, I still suspect that this
patch has such problem. I guess we need to get the reference (and
check the status) before sending in-kernel requests. And that's why I
don't like in-kernel request support (making the reference model
complicated).
I presume here you mean taking a kref of bcd->ref? So essentially
we'd want to:
kref_get(&bcd->ref);
...
execute command.
...
kref_put(&bcd->ref, bsg_kref_release_function);
in bsg_private_command()?
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