Hi All
I am in the process of porting a driver written for 2.6.21 that uses
dm_io_async_bvec and dm_io_sync_vm. Looks like in the latest kernel
both these API s have been removed.
After looking at the patch I created 2 wrapper functions as follows.
static int _my_dm_io_async_bvec(unsigned int num_regions, struct io_region
*where, int rw, struct bio_vec *bvec, io_notify_fn fn, void *context)
{
struct io_job *job=(struct io_job *)context;
struct io_job_owner *cctx= job->owner;
struct dm_io_request iorq;
iorq.bi_rw = (rw | (1 << BIO_RW_SYNC));
iorq.mem.type = DM_IO_BVEC;
iorq.mem.ptr.bvec = bvec;
iorq.notify.fn = fn;
iorq.notify.context = context;
iorq.client = cctx->dm_ioclnt;
return dm_io(&iorq,num_regions,where,NULL);
}
static int _my_dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw, void *data, unsigned long *error_bits, struct io_job_owner *cctx)
{
struct dm_io_request iorq;
iorq.bi_rw= (rw | (1 << BIO_RW_SYNC));
iorq.mem.type=DM_IO_VMA;
iorq.mem.ptr.vma=data;
iorq.notify.fn=NULL;
iorq.notify.context=NULL;
iorq.client=cctx->mdx_ioclnt;
return dm_io(&iorq,num_regions,where,NULL);
}
Except
passing in the owner of the io job in dm_io_sync_vm the calling
convention is the same as what we had in 2.6.21. I create the dm io
clients in the constructor of the dm.
Here is the question. As advised in the comment in dm_io if I use the BIO_RW_SYNC flag my performance tanks. If I don't use it I get data corruption within my dm. How do I get around this? Is there an example I could follow that previously used these API s and now using dm-io that you can direct me to?
My porting was based on the dm-raid1 port.
Interestingly they dont use the flag BIO_RW_SYNC and I cannot find a place
where they call blk_unplug() with regards to dm-io in that code.
Some suggestions are very welcome
Thanks in advance
Yes2Tech
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