Re: [PATCH] s390 hypfs fixes for 2.6.18-rc1-mm1

From: Badari Pulavarty
Date: Thu Jul 13 2006 - 13:35:06 EST


On Thu, 2006-07-13 at 17:41 +0200, Michael Holzheu wrote:
> Badari Pulavarty <pbadari@xxxxxxxxxx> wrote on 07/13/2006 04:31:00 PM:
> > Andrew Morton wrote:
> > > On Wed, 12 Jul 2006 21:17:53 -0700
> > > Badari Pulavarty <pbadari@xxxxxxxxxx> wrote:
> > >
>
> [snip]
>
> > >
> > > err, "temporary" things tend to become permanent. What's the real fix?
> > >
> > I am not sure, if we really need to vectorize this method or not -
> > meaning will this be ever called
> > with more than one items in the vector.
> >
> > Micheal, is it possible ? Can some one directly use AIO interface on
> > hypfs ? If not, we can always
> > look at only first element and ignore rest of them. Otherwise, we need
> > to iterate on all the elements
> > of the vector.
>
> Of course it is possible that someone uses AIO on hypfs files, but
> normally the synchronous IO functions are used. I used the AIO
> implementation together with do_sync_read/write() only because
> it was not more effort regarding the implementation and we got
> the AIO interface for free.
>
> Nevertheless we probably should implement the complete
> function.

Well, if you say so.. I have no idea what hypfs provides,
if you think that some one can do vector and/or async
operations on these files, its worth adding the complexity.

I was inclined towards just dealing with only single entry
in the vector and fail if some one called with multiple vectors.
But, its your call. Here is the complete code - completely untested :(
Could you please compile and test it ?

Thanks,
Badari

Vectorize aio interfaces to hypfs to fit new vfs ops interfaces.

Signed-off-by: Badari Pulavarty <pbadari@xxxxxxxxxx>

Index: linux-2.6.18-rc1/arch/s390/hypfs/inode.c
===================================================================
--- linux-2.6.18-rc1.orig/arch/s390/hypfs/inode.c 2006-07-11 21:28:07.000000000 -0700
+++ linux-2.6.18-rc1/arch/s390/hypfs/inode.c 2006-07-13 10:47:07.000000000 -0700
@@ -134,36 +134,50 @@ static int hypfs_open(struct inode *inod
return 0;
}

-static ssize_t hypfs_aio_read(struct kiocb *iocb, __user char *buf,
- size_t count, loff_t offset)
+static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
+ unsigned long nr_segs, loff_t offset)
{
char *data;
size_t len;
struct file *filp = iocb->ki_filp;
+ int i, ret = 0;

data = filp->private_data;
len = strlen(data);
- if (offset > len) {
- count = 0;
- goto out;
- }
- if (count > len - offset)
- count = len - offset;
- if (copy_to_user(buf, data + offset, count)) {
- count = -EFAULT;
+ if (offset < len)
+ len -= offset;
+ else
goto out;
+
+ for (i=0; i < nr_segs; i++) {
+ char __user *buf = iov[i].iov_base;
+ size_t count = iov[i].iov_len;
+
+ if (count > len)
+ count = len;
+ if (copy_to_user(buf, data + offset, count)) {
+ if (!ret)
+ ret = -EFAULT;
+ break;
+ }
+ offset += count;
+ len -= count;
+ ret += count;
+ if (len == 0)
+ break;
}
- iocb->ki_pos += count;
+ iocb->ki_pos = offset;
file_accessed(filp);
out:
- return count;
+ return ret;
}
-static ssize_t hypfs_aio_write(struct kiocb *iocb, const char __user *buf,
- size_t count, loff_t pos)
+static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
+ unsigned long nr_segs, loff_t offset)
{
int rc;
struct super_block *sb;
struct hypfs_sb_info *fs_info;
+ size_t count = iov_length(iov, nr_segs);

sb = iocb->ki_filp->f_dentry->d_inode->i_sb;
fs_info = sb->s_fs_info;



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