On Fri, 2017-01-13 at 14:54 -0800, Andrew Morton wrote:
> On Fri, 13 Jan 2017 16:34:18 -0700 Toshi Kani <toshi.kani@xxxxxxx>
> wrote:
>
> > DAX IO path does not support iostat, but its metadata IO path does.
> > Therefore, iostat shows metadata IO statistics only, which has been
> > confusing to users.
> >
> > Add iostat support to the DAX read/write path.
> >
> > Note, iostat still does not support the DAX mmap path as it allows
> > user applications to access directly.
> >
> > ...
> >
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -1058,12 +1058,24 @@ dax_iomap_rw(struct kiocb *iocb, struct
> > iov_iter *iter,
> > {
> > struct address_space *mapping = iocb->ki_filp->f_mapping;
> > struct inode *inode = mapping->host;
> > + struct gendisk *disk = inode->i_sb->s_bdev->bd_disk;
> > loff_t pos = iocb->ki_pos, ret = 0, done = 0;
> > unsigned flags = 0;
> > + unsigned long start = 0;
> > + int do_acct = blk_queue_io_stat(disk->queue);
>
> (The poorly named) blk_queue_io_stat() actually returns a bool. This
> is well concealed because blk_queue_io_stat() is unnecessarily
> implemented as a macro (why oh why).
It was unclear to me what type I needed to use. test_bit() is 'bool'
in arch/x86/include/asm/bitops.h but is 'int' in include/asm-
generic/bitops/non-atomic.h. So, I used 'int' for safe...
Thanks,
-Toshi
>
> --- a/fs/dax.c~dax-enable-iostat-for-read-write-fix
> +++ a/fs/dax.c
> @@ -1085,7 +1085,7 @@ dax_iomap_rw(struct kiocb *iocb, struct
> loff_t pos = iocb->ki_pos, ret = 0, done = 0;
> unsigned flags = 0;
> unsigned long start = 0;
> - int do_acct = blk_queue_io_stat(disk->queue);
> + bool do_acct = blk_queue_io_stat(disk->queue);
>
> if (iov_iter_rw(iter) == WRITE)
> flags |= IOMAP_WRITE;
> _
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