Messages in this thread | | | Date | Fri, 2 Mar 2007 08:52:53 -0800 | From | Randy Dunlap <> | Subject | Re: [PATCH] Loop device - Tracking page writes made to a loop device through mmap |
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On Fri, 2 Mar 2007 22:13:46 +1100 (EST) Kandan Venkataraman wrote:
> I am resending the message. The first few lines in the diff of the > original message seemed to have an extra space added by the time it got to > the mailing list. Hopefully this does not happen the second time around. > > Also, I missed out on putting a tab space on one line. > > > I have incorporated all the changes you mentioned, except for one. Thank you very much for taking the time to > review the code. I still retreive def_blk_fops as I did before, but I have put this in a separate function for now.
OK, that's a good compromise, at least for now.
> I have included a test program. Before you run the test program, please create the backing storage file > for the loop device as follows > > dd if=/dev/zero of=/root/file bs=4K count=10 > > Set bs to be whatever pagesize is in your machine. In my machine it was 4K.
Thanks.
[snipped]
> Now I will explain what kind of software would find the new ioctls useful.
That's a good explanation, thanks. And your original patch description was also thorough (IMO).
> diff -uprN linux-2.6.19.2/drivers/block/loop.c linux-2.6.19.2-new/drivers/block/loop.c > --- linux-2.6.19.2/drivers/block/loop.c 2007-03-02 22:05:06.000000000 +1100 > +++ linux-2.6.19.2-new/drivers/block/loop.c 2007-03-02 22:03:49.000000000 +1100 > @@ -74,12 +74,16 @@ > #include <linux/highmem.h> > #include <linux/gfp.h> > #include <linux/kthread.h> > +#include <linux/mm.h>
That looks fishy. Have you tried to apply the patch from this email? I'm not finding patch (program) happy with the patch file. (too much leading whitespace on non-patched lines)
> > #include <asm/uaccess.h> > > static int max_loop = 8; > static struct loop_device *loop_dev; > static struct gendisk **disks; > +static kmem_cache_t *pgoff_elem_cache; > +static char* cache_name = "loop_pgoff_elem_cache";
stataic char *cache_name
> +static struct file_operations loop_fops; > > /* > * Transfer functions > +static int loop_get_pgwrites(struct loop_device *lo, struct loop_pgoff_array __user *arg) > +{ > + struct file *filp = lo->lo_backing_file; > + struct loop_pgoff_array array; > + loff_t i = 0; > + struct rb_node *rb_node = rb_first(&lo->pgoff_tree); > + > + if (lo->lo_state != Lo_bound) > + return -ENXIO; > + > + if (filp == NULL || !lo->lo_track_pgwrite) > + return -EINVAL; > + > + if (copy_from_user(&array, arg, sizeof (struct loop_pgoff_array))) > + return -EFAULT; > + > + while (i < array.max && rb_node != NULL) { > + > + if (put_user(rb_entry(rb_node, struct pgoff_elem, node)->offset, array.pgoff + i))
Still need to break (split) several long lines.
> + return -EFAULT; > + > + ++i; > + rb_node = rb_next(rb_node); > + } > + array.num = i; > + > + if (copy_to_user(arg, &array, sizeof(array))) > + return -EFAULT; > + > + return 0; > +} > > /* > * loop_change_fd switched the backing store of a loopback device to > @@ -1322,10 +1414,67 @@ static long lo_compat_ioctl(struct file > } > #endif > > +static int loop_file_mmap(struct file * file, struct vm_area_struct * vma) > +{ > + /* This is used for a general mmap of a disk file */ > + int err = generic_file_mmap(file, vma); > + > + if (err) > + return err;
indentation
> + > + vma->vm_ops = &loop_file_vm_ops; > + return 0; > +} > +
--- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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