On Fri, Jan 30, 2009 at 1:11 AM, Akira Fujita <a-fujita@xxxxxxxxxxxxx> wrote:
> Hi,
>
> I have rewritten ext4 online defrag patches based on the comments from Ted.
> In the new defrag, create donor inode in the user space instead of kernel space,
> and then allocate contiguous blocks to it with fallocate().
> In kernel space, exchange the blocks between target inode and donor inode,
> and then copy the file data of target inode to donor inode every 64MB.
> The EXT4_IOC_DEFRAG ioctl becomes simpler than the old one,
> so it may be useful for other purposes.
>
> #define EXT4_IOC_DEFRAG _IOW('f', 15, struct move_extent)
>
Do we want the ioctl name to be specific to defrag? I thought Ted's
goal was to make it more generic? I can also envision this same ioctl
being implemented by other file systems so EXT4 seems an inappropriate
prefix.
Thoughts?
> struct move_extent {
> int org_fd; /* original file descriptor */
> int dest_fd; /* destination file descriptor */
> ext4_lblk_t start; /* logical offset of org_fd and dest_fd */
> ext4_lblk_t len; /* exchange block length */
> };
I would also like to see .dest_fd changed to .donor_fd.
I would like to see the ABI be more flexible and have .start be broken
into 2 fields:
.start_orig
.start_donor
And I don't think they should be of type ext4_lblk_t. Something more
generic seems appropriate.
Thoughts?
Greg
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