Hi Amir,
I finally got it working this morning, but thanks for your reply.
Indeed all I had to do was to modify i_data... I got confused because
of this:
On the kernel I have (haven't checked other versions), I see:
include/linux/ext3_fs_i.h:
struct ext3_inode_info {
__le32 i_data[15]; /* unconverted */
...
}
include/linux/ext3_fs.h:
struct ext3_inode {
...
__le32 i_block[EXT3_N_BLOCKS}; /* Pointers to blocks */
...
}
I never associated the two as being the same, even though I obviously
knew EXT3_N_BLOCKS is 15, and the comments on ext3_fs_i.h are not very
useful, are they? :-/
When I glanced at them, I just assumed it was some raw unconverted
stuff that had nothing to do with what I wanted.
And yes, as you pointed out and as I said late last night, my fears
were confirmed: my changes were being overwritten by the
ext3_inode_info later on. :-(
But I'm glad it's (almost) all working now. I had tried to look for
the code that manipulate inodes (and not buffer_heads), but I was
overlooking anything related to an ext3_inode_info struct (I had in my
head that things were related to the ext3_inode struct). After
checking out the code pointed out to me here in the list (fs/ext4/
migrate.c) I finally got it working. Thanks again to Greg and Andreas
as well.
Regards,
Felipe
On 23 Oct 2010, at 17:48, Amir Goldstein wrote:
On Tue, Oct 19, 2010 at 5:23 PM, Felipe Franciosi
<felipe@xxxxxxxxxxxx> wrote:
Dear all,
I am experimenting on a 2.6.20.3-ubuntu1 kernel to prototype and
evaluate
different methods for migrating datablocks for a given inode on the
fly.
I have created an ioctl call that implements some verifications and
invokes
a function I wrote in balloc.c for such migration.
Upon receiving a struct inode*, I retrieve the corresponding iloc
using the
ext3_get_inode_iloc() function and then the struct ext3_inode*
using the
ext3_raw_inode() on the iloc. I have confirmed the pointer is
correct by
printing several ext3_inode relevant fields.
you've complicated things too much.
all you have to do is modify EXT3_I(inode)->i_data and then call
ext3_mark_inode_dirty().
the rest of the iloc and raw inode stuff is taken care of by
ext3_put_inode().
After making my modifications to the i_block array, I am finding it
impossible to commit these changes to the inode itself.
that is because your changes are being overriden by the unmodified
ei->i_data.
I have tried different things such as marking the iloc.bh
buffer_head as
dirty and submitting it for writing, marking the page as dirty,
etc, but I
think I'm missing something more fundamental. Most of my attempts
were
planned according to what I've seen inside similar code of
buffer_head
manipulation.
maybe you should have looked at code that modifies inodes instead...
Can anyone shed some light on what I'm missing?
hope this helps,
Amir.
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