On Wed, 31 May 2006 13:53:16 -0400
Peter Staubach <[email protected]> wrote:
>
A few issues here.
>
> I embarked on this work due to a bug reported by one of Red Hat's large
> customers. They are finding that files, which should have been backed
> up, were not getting backed up. This is due to the mtime on the files
> not changing and their backup software looking for mtime changes. This
> is corruption and I need to get it fixed, sooner as opposed to later.
>
> While I would like to get this fixed on top of Peter Zijlstra's changes,
> the process for those is looking long and complicated. I am wondering
> if we could consider these changes and then add the requirement of
> maintaining these semantics to those that Peter's work is attempting to
> address.
>
We seem to be having a problem getting a coherent changelog. A changelog
should describe why the patch exists, what it does and how it does it.
Please develop and maintain a changelog for each patch and reissue the
changelog with each reissuing of a patch, thanks.
This sequence:
+ if (test_and_clear_bit(AS_MCTIME, &mapping->flags))
+ inode_update_time(inode);
appears all over the place and should be implemented in a helper function.
The patch should work correctly for mmaps of block devices and I don't
think it does. Sometimes it updates the timestamp on the kernel-internal
blockdev inode at mapping->host and sometimes it updates the inode of the
device node (/dev/hda1) at file->f_dentry->d_inode. It should be updating
the /dev/hda1 inode.
The change to unlink_file_vma() is awkward, IMO. It means that this helper
function "knows" things about what its caller is using it for. I'd suggest
that this code should be moved up to a higher level where we have a more
sure semantic context, rather than being implemented in some low-level
helper function where it happens to be convenient.
Also, inode_update_time() can sleep.
mark_inode_dirty_sync()->__mark_inode_dirty()->ext3_dirty_inode(). This is
despite Documentation/filesystems/Locking saying "must not sleep". But
unlink_file_vma() (at least) is called from atomic context:
unmap_region()
->tlb_gather_mmu()
->preempt_disable()
->free_pgtables()
->unlink_file_vma()
->tlb_finish_mmu()
->preempt_enable()
Which _should_ have triggered warnings if full kernel debugging was enabled
and sufficient testing was performed. Perhaps a might_sleep() is needed in
_mark_inode_dirty().
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
