Thanks for letting me know, Neil. I already know that I just have to
be patient, and eventually you will attend.
Thanks!
Alex.
On Tue, Jul 31, 2012 at 5:11 AM, NeilBrown <neilb@xxxxxxx> wrote:
> On Tue, 24 Jul 2012 22:30:33 +0300 Alexander Lyakas <alex.bolshoy@xxxxxxxxx>
> wrote:
>
>> Hi Neil,
>> apparently you decided not to apply that patch?
>
> No, worse than that. I marked your email as 'needs attention'. That appears
> to be an almost-certain guarantee that I'll never look at it again - must be
> a bug in my brain. Apologies.
>
>> On Tue, Jul 17, 2012 at 4:17 PM, Alexander Lyakas
>> <alex.bolshoy@xxxxxxxxx> wrote:
>> > Thanks for your comments, I got confused with the REQUESTED bit.
>> > I prepared the patch, with couple of notes:
>> >
>> > 1/ I decided to be more careful and schedule a write only in case of
>> > resync or repair. I was not sure whether we should try to correct bad
>> > blocks on device X, when device Y is recovering. Pls change it if you
>> > feel otherwise.
>
> That looks sensible. I've left it as it is.
>
>> >
>> > 2/ I tested and committed the patch on top of ubuntu-precise 3.2.0-25.
>> > I looked at your "for-next" branch, and saw that there is some new
>> > code, which handles hot-replace, which I am not familiar with at this
>> > point.
>
> It shouldn't make any important change to this patch.
> For RAID1, hot-replace just means there can be twice as many devices as you
> would expect.
>
>
>> >
>> > Final note: I noticed that badblocks_show() fails if there are too
>> > many bad blocks. It returns value larger than PAGE_SIZE, and then the
>> > following linux code complains:
>> > fs/sysfs/file.c:fill_read_buffer()
>> > /*
>> > * The code works fine with PAGE_SIZE return but it's likely to
>> > * indicate truncated result or overflow in normal use cases.
>> > */
>> > if (count >= (ssize_t)PAGE_SIZE) {
>> > print_symbol("fill_read_buffer: %s returned bad count\n",
>> > (unsigned long)ops->show);
>> > /* Try to struggle along */
>> > count = PAGE_SIZE - 1;
>> > }
>> >
>> > So I am not sure how to solve it, but it would be good for
>> > user/application to receive the full list of bad blocks. Perhaps
>> > application can pass fd via some ioctl (I feel you don't like ioctls),
>> > and then kernel can use vfs_write() to print all the bad blocks to the
>> > fd. Or simply return the bad blocks list through the ioctl output to
>> > mdadm, and mdadm would print them. Perhaps some other way.
>
> It isn't possible to get a full list of bad blocks from sysfs, much as it is
> not possible to read the write-intent-bitmap or other metadata.
>
> The main purpose for the two bad-blocks files in sysfs is to allow a
> user-space metadata manager (mdmon) to find out when the kernel discovers a
> bad block, to record in the metadata, and then to acknowledge it.
> It is always possible to read the first entry from
> the unacknowledged_bad_blocks file, then acknowledge it and so remove it from
> the list, and in that way you can get all unacknowledged bad blocks.
> Acknowledged bad blocks will be listed in the metadata already.
>
> Still... I should probably fix the code so that it never displays a partial
> truncated number, but stops before PAGE_SIZE..
>
>
> Thanks,
> NeilBrown
>
>
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