Messages in this thread | | | Subject | Re: [PATCH] 2.6.10 - direct-io async short read bug | From | Badari Pulavarty <> | Date | 08 Mar 2005 09:23:35 -0800 |
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On Tue, 2005-03-08 at 01:09, Suparna Bhattacharya wrote:
> > Hmm, shouldn't dio->result ideally have been adjusted to be within > i_size at the time of io submission, so we don't have to deal with > this during completion ? We are creating bios with the right size > after all. > > We have this: > if (!buffer_mapped(map_bh)) { > .... > if (dio->block_in_file >= > i_size_read(dio->inode)>>blkbits) { > /* We hit eof */ > page_cache_release(page); > goto out; > } >
This check will catch only if there is no block on the disk. In the current test case, the filesize = 3K and filesystem blocksize=4K. So, we have a block (beyond filesize). The test tries to read 4K. None of the checks catch this case and it submits 4K IO.
> and > dio->result += iov[seg].iov_len - > ((dio->final_block_in_request - dio->block_in_file) << > blkbits); > > > can you spot what is going wrong here that we have to try and > workaround this later ?
Andrew, please don't apply the original patch. We shouldn't even attempt to submit IO beyond the filesize. We should truncate the IO request to filesize. I will send a patch today to fix this.
Thanks, Badari
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