Re: [patch 3/3] fs: fix cont vs deadlock patches

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OGAWA Hirofumi wrote:
Nick Piggin <npiggin@xxxxxxx> writes:


		status = __block_prepare_write(inode, new_page, zerofrom,
						PAGE_CACHE_SIZE, get_block);
		if (status)
@@ -2110,7 +2111,7 @@
		memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom);
		flush_dcache_page(new_page);
		kunmap_atomic(kaddr, KM_USER0);
-		generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
+		__block_commit_write(inode, new_page, zerofrom, PAGE_CACHE_SIZE);

Whatever function this is doesn't need to update i_size?

Yes, it is the code in cont_prepare_write that is expanding a hole
at the end of file.

We can do this now because fat_commit_write is now changed to call
generic_commit_write in the case of a non-zero length.

I think it is an improvement because now the file will not get
arbitrarily extended in the case of a write failure somewhere down
the track.


Ah, unfortunately we can't this. If we don't update ->i_size before
page_cache_release, pdflush will think these pages is outside ->i_size
and just clean the page without writing it.

I see. I guess you need to synchronise your writepage versus this
extention in order to handle it properly then. I won't bother with
that though: it won't be worse than it was before.

Thanks for review, do you agree with the other hunks?

--
SUSE Labs, Novell Inc.
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