Messages in this thread | | | Date | Fri, 14 May 2004 00:37:43 -0400 | From | Theodore Ts'o <> | Subject | Re: [Ext2-devel] Re: [RFC/RFT] [PATCH] EXT3: Retry allocation after journal commit |
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On Thu, May 13, 2004 at 07:53:10PM -0700, Andrew Morton wrote: > "Theodore Ts'o" <tytso@mit.edu> wrote: > > > > It is possible for block allocation to fail, even if there is space in > > the filesystem, because all of the free blocks were recently deleted and > > so could not be allocated until after the currently running transaction > > is committed. This can result in a very strange and surprising result > > where a system call such as a mkdir() will fail even though there is > > plenty of disk space apparently available. > > I merged a little patch for this into post-2.6.6, but that only addresses > prepare_write().
Oh, sorry, I didn't see that patch. The specific bug I was trying to fix was actually in mkdir though (the regression test suite did the equivalent of rm -rf /mntpt/*, followed by mkdir's which failed).
I can respin the patch versus BK-latest.
> I wonder if there's much value in having ext3_has_free_blocks()? We could > just retry three times even if the fs is really full?
We could; it's an error path, after all. On the other hand, the cost of ext3_has_free_blocks() is pretty small, and if we know that there's no point doing the retry, why not skip the work.
> I'd be inclined to pass a pointer to the `retry' counter into > ext3_should_retry_alloc() and implement the counting in there. It'll tidy > things up a bit and consolidates that piece of policy in a single place.
Yes, good point.
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