Re: [RFC/RFT] [PATCH] EXT3: Retry allocation after journal commit

[Andrew Morton]

"Theodore Ts'o" <tytso@xxxxxxx> 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().

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?

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.

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