linux-ext4 - Re: [PATCH] ext4: Allocate entire range in zero range

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Message-ID: <20150403041100.GI10991@thunk.org>
Date:	Fri, 3 Apr 2015 00:11:00 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Lukas Czerner <lczerner@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: Allocate entire range in zero range

On Wed, Feb 18, 2015 at 05:49:28PM +0100, Lukas Czerner wrote:
> Currently there is a bug in zero range code which causes zero range
> calls to only allocate block aligned portion of the range, while
> ignoring the rest in some cases.
> 
> In some cases, namely if the end of the range is past isize, we do
> attempt to preallocate the last nonaligned block. However this might
> cause kernel to BUG() in some carefully designed zero range requests on
> setups where page size > block size.
> 
> Fix this problem by first preallocating the entire range, including the
> nonaligned edges and converting the written extents to unwritten in the
> next step. This approach will also give us the advantage of having the
> range to be as linearly contiguous as possible.
> 
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>

Thanks, applied.  Apologies for the delay.

						- Ted
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