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Message-ID: <20130128153836.GH22711@thunk.org> Date: Mon, 28 Jan 2013 10:38:36 -0500 From: Theodore Ts'o <tytso@....edu> To: Dmitry Monakhov <dmonakhov@...nvz.org> Cc: Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org Subject: Re: [PATCH 04/12] ext4: Disable merging of uninitialized extents On Mon, Jan 28, 2013 at 07:02:55PM +0400, Dmitry Monakhov wrote: > Actually this patch consists of two peaces > 1) disable merging of uninitialized extents. (1 line change) I'm > absolutely agree with it. To be clear, that's this patch chunk (one line change not including comments :-), right? --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1579,11 +1576,13 @@ int ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1, struct ext4_extent *ex2) { /* - * Make sure that either both extents are uninitialized, or - * both are _not_. + * Make sure that both extents are initialized. We don't merge + * uninitialized extents so that we can be sure that end_io code has + * the extent that was written properly split out and conversion to + * initialized is trivial. */ - if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2)) + if (ext4_ext_is_uninitialized(ex1) || ext4_ext_is_uninitialized(ex2)) return 0; The one thing I'm a bit worried about is how much worse will extent fragmentation be once we do this, but it's clear we need to strive for correctness first. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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