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Message-ID: <20080930130247.GM10831@mit.edu> Date: Tue, 30 Sep 2008 09:02:47 -0400 From: Theodore Tso <tytso@....edu> To: Alex Tomas <bzzz@....com> Cc: Andreas Dilger <adilger@....com>, linux-ext4@...r.kernel.org Subject: Re: Potential bug in mballoc --- reusing data blocks before txn commit On Tue, Sep 30, 2008 at 08:35:21AM +0400, Alex Tomas wrote: > why we need a tree? at least for the purpose of keeping blocks unavailable > we'd need just a list as at commit we free them all. For ext4, the only reason to use a tree would be to allow us to merge deleted extents. This might not be worth the complexity, though, I admit it. For ext3, we could use it to replace the the use of bh->b_committed_data --- in which case, we would need to use a rbtree so we can quickly look up to see which blocks can't be allocated yet. >> The other thing which I should check is that if we are using this >> scheme, I think we shouldn't need to keep the shadow copy of the block >> bitmap buffers any more. I would imagine we still need them for the >> inode bitmaps, for the same reason, though. > > shadow copy holds preallocated blocks Are we talking about the same thing? I was referring to the jh->b_committed_data, which isn't used by mballoc at all. - 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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