linux-ext4 - Re: [PATCH 1/3] lib/ext2fs: Add ext2fs

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Message-ID: <20130105224059.GA29789@thunk.org>
Date:	Sat, 5 Jan 2013 17:40:59 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	"Darrick J. Wong" <darrick.wong@...cle.com>
Cc:	Darren Hart <dvhart@...radead.org>, linux-ext4@...r.kernel.org,
	adilger@...ger.ca, sgw@...ux.intel.com
Subject: Re: [PATCH 1/3] lib/ext2fs: Add ext2fs_symlink

On Sat, Jan 05, 2013 at 12:07:16PM -0800, Darrick J. Wong wrote:
> Given that you can have at most one data block anyway, does it matter to set
> EXTENTS_FL?

It doesn't matter either way.

> Also, what happens to the inode + data block if the ext2fs_link fails?  I don't
> see any code that explicitly rolls back those allocations, but maybe I missed
> something?

It's fine.  We don't actually update the block bitmap, nor update the
block group statistics, until the very end, when the proposed code does this:

	 */
	if (!fastlink)
		ext2fs_block_alloc_stats2(fs, blk, +1);
	ext2fs_inode_alloc_stats2(fs, ino, +1, 1);

This is one of the reasons why ext2fs_new_block and ext2fs_new_inode
don't actually mark the block and inode as in use.  You could argue
they are misnamed; something like ext2fs_find_unused_{block,inode}()
would have been better names, but what I can say?  I didn't think of
that back in 1996....

					- Ted
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