From: Ted Ts'o <tytso@mit.edu>
To: Andreas Dilger <adilger@whamcloud.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH] ext4: avoid setting directory i_nlink to zero
Date: Wed, 26 Oct 2011 03:30:40 -0400 [thread overview]
Message-ID: <20111026073040.GM31921@thunk.org> (raw)
In-Reply-To: <1319556785-34754-1-git-send-email-adilger@whamcloud.com>
On Tue, Oct 25, 2011 at 09:33:05AM -0600, Andreas Dilger wrote:
> If a directory with more than EXT4_LINK_MAX subdirectories, the nlink
> count is set to 1. Subsequently, if any subdirectories are deleted,
> ext4_dec_count() decrements the i_nlink count, which may go to 0
> temporarily before being incremented back to 1.
>
> While this is done under i_mutex, which prevents races for directory
> and inode operations that check i_nlink, the temporary i_nlink == 0
> case is exposed to userspace via stat() and similar calls that do not
> hold i_mutex.
>
> Instead, change the code to not decrement i_nlink count for any
> directories that do not already have i_nlink larger than 2.
>
> Reported-by: Cliff White <cliffw@whamcloud.com>
> Reviewed-by: Johann Lombardi <johann@whamcloud.com>
> Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Applied, thanks.
- Ted
prev parent reply other threads:[~2011-10-26 7:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-25 15:33 [PATCH] ext4: avoid setting directory i_nlink to zero Andreas Dilger
2011-10-26 7:30 ` Ted Ts'o [this message]
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