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From: Eric Biggers <ebiggers@kernel.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Daniel Rosenberg <drosen@google.com>,
	Theodore Ts'o <tytso@mit.edu>,
	linux-ext4@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
	Chao Yu <chao@kernel.org>,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-fscrypt@vger.kernel.org,
	Richard Weinberger <richard@nod.at>,
	linux-mtd@lists.infradead.org,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org,
	Gabriel Krisman Bertazi <krisman@collabora.com>,
	kernel-team@android.com
Subject: Re: [PATCH v7 6/8] f2fs: Handle casefolding with Encryption
Date: Tue, 11 Feb 2020 22:06:42 -0800
Message-ID: <20200212060642.GJ870@sol.localdomain> (raw)
In-Reply-To: <20200212055511.GL23230@ZenIV.linux.org.uk>

On Wed, Feb 12, 2020 at 05:55:11AM +0000, Al Viro wrote:
> On Tue, Feb 11, 2020 at 09:10:13PM -0800, Eric Biggers wrote:
> 
> > How about:
> > 
> > int f2fs_ci_compare(const struct inode *parent, const struct qstr *name,
> > 		    u8 *de_name, size_t de_name_len, bool quick)
> > {
> > 	const struct super_block *sb = parent->i_sb;
> > 	const struct unicode_map *um = sb->s_encoding;
> > 	struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len);
> > 	struct qstr entry = QSTR_INIT(de_name, de_name_len);
> > 	int ret;
> > 
> > 	if (IS_ENCRYPTED(parent)) {
> 
> oops.  parent->d_inode is unstable here; could have become NULL by that
> point.
> 
> > 	if (quick)
> > 		ret = utf8_strncasecmp_folded(um, name, &entry);
> > 	else
> > 		ret = utf8_strncasecmp(um, name, &entry);
> > 	if (ret < 0) {
> > 		/* Handle invalid character sequence as either an error
> > 		 * or as an opaque byte sequence.
> > 		 */
> 
> Really?  How would the callers possibly tell mismatch from an
> error?  And if they could, would would they *do* with that
> error, seeing that it might be an effect of a race with
> rename()?
> 
> Again, ->d_compare() is NOT given a stable name.  Or *parent.  Or
> (parent->d_inode).

After the patch earlier in the series that created generic_ci_d_compare() and
switched f2fs to use it, f2fs_ci_compare() is only called when the filesystem is
actually searching a directory, not from ->d_compare().  So the names and
parent->d_inode are stable in it.

But, that also means the GFP_ATOMIC isn't needed, and f2fs_ci_compare() should
be made 'static'.

- Eric

  reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-08  1:35 [PATCH v7 0/8] Support fof Casefolding and Encryption Daniel Rosenberg
2020-02-08  1:35 ` [PATCH v7 1/8] unicode: Add utf8_casefold_iter Daniel Rosenberg
2020-02-12  3:38   ` Eric Biggers
2020-02-14 21:47     ` Daniel Rosenberg
2020-02-17 19:02       ` Gabriel Krisman Bertazi
2020-02-08  1:35 ` [PATCH v7 2/8] fs: Add standard casefolding support Daniel Rosenberg
2020-02-08  2:12   ` Al Viro
2020-02-10 23:11     ` Daniel Rosenberg
2020-02-10 23:42       ` Al Viro
2020-02-12  6:34         ` Eric Biggers
2020-02-12  6:57           ` Eric Biggers
2020-02-20  2:27             ` Daniel Rosenberg
2020-02-12  3:55   ` Eric Biggers
2020-02-08  1:35 ` [PATCH v7 3/8] f2fs: Use generic " Daniel Rosenberg
2020-02-12  4:05   ` Eric Biggers
2020-02-08  1:35 ` [PATCH v7 4/8] ext4: " Daniel Rosenberg
2020-02-08  1:35 ` [PATCH v7 5/8] fscrypt: Have filesystems handle their d_ops Daniel Rosenberg
2020-02-12  4:33   ` Eric Biggers
2020-02-08  1:35 ` [PATCH v7 6/8] f2fs: Handle casefolding with Encryption Daniel Rosenberg
2020-02-12  5:10   ` Eric Biggers
2020-02-12  5:55     ` Al Viro
2020-02-12  6:06       ` Eric Biggers [this message]
2020-02-12  5:47   ` Eric Biggers
2020-02-08  1:35 ` [PATCH v7 7/8] ext4: Hande casefolding with encryption Daniel Rosenberg
2020-02-12  5:59   ` Eric Biggers
2020-02-08  1:35 ` [PATCH v7 8/8] ext4: Optimize match for casefolded encrypted dirs Daniel Rosenberg
2020-02-12  6:12 ` [PATCH v7 0/8] Support fof Casefolding and Encryption Eric Biggers
2020-02-13  0:01   ` Daniel Rosenberg

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