Eric Biggers <ebiggers@xxxxxxxxxx> writes:
> On Mon, Mar 21, 2022 at 11:00:02PM -0400, Gabriel Krisman Bertazi wrote:
>> By using fscrypt_name here, we can hide most of the caching casefold
>> logic from ext4. The condition in ext4_match is now quite redundant,
>> but this is addressed in the next patch.
>>
>> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
>> ---
>> fs/ext4/namei.c | 26 ++++++++++++--------------
>> include/linux/fscrypt.h | 4 ++++
>> 2 files changed, 16 insertions(+), 14 deletions(-)
>>
>> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
>> index 8976e5a28c73..71b4b05fae89 100644
>> --- a/fs/ext4/namei.c
>> +++ b/fs/ext4/namei.c
>> @@ -1321,10 +1321,9 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
>> /**
>> * ext4_ci_compare() - Match (case-insensitive) a name with a dirent.
>> * @parent: Inode of the parent of the dentry.
>> - * @name: name under lookup.
>> + * @fname: name under lookup.
>> * @de_name: Dirent name.
>> * @de_name_len: dirent name length.
>> - * @quick: whether @name is already casefolded.
>> *
>> * Test whether a case-insensitive directory entry matches the filename
>> * being searched. If quick is set, the @name being looked up is
>> @@ -1333,8 +1332,9 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
>> * Return: > 0 if the directory entry matches, 0 if it doesn't match, or
>> * < 0 on error.
>> */
>> -static int ext4_ci_compare(const struct inode *parent, const struct qstr *name,
>> - u8 *de_name, size_t de_name_len, bool quick)
>> +static int ext4_ci_compare(const struct inode *parent,
>> + const struct fscrypt_name *fname,
>> + u8 *de_name, size_t de_name_len)
>> {
>> const struct super_block *sb = parent->i_sb;
>> const struct unicode_map *um = sb->s_encoding;
>> @@ -1357,10 +1357,10 @@ static int ext4_ci_compare(const struct inode *parent, const struct qstr *name,
>> entry.len = decrypted_name.len;
>> }
>>
>> - if (quick)
>> - ret = utf8_strncasecmp_folded(um, name, &entry);
>> + if (fname->cf_name.name)
>> + ret = utf8_strncasecmp_folded(um, &fname->cf_name, &entry);
>> else
>> - ret = utf8_strncasecmp(um, name, &entry);
>> + ret = utf8_strncasecmp(um, fname->usr_fname, &entry);
>>
>> if (!ret)
>> match = true;
>> @@ -1370,8 +1370,8 @@ static int ext4_ci_compare(const struct inode *parent, const struct qstr *name,
>> * the names have invalid characters.
>> */
>> ret = 0;
>> - match = ((name->len == entry.len) &&
>> - !memcmp(name->name, entry.name, entry.len));
>> + match = ((fname->usr_fname->len == entry.len) &&
>> + !memcmp(fname->usr_fname->name, entry.name, entry.len));
>> }
>>
>> out:
>> @@ -1440,6 +1440,8 @@ static bool ext4_match(struct inode *parent,
>> #endif
>>
>> #if IS_ENABLED(CONFIG_UNICODE)
>> + f.cf_name = fname->cf_name;
>> +
>> if (parent->i_sb->s_encoding && IS_CASEFOLDED(parent) &&
>> (!IS_ENCRYPTED(parent) || fscrypt_has_encryption_key(parent))) {
>> if (fname->cf_name.name) {
>> @@ -1451,13 +1453,9 @@ static bool ext4_match(struct inode *parent,
>> return false;
>> }
>> }
>> - ret = ext4_ci_compare(parent, &fname->cf_name, de->name,
>> - de->name_len, true);
>> - } else {
>> - ret = ext4_ci_compare(parent, fname->usr_fname,
>> - de->name, de->name_len, false);
>> }
>>
>> + ret = ext4_ci_compare(parent, &f, de->name, de->name_len);
>> if (ret < 0) {
>> /*
>> * Treat comparison errors as not a match. The
>> diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
>> index 91ea9477e9bd..5dc4b3c805e4 100644
>> --- a/include/linux/fscrypt.h
>> +++ b/include/linux/fscrypt.h
>> @@ -36,6 +36,10 @@ struct fscrypt_name {
>> u32 minor_hash;
>> struct fscrypt_str crypto_buf;
>> bool is_nokey_name;
>> +
>> +#ifdef CONFIG_UNICODE
>> + struct qstr cf_name;
>> +#endif
>> };
>>
>
> This seems like the wrong approach. struct fscrypt_name shouldn't have fields
> that aren't used by the fs/crypto/ layer.
>
> Did you check what f2fs does? It has a struct f2fs_filename to represent
> everything f2fs needs to know about a filename, and it only uses
> struct fscrypt_name when communicating with the fs/crypto/ layer.
>
> struct ext4_filename already exists. Couldn't you use that here?
Hi Eric,
The reason I'm not using struct ext4_filename here is because I'm trying
to make this generic, so this function can be shared across filesystems
implementing casefold. Since the fscrypt_name abstraction is used for
case-sensitive comparison, I was trying to reuse that type for
case-insensitive as well. It seemed unnecessary to define a generic
casefold_name type just for passing the cf_name and disk_name to this
function, considering that fscrypt_name is already initialized by
ext4_match.
--
Gabriel Krisman Bertazi
