| Message ID | 20240220085235.71132-4-eugen.hristev@collabora.com |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Cache insensitive cleanup for ext4/f2fs | expand |
Eugen Hristev <eugen.hristev@collabora.com> writes: > From: Gabriel Krisman Bertazi <krisman@collabora.com> > > generic_ci_match can be used by case-insensitive filesystems to compare > strings under lookup with dirents in a case-insensitive way. This > function is currently reimplemented by each filesystem supporting > casefolding, so this reduces code duplication in filesystem-specific > code. Just a note that this conflicts with the other patchset to generic helpers that I just applied. The conflict is trivial, If you could base the next iteration on top of my for-next, it would be helpful. > > Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> > [eugen.hristev@collabora.com: rework to first test the exact match] > Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com> > --- > fs/libfs.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/fs.h | 4 +++ > 2 files changed, 89 insertions(+) > > diff --git a/fs/libfs.c b/fs/libfs.c > index bb18884ff20e..65e2fb17a2b6 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -1773,6 +1773,91 @@ static const struct dentry_operations generic_ci_dentry_ops = { > .d_hash = generic_ci_d_hash, > .d_compare = generic_ci_d_compare, > }; > + > +/** > + * generic_ci_match() - Match a name (case-insensitively) with a dirent. > + * This is a filesystem helper for comparison with directory entries. > + * generic_ci_d_compare should be used in VFS' ->d_compare instead. > + * > + * @parent: Inode of the parent of the dirent under comparison > + * @name: name under lookup. > + * @folded_name: Optional pre-folded name under lookup > + * @de_name: Dirent name. > + * @de_name_len: dirent name length. > + * > + * Test whether a case-insensitive directory entry matches the filename > + * being searched. If @folded_name is provided, it is used instead of > + * recalculating the casefold of @name. > + * > + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or > + * < 0 on error. > + */ > +int generic_ci_match(const struct inode *parent, > + const struct qstr *name, > + const struct qstr *folded_name, > + const u8 *de_name, u32 de_name_len) > +{ > + 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 dirent = QSTR_INIT(de_name, de_name_len); > + int res, match = 0; > + > + if (IS_ENCRYPTED(parent)) { > + const struct fscrypt_str encrypted_name = > + FSTR_INIT((u8 *) de_name, de_name_len); > + > + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) > + return -EINVAL; > + > + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); > + if (!decrypted_name.name) > + return -ENOMEM; > + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, > + &decrypted_name); > + if (res < 0) > + goto out; > + dirent.name = decrypted_name.name; > + dirent.len = decrypted_name.len; > + } > + > + /* > + * Attempt a case-sensitive match first. It is cheaper and > + * should cover most lookups, including all the sane > + * applications that expect a case-sensitive filesystem. > + * This comparison is safe under RCU because the caller > + * guarantees the consistency between str and len. See > + * __d_lookup_rcu_op_compare() for details. As I mentioned in the previous review, there's no RCU here. This comment makes no sense here. > + */ > + if (folded_name->name) { > + if (dirent.len == folded_name->len && > + !memcmp(folded_name->name, dirent.name, dirent.len)) { > + match = 1; > + goto out; > + } > + res = utf8_strncasecmp_folded(um, folded_name, &dirent); > + } else { > + if (dirent.len == name->len && > + !memcmp(name->name, dirent.name, dirent.len) && > + (!sb_has_strict_encoding(sb) || !utf8_validate(um, name))) { > + match = 1; > + goto out; > + } > + res = utf8_strncasecmp(um, name, &dirent); > + } > + > +out: > + kfree(decrypted_name.name); > + if (match) /* matched by direct comparison */ > + return 1; > + else if (!res) /* matched by utf8 comparison */ > + return 1; > + else if (res < 0) /* error on utf8 comparison */ > + return res; > + return 0; /* no match */ > +} It can be simplified to if (res < 0) return res; return (match || !res); > > #ifdef CONFIG_FS_ENCRYPTION > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 820b93b2917f..7af691ff8d44 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -3296,6 +3296,10 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int); > extern int generic_check_addressable(unsigned, u64); > > extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry); > +extern int generic_ci_match(const struct inode *parent, > + const struct qstr *name, > + const struct qstr *folded_name, > + const u8 *de_name, u32 de_name_len); > > static inline bool sb_has_encoding(const struct super_block *sb) > {
diff --git a/fs/libfs.c b/fs/libfs.c index bb18884ff20e..65e2fb17a2b6 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1773,6 +1773,91 @@ static const struct dentry_operations generic_ci_dentry_ops = { .d_hash = generic_ci_d_hash, .d_compare = generic_ci_d_compare, }; + +/** + * generic_ci_match() - Match a name (case-insensitively) with a dirent. + * This is a filesystem helper for comparison with directory entries. + * generic_ci_d_compare should be used in VFS' ->d_compare instead. + * + * @parent: Inode of the parent of the dirent under comparison + * @name: name under lookup. + * @folded_name: Optional pre-folded name under lookup + * @de_name: Dirent name. + * @de_name_len: dirent name length. + * + * Test whether a case-insensitive directory entry matches the filename + * being searched. If @folded_name is provided, it is used instead of + * recalculating the casefold of @name. + * + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or + * < 0 on error. + */ +int generic_ci_match(const struct inode *parent, + const struct qstr *name, + const struct qstr *folded_name, + const u8 *de_name, u32 de_name_len) +{ + 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 dirent = QSTR_INIT(de_name, de_name_len); + int res, match = 0; + + if (IS_ENCRYPTED(parent)) { + const struct fscrypt_str encrypted_name = + FSTR_INIT((u8 *) de_name, de_name_len); + + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) + return -EINVAL; + + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); + if (!decrypted_name.name) + return -ENOMEM; + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, + &decrypted_name); + if (res < 0) + goto out; + dirent.name = decrypted_name.name; + dirent.len = decrypted_name.len; + } + + /* + * Attempt a case-sensitive match first. It is cheaper and + * should cover most lookups, including all the sane + * applications that expect a case-sensitive filesystem. + * + * This comparison is safe under RCU because the caller + * guarantees the consistency between str and len. See + * __d_lookup_rcu_op_compare() for details. + */ + if (folded_name->name) { + if (dirent.len == folded_name->len && + !memcmp(folded_name->name, dirent.name, dirent.len)) { + match = 1; + goto out; + } + res = utf8_strncasecmp_folded(um, folded_name, &dirent); + } else { + if (dirent.len == name->len && + !memcmp(name->name, dirent.name, dirent.len) && + (!sb_has_strict_encoding(sb) || !utf8_validate(um, name))) { + match = 1; + goto out; + } + res = utf8_strncasecmp(um, name, &dirent); + } + +out: + kfree(decrypted_name.name); + if (match) /* matched by direct comparison */ + return 1; + else if (!res) /* matched by utf8 comparison */ + return 1; + else if (res < 0) /* error on utf8 comparison */ + return res; + return 0; /* no match */ +} +EXPORT_SYMBOL(generic_ci_match); #endif #ifdef CONFIG_FS_ENCRYPTION diff --git a/include/linux/fs.h b/include/linux/fs.h index 820b93b2917f..7af691ff8d44 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3296,6 +3296,10 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int); extern int generic_check_addressable(unsigned, u64); extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry); +extern int generic_ci_match(const struct inode *parent, + const struct qstr *name, + const struct qstr *folded_name, + const u8 *de_name, u32 de_name_len); static inline bool sb_has_encoding(const struct super_block *sb) {