fs: Create a generic is_dot_dotdot() utility

De-duplicate the same functionality in several places by hoisting
the is_dot_dotdot() utility function into linux/fs.h.

Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 7b3fc189593a5ac67d7e68b6cb8be55d57348cdc..0ad52fbe51c944eded295196a4cd27f91301571a 100644 (file)
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -74,13 +74,7 @@ struct fscrypt_nokey_name {
 
 static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
 {
-       if (str->len == 1 && str->name[0] == '.')
-               return true;
-
-       if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
-               return true;
-
-       return false;
+       return is_dot_dotdot(str->name, str->len);
 }
 
 /**

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 03bd55069d8600bb5b838150e1a74da0fc1e4a1d..2fe0f3af1a08ec5831d2609862e0e9a80c9b0475 100644 (file)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1949,16 +1949,6 @@ out:
        return rc;
 }
 
-static bool is_dot_dotdot(const char *name, size_t name_size)
-{
-       if (name_size == 1 && name[0] == '.')
-               return true;
-       else if (name_size == 2 && name[0] == '.' && name[1] == '.')
-               return true;
-
-       return false;
-}
-
 /**
  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
  * @plaintext_name: The plaintext name

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index dcf7d86c2ce4f7cce44858d52681b79a3428f4b7..07ea3d62b2982d308439cd9c4008b0c7113df5fa 100644 (file)
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -244,16 +244,6 @@ struct getdents_callback {
        int sequence;           /* sequence counter */
 };
 
-/* Copied from lookup_one_common() */
-static inline bool is_dot_dotdot(const char *name, size_t len)
-{
-       if (unlikely(name[0] == '.')) {
-               if (len < 2 || (len == 2 && name[1] == '.'))
-                       return true;
-       }
-       return false;
-}
-
 /*
  * A rather strange filldir function to capture
  * the name matching the specified inode number.

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9043cedfa12bacf6e5ffb86f331a13756a2e4694..322a3b8a35339aa805653668ba854e77e8b1aabf 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3368,17 +3368,6 @@ static inline bool f2fs_cp_error(struct f2fs_sb_info *sbi)
        return is_set_ckpt_flags(sbi, CP_ERROR_FLAG);
 }
 
-static inline bool is_dot_dotdot(const u8 *name, size_t len)
-{
-       if (len == 1 && name[0] == '.')
-               return true;
-
-       if (len == 2 && name[0] == '.' && name[1] == '.')
-               return true;
-
-       return false;
-}
-
 static inline void *f2fs_kmalloc(struct f2fs_sb_info *sbi,
                                        size_t size, gfp_t flags)
 {

diff --git a/fs/namei.c b/fs/namei.c
index 71c13b2990b44f426a778bb0ad8f969a89387b4f..2386a70667fa5b088fa2ee8be5630eede78b6b48 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2667,10 +2667,8 @@ static int lookup_one_common(struct mnt_idmap *idmap,
        if (!len)
                return -EACCES;
 
-       if (unlikely(name[0] == '.')) {
-               if (len < 2 || (len == 2 && name[1] == '.'))
-                       return -EACCES;
-       }
+       if (is_dot_dotdot(name, len))
+               return -EACCES;
 
        while (len--) {
                unsigned int c = *(const unsigned char *)name++;

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 98b7a7a8c42e36cc140d14797cf8eb00f7c36f76..baa64344a30823c0956b11082fa2f8b20fa9bf41 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2846,6 +2846,17 @@ extern bool path_is_under(const struct path *, const struct path *);
 
 extern char *file_path(struct file *, char *, int);
 
+/**
+ * is_dot_dotdot - returns true only if @name is "." or ".."
+ * @name: file name to check
+ * @len: length of file name, in bytes
+ */
+static inline bool is_dot_dotdot(const char *name, size_t len)
+{
+       return len && unlikely(name[0] == '.') &&
+               (len == 1 || (len == 2 && name[1] == '.'));
+}
+
 #include <linux/err.h>
 
 /* needed for stackable file system support */