fscrypto: make filename crypto functions return 0 on success

Several filename crypto functions: fname_decrypt(),
fscrypt_fname_disk_to_usr(), and fscrypt_fname_usr_to_disk(), returned
the output length on success or -errno on failure.  However, the output
length was redundant with the value written to 'oname->len'.  It is also
potentially error-prone to make callers have to check for '< 0' instead
of '!= 0'.

Therefore, make these functions return 0 instead of a length, and make
the callers who cared about the return value being a length use
'oname->len' instead.  For consistency also make other callers check for
a nonzero result rather than a negative result.

This change also fixes the inconsistency of fname_encrypt() actually
already returning 0 on success, not a length like the other filename
crypto functions and as documented in its function comment.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>

2 files changed, 6 insertions, 6 deletions

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 9054aeac8015..8716943335b1 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -786,7 +786,7 @@ bool f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
 
                 if (f2fs_encrypted_inode(d->inode)) {
                         int save_len = fstr->len;
-                        int ret;
+                        int err;
 
                         de_name.name = f2fs_kmalloc(de_name.len, GFP_NOFS);
                         if (!de_name.name)
@@ -794,11 +794,11 @@ bool f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
 
                         memcpy(de_name.name, d->filename[bit_pos], de_name.len);
 
-                        ret = fscrypt_fname_disk_to_usr(d->inode,
+                        err = fscrypt_fname_disk_to_usr(d->inode,
                                                 (u32)de->hash_code, 0,
                                                 &de_name, fstr);
                         kfree(de_name.name);
-                        if (ret < 0)
+                        if (err)
                                 return true;
 
                         de_name = *fstr;
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 73fa356f8fbb..afd56332d34c 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -449,7 +449,7 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
                 ostr.name = sd->encrypted_path;
                 ostr.len = disk_link.len;
                 err = fscrypt_fname_usr_to_disk(inode, &istr, &ostr);
-                if (err < 0)
+                if (err)
                         goto err_out;
 
                 sd->len = cpu_to_le16(ostr.len);
@@ -1048,7 +1048,7 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
                 goto errout;
 
         res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr);
-        if (res < 0)
+        if (res)
                 goto errout;
 
         /* this is broken symlink case */
@@ -1060,7 +1060,7 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
         paddr = pstr.name;
 
         /* Null-terminate the name */
-        paddr[res] = '\0';
+        paddr[pstr.len] = '\0';
 
         put_page(cpage);
         set_delayed_call(done, kfree_link, paddr);