ext2: check xattr name_len before acquiring xattr_sem in ext2_xattr_get

In ext2_xattr_get(), the code will acquire xattr_sem first, later checks
the length of xattr name_len > 255. It's unnecessarily time consuming and
also ext2_xattr_set() checks the length before other checks. So move the
check before acquiring xattr_sem to make these two functions consistent.

Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 5299706..d27b71f 100644 (file)
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -161,6 +161,10 @@ ext2_xattr_get(struct inode *inode, int name_index, const char *name,
 
        if (name == NULL)
                return -EINVAL;
+       name_len = strlen(name);
+       if (name_len > 255)
+               return -ERANGE;
+
        down_read(&EXT2_I(inode)->xattr_sem);
        error = -ENODATA;
        if (!EXT2_I(inode)->i_file_acl)
@@ -181,12 +185,8 @@ bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
                error = -EIO;
                goto cleanup;
        }
-       /* find named attribute */
-       name_len = strlen(name);
 
-       error = -ERANGE;
-       if (name_len > 255)
-               goto cleanup;
+       /* find named attribute */
        entry = FIRST_ENTRY(bh);
        while (!IS_LAST_ENTRY(entry)) {
                struct ext2_xattr_entry *next =