ext4: optimize __ext4_check_dir_entry()

Make __ext4_check_dir_entry() a bit easier to understand, and reduce
the object size of the function by over 11%.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20191209004346.38526-1-tytso@mit.edu
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 6305d5ec25af9a4f1725385308580dc5a4abe600..9f00fc0bf21d2ac59d8f589bd58061d091dcb478 100644 (file)
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -72,6 +72,7 @@ int __ext4_check_dir_entry(const char *function, unsigned int line,
        const char *error_msg = NULL;
        const int rlen = ext4_rec_len_from_disk(de->rec_len,
                                                dir->i_sb->s_blocksize);
+       const int next_offset = ((char *) de - buf) + rlen;
 
        if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
                error_msg = "rec_len is smaller than minimal";
@@ -79,13 +80,11 @@ int __ext4_check_dir_entry(const char *function, unsigned int line,
                error_msg = "rec_len % 4 != 0";
        else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
                error_msg = "rec_len is too small for name_len";
-       else if (unlikely(((char *) de - buf) + rlen > size))
+       else if (unlikely(next_offset > size))
                error_msg = "directory entry overrun";
-       else if (unlikely(((char *) de - buf) + rlen >
-                         size - EXT4_DIR_REC_LEN(1) &&
-                         ((char *) de - buf) + rlen != size)) {
+       else if (unlikely(next_offset > size - EXT4_DIR_REC_LEN(1) &&
+                         next_offset != size))
                error_msg = "directory entry too close to block end";
-       }
        else if (unlikely(le32_to_cpu(de->inode) >
                        le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
                error_msg = "inode out of bounds";