ext4: Avoid rec_len overflow with 64KB block size

With 64KB blocksize, a directory entry can have size 64KB which does not fit
into 16 bits we have for entry lenght. So we store 0xffff instead and convert
value when read from / written to disk. The patch also converts some places
to use ext4_next_entry() when we are changing them anyway.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index dfe4487fc739..fb31c1aba989 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -767,6 +767,26 @@ struct ext4_dir_entry_2 {
 #define EXT4_DIR_ROUND                  (EXT4_DIR_PAD - 1)
 #define EXT4_DIR_REC_LEN(name_len)      (((name_len) + 8 + EXT4_DIR_ROUND) & \
                                          ~EXT4_DIR_ROUND)
+#define EXT4_MAX_REC_LEN                ((1<<16)-1)
+
+static inline unsigned ext4_rec_len_from_disk(__le16 dlen)
+{
+        unsigned len = le16_to_cpu(dlen);
+
+        if (len == EXT4_MAX_REC_LEN)
+                return 1 << 16;
+        return len;
+}
+
+static inline __le16 ext4_rec_len_to_disk(unsigned len)
+{
+        if (len == (1 << 16))
+                return cpu_to_le16(EXT4_MAX_REC_LEN);
+        else if (len > (1 << 16))
+                BUG();
+        return cpu_to_le16(len);
+}
+
 /*
  * Hash Tree Directory indexing
  * (c) Daniel Phillips, 2001