nilfs2: 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 length.  So this patch stores
0xffff instead and converts value when read from / written to disk.

Nilfs derives its directory implementation from ext2 filesystem, and
this draws upon the corresponding change on ext2.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index 7dd4cd494490..970828a5ffc5 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -326,7 +326,25 @@ enum {
 #define NILFS_DIR_ROUND                 (NILFS_DIR_PAD - 1)
 #define NILFS_DIR_REC_LEN(name_len)     (((name_len) + 12 + NILFS_DIR_ROUND) & \
                                         ~NILFS_DIR_ROUND)
+#define NILFS_MAX_REC_LEN               ((1<<16)-1)
 
+static inline unsigned nilfs_rec_len_from_disk(__le16 dlen)
+{
+        unsigned len = le16_to_cpu(dlen);
+
+        if (len == NILFS_MAX_REC_LEN)
+                return 1 << 16;
+        return len;
+}
+
+static inline __le16 nilfs_rec_len_to_disk(unsigned len)
+{
+        if (len == (1 << 16))
+                return cpu_to_le16(NILFS_MAX_REC_LEN);
+        else if (len > (1 << 16))
+                BUG();
+        return cpu_to_le16(len);
+}
 
 /**
  * struct nilfs_finfo - file information