ext4: Fix time encoding with extra epoch bits

(cherry picked from commit c1fccc0696bcaff6008c11865091f5ec4b0937ab)

"Looking at ext4.h, I think the setting of extra time fields forgets to
mask the epoch bits so the epoch part overwrites nsec part. The second
change is only for coherency (2 -> EXT4_EPOCH_BITS)."

Thanks to Damien Guibouret for pointing out this problem.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 7c0e3b6292ef901b628e9bebbeda0caf71ee2a2c..bd2150114732afc7ffcdfedfb66fc90a85f69312 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -522,8 +522,8 @@ struct move_extent {
 static inline __le32 ext4_encode_extra_time(struct timespec *time)
 {
        return cpu_to_le32((sizeof(time->tv_sec) > 4 ?
-                          time->tv_sec >> 32 : 0) |
-                          ((time->tv_nsec << 2) & EXT4_NSEC_MASK));
+                          (time->tv_sec >> 32) & EXT4_EPOCH_MASK : 0) |
+                          ((time->tv_nsec << EXT4_EPOCH_BITS) & EXT4_NSEC_MASK));
 }
 
 static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
@@ -531,7 +531,7 @@ static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
        if (sizeof(time->tv_sec) > 4)
               time->tv_sec |= (__u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK)
                               << 32;
-       time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> 2;
+       time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS;
 }
 
 #define EXT4_INODE_SET_XTIME(xtime, inode, raw_inode)                         \