ext4: zero out nanosecond timestamps for small inodes

When nanosecond timestamp resolution isn't supported on an ext4
partition (inode size = 128), stat() appears to be returning
uninitialized garbage in the nanosecond component of timestamps.

EXT4_INODE_GET_XTIME should zero out tv_nsec when EXT4_FITS_IN_INODE
evaluates to false.

Reported-by: Jordan Russell <jr-list-2010@quo.to>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 49f1ceaac57d..8104ab7eb7d4 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -693,6 +693,8 @@ do {									       \
         if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra))     \
                 ext4_decode_extra_time(&(inode)->xtime,                        \
                                        raw_inode->xtime ## _extra);            \
+        else                                                                   \
+                (inode)->xtime.tv_nsec = 0;                                    \
 } while (0)
 
 #define EXT4_EINODE_GET_XTIME(xtime, einode, raw_inode)                        \
@@ -703,6 +705,8 @@ do {									       \
         if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime ## _extra))            \
                 ext4_decode_extra_time(&(einode)->xtime,                       \
                                        raw_inode->xtime ## _extra);            \
+        else                                                                   \
+                (einode)->xtime.tv_nsec = 0;                                   \
 } while (0)
 
 #define i_disk_version osd1.linux1.l_i_version