GFS2: Fix lseek after SEEK_DATA, SEEK_HOLE have been added

We need to take the inode's glock whenever the inode's size
is referenced, otherwise it might not be uptodate. Even
though generic_file_llseek_unlocked() doesn't implement
SEEK_DATA, SEEK_HOLE directly, it does reference the inode's
size in those cases, so we need to add them to the list
of origins which need the glock.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 4416a1c..d717b72 100644 (file)
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -59,15 +59,24 @@ static loff_t gfs2_llseek(struct file *file, loff_t offset, int origin)
        struct gfs2_holder i_gh;
        loff_t error;
 
-       if (origin == 2) {
+       switch (origin) {
+       case SEEK_END: /* These reference inode->i_size */
+       case SEEK_DATA:
+       case SEEK_HOLE:
                error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
                                           &i_gh);
                if (!error) {
                        error = generic_file_llseek_unlocked(file, offset, origin);
                        gfs2_glock_dq_uninit(&i_gh);
                }
-       } else
+               break;
+       case SEEK_CUR:
+       case SEEK_SET:
                error = generic_file_llseek_unlocked(file, offset, origin);
+               break;
+       default:
+               error = -EINVAL;
+       }
 
        return error;
 }