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>

1 files changed, 11 insertions, 2 deletions

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 4416a1cfa1fe..d717b72500a4 100644
--- 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;
 }