xfs: in btree_lshift, only allocate temporary cursor when needed

We only need the temporary cursor in _btree_lshift if we're shifting
in an overlapped btree.  Therefore, factor that into a single block
of code so we avoid unnecessary cursor duplication.

Also fix use of the wrong cursor when checking for corruption in
xfs_btree_rshift().

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 40c19f8..b5c213a 100644 (file)
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -2397,29 +2397,29 @@ xfs_btree_lshift(
         * Using a temporary cursor, update the parent key values of the
         * block on the left.
         */
-       error = xfs_btree_dup_cursor(cur, &tcur);
-       if (error)
-               goto error0;
-       i = xfs_btree_firstrec(tcur, level);
-       XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, error0);
-
-       error = xfs_btree_decrement(tcur, level, &i);
-       if (error)
-               goto error1;
+       if (cur->bc_flags & XFS_BTREE_OVERLAPPING) {
+               error = xfs_btree_dup_cursor(cur, &tcur);
+               if (error)
+                       goto error0;
+               i = xfs_btree_firstrec(tcur, level);
+               XFS_WANT_CORRUPTED_GOTO(tcur->bc_mp, i == 1, error0);
 
-       /* Update the parent keys of the right block. */
-       error = xfs_btree_update_keys(cur, level);
-       if (error)
-               goto error1;
+               error = xfs_btree_decrement(tcur, level, &i);
+               if (error)
+                       goto error1;
 
-       /* Update the parent high keys of the left block, if needed. */
-       if (tcur->bc_flags & XFS_BTREE_OVERLAPPING) {
+               /* Update the parent high keys of the left block, if needed. */
                error = xfs_btree_update_keys(tcur, level);
                if (error)
                        goto error1;
+
+               xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
        }
 
-       xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
+       /* Update the parent keys of the right block. */
+       error = xfs_btree_update_keys(cur, level);
+       if (error)
+               goto error0;
 
        /* Slide the cursor value left one. */
        cur->bc_ptrs[level]--;
@@ -2580,7 +2580,7 @@ xfs_btree_rshift(
        if (error)
                goto error0;
        i = xfs_btree_lastrec(tcur, level);
-       XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, error0);
+       XFS_WANT_CORRUPTED_GOTO(tcur->bc_mp, i == 1, error0);
 
        error = xfs_btree_increment(tcur, level, &i);
        if (error)