xfs: lock out page faults from extent swap operations

[deliverable/linux.git] / fs / xfs / xfs_bmap_util.c

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 22a5dcb70b327293c1278a6fd44685e0b2ecc502..7efa23e72a90321bbc122b30b20828074936d134 100644 (file)
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1599,13 +1599,6 @@ xfs_swap_extent_flush(
        /* Verify O_DIRECT for ftmp */
        if (VFS_I(ip)->i_mapping->nrpages)
                return -EINVAL;
-
-       /*
-        * Don't try to swap extents on mmap()d files because we can't lock
-        * out races against page faults safely.
-        */
-       if (mapping_mapped(VFS_I(ip)->i_mapping))
-               return -EBUSY;
        return 0;
 }
 
@@ -1633,13 +1626,14 @@ xfs_swap_extents(
        }
 
        /*
-        * Lock up the inodes against other IO and truncate to begin with.
-        * Then we can ensure the inodes are flushed and have no page cache
-        * safely. Once we have done this we can take the ilocks and do the rest
-        * of the checks.
+        * Lock the inodes against other IO, page faults and truncate to
+        * begin with.  Then we can ensure the inodes are flushed and have no
+        * page cache safely. Once we have done this we can take the ilocks and
+        * do the rest of the checks.
         */
-       lock_flags = XFS_IOLOCK_EXCL;
+       lock_flags = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
        xfs_lock_two_inodes(ip, tip, XFS_IOLOCK_EXCL);
+       xfs_lock_two_inodes(ip, tip, XFS_MMAPLOCK_EXCL);
 
        /* Verify that both files have the same format */
        if ((ip->i_d.di_mode & S_IFMT) != (tip->i_d.di_mode & S_IFMT)) {
@@ -1666,8 +1660,16 @@ xfs_swap_extents(
                xfs_trans_cancel(tp, 0);
                goto out_unlock;
        }
+
+       /*
+        * Lock and join the inodes to the tansaction so that transaction commit
+        * or cancel will unlock the inodes from this point onwards.
+        */
        xfs_lock_two_inodes(ip, tip, XFS_ILOCK_EXCL);
        lock_flags |= XFS_ILOCK_EXCL;
+       xfs_trans_ijoin(tp, ip, lock_flags);
+       xfs_trans_ijoin(tp, tip, lock_flags);
+
 
        /* Verify all data are being swapped */
        if (sxp->sx_offset != 0 ||
@@ -1720,9 +1722,6 @@ xfs_swap_extents(
                        goto out_trans_cancel;
        }
 
-       xfs_trans_ijoin(tp, ip, lock_flags);
-       xfs_trans_ijoin(tp, tip, lock_flags);
-
        /*
         * Before we've swapped the forks, lets set the owners of the forks
         * appropriately. We have to do this as we are demand paging the btree
@@ -1856,5 +1855,5 @@ out_unlock:
 
 out_trans_cancel:
        xfs_trans_cancel(tp, 0);
-       goto out_unlock;
+       goto out;
 }