Commit 34353029 authored Sep 23, 2008 by Chris Mason

Btrfs: Fix race against disk_i_size updates



The code to update the on disk i_size happens before the
ordered_extent record is removed.  So, it is possible for multiple
ordered_extent completion routines to run at the same time, and to
find each other in the ordered tree.

The end result is they both decide not to update disk_i_size, leaving
it too small.  This temporary fix just puts the updates inside
the extent_mutex.  A real solution would be stronger ordering of
disk_i_size updates against removing the ordered extent from the tree.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

parent 31840ae1

fs/btrfs/inode.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -608,9 +608,11 @@ nocow:
		add_pending_csums(trans, inode, ordered_extent->file_offset,
		&ordered_extent->list);

		mutex_lock(&BTRFS_I(inode)->extent_mutex);
		btrfs_ordered_update_i_size(inode, ordered_extent);
		btrfs_update_inode(trans, root, inode);
		btrfs_remove_ordered_extent(inode, ordered_extent);
		mutex_unlock(&BTRFS_I(inode)->extent_mutex);

		/* once for us */
		btrfs_put_ordered_extent(ordered_extent);

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