udf: add assertions

Add a few assertions into udf_discard_prealloc() to check that the file is
sane (mostly helps debugging further patches ;).

Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/udf/truncate.c b/fs/udf/truncate.c
index 0449b2216e71..0e328cdc9a45 100644
--- a/fs/udf/truncate.c
+++ b/fs/udf/truncate.c
@@ -88,8 +88,9 @@ void udf_discard_prealloc(struct inode * inode)
         {
                 etype = netype;
                 lbcount += elen;
-                if (lbcount > inode->i_size && lbcount - inode->i_size < inode->i_sb->s_blocksize)
+                if (lbcount > inode->i_size && lbcount - elen < inode->i_size)
                 {
+                        WARN_ON(lbcount - inode->i_size >= inode->i_sb->s_blocksize);
                         nelen = elen - (lbcount - inode->i_size);
                         epos.offset -= adsize;
                         extent_trunc(inode, &epos, eloc, etype, elen, nelen);
@@ -119,6 +120,7 @@ void udf_discard_prealloc(struct inode * inode)
         }
         UDF_I_LENEXTENTS(inode) = lbcount;
 
+        WARN_ON(lbcount != inode->i_size);
         brelse(epos.bh);
 }