ext3: Fix an overflow in ext3_trim_fs.

[karo-tx-linux.git] / fs / ext3 / balloc.c

diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index db1906b4e39cff78ac59d9326e96605b0ab73025..153242187fce7b3ddade632f538d8bec5ab47724 100644 (file)
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -2127,10 +2127,15 @@ int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)
                if (free_blocks < minlen)
                        continue;
 
-               if (len >= EXT3_BLOCKS_PER_GROUP(sb))
-                       len -= (EXT3_BLOCKS_PER_GROUP(sb) - first_block);
-               else
+               /*
+                * For all the groups except the last one, last block will
+                * always be EXT3_BLOCKS_PER_GROUP(sb), so we only need to
+                * change it for the last group in which case first_block +
+                * len < EXT3_BLOCKS_PER_GROUP(sb).
+                */
+               if (first_block + len < EXT3_BLOCKS_PER_GROUP(sb))
                        last_block = first_block + len;
+               len -= last_block - first_block;
 
                ret = ext3_trim_all_free(sb, group, first_block,
                                        last_block, minlen);