[LogFS] Prevent memory corruption on large deletes
Removing sufficiently large files would create aliases for a large
number of segments. This in turn results in a large number of journal
entries and an overflow of s_je_array.
Cheap fix is to add a BUG_ON, turning memory corruption into something
annoying, but less dangerous. Real fix is to count the number of
affected segments and prevent the problem completely.
Signed-off-by: Joern Engel <joern@logfs.org>
diff --git a/fs/logfs/gc.c b/fs/logfs/gc.c
index 92949f9..e8253e7 100644
--- a/fs/logfs/gc.c
+++ b/fs/logfs/gc.c
@@ -458,6 +458,14 @@
struct logfs_block *block;
int round, progress, last_progress = 0;
+ /*
+ * Doing too many changes to the segfile at once would result
+ * in a large number of aliases. Write the journal before
+ * things get out of hand.
+ */
+ if (super->s_shadow_tree.no_shadowed_segments >= MAX_OBJ_ALIASES)
+ logfs_write_anchor(sb);
+
if (no_free_segments(sb) >= target &&
super->s_no_object_aliases < MAX_OBJ_ALIASES)
return;