[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>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/logfs/journal.c b/fs/logfs/journal.c
index d57c7b07b60b..2c22a4ad5329 100644
--- a/fs/logfs/journal.c
+++ b/fs/logfs/journal.c
@@ -493,6 +493,8 @@ static void account_shadows(struct super_block *sb)
 
         btree_grim_visitor64(&tree->new, (unsigned long)sb, account_shadow);
         btree_grim_visitor64(&tree->old, (unsigned long)sb, account_shadow);
+        btree_grim_visitor32(&tree->segment_map, 0, NULL);
+        tree->no_shadowed_segments = 0;
 
         if (li->li_block) {
                 /*
@@ -660,6 +662,7 @@ static int logfs_write_je_buf(struct super_block *sb, void *buf, u16 type,
         if (ofs < 0)
                 return ofs;
         logfs_buf_write(area, ofs, super->s_compressed_je, len);
+        BUG_ON(super->s_no_je >= MAX_JOURNAL_ENTRIES);
         super->s_je_array[super->s_no_je++] = cpu_to_be64(ofs);
         return 0;
 }