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[LogFS] Prevent memory corruption on large deletes

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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>
This commit is contained in:
Joern Engel
2010-04-13 17:46:37 +02:00
parent e05c378f49
commit 032d8f7268
5 changed files with 34 additions and 1 deletions
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3
fs/logfs/journal.c
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@@ -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;
}