Commit 475d0db7 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Al Viro

fs: Fix theoretical division by 0 in super_cache_scan().

total_objects could be 0 and is used as a denom.

While total_objects is a "long", total_objects == 0 unlikely happens for
3.12 and later kernels because 32-bit architectures would not be able to
hold (1 << 32) objects. However, total_objects == 0 may happen for kernels
between 3.1 and 3.11 because total_objects in prune_super() was an "int"
and (e.g.) x86_64 architecture might be able to hold (1 << 32) objects.
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: stable <stable@kernel.org> # 3.1+
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b8314f93
...@@ -80,6 +80,8 @@ static unsigned long super_cache_scan(struct shrinker *shrink, ...@@ -80,6 +80,8 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
inodes = list_lru_count_node(&sb->s_inode_lru, sc->nid); inodes = list_lru_count_node(&sb->s_inode_lru, sc->nid);
dentries = list_lru_count_node(&sb->s_dentry_lru, sc->nid); dentries = list_lru_count_node(&sb->s_dentry_lru, sc->nid);
total_objects = dentries + inodes + fs_objects + 1; total_objects = dentries + inodes + fs_objects + 1;
if (!total_objects)
total_objects = 1;
/* proportion the scan between the caches */ /* proportion the scan between the caches */
dentries = mult_frac(sc->nr_to_scan, dentries, total_objects); dentries = mult_frac(sc->nr_to_scan, dentries, total_objects);
......
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