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authorTejun Heo <tj@kernel.org>2019-11-05 00:54:29 +0100
committerTejun Heo <tj@kernel.org>2019-11-12 17:18:03 +0100
commite23f568aa63f64cd6b355094224cc9356c0f696b (patch)
treefdefc12ecadf8a7677cf7230613a33d6e86e98e0 /fs/kernfs/dir.c
parentkselftests: cgroup: Avoid the reuse of fd after it is deallocated (diff)
downloadlinux-e23f568aa63f64cd6b355094224cc9356c0f696b.tar.xz
linux-e23f568aa63f64cd6b355094224cc9356c0f696b.zip
kernfs: fix ino wrap-around detection
When the 32bit ino wraps around, kernfs increments the generation number to distinguish reused ino instances. The wrap-around detection tests whether the allocated ino is lower than what the cursor but the cursor is pointing to the next ino to allocate so the condition never triggers. Fix it by remembering the last ino and comparing against that. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Fixes: 4a3ef68acacf ("kernfs: implement i_generation") Cc: Namhyung Kim <namhyung@kernel.org> Cc: stable@vger.kernel.org # v4.14+
Diffstat (limited to 'fs/kernfs/dir.c')
-rw-r--r--fs/kernfs/dir.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 6ebae6bbe6a5..7d4af6cea2a6 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -622,7 +622,6 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
{
struct kernfs_node *kn;
u32 gen;
- int cursor;
int ret;
name = kstrdup_const(name, GFP_KERNEL);
@@ -635,11 +634,11 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
idr_preload(GFP_KERNEL);
spin_lock(&kernfs_idr_lock);
- cursor = idr_get_cursor(&root->ino_idr);
ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
- if (ret >= 0 && ret < cursor)
+ if (ret >= 0 && ret < root->last_ino)
root->next_generation++;
gen = root->next_generation;
+ root->last_ino = ret;
spin_unlock(&kernfs_idr_lock);
idr_preload_end();
if (ret < 0)