From: Tejun Heo Date: Mon, 4 Nov 2019 23:54:29 +0000 (-0800) Subject: kernfs: fix ino wrap-around detection X-Git-Tag: v5.5-rc1~178^2~12 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e23f568aa63f64cd6b355094224cc9356c0f696b;p=users%2Fdwmw2%2Flinux.git 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 Reviewed-by: Greg Kroah-Hartman Fixes: 4a3ef68acacf ("kernfs: implement i_generation") Cc: Namhyung Kim Cc: stable@vger.kernel.org # v4.14+ --- diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 6ebae6bbe6a5e..7d4af6cea2a63 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) diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 936b61bd504e4..f797ccc650e79 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -187,6 +187,7 @@ struct kernfs_root { /* private fields, do not use outside kernfs proper */ struct idr ino_idr; + u32 last_ino; u32 next_generation; struct kernfs_syscall_ops *syscall_ops;