From ba16b2846a8c6965d0d35be3968bc10f6277812d Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Wed, 12 Jul 2017 11:49:48 -0700 Subject: kernfs: add an API to get kernfs node from inode number Add an API to get kernfs node from inode number. We will need this to implement exportfs operations. This API will be used in blktrace too later, so it should be as fast as possible. To make the API lock free, kernfs node is freed in RCU context. And we depend on kernfs_node count/ino number to filter out stale kernfs nodes. Acked-by: Tejun Heo Acked-by: Greg Kroah-Hartman Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe --- fs/kernfs/mount.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'fs/kernfs/mount.c') diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index d5b149a45be1..69c48bec8a63 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -330,7 +330,16 @@ struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns) void __init kernfs_init(void) { + + /* + * the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino + * can access the slab lock free. This could introduce stale nodes, + * please see how kernfs_find_and_get_node_by_ino filters out stale + * nodes. + */ kernfs_node_cache = kmem_cache_create("kernfs_node_cache", sizeof(struct kernfs_node), - 0, SLAB_PANIC, NULL); + 0, + SLAB_PANIC | SLAB_TYPESAFE_BY_RCU, + NULL); } -- cgit v1.2.3