@@ -24,6 +24,27 @@
#include "internal.h"
#include "mount.h"
+static struct kmem_cache *pidfs_cachep __ro_after_init;
+
+/*
+ * Stashes information that userspace needs to access even after the
+ * process has been reaped.
+ */
+struct pidfs_exit_info {
+ __u64 cgroupid;
+ __u64 exit_code;
+};
+
+struct pidfs_inode {
+ struct pidfs_exit_info exit_info;
+ struct inode vfs_inode;
+};
+
+static inline struct pidfs_inode *pidfs_i(struct inode *inode)
+{
+ return container_of(inode, struct pidfs_inode, vfs_inode);
+}
+
static struct rb_root pidfs_ino_tree = RB_ROOT;
#if BITS_PER_LONG == 32
@@ -492,9 +513,29 @@ static void pidfs_evict_inode(struct inode *inode)
put_pid(pid);
}
+static struct inode *pidfs_alloc_inode(struct super_block *sb)
+{
+ struct pidfs_inode *pi;
+
+ pi = alloc_inode_sb(sb, pidfs_cachep, GFP_KERNEL);
+ if (!pi)
+ return NULL;
+
+ memset(&pi->exit_info, 0, sizeof(pi->exit_info));
+
+ return &pi->vfs_inode;
+}
+
+static void pidfs_free_inode(struct inode *inode)
+{
+ kmem_cache_free(pidfs_cachep, pidfs_i(inode));
+}
+
static const struct super_operations pidfs_sops = {
+ .alloc_inode = pidfs_alloc_inode,
.drop_inode = generic_delete_inode,
.evict_inode = pidfs_evict_inode,
+ .free_inode = pidfs_free_inode,
.statfs = simple_statfs,
};
@@ -704,8 +745,19 @@ struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags)
return pidfd_file;
}
+static void pidfs_inode_init_once(void *data)
+{
+ struct pidfs_inode *pi = data;
+
+ inode_init_once(&pi->vfs_inode);
+}
+
void __init pidfs_init(void)
{
+ pidfs_cachep = kmem_cache_create("pidfs_cache", sizeof(struct pidfs_inode), 0,
+ (SLAB_HWCACHE_ALIGN | SLAB_RECLAIM_ACCOUNT |
+ SLAB_ACCOUNT | SLAB_PANIC),
+ pidfs_inode_init_once);
pidfs_mnt = kern_mount(&pidfs_type);
if (IS_ERR(pidfs_mnt))
panic("Failed to mount pidfs pseudo filesystem");
Signed-off-by: Christian Brauner <brauner@kernel.org> --- fs/pidfs.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+)