From efb170c22867cdc6f770de441bdefecec6712199 Mon Sep 17 00:00:00 2001 From: Al Viro <viro@zeniv.linux.org.uk> Date: Thu, 7 Aug 2014 08:39:04 -0400 Subject: take fs_pin stuff to fs/* Add a new field to fs_pin - kill(pin). That's what umount and r/o remount will be calling for all pins attached to vfsmount and superblock resp. Called after bumping the refcount, so it won't go away under us. Dropping the refcount is responsibility of the instance. All generic stuff moved to fs/fs_pin.c; the next step will rip all the knowledge of kernel/acct.c from fs/super.c and fs/namespace.c. After that - death to mnt_pin(); it was intended to be usable as generic mechanism for code that wants to attach objects to vfsmount, so that they would not make the sucker busy and would get killed on umount. Never got it right; it remained acct.c-specific all along. Now it's very close to being killable. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- fs/fs_pin.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 fs/fs_pin.c (limited to 'fs/fs_pin.c') diff --git a/fs/fs_pin.c b/fs/fs_pin.c new file mode 100644 index 000000000000..f3ce0b874a44 --- /dev/null +++ b/fs/fs_pin.c @@ -0,0 +1,77 @@ +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/fs_pin.h> +#include "mount.h" + +static void pin_free_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct fs_pin, rcu)); +} + +static DEFINE_SPINLOCK(pin_lock); + +void pin_put(struct fs_pin *p) +{ + if (atomic_long_dec_and_test(&p->count)) + call_rcu(&p->rcu, pin_free_rcu); +} + +void pin_remove(struct fs_pin *pin) +{ + spin_lock(&pin_lock); + hlist_del(&pin->m_list); + hlist_del(&pin->s_list); + spin_unlock(&pin_lock); +} + +void pin_insert(struct fs_pin *pin, struct vfsmount *m) +{ + spin_lock(&pin_lock); + hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins); + hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins); + spin_unlock(&pin_lock); +} + +void acct_auto_close_mnt(struct hlist_head *list) +{ + while (1) { + struct hlist_node *p; + struct fs_pin *pin; + rcu_read_lock(); + p = ACCESS_ONCE(list->first); + if (!p) { + rcu_read_unlock(); + break; + } + pin = hlist_entry(p, struct fs_pin, m_list); + if (!atomic_long_inc_not_zero(&pin->count)) { + rcu_read_unlock(); + cpu_relax(); + continue; + } + rcu_read_unlock(); + pin->kill(pin); + } +} + +void acct_auto_close(struct hlist_head *list) +{ + while (1) { + struct hlist_node *p; + struct fs_pin *pin; + rcu_read_lock(); + p = ACCESS_ONCE(list->first); + if (!p) { + rcu_read_unlock(); + break; + } + pin = hlist_entry(p, struct fs_pin, s_list); + if (!atomic_long_inc_not_zero(&pin->count)) { + rcu_read_unlock(); + cpu_relax(); + continue; + } + rcu_read_unlock(); + pin->kill(pin); + } +} -- cgit v1.2.3