releases/3.19.7/mnt-improve-the-umount_tree-flags.patch

   1 From e819f152104c9f7c9fe50e1aecce6f5d4bf06d65 Mon Sep 17 00:00:00 2001
   2 From: "Eric W. Biederman" <ebiederm@xmission.com>
   3 Date: Wed, 24 Dec 2014 07:20:01 -0600
   4 Subject: mnt: Improve the umount_tree flags
   5
   6 From: "Eric W. Biederman" <ebiederm@xmission.com>
   7
   8 commit e819f152104c9f7c9fe50e1aecce6f5d4bf06d65 upstream.
   9
  10 - Remove the unneeded declaration from pnode.h
  11 - Mark umount_tree static as it has no callers outside of namespace.c
  12 - Define an enumeration of umount_tree's flags.
  13 - Pass umount_tree's flags in by name
  14
  15 This removes the magic numbers 0, 1 and 2 making the code a little
  16 clearer and makes it possible for there to be lazy unmounts that don't
  17 propagate.  Which is what __detach_mounts actually wants for example.
  18
  19 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  fs/namespace.c |   31 ++++++++++++++++---------------
  24  fs/pnode.h     |    1 -
  25  2 files changed, 16 insertions(+), 16 deletions(-)
  26
  27 --- a/fs/namespace.c
  28 +++ b/fs/namespace.c
  29 @@ -1323,14 +1323,15 @@ static inline void namespace_lock(void)
  30         down_write(&namespace_sem);
  31  }
  32
  33 +enum umount_tree_flags {
  34 +       UMOUNT_SYNC = 1,
  35 +       UMOUNT_PROPAGATE = 2,
  36 +};
  37  /*
  38   * mount_lock must be held
  39   * namespace_sem must be held for write
  40 - * how = 0 => just this tree, don't propagate
  41 - * how = 1 => propagate; we know that nobody else has reference to any victims
  42 - * how = 2 => lazy umount
  43   */
  44 -void umount_tree(struct mount *mnt, int how)
  45 +static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
  46  {
  47         HLIST_HEAD(tmp_list);
  48         struct mount *p;
  49 @@ -1344,7 +1345,7 @@ void umount_tree(struct mount *mnt, int
  50         hlist_for_each_entry(p, &tmp_list, mnt_hash)
  51                 list_del_init(&p->mnt_child);
  52
  53 -       if (how)
  54 +       if (how & UMOUNT_PROPAGATE)
  55                 propagate_umount(&tmp_list);
  56
  57         hlist_for_each_entry(p, &tmp_list, mnt_hash) {
  58 @@ -1352,7 +1353,7 @@ void umount_tree(struct mount *mnt, int
  59                 list_del_init(&p->mnt_list);
  60                 __touch_mnt_namespace(p->mnt_ns);
  61                 p->mnt_ns = NULL;
  62 -               if (how < 2)
  63 +               if (how & UMOUNT_SYNC)
  64                         p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
  65                 if (mnt_has_parent(p)) {
  66                         hlist_del_init(&p->mnt_mp_list);
  67 @@ -1457,14 +1458,14 @@ static int do_umount(struct mount *mnt,
  68
  69         if (flags & MNT_DETACH) {
  70                 if (!list_empty(&mnt->mnt_list))
  71 -                       umount_tree(mnt, 2);
  72 +                       umount_tree(mnt, UMOUNT_PROPAGATE);
  73                 retval = 0;
  74         } else {
  75                 shrink_submounts(mnt);
  76                 retval = -EBUSY;
  77                 if (!propagate_mount_busy(mnt, 2)) {
  78                         if (!list_empty(&mnt->mnt_list))
  79 -                               umount_tree(mnt, 1);
  80 +                               umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
  81                         retval = 0;
  82                 }
  83         }
  84 @@ -1496,7 +1497,7 @@ void __detach_mounts(struct dentry *dent
  85         lock_mount_hash();
  86         while (!hlist_empty(&mp->m_list)) {
  87                 mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
  88 -               umount_tree(mnt, 2);
  89 +               umount_tree(mnt, UMOUNT_PROPAGATE);
  90         }
  91         unlock_mount_hash();
  92         put_mountpoint(mp);
  93 @@ -1658,7 +1659,7 @@ struct mount *copy_tree(struct mount *mn
  94  out:
  95         if (res) {
  96                 lock_mount_hash();
  97 -               umount_tree(res, 0);
  98 +               umount_tree(res, UMOUNT_SYNC);
  99                 unlock_mount_hash();
 100         }
 101         return q;
 102 @@ -1682,7 +1683,7 @@ void drop_collected_mounts(struct vfsmou
 103  {
 104         namespace_lock();
 105         lock_mount_hash();
 106 -       umount_tree(real_mount(mnt), 0);
 107 +       umount_tree(real_mount(mnt), UMOUNT_SYNC);
 108         unlock_mount_hash();
 109         namespace_unlock();
 110  }
 111 @@ -1865,7 +1866,7 @@ static int attach_recursive_mnt(struct m
 112   out_cleanup_ids:
 113         while (!hlist_empty(&tree_list)) {
 114                 child = hlist_entry(tree_list.first, struct mount, mnt_hash);
 115 -               umount_tree(child, 0);
 116 +               umount_tree(child, UMOUNT_SYNC);
 117         }
 118         unlock_mount_hash();
 119         cleanup_group_ids(source_mnt, NULL);
 120 @@ -2045,7 +2046,7 @@ static int do_loopback(struct path *path
 121         err = graft_tree(mnt, parent, mp);
 122         if (err) {
 123                 lock_mount_hash();
 124 -               umount_tree(mnt, 0);
 125 +               umount_tree(mnt, UMOUNT_SYNC);
 126                 unlock_mount_hash();
 127         }
 128  out2:
 129 @@ -2416,7 +2417,7 @@ void mark_mounts_for_expiry(struct list_
 130         while (!list_empty(&graveyard)) {
 131                 mnt = list_first_entry(&graveyard, struct mount, mnt_expire);
 132                 touch_mnt_namespace(mnt->mnt_ns);
 133 -               umount_tree(mnt, 1);
 134 +               umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
 135         }
 136         unlock_mount_hash();
 137         namespace_unlock();
 138 @@ -2487,7 +2488,7 @@ static void shrink_submounts(struct moun
 139                         m = list_first_entry(&graveyard, struct mount,
 140                                                 mnt_expire);
 141                         touch_mnt_namespace(m->mnt_ns);
 142 -                       umount_tree(m, 1);
 143 +                       umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC);
 144                 }
 145         }
 146  }
 147 --- a/fs/pnode.h
 148 +++ b/fs/pnode.h
 149 @@ -47,7 +47,6 @@ int get_dominating_id(struct mount *mnt,
 150  unsigned int mnt_get_count(struct mount *mnt);
 151  void mnt_set_mountpoint(struct mount *, struct mountpoint *,
 152                         struct mount *);
 153 -void umount_tree(struct mount *, int);
 154  struct mount *copy_tree(struct mount *, struct dentry *, int);
 155  bool is_path_reachable(struct mount *, struct dentry *,
 156                          const struct path *root);