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authorAl Viro <viro@zeniv.linux.org.uk>2014-08-07 09:12:31 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-08-07 14:40:09 -0400
commit3064c3563ba4c23e2c7a47254ec056ed9ba0098a (patch)
tree806bc1df85e925686cc1075b659a6d6fe3e14aec /fs/namespace.c
parent8fa1f1c2bd86007beb4a4845e6087ac4a704dc80 (diff)
downloadop-kernel-dev-3064c3563ba4c23e2c7a47254ec056ed9ba0098a.zip
op-kernel-dev-3064c3563ba4c23e2c7a47254ec056ed9ba0098a.tar.gz
death to mnt_pinned
Rather than playing silly buggers with vfsmount refcounts, just have acct_on() ask fs/namespace.c for internal clone of file->f_path.mnt and replace it with said clone. Then attach the pin to original vfsmount. Voila - the clone will be alive until the file gets closed, making sure that underlying superblock remains active, etc., and we can drop the original vfsmount, so that it's not kept busy. If the file lives until the final mntput of the original vfsmount, we'll notice that there's an fs_pin (one in bsd_acct_struct that holds that file) and mnt_pin_kill() will take it out. Since ->kill() is synchronous, we won't proceed past that point until these files are closed (and private clones of our vfsmount are gone), so we get the same ordering warranties we used to get. mnt_pin()/mnt_unpin()/->mnt_pinned is gone now, and good riddance - it never became usable outside of kernel/acct.c (and racy wrt umount even there). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c35
1 files changed, 9 insertions, 26 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 0e4ce51..65af9d0 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -937,7 +937,6 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
static void mntput_no_expire(struct mount *mnt)
{
-put_again:
rcu_read_lock();
mnt_add_count(mnt, -1);
if (likely(mnt->mnt_ns)) { /* shouldn't be the last one */
@@ -950,14 +949,6 @@ put_again:
unlock_mount_hash();
return;
}
- if (unlikely(mnt->mnt_pinned)) {
- mnt_add_count(mnt, mnt->mnt_pinned + 1);
- mnt->mnt_pinned = 0;
- rcu_read_unlock();
- unlock_mount_hash();
- mnt_pin_kill(mnt);
- goto put_again;
- }
if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) {
rcu_read_unlock();
unlock_mount_hash();
@@ -980,6 +971,8 @@ put_again:
* so mnt_get_writers() below is safe.
*/
WARN_ON(mnt_get_writers(mnt));
+ if (unlikely(mnt->mnt_pins.first))
+ mnt_pin_kill(mnt);
fsnotify_vfsmount_delete(&mnt->mnt);
dput(mnt->mnt.mnt_root);
deactivate_super(mnt->mnt.mnt_sb);
@@ -1007,25 +1000,15 @@ struct vfsmount *mntget(struct vfsmount *mnt)
}
EXPORT_SYMBOL(mntget);
-void mnt_pin(struct vfsmount *mnt)
+struct vfsmount *mnt_clone_internal(struct path *path)
{
- lock_mount_hash();
- real_mount(mnt)->mnt_pinned++;
- unlock_mount_hash();
-}
-EXPORT_SYMBOL(mnt_pin);
-
-void mnt_unpin(struct vfsmount *m)
-{
- struct mount *mnt = real_mount(m);
- lock_mount_hash();
- if (mnt->mnt_pinned) {
- mnt_add_count(mnt, 1);
- mnt->mnt_pinned--;
- }
- unlock_mount_hash();
+ struct mount *p;
+ p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE);
+ if (IS_ERR(p))
+ return ERR_CAST(p);
+ p->mnt.mnt_flags |= MNT_INTERNAL;
+ return &p->mnt;
}
-EXPORT_SYMBOL(mnt_unpin);
static inline void mangle(struct seq_file *m, const char *s)
{
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