[PATCH 3.4 04/91] get rid of propagate_umount() mistakenly treating slaves as busy.

From: lizf
Date: Thu Nov 27 2014 - 03:46:09 EST


From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

3.4.105-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit 88b368f27a094277143d8ecd5a056116f6a41520 upstream.

The check in __propagate_umount() ("has somebody explicitly mounted
something on that slave?") is done *before* taking the already doomed
victims out of the child lists.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
[lizf: Backported to 3.4:
- adjust context
- s/hlist_for_each_entry/list_for_each_entry/]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
fs/namespace.c | 4 +++-
fs/pnode.c | 4 +++-
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 4e46539..2985879 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1066,6 +1066,9 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
for (p = mnt; p; p = next_mnt(p, mnt))
list_move(&p->mnt_hash, &tmp_list);

+ list_for_each_entry(p, &tmp_list, mnt_hash)
+ list_del_init(&p->mnt_child);
+
if (propagate)
propagate_umount(&tmp_list);

@@ -1076,7 +1079,6 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
if (p->mnt_ns)
__mnt_make_shortterm(p);
p->mnt_ns = NULL;
- list_del_init(&p->mnt_child);
if (mnt_has_parent(p)) {
p->mnt_parent->mnt_ghosts++;
dentry_reset_mounted(p->mnt_mountpoint);
diff --git a/fs/pnode.c b/fs/pnode.c
index ab5fa9e..f61dcb4 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -333,8 +333,10 @@ static void __propagate_umount(struct mount *mnt)
* umount the child only if the child has no
* other children
*/
- if (child && list_empty(&child->mnt_mounts))
+ if (child && list_empty(&child->mnt_mounts)) {
+ list_del_init(&child->mnt_child);
list_move_tail(&child->mnt_hash, &mnt->mnt_hash);
+ }
}
}

--
1.9.1

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