On 05/30/2012 06:58 PM, jeff.liu@xxxxxxxxxx wrote:
Introduce two functions to lock/unlock a particular mount namespace
when container quota operations is performed.
Signed-off-by: Jie Liu<jeff.liu@xxxxxxxxxx>
---
fs/namespace.c | 17 +++++++++++++++++
include/linux/mnt_namespace.h | 13 +++++++++++++
2 files changed, 30 insertions(+), 0 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index e608199..8823ba8 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2633,3 +2633,20 @@ bool our_mnt(struct vfsmount *mnt)
{
return check_mnt(real_mount(mnt));
}
+
+/*
+ * Lock the mount namespace when performing a particular container
+ * disk quotactl operation, especially to protect removing it.
+ */
+void lock_mnt_ns(struct mnt_namespace *ns)
+{
+ down_write(&namespace_sem);
+}
+
+/*
+ * Unlock the mount namespace after quotactl on that was done.
+ */
+void unlock_mnt_ns(struct mnt_namespace *ns)
+{
+ up_write(&namespace_sem);
+}
diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h
index 5a8e390..ff72ed5 100644
--- a/include/linux/mnt_namespace.h
+++ b/include/linux/mnt_namespace.h
@@ -9,6 +9,19 @@ extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *,
struct fs_struct *);
extern void put_mnt_ns(struct mnt_namespace *ns);
+#ifdef CONFIG_NS_QUOTA
+extern void lock_mnt_ns(struct mnt_namespace *);
+extern void unlock_mnt_ns(struct mnt_namespace *);
+#else
+void lock_mnt_ns(struct mnt_namespace *)
+{
+}
+
+void unlock_mnt_ns(struct mnt_namespace *)
+{
+}
+#endif
+
Seems weird. There is nothing ns-quota specific in locking a namespace.
Also, just grabbing a lock from an outer subsystem is quite ugly. If you
are grabbing a namespace lock, this suggests you are tweaking namespace
data. So you should have that file provide you with a function that does
the full operation.
Of course there are exceptions to that, but it rings a bell.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
