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-rw-r--r--fs/dcache.c39
-rw-r--r--include/linux/dcache.h1
2 files changed, 40 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 5c7cc953ac81..8515875854b6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1306,6 +1306,45 @@ int have_submounts(struct dentry *parent)
}
EXPORT_SYMBOL(have_submounts);
+struct check_mount {
+ struct vfsmount *mnt;
+ unsigned int mounted;
+};
+
+static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry)
+{
+ struct check_mount *info = data;
+ struct path path = { .mnt = info->mnt, .dentry = dentry };
+
+ if (likely(!d_mountpoint(dentry)))
+ return D_WALK_CONTINUE;
+ if (__path_is_mountpoint(&path)) {
+ info->mounted = 1;
+ return D_WALK_QUIT;
+ }
+ return D_WALK_CONTINUE;
+}
+
+/**
+ * path_has_submounts - check for mounts over a dentry in the
+ * current namespace.
+ * @parent: path to check.
+ *
+ * Return true if the parent or its subdirectories contain
+ * a mount point in the current namespace.
+ */
+int path_has_submounts(const struct path *parent)
+{
+ struct check_mount data = { .mnt = parent->mnt, .mounted = 0 };
+
+ read_seqlock_excl(&mount_lock);
+ d_walk(parent->dentry, &data, path_check_mount, NULL);
+ read_sequnlock_excl(&mount_lock);
+
+ return data.mounted;
+}
+EXPORT_SYMBOL(path_has_submounts);
+
/*
* Called by mount code to set a mountpoint and check if the mountpoint is
* reachable (e.g. NFS can unhash a directory dentry and then the complete
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index bc529ce88ed0..0ffaf7aef9ae 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -255,6 +255,7 @@ extern void d_prune_aliases(struct inode *);
/* test whether we have any submounts in a subdir tree */
extern int have_submounts(struct dentry *);
+extern int path_has_submounts(const struct path *);
/*
* This adds the entry to the hash queues.