70 lines
2.1 KiB
Diff
70 lines
2.1 KiB
Diff
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From 04c7737b94059b8935abd0c09ac8745eba89ad90 Mon Sep 17 00:00:00 2001
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From: Miklos Szeredi <mszeredi@suse.cz>
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Date: Thu, 27 Jun 2013 16:39:49 +0200
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Subject: [PATCH 4/9] vfs: introduce clone_private_mount()
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Overlayfs needs a private clone of the mount, so create a function for
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this and export to modules.
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Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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---
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fs/namespace.c | 27 +++++++++++++++++++++++++++
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include/linux/mount.h | 3 +++
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2 files changed, 30 insertions(+)
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diff --git a/fs/namespace.c b/fs/namespace.c
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index 7b1ca9b..455e6ea 100644
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--- a/fs/namespace.c
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+++ b/fs/namespace.c
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@@ -1442,6 +1442,33 @@ void drop_collected_mounts(struct vfsmount *mnt)
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namespace_unlock();
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}
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+/**
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+ * clone_private_mount - create a private clone of a path
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+ *
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+ * This creates a new vfsmount, which will be the clone of @path. The new will
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+ * not be attached anywhere in the namespace and will be private (i.e. changes
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+ * to the originating mount won't be propagated into this).
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+ *
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+ * Release with mntput().
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+ */
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+struct vfsmount *clone_private_mount(struct path *path)
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+{
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+ struct mount *old_mnt = real_mount(path->mnt);
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+ struct mount *new_mnt;
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+
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+ if (IS_MNT_UNBINDABLE(old_mnt))
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+ return ERR_PTR(-EINVAL);
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+
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+ down_read(&namespace_sem);
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+ new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
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+ up_read(&namespace_sem);
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+ if (IS_ERR(new_mnt))
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+ return ERR_CAST(new_mnt);
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+
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+ return &new_mnt->mnt;
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+}
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+EXPORT_SYMBOL_GPL(clone_private_mount);
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+
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int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
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struct vfsmount *root)
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{
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diff --git a/include/linux/mount.h b/include/linux/mount.h
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index 73005f9..435f281 100644
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--- a/include/linux/mount.h
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+++ b/include/linux/mount.h
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@@ -68,6 +68,9 @@ extern void mnt_pin(struct vfsmount *mnt);
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extern void mnt_unpin(struct vfsmount *mnt);
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extern int __mnt_is_readonly(struct vfsmount *mnt);
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+struct path;
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+extern struct vfsmount *clone_private_mount(struct path *path);
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+
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struct file_system_type;
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extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
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int flags, const char *name,
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--
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1.8.3.2
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