49 lines
1.3 KiB
C
49 lines
1.3 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Common helpers for stackable filesystems and backing files.
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*
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* Copyright (C) 2023 CTERA Networks.
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*/
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#include <linux/fs.h>
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#include <linux/backing-file.h>
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#include "internal.h"
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/**
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* backing_file_open - open a backing file for kernel internal use
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* @user_path: path that the user reuqested to open
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* @flags: open flags
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* @real_path: path of the backing file
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* @cred: credentials for open
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*
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* Open a backing file for a stackable filesystem (e.g., overlayfs).
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* @user_path may be on the stackable filesystem and @real_path on the
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* underlying filesystem. In this case, we want to be able to return the
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* @user_path of the stackable filesystem. This is done by embedding the
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* returned file into a container structure that also stores the stacked
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* file's path, which can be retrieved using backing_file_user_path().
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*/
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struct file *backing_file_open(const struct path *user_path, int flags,
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const struct path *real_path,
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const struct cred *cred)
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{
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struct file *f;
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int error;
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f = alloc_empty_backing_file(flags, cred);
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if (IS_ERR(f))
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return f;
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path_get(user_path);
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*backing_file_user_path(f) = *user_path;
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error = vfs_open(real_path, f);
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if (error) {
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fput(f);
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f = ERR_PTR(error);
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}
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return f;
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}
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EXPORT_SYMBOL_GPL(backing_file_open);
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