mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 03:40:52 +07:00
149 lines
3.6 KiB
C
149 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2005-2019 Junjiro R. Okajima
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*
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* This program, aufs is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* support for loopback block device as a branch
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*/
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#include "aufs.h"
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/* added into drivers/block/loop.c */
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static struct file *(*backing_file_func)(struct super_block *sb);
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/*
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* test if two lower dentries have overlapping branches.
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*/
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int au_test_loopback_overlap(struct super_block *sb, struct dentry *h_adding)
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{
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struct super_block *h_sb;
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struct file *backing_file;
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if (unlikely(!backing_file_func)) {
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/* don't load "loop" module here */
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backing_file_func = symbol_get(loop_backing_file);
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if (unlikely(!backing_file_func))
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/* "loop" module is not loaded */
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return 0;
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}
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h_sb = h_adding->d_sb;
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backing_file = backing_file_func(h_sb);
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if (!backing_file)
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return 0;
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h_adding = backing_file->f_path.dentry;
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/*
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* h_adding can be local NFS.
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* in this case aufs cannot detect the loop.
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*/
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if (unlikely(h_adding->d_sb == sb))
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return 1;
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return !!au_test_subdir(h_adding, sb->s_root);
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}
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/* true if a kernel thread named 'loop[0-9].*' accesses a file */
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int au_test_loopback_kthread(void)
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{
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int ret;
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struct task_struct *tsk = current;
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char c, comm[sizeof(tsk->comm)];
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ret = 0;
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if (tsk->flags & PF_KTHREAD) {
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get_task_comm(comm, tsk);
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c = comm[4];
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ret = ('0' <= c && c <= '9'
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&& !strncmp(comm, "loop", 4));
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}
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return ret;
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}
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/* ---------------------------------------------------------------------- */
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#define au_warn_loopback_step 16
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static int au_warn_loopback_nelem = au_warn_loopback_step;
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static unsigned long *au_warn_loopback_array;
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void au_warn_loopback(struct super_block *h_sb)
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{
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int i, new_nelem;
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unsigned long *a, magic;
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static DEFINE_SPINLOCK(spin);
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magic = h_sb->s_magic;
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spin_lock(&spin);
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a = au_warn_loopback_array;
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for (i = 0; i < au_warn_loopback_nelem && *a; i++)
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if (a[i] == magic) {
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spin_unlock(&spin);
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return;
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}
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/* h_sb is new to us, print it */
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if (i < au_warn_loopback_nelem) {
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a[i] = magic;
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goto pr;
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}
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/* expand the array */
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new_nelem = au_warn_loopback_nelem + au_warn_loopback_step;
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a = au_kzrealloc(au_warn_loopback_array,
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au_warn_loopback_nelem * sizeof(unsigned long),
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new_nelem * sizeof(unsigned long), GFP_ATOMIC,
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/*may_shrink*/0);
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if (a) {
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au_warn_loopback_nelem = new_nelem;
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au_warn_loopback_array = a;
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a[i] = magic;
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goto pr;
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}
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spin_unlock(&spin);
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AuWarn1("realloc failed, ignored\n");
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return;
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pr:
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spin_unlock(&spin);
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pr_warn("you may want to try another patch for loopback file "
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"on %s(0x%lx) branch\n", au_sbtype(h_sb), magic);
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}
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int au_loopback_init(void)
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{
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int err;
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struct super_block *sb __maybe_unused;
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BUILD_BUG_ON(sizeof(sb->s_magic) != sizeof(*au_warn_loopback_array));
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err = 0;
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au_warn_loopback_array = kcalloc(au_warn_loopback_step,
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sizeof(unsigned long), GFP_NOFS);
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if (unlikely(!au_warn_loopback_array))
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err = -ENOMEM;
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return err;
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}
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void au_loopback_fin(void)
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{
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if (backing_file_func)
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symbol_put(loop_backing_file);
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au_kfree_try_rcu(au_warn_loopback_array);
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}
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