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76 lines
1.8 KiB
76 lines
1.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Implement the manual drop-all-pagecache function |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/mm.h> |
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#include <linux/fs.h> |
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#include <linux/writeback.h> |
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#include <linux/sysctl.h> |
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#include <linux/gfp.h> |
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#include "internal.h" |
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/* A global variable is a bit ugly, but it keeps the code simple */ |
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int sysctl_drop_caches; |
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static void drop_pagecache_sb(struct super_block *sb, void *unused) |
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{ |
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struct inode *inode, *toput_inode = NULL; |
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spin_lock(&sb->s_inode_list_lock); |
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list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
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spin_lock(&inode->i_lock); |
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/* |
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* We must skip inodes in unusual state. We may also skip |
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* inodes without pages but we deliberately won't in case |
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* we need to reschedule to avoid softlockups. |
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*/ |
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if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || |
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(inode->i_mapping->nrpages == 0 && !need_resched())) { |
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spin_unlock(&inode->i_lock); |
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continue; |
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} |
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__iget(inode); |
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spin_unlock(&inode->i_lock); |
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spin_unlock(&sb->s_inode_list_lock); |
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invalidate_mapping_pages(inode->i_mapping, 0, -1); |
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iput(toput_inode); |
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toput_inode = inode; |
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cond_resched(); |
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spin_lock(&sb->s_inode_list_lock); |
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} |
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spin_unlock(&sb->s_inode_list_lock); |
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iput(toput_inode); |
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} |
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int drop_caches_sysctl_handler(struct ctl_table *table, int write, |
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void *buffer, size_t *length, loff_t *ppos) |
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{ |
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int ret; |
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ret = proc_dointvec_minmax(table, write, buffer, length, ppos); |
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if (ret) |
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return ret; |
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if (write) { |
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static int stfu; |
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if (sysctl_drop_caches & 1) { |
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iterate_supers(drop_pagecache_sb, NULL); |
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count_vm_event(DROP_PAGECACHE); |
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} |
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if (sysctl_drop_caches & 2) { |
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drop_slab(); |
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count_vm_event(DROP_SLAB); |
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} |
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if (!stfu) { |
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pr_info("%s (%d): drop_caches: %d\n", |
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current->comm, task_pid_nr(current), |
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sysctl_drop_caches); |
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} |
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stfu |= sysctl_drop_caches & 4; |
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} |
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return 0; |
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}
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