77 lines
1.6 KiB
C
77 lines
1.6 KiB
C
/*
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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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/* 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)
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{
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struct inode *inode, *toput_inode = NULL;
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spin_lock(&inode_lock);
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list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
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if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
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continue;
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if (inode->i_mapping->nrpages == 0)
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continue;
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__iget(inode);
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spin_unlock(&inode_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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spin_lock(&inode_lock);
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}
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spin_unlock(&inode_lock);
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iput(toput_inode);
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}
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static void drop_pagecache(void)
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{
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struct super_block *sb, *n;
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spin_lock(&sb_lock);
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list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
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if (list_empty(&sb->s_instances))
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continue;
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sb->s_count++;
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spin_unlock(&sb_lock);
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down_read(&sb->s_umount);
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if (sb->s_root)
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drop_pagecache_sb(sb);
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up_read(&sb->s_umount);
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spin_lock(&sb_lock);
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__put_super(sb);
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}
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spin_unlock(&sb_lock);
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}
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static void drop_slab(void)
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{
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int nr_objects;
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do {
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nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
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} while (nr_objects > 10);
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}
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int drop_caches_sysctl_handler(ctl_table *table, int write,
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void __user *buffer, size_t *length, loff_t *ppos)
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{
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proc_dointvec_minmax(table, write, buffer, length, ppos);
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if (write) {
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if (sysctl_drop_caches & 1)
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drop_pagecache();
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if (sysctl_drop_caches & 2)
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drop_slab();
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}
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return 0;
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}
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