af065b8a19
Many inodes have no pagecache, so we can avoid lots of lock-takings. Signed-off-by: Jan Kara <jack@suse.cz> Cc: Fengguang Wu <wfg@mail.ustc.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
76 lines
1.6 KiB
C
76 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_WILL_FREE))
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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, true);
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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;
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spin_lock(&sb_lock);
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restart:
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list_for_each_entry(sb, &super_blocks, s_list) {
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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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if (__put_super_and_need_restart(sb))
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goto restart;
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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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struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
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{
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proc_dointvec_minmax(table, write, file, 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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