Commit eccb95ce authored Apr 29, 2008 by Jan Kara Committed by Linus Torvalds Apr 29, 2008

vfs: fix lock inversion in drop_pagecache_sb()



Fix longstanding lock inversion in drop_pagecache_sb by dropping inode_lock
before calling __invalidate_mapping_pages().  We just have to make sure inode
won't go away from under us by keeping reference to it and putting the
reference only after we have safely resumed the scan of the inode list.  A bit
tricky but not too bad...

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: David Chinner <dgc@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent a8522509

fs/drop_caches.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -14,15 +14,21 @@ int sysctl_drop_caches;

		static void drop_pagecache_sb(struct super_block *sb)
		{
		struct inode *inode;
		struct inode inode, toput_inode = NULL;

		spin_lock(&inode_lock);
		list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
		if (inode->i_state & (I_FREEING\|I_WILL_FREE))
		continue;
		__iget(inode);
		spin_unlock(&inode_lock);
		__invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
		iput(toput_inode);
		toput_inode = inode;
		spin_lock(&inode_lock);
		}
		spin_unlock(&inode_lock);
		iput(toput_inode);
		}

		static void drop_pagecache(void)

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