From eccb95cee4f0d56faa46ef22fb94dd4a3578d3eb Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 29 Apr 2008 00:59:37 -0700 Subject: [PATCH] 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 Cc: Fengguang Wu Cc: David Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/drop_caches.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/drop_caches.c b/fs/drop_caches.c index e2c6b6500c..50f9087635 100644 --- a/fs/drop_caches.c +++ b/fs/drop_caches.c @@ -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) -- 2.39.5