Commit eccb95ce authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds

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: default avatarJan Kara <jack@suse.cz>
Cc: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: David Chinner <dgc@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a8522509
...@@ -14,15 +14,21 @@ int sysctl_drop_caches; ...@@ -14,15 +14,21 @@ int sysctl_drop_caches;
static void drop_pagecache_sb(struct super_block *sb) static void drop_pagecache_sb(struct super_block *sb)
{ {
struct inode *inode; struct inode *inode, *toput_inode = NULL;
spin_lock(&inode_lock); spin_lock(&inode_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (inode->i_state & (I_FREEING|I_WILL_FREE)) if (inode->i_state & (I_FREEING|I_WILL_FREE))
continue; continue;
__iget(inode);
spin_unlock(&inode_lock);
__invalidate_mapping_pages(inode->i_mapping, 0, -1, true); __invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
iput(toput_inode);
toput_inode = inode;
spin_lock(&inode_lock);
} }
spin_unlock(&inode_lock); spin_unlock(&inode_lock);
iput(toput_inode);
} }
static void drop_pagecache(void) static void drop_pagecache(void)
......
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