Messages in this thread | | | Date | Wed, 26 Mar 2008 08:44:36 +0800 | From | Fengguang Wu <> | Subject | Re: [PATCH] vfs: Fix lock inversion in drop_pagecache_sb() |
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On Tue, Mar 25, 2008 at 07:12:27PM +0100, Jan Kara wrote: > 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...
Reviewed-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
It's a handy trick to iterate through the list_head :-) I have practiced this in my filecache code, and it works nice.
Fengguang
> Signed-off-by: Jan Kara <jack@suse.cz> > CC: Fengguang Wu <wfg@mail.ustc.edu.cn> > CC: David Chinner <dgc@sgi.com> > > --- > fs/drop_caches.c | 8 +++++++- > 1 files changed, 7 insertions(+), 1 deletions(-) > > diff --git a/fs/drop_caches.c b/fs/drop_caches.c > index 59375ef..f5aae26 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); > } > > void drop_pagecache(void) > -- > 1.5.2.4 >
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