From 9ac17415d909b7e0d991f1ed4a51b0a6ec311218 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 8 Dec 2015 03:07:22 -0500 Subject: [PATCH] 9p: ->evict_inode() should kick out ->i_data, not ->i_mapping commit 4ad78628445d26e5e9487b2e8f23274ad7b0f5d3 upstream. For block devices the pagecache is associated with the inode on bdevfs, not with the aliasing ones on the mountable filesystems. The latter have its own ->i_data empty and ->i_mapping pointing to the (unique per major/minor) bdevfs inode. That guarantees cache coherence between all block device inodes with the same device number. Eviction of an alias inode has no business trying to evict the pages belonging to bdevfs one; moreover, ->i_mapping is only safe to access when the thing is opened. At the time of ->evict_inode() the victim is definitely *not* opened. We are about to kill the address space embedded into struct inode (inode->i_data) and that's what we need to empty of any pages. 9p instance tries to empty inode->i_mapping instead, which is both unsafe and bogus - if we have several device nodes with the same device number in different places, closing one of them should not try to empty the (shared) page cache. Fortunately, other instances in the tree are OK; they are evicting from &inode->i_data instead, as 9p one should. Reported-by: "Suzuki K. Poulose" Tested-by: "Suzuki K. Poulose" Signed-off-by: Al Viro [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- fs/9p/vfs_inode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c index bf1df722dc02..adedfd401a30 100644 --- a/fs/9p/vfs_inode.c +++ b/fs/9p/vfs_inode.c @@ -435,9 +435,9 @@ void v9fs_evict_inode(struct inode *inode) { struct v9fs_inode *v9inode = V9FS_I(inode); - truncate_inode_pages(inode->i_mapping, 0); + truncate_inode_pages(&inode->i_data, 0); end_writeback(inode); - filemap_fdatawrite(inode->i_mapping); + filemap_fdatawrite(&inode->i_data); #ifdef CONFIG_9P_FSCACHE v9fs_cache_inode_put_cookie(inode); -- 2.39.2