On Wed, Jan 20, 2021 at 05:06:08PM +0100, Jan Kara wrote: > > Amir has reported [1] a that ext4 has a potential issues when reads can race > with hole punching possibly exposing stale data from freed blocks or even > corrupting filesystem when stale mapping data gets used for writeout. The > problem is that during hole punching, new page cache pages can get instantiated > in a punched range after truncate_inode_pages() has run but before the > filesystem removes blocks from the file. In principle any filesystem > implementing hole punching thus needs to implement a mechanism to block > instantiating page cache pages during hole punching to avoid this race. This is > further complicated by the fact that there are multiple places that can > instantiate pages in page cache. We can have regular read(2) or page fault > doing this but fadvise(2) or madvise(2) can also result in reading in page > cache pages through force_page_cache_readahead(). What's the current status of this patch set? I'm going through pending patches and it looks like folks don't like Jan's proposed solution. What are next steps? Thanks, - Ted
