On Thu, Jan 28, 2016 at 09:32:11AM -0700, Ross Zwisler wrote: > On Thu, Jan 28, 2016 at 02:16:30PM +0100, Jan Kara wrote: > > On Wed 27-01-16 12:01:48, Ross Zwisler wrote: > > > As it is currently written ext4_dax_mkwrite() assumes that the call into > > > __dax_mkwrite() will not have to do a block allocation so it doesn't create > > > a journal entry. For a read that creates a zero page to cover a hole > > > followed by a write that actually allocates storage this is incorrect. The > > > ext4_dax_mkwrite() -> __dax_mkwrite() -> __dax_fault() path calls > > > get_blocks() to allocate storage. > > > > > > Fix this by having the ->page_mkwrite fault handler call ext4_dax_fault() > > > as this function already has all the logic needed to allocate a journal > > > entry and call __dax_fault(). > > > > > > Also update the ext2 fault handlers in this same way to remove duplicate > > > code and keep the logic between ext2 and ext4 the same. > > > > > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > > > > Ah, ok, you are right. The patch looks good but Matthew is reworking the > > area more (so ext4_da_mkwrite() is likely to return) so it this worth it? > > Or do you expect Matthew's patches to land much later? > > Yep, Matthew is in the process of reworking all of the DAX fault handling. > > I was thinking that we might want to take this patch for v4.5, since it fixes > a bug that I'm guessing could lead to some sort of corruption (lack of a > journal entry entry for an allocating write), and then Matthew's reworks would > land in v4.6? Hey Jan, Looks like this patch didn't ever get merged for v4.5? Is it still queued for v4.6? Thanks, - Ross -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
