Hi Jan, sorry for the delay, I've been overloaded with various projects recently.. > Ping? I have ext4 DAX read & write path working with the iomap code but to > convert the fault path, I need this resolved. Are you OK with moving > iomap_begin() / iomap_end() calls outside of page lock / entry lock in the > fault path? Yes, that sounds fine. > > I was also thinking about the implications of iomap_begin() (and thus block > allocation for buffered writes in nodelalloc case) being no longer protected > by page lock and at least for ext2 / ext3 compatibility modes this will > lead to uninitialized data exposure when page fault races in the right way > with buffered write. So current locking scheme in iomap code is not easily > usable for ext4 for buffered writes. Right, the iomap I/O code assumes that you either use delalloc, or that your have unwritten extents that your convert to written once I/O has finished. XFS uses the latter feature for direct I/O, or if an extent size hints is set. I can't really think of a good way to handle file systems without either feature - the problem is that we'd have to introduce a file-wide (or range based) lock to protect allocated but not written ranges. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
