On Thu, Apr 04, 2013 at 12:02:53AM -0700, Andrew Morton wrote: > > Well perhaps the vfs tree should start paying some attention to the > > rest of the world, particularly after -rc5. > > I can't even find this "lift sb_start_write() out of ->write()". Not on fsdevel, > not on lkml. What the heck is it and why was it so important? Deadlocks around splice; see the threads re overlayfs/unionmount/aufs and deadlocks in their copyup implementations. See also XFS freeze-related deadlocks, etc. The thing is, sb_start_write() is pretty high in locking hierarchy (outside ->i_mutex, etc.), but ->splice_write() and friends had it buried pretty deep. With distinctly unpleasant results, including ->..._write() instances using generic ones (which took the lock) *and* doing some IO outside of those (ext4, for example; ocfs2 also looked fishy in that respect, IIRC). The obvious solution is to lift taking that lock out of the methods, which had been done. It had been discussed on fsdevel and sat in #experimental for several weeks; time for it to go into #for-next. -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
