> On Mon, Jun 02, 2014 at 03:06:13PM +0200, Lukáš Czerner wrote: > > > > So what will happen when there is not enough space when "inserting a > > > > range" ? And how should user proceed from there ? > > > If insert range fails with an ENOSPC error, user could use collapse > > > range on the same range to remove the hole. > > > And after freeing more space, he can again try inserting range. > > > Ofcourse, this type of guidance should be properly documented in > > > manpage. When updating fallocate(2) manpage, I will keep in mind to > > > describe ENOSPC handling. > > > > Why collapse ? The hole is already there right ? Why not just use > > fallocate to allocate the space for the hole. And that's my point > > actually. Why not do it this way in the first place, because this is > > really counterintuitive. > > It's worse than that. It's possible that the reason why you got the > ENOSPC warning was because the operation to move the extents down > required allocating a block, and it was *that* block allocation which > failed. So it's not deterministic whether or not the file's extent > mappings were modified after a ENOSPC error, and so it's not clear > whether or not a collapse_range function will undo the range that had > been inserted --- or whether it ends up deleting existing data blocks. > > In generally, you really want system calls to have all-or-nothing > effects, where if the system call returns an error, the state of the > file has not been changed. And for that reason, I agree with Lukáš > that it is really a good idea to decouple moving the blocks down, and > allocating space --- and to make sure that if there is any failure > while inserting the range, the state of the file is not modified at all. Okay, I will remove allocating space part in insert range patch. But renaming flags as FALLOC_FL_INSERT_HOLE is needed to concent with XFS people. Because Dave prefered to call it FALLOC_FL_INSERT_RANGE so that it looks like it is related to collapse range. Hi Dave. Do you have any objection about renaming as insert hole ? Thanks for opinions! > > Cheers, > > - Ted -- 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
