On Fri, Jun 13, 2025 at 08:04:46AM -0700, Darrick J. Wong wrote: > On Fri, Jun 13, 2025 at 11:01:25AM +0530, Ojaswin Mujoo wrote: > > On Thu, Jun 12, 2025 at 07:36:14AM -0700, Darrick J. Wong wrote: > > > On Thu, Jun 12, 2025 at 11:41:16AM +0530, Ojaswin Mujoo wrote: > > > > On Wed, Jun 11, 2025 at 07:30:05AM -0700, Darrick J. Wong wrote: > > > > > On Wed, Jun 11, 2025 at 03:04:44PM +0530, Ojaswin Mujoo wrote: > > > > > > From: "Ritesh Harjani (IBM)" <ritesh.list@xxxxxxxxx> > > > > > > > > > > > > Insert range and collapse range only works with bigalloc in case > > > > > > the range is cluster size aligned, which fsx doesnt take care. To > > > > > > work past this, disable insert range and collapse range on ext4, if > > > > > > bigalloc is enabled. > > > > > > > > > > Hmmm, insert/collapse-range have the same behavior on xfs realtime, > > > > > maybe we should amend test() in fsx to round to the allocation unit > > > > > size? > > > > Hey Darrick, > > > > > > > > Yes makes sense but as you mentioned, I'm not sure if there > > > > is a way to programatically detect the bigalloc cluster size (or > > > > allocation unit in general) like we do for xfs. > > > > > > I don't either, but maybe we should have a way reveal the allocation > > > unit size for a given file? Yet another statx field? :P > > > > > > (It /would/ be useful for programs that use collapse/insert range) > > > > Yes it would, at the very least, help with defining clear semantics for > > collapse/insert range with bigalloc/rtvol because right now those > > operations just EINVAL if the range is not aligned correctly, which is > > confusing since it is not documented how to do it properly. > > > > xfs does have an ioctl to get the geometry for rtvol. I think you are > > suggesting a more generic statx field which can be used by other FSes as > > well, right? > > Right, since other filesystems (fat, ntfs, etc) also have allocation > units larger than the fsblock size. Most of the time the allocunit > amplification simply doesn't matter to applications, but once in a while > it does (collapse/insert range, cow) affect performance. > > --D Makes sense Darrick. I can look into it. For this patch, is it okay to keep the approach of disabling collapse/insert range for bigalloc for now and we can change fsx later if we add support for exposing alloc units. Regards, Ojaswin
