On Wed, Jul 14, 2021 at 1:48 AM Theodore Y. Ts'o <tytso@xxxxxxx> wrote: > > On Tue, Jul 13, 2021 at 06:27:37PM +0530, Shyam Prasad N wrote: > > > > Also, is this parameter also respected when a hole is punched in the > > middle of an allocated data extent? i.e. is there still a possibility > > that a punched hole does not translate to splitting the data extent, > > even when extent_max_zeroout_kb is set to 0? > > Ext4 doesn't ever try to zero blocks as part of a punch operation. > It's true a file system is allowed to do it, but I would guess most > wouldn't, since the presumption is that userspace is actually trying > to free up disk space, and so you would want to release the disk > blocks in the punch hole case. > > The more interesting one is the FALLOC_FL_ZERO_RANGE_FL operation, > which *should* work by transitioning the extent to be uninitialized, > but there might be cases where writing a few zero blocks might be > faster in some cases. That should use the same code path which > resepects the max_zeroout configuration parameter for ext4. > > Cheers, > > - Ted Thanks a lot for your replies, Ted. This was useful. -- Regards, Shyam
