On 2025/1/16 5:07, Chaitanya Kulkarni wrote: > On 1/15/25 03:46, Zhang Yi wrote: >> Currently, we can use the fallocate command to quickly create a >> pre-allocated file. However, on most filesystems, such as ext4 and XFS, >> fallocate create pre-allocation blocks in an unwritten state, and the >> FALLOC_FL_ZERO_RANGE flag also behaves similarly. The extent state must >> be converted to a written state when the user writes data into this >> range later, which can trigger numerous metadata changes and consequent >> journal I/O. This may leads to significant write amplification and >> performance degradation in synchronous write mode. Therefore, we need a >> method to create a pre-allocated file with written extents that can be >> used for pure overwriting. At the monent, the only method available is >> to create an empty file and write zero data into it (for example, using >> 'dd' with a large block size). However, this method is slow and consumes >> a considerable amount of disk bandwidth, we must pre-allocate files in >> advance but cannot add pre-allocated files while user business services >> are running. > > it will be very useful if we can get some blktests for scsi/nvme/dm. > Please note that this not a blocker to get this path series to be merged, > but this will help everyone including regular tests runs we do to ensure > the stability of new interface. Hello, Chaitanya, Thanks for your feedback! Yeah, the proposal for this series is still under discussion, I will add counterpart tests to both blktests and fstests once the solution is determined. > > if you do please CC and Shinichiro (added to CC list) to we can help those > tests review and potentially also can provide tested by tag tht can help > this work to move forward. > Sure, this will be very helpful. Thanks, Yi.
