On 3/18/25 11:09 AM, Anna Schumaker wrote: > Hi Takeshi, > > On 3/18/25 11:00 AM, Takeshi Nishimura wrote: >> Zhang Yi <yi.zhang@xxxxxxxxxx> wrote in linux-fsdevel@xxxxxxxxxxxxxxx: >>> Add support for FALLOC_FL_WRITE_ZEROES. This first allocates blocks as >>> unwritten, then issues a zero command outside of the running journal >>> handle, and finally converts them to a written state. >> >> Picking up where the NFS4.2 WRITE_SAME discussion stalled: >> FALLOC_FL_WRITE_ZEROES is coming, and IMO the only way to implement >> that for NFS is via WRITE_SAME. >> >> How to proceed? > > I've been working on patches for implementing FALLOC_FL_ZERO_RANGE support > in the NFS client using WRITE_SAME. I've also been experimenting with adding > an ioctl for the generic pattern writing part. I'm expecting to talk about > what I have for ioctl API at LSF next week, and I'll post an initial round > of patches shortly after. > > I do still need to think through any edge cases and write tests for > pynfs and fstests before anything can be merged. Takeshi, it would be immensely helpful to us if you could provide some detail about how exactly you intend to make use of WRITE_SAME so we can focus the development, review, and testing efforts. So far we don't have any specific use cases, but there is some skepticism (as voiced in the previous thread) about whether this facility will actually be useful. For example, do you expect to have SCSI devices that accelerate WRITE_SAME? How will your applications use this? What kind (and size) of patterns do you expect to need? -- Chuck Lever
