Jeremy Allison <jra@xxxxxxxxx> writes: > On Thu, Dec 07, 2023 at 03:58:46PM +0000, David Howells wrote: >>Hi Steve, Namjae, Jeremy, >> >>At the moment certain fallocate() operations aren't very well implemented in >>the cifs filesystem on Linux, either because the protocol doesn't fully >>support them or because the ops being used don't also set the EOF marker at >>the same time and a separate RPC must be made to do that. >> >>For instance: >> >> - FALLOC_FL_ZERO_RANGE does some zeroing and then sets the EOF as two >> distinctly separate operations. The code prevents you from doing this op >> under some circumstances as it doesn't have an oplock and doesn't want to >> race with a third party (note that smb3_punch_hole() doesn't have this >> check). >> >> - FALLOC_FL_COLLAPSE_RANGE uses COPYCHUNK to move the file down and then sets >> the EOF as two separate operations as there is no protocol op for this. >> However, the copy will likely fail if the ranges overlap and it's >> non-atomic with respect to a third party. >> >> - FALLOC_FL_INSERT_RANGE has the same issues as FALLOC_FL_COLLAPSE_RANGE. >> >>Question: Would it be possible to do all of these better by using compounding >>with SMB2_FLAGS_RELATED_OPERATIONS? In particular, if two components of a >>compound are marked related, does the second get skipped if the first fails? > > Yes: > > https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/46dd4182-62d3-4e30-9fe5-e2ec124edca1 > > "When the current operation requires a FileId and the previous operation > either contains or generates a FileId, if the previous operation fails > with an error, the server SHOULD<253> fail the current operation with > the same error code returned by the previous operation." David, you could extend smb2_compound_op() like I did for compound create+{get,set}_reparse+getinfo+close in [1][2][3]. [1] https://lore.kernel.org/r/20231126025510.28147-2-pc@xxxxxxxxxxxxx [2] https://lore.kernel.org/r/20231126025510.28147-3-pc@xxxxxxxxxxxxx [3] https://lore.kernel.org/r/20231126025510.28147-8-pc@xxxxxxxxxxxxx
