On Tue, 2022-04-12 at 22:12 +0800, chenxiaosong (A) wrote: > 在 2022/4/12 21:56, Trond Myklebust 写道: > > On Tue, 2022-04-12 at 21:46 +0800, chenxiaosong (A) wrote: > > > > > > Other filesystem will _not_ clear writeback error on close(). > > > And other filesystem will _not_ clear writeback error on async > > > write() too. > > > > > > Other filesystem _only_ clear writeback error on fsync() or sync > > > write(). > > > > > > > Yes. We might even consider not reporting writeback errors at all > > in > > close(), since most developers don't check it. We certainly don't > > want > > to clear those errors there because the manpages don't document > > that as > > being the case. > > > > > Should NFS follow the same semantics as all the other > > > filesystems? > > > > It needs to follow the semantics described in the manpage for > > write(2) > > and fsync(2) as closely as possible, yes. That documentation is > > supposed to be normative for application developers. > > > > We won't guarantee to immediately report ENOSPC like other > > filesystems > > do (because that would require us to only support synchronous > > writes), > > however that behaviour is already documented in the manpage. > > > > We may also report some errors that are not documented in the > > manpage > > (e.g. EACCES or EROFS) simply because those errors cannot always be > > reported at open() time, as would be the case for a local > > filesystem. > > That's just how the NFS protocol works (particularly for the case > > of > > the stateless NFSv3 protocol). > > > > After merging your patchset, NFS will clear wb error on async > write(), > is this reasonable? > It will clear ENOSPC, EDQUOT and EFBIG. It should not clear other errors that are not supposed to be reported by write(). > And more importantly, we can not detect new error by using > filemap_sample_wb_err()/filemap_sample_wb_err() while > nfs_wb_all(),just > as I described: > > ```c > since = filemap_sample_wb_err() = 0 > errseq_sample > if (!(old & ERRSEQ_SEEN)) // nobody see the error > return 0; > nfs_wb_all // no new error > error = filemap_check_wb_err(..., since) != 0 // unexpected error > ``` As I keep repeating, that is _documented behaviour_! -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
