Messages in this thread | | | Date | Tue, 12 Apr 2022 22:12:57 +0800 | Subject | Re: [PATCH -next 1/2] nfs: nfs{,4}_file_flush should consume writeback error | From | "chenxiaosong (A)" <> |
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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?
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 ```
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