Messages in this thread | | | Date | Mon, 11 Apr 2022 22:15:09 +0800 | Subject | Re: [PATCH -next,v2 0/3] nfs: handle writeback errors correctly | From | "chenxiaosong (A)" <> |
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ping ...
在 2022/4/1 15:03, chenxiaosong (A) 写道: > 在 2022/4/1 11:44, ChenXiaoSong 写道: >> v1: >> cover letter: (nfs: check writeback errors correctly) >> >> v2: >> - return more nuanced writeback errors in nfs_file_write(). >> - return writeback error in close()->flush() without consumed it. >> - fix: nfs_file_write() will always call nfs_wb_all() even if there is no >> new writeback error. >> >> >> ChenXiaoSong (3): >> NFS: return more nuanced writeback errors in nfs_file_write() >> NFS: nfs{,4}_file_flush() return correct writeback errors >> Revert "nfs: nfs_file_write() should check for writeback errors" >> >> fs/nfs/file.c | 23 ++++++++++------------- >> fs/nfs/nfs4file.c | 8 ++++---- >> fs/nfs/write.c | 5 +---- >> 3 files changed, 15 insertions(+), 21 deletions(-) >> > > It is not a good idea to modify error sequence mechanism, as the > `lib/errseq.c` described: > > 22 * Note that there is a risk of collisions if new errors are > being recorded > 23 * frequently, since we have so few bits to use as a counter. > 24 * > 25 * To mitigate this, one bit is used as a flag to tell whether > the value has > 26 * been sampled since a new value was recorded. That allows us > to avoid bumping > 27 * the counter if no one has sampled it since the last time an > error was > 28 * recorded. > > > So, if we want to report nuanced writeback error, it is better to detect > wb error from filemap_check_errors(), and then return > -(file->f_mapping->wb_err & MAX_ERRNO) to userspace without consume it. > > nfs_mapping_set_error > mapping_set_error > __filemap_set_wb_err // record error sequence > errseq_set > set_bit(..., &mapping->flags) // record address_space flag > > // it is not used to be reported, just used to detect > error = filemap_check_errors // -ENOSPC or -EIO > test_and_clear_bit(..., &mapping->flags) // error bit cleared > > // now we try to return nuanced writeback error > if (error) > return filemap_check_wb_err(file->f_mapping, 0); > return -(file->f_mapping->wb_err & MAX_ERRNO) >
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