Messages in this thread | | | Date | Fri, 1 Apr 2022 15:03:34 +0800 | Subject | Re: [PATCH -next,v2 0/3] nfs: handle writeback errors correctly | From | "chenxiaosong (A)" <> |
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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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