lkml.org 
[lkml]   [2022]   [Apr]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH -next,v2 0/3] nfs: handle writeback errors correctly
From
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)
>

\
 
 \ /
  Last update: 2022-04-11 16:19    [W:0.056 / U:0.576 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site