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)
