2022-04-10 02:25:36

by Trond Myklebust

Subject: [PATCH 2/2] NFS: Don't report write errors twice

From: Trond Myklebust <[email protected]>

Any errors reported by the write() system call need to be cleared from
the file descriptor's error tracking. The current call to nfs_wb_all()
causes the error to be reported, but since it doesn't call
file_check_and_advance_wb_err(), we can end up reporting the same error
a second time when the application calls fsync().

Reported-by: ChenXiaoSong <[email protected]>
Fixes: ce368536dd61 ("nfs: nfs_file_write() should check for writeback errors")
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/file.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 81c80548a5c6..54dc6f176f5c 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -677,9 +677,10 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
/* Return error values */
error = filemap_check_wb_err(file->f_mapping, since);
if (nfs_need_check_write(file, inode, error)) {
- int err = nfs_wb_all(inode);
- if (err < 0)
- result = err;
+ nfs_wb_all(inode);
+ error = file_check_and_advance_wb_err(file);
+ if (error < 0)
+ result = error;
}
nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
out:
--
2.35.1

2022-04-11 22:23:03

by ChenXiaoSong

Subject: Re: [PATCH 2/2] NFS: Don't report write errors twice

在 2022/4/10 4:01, [email protected] 写道:
> From: Trond Myklebust <[email protected]>
>
> Any errors reported by the write() system call need to be cleared from
> the file descriptor's error tracking. The current call to nfs_wb_all()
> causes the error to be reported, but since it doesn't call
> file_check_and_advance_wb_err(), we can end up reporting the same error
> a second time when the application calls fsync().
>
> Reported-by: ChenXiaoSong <[email protected]>
> Fixes: ce368536dd61 ("nfs: nfs_file_write() should check for writeback errors")
> Signed-off-by: Trond Myklebust <[email protected]>
> ---
> fs/nfs/file.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
> index 81c80548a5c6..54dc6f176f5c 100644
> --- a/fs/nfs/file.c
> +++ b/fs/nfs/file.c
> @@ -677,9 +677,10 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
> /* Return error values */
> error = filemap_check_wb_err(file->f_mapping, since);
> if (nfs_need_check_write(file, inode, error)) {
> - int err = nfs_wb_all(inode);
> - if (err < 0)
> - result = err;
> + nfs_wb_all(inode);
> + error = file_check_and_advance_wb_err(file);
> + if (error < 0)
> + result = error;
> }
> nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
> out:
>

After merging this patchset, second `dd` of the following reproducer
will still report unexpected error: No space left on device.

Reproducer:
nfs server | nfs client

-----------------------------|---------------------------------------------
# No space left on server |
fallocate -l 100G /svr/nospc |
| mount -t nfs $nfs_server_ip:/ /mnt
|
| # Expected error: No space left on device
| dd if=/dev/zero of=/mnt/file count=1
ibs=10K
|
| # Release space on mountpoint
| rm /mnt/nospc
|
| # Unexpected error: No space left on device
| dd if=/dev/zero of=/mnt/file count=1
ibs=10K