Re: [PATCH v2 08/16] CIFS: Separate writing from iovec write

[Pavel Shilovsky <pshilovsky-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>]

2014-07-21 9:05 GMT+04:00 Shirish Pargaonkar <shirishpargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> On Fri, Jun 27, 2014 at 4:57 AM, Pavel Shilovsky <pshilovsky-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org> wrote:
>> Signed-off-by: Pavel Shilovsky <pshilovsky-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>
>> ---
>>  fs/cifs/file.c | 79 ++++++++++++++++++++++++++++++++++------------------------
>>  1 file changed, 47 insertions(+), 32 deletions(-)
>>
>> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>> index e2a735a..06080e0 100644
>> --- a/fs/cifs/file.c
>> +++ b/fs/cifs/file.c
>> @@ -2468,41 +2468,17 @@ wdata_fill_from_iovec(struct cifs_writedata *wdata, struct iov_iter *from,
>>         return rc;
>>  }
>>
>> -static ssize_t
>> -cifs_iovec_write(struct file *file, struct iov_iter *from, loff_t *poffset)
>> +static int
>> +cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
>> +                    struct cifsFileInfo *open_file,
>> +                    struct cifs_sb_info *cifs_sb, struct list_head *wdata_list)
>>  {
>> +       int rc = 0;
>> +       size_t cur_len;
>>         unsigned long nr_pages, i;
>> -       size_t len, cur_len;
>> -       ssize_t total_written = 0;
>> -       loff_t offset;
>> -       struct cifsFileInfo *open_file;
>> -       struct cifs_tcon *tcon;
>> -       struct cifs_sb_info *cifs_sb;
>> -       struct cifs_writedata *wdata, *tmp;
>> -       struct list_head wdata_list;
>> -       int rc;
>> +       struct cifs_writedata *wdata;
>>         pid_t pid;
>>
>> -       len = iov_iter_count(from);
>> -       rc = generic_write_checks(file, poffset, &len, 0);
>> -       if (rc)
>> -               return rc;
>> -
>> -       if (!len)
>> -               return 0;
>> -
>> -       iov_iter_truncate(from, len);
>> -
>> -       INIT_LIST_HEAD(&wdata_list);
>> -       cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
>> -       open_file = file->private_data;
>> -       tcon = tlink_tcon(open_file->tlink);
>> -
>> -       if (!tcon->ses->server->ops->async_writev)
>> -               return -ENOSYS;
>> -
>> -       offset = *poffset;
>> -
>>         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
>>                 pid = open_file->pid;
>>         else
>> @@ -2546,11 +2522,50 @@ cifs_iovec_write(struct file *file, struct iov_iter *from, loff_t *poffset)
>>                         break;
>>                 }
>>
>> -               list_add_tail(&wdata->list, &wdata_list);
>> +               list_add_tail(&wdata->list, wdata_list);
>>                 offset += cur_len;
>>                 len -= cur_len;
>>         } while (len > 0);
>>
>> +       return rc;
>> +}
>> +
>> +static ssize_t
>> +cifs_iovec_write(struct file *file, struct iov_iter *from, loff_t *poffset)
>> +{
>> +       size_t len;
>> +       ssize_t total_written = 0;
>> +       loff_t offset;
>> +       struct cifsFileInfo *open_file;
>> +       struct cifs_tcon *tcon;
>> +       struct cifs_sb_info *cifs_sb;
>> +       struct cifs_writedata *wdata, *tmp;
>> +       struct list_head wdata_list;
>> +       int rc;
>> +
>> +       len = iov_iter_count(from);
>> +       rc = generic_write_checks(file, poffset, &len, 0);
>> +       if (rc)
>> +               return rc;
>> +
>> +       if (!len)
>> +               return 0;
>> +
>> +       iov_iter_truncate(from, len);
>> +
>> +       INIT_LIST_HEAD(&wdata_list);
>> +       cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
>> +       open_file = file->private_data;
>> +       tcon = tlink_tcon(open_file->tlink);
>> +
>> +       if (!tcon->ses->server->ops->async_writev)
>> +               return -ENOSYS;
>> +
>> +       offset = *poffset;
>
> we do not use offset in this function after assignment

Yes!

>
>> +
>> +       rc = cifs_write_from_iter(*poffset, len, from, open_file, cifs_sb,
>> +                                 &wdata_list);
>
> and do not act on the value of rc (if ENOMEM) here.
>

This patch doesn't change the logic of the function: if at least one
write succeeds, we return a short write regardless of any error from
other writes.

-- 
Best regards,
Pavel Shilovsky.