[ltt-dev] [PATCH] nfs: add support for splice writes

[Masahiro Tamori]

Hello Suresh and Mathieu,

2009/4/2 Suresh Jayaraman <sjayaraman at suse.de>:
> Mathieu Desnoyers wrote:
>> * Suresh Jayaraman (sjayaraman at suse.de) wrote:
>>> This patch attempts to add splice writes support. In essence, it just
>>> calls generic_file_splice_write() after doing a little sanity check.
>>> This would allow LTTng users that are using NFS to store trace data.
>>> There could be more applications that could be benefitted too.
>>>
>>> I have tested this using the Jens' test program and have found no
>>> real issues. The test program is inlined below:
>>>
>>
>> There is just a small checkpatch nit that I'll fix directly in place in
>> the LTTng tree.
>>
>> WARNING: %Ld/%Lu are not-standard C, use %lld/%llu
>> #93: FILE: fs/nfs/file.c:564:
>> +   dprintk("NFS splice_write(%s/%s, %lu@%Lu)\n",
>>
>> total: 0 errors, 1 warnings, 42 lines checked
>>
>
> Yes, I noticed it. There are quite a few places in nfs code where we
> happened to use that (that doesn't imply that it shouldn't be fixed), so
> I thought it's OK.
>
>> That's great ! I'll pull it in the LTTng tree so my users can try it.
>> They currently cannot write LTTng traces to NFS mounts anyway.
>
> Yes, please report the test results. Would appreciate it very much.
>
>
> Thanks,

Thank you for creating a patch !!

I tested it, and it works fine.

My environment is following,
LTTV 0.12.10
LTTng 0.100
LTT Control 0.65
Kernles 2.6.29

LTTng version is old now, but the test is passed on ARM11 target.

Furthermore, I run the splice test and the test is passed too.
The test code is copied from
http://kzk9.net/blog/2007/05/splice2.html
(Japanese page)

Thanks all people who commented this issue.

Best regards,
Masahiro Tamori

>
>>>
>>> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
>>> index 90f292b..13d6a00 100644
>>> --- a/fs/nfs/file.c
>>> +++ b/fs/nfs/file.c
>>> @@ -47,6 +47,9 @@ static ssize_t nfs_file_splice_read(struct file *filp, loff_t *ppos,
>>>                   size_t count, unsigned int flags);
>>> static ssize_t nfs_file_read(struct kiocb *, const struct iovec *iov,
>>>               unsigned long nr_segs, loff_t pos);
>>> +static ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
>>> +                  struct file *filp, loff_t *ppos,
>>> +                  size_t count, unsigned int flags);
>>> static ssize_t nfs_file_write(struct kiocb *, const struct iovec *iov,
>>>               unsigned long nr_segs, loff_t pos);
>>> static int nfs_file_flush(struct file *, fl_owner_t id);
>>> @@ -76,6 +79,7 @@ const struct file_operations nfs_file_operations = {
>>>   .lock      = nfs_lock,
>>>   .flock     = nfs_flock,
>>>   .splice_read  = nfs_file_splice_read,
>>> +  .splice_write  = nfs_file_splice_write,
>>>   .check_flags  = nfs_check_flags,
>>>   .setlease    = nfs_setlease,
>>> };
>>> @@ -550,6 +554,26 @@ out_swapfile:
>>>   goto out;
>>> }
>>>
>>> +static ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
>>> +                 struct file *filp, loff_t *ppos,
>>> +                 size_t count, unsigned int flags)
>>> +{
>>> +  struct dentry *dentry = filp->f_path.dentry;
>>> +  struct inode *inode = dentry->d_inode;
>>> +
>>> +  dprintk("NFS splice_write(%s/%s, %lu@%Lu)\n",
>>> +      dentry->d_parent->d_name.name, dentry->d_name.name,
>>> +      (unsigned long) count, (unsigned long long) *ppos);
>>> +
>>> +  if (IS_SWAPFILE(inode)) {
>>> +      printk(KERN_INFO "NFS: attempt to write to active swap"
>>> +          "file!\n");
>>> +      return -EBUSY;
>>> +  }
>>> +
>>> +  return generic_file_splice_write(pipe, filp, ppos, count, flags);
>>> +}
>>> +
>>> static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
>>> {
>>>   struct inode *inode = filp->f_mapping->host;
>>>
>>
>
>
> --
> Suresh Jayaraman
>
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