Re: Re: [PATCH V2 1/2] ceph: Implement readv/preadv for sync operation.

[majianpeng <majianpeng@gmail.com>]

>On 09/09/2013 10:09 AM, majianpeng wrote:
>>> On 09/06/2013 04:48 PM, majianpeng wrote:
>>>> For readv/preadv sync-operatoin, ceph only do the first iov.
>>>> It don't think other iovs.Now implement this.
>>>>
>>>> V2:
>>>>   -add generic_segment_checks
>>>>   -using struct iov_iter replace cloning the iovs.
>>>>   -return previous successfully copied if ceph_copy_page_vector_to_user
>>>>    met error.
>>>>
>>>> Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
>>>> ---
>>>>  fs/ceph/file.c | 174 ++++++++++++++++++++++++++++++++++++++++-----------------
>>>>  1 file changed, 123 insertions(+), 51 deletions(-)
>>>>
>>>> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>>>> index 3de8982..1c28c52 100644
>>>> --- a/fs/ceph/file.c
>>>> +++ b/fs/ceph/file.c
>>>> @@ -408,51 +408,109 @@ more:
>>>>   *
>>>>   * If the read spans object boundary, just do multiple reads.
>>>>   */
>>>> -static ssize_t ceph_sync_read(struct file *file, char __user *data,
>>>> -			      unsigned len, loff_t *poff, int *checkeof)
>>>> +static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
>>>> +				int *checkeof)
>>>>  {
>>>> +	struct file *file = iocb->ki_filp;
>>>>  	struct inode *inode = file_inode(file);
>>>>  	struct page **pages;
>>>> -	u64 off = *poff;
>>>> -	int num_pages, ret;
>>>> +	u64 off = iocb->ki_pos;
>>>> +	int num_pages, ret, n;
>>>>  
>>>> -	dout("sync_read on file %p %llu~%u %s\n", file, off, len,
>>>> +	dout("sync_read on file %p %llu~%u %s\n", file, off,
>>>> +	     (unsigned)iocb->ki_left,
>>>>  	     (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
>>>> -
>>>> -	if (file->f_flags & O_DIRECT) {
>>>> -		num_pages = calc_pages_for((unsigned long)data, len);
>>>> -		pages = ceph_get_direct_page_vector(data, num_pages, true);
>>>> -	} else {
>>>> -		num_pages = calc_pages_for(off, len);
>>>> -		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
>>>> -	}
>>>> -	if (IS_ERR(pages))
>>>> -		return PTR_ERR(pages);
>>>> -
>>>>  	/*
>>>>  	 * flush any page cache pages in this range.  this
>>>>  	 * will make concurrent normal and sync io slow,
>>>>  	 * but it will at least behave sensibly when they are
>>>>  	 * in sequence.
>>>>  	 */
>>>> -	ret = filemap_write_and_wait(inode->i_mapping);
>>>> +	ret = filemap_write_and_wait_range(inode->i_mapping, off,
>>>> +						off + iocb->ki_left);
>>>>  	if (ret < 0)
>>>> -		goto done;
>>>> +		return ret;
>>>>  
>>>> -	ret = striped_read(inode, off, len, pages, num_pages, checkeof,
>>>> -			   file->f_flags & O_DIRECT,
>>>> -			   (unsigned long)data & ~PAGE_MASK);
>>>> +	if (file->f_flags & O_DIRECT) {
>>>> +		for (n = 0; n < i->nr_segs; n++) {
>>>> +			void __user *data = i->iov[n].iov_base;
>>>> +			size_t len = i->iov[n].iov_len;
>>>> +
>>>> +			if (n == 0) {
>>>> +				len -=  i->iov_offset;
>>>> +				data += i->iov_offset;
>>>> +			}
>>>> +
>>>> +			num_pages = calc_pages_for((unsigned long)data, len);
>>>> +			pages = ceph_get_direct_page_vector(data,
>>>> +							    num_pages, true);
>>>> +			if (IS_ERR(pages))
>>>> +				return PTR_ERR(pages);
>>>> +
>>>> +			ret = striped_read(inode, off, len,
>>>> +					   pages, num_pages, checkeof,
>>>> +					   1, (unsigned long)data & ~PAGE_MASK);
>>>> +			ceph_put_page_vector(pages, num_pages, true);
>>>> +
>>>> +			if (ret <= 0)
>>>> +				break;
>>>> +			off += ret;
>>>> +			if (ret < len)
>>>> +				break;
>>>> +		}
>>>>  
>>>> -	if (ret >= 0 && (file->f_flags & O_DIRECT) == 0)
>>>> -		ret = ceph_copy_page_vector_to_user(pages, data, off, ret);
>>>> -	if (ret >= 0)
>>>> -		*poff = off + ret;
>>>> +		if (off > iocb->ki_pos) {
>>>> +			ret = off - iocb->ki_pos;
>>>> +			iocb->ki_pos = off;
>>>> +			iocb->ki_left -= ret;
>>>> +		}
>>>> +	} else {
>>>> +		size_t len = iocb->ki_left;
>>>>  
>>>> -done:
>>>> -	if (file->f_flags & O_DIRECT)
>>>> -		ceph_put_page_vector(pages, num_pages, true);
>>>> -	else
>>>> +		num_pages = calc_pages_for(off, len);
>>>> +		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
>>>> +		if (IS_ERR(pages))
>>>> +			return PTR_ERR(pages);
>>>> +		ret = striped_read(inode, off, len, pages,
>>>> +					num_pages, checkeof, 0, 0);
>>>> +		len = ret;
>>>> +		if (len) {
>>>> +			int l, k = 0;
>>>> +			size_t left = len;
>>>> +
>>>> +			for (n = 0; n < i->nr_segs && left; n++) {
>>>> +				void __user *data = i->iov[n].iov_base;
>>>> +				l = min(left, i->iov[n].iov_len);
>>>> +
>>>> +				if (n == 0) {
>>>> +					data += i->iov_offset;
>>>> +					l = min(i->iov[0].iov_len - i->iov_offset,
>>>> +						left);
>>>> +				}
>>>> +
>>>> +				ret = ceph_copy_page_vector_to_user(&pages[k],
>>>> +								    data, off,
>>>> +								    l);
>>>> +				if (ret > 0) {
>>>> +					left -= ret;
>>>> +					off += ret;
>>>> +					k = calc_pages_for(iocb->ki_pos,
>>>> +							   len - left + 1) - 1;
>>>> +					BUG_ON(k >= num_pages && left);
>>>> +				} else
>>>> +					break;
>>>> +			}
>>>
>>> I think it's better to call iov_iter_advance() here instead of in ceph_aio_read(),
>>> and change the code to something like:
>>> ----
>>> while (iov_iter_count(&i) && left > 0) {
>>>   void __user *data = i->iov->iov_base + i->iov_offset;
>>>   l = min(left, i->iov->iov_len - i->iov_offset);
>>>
>>>   ret = ceph_copy_page_vector_to_user(&pages[k], data, off, l);
>>>   if (ret > 0) {
>>>     iov_iter_advance(&i, ret);
>>>     left -= ret;
>>>     off += ret;
>>>     k = calc_pages_for(iocb->ki_pos, len - left + 1) - 1;
>>>     BUG_ON(k >= num_pages && left);
>>>   } else
>>>     break;
>>> }
>>>
>>>
>>> rest change looks good.
>>>
>>> Regards
>>> Yan, Zheng
>>>
>> Thanks!
>> Jianpeng Ma
>> 
>> 
>> Subject:ceph: Implement readv/preadv for sync operation.
>> 
>> For readv/preadv sync-operatoin, ceph only do the first iov.
>> It don't think other iovs.Now implement this.
>> 
>> V2:
>>   -add generic_segment_checks
>>   -using struct iov_iter replace cloning the iovs.
>>   -return previous successfully copied if ceph_copy_page_vector_to_user
>>    met error.
>> 
>> Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
>> ---
>>  fs/ceph/file.c | 171 ++++++++++++++++++++++++++++++++++++++++-----------------
>>  1 file changed, 120 insertions(+), 51 deletions(-)
>> 
>> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>> index 3de8982..78018c9 100644
>> --- a/fs/ceph/file.c
>> +++ b/fs/ceph/file.c
>> @@ -408,51 +408,106 @@ more:
>>   *
>>   * If the read spans object boundary, just do multiple reads.
>>   */
>> -static ssize_t ceph_sync_read(struct file *file, char __user *data,
>> -			      unsigned len, loff_t *poff, int *checkeof)
>> +static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
>> +				int *checkeof)
>>  {
>> +	struct file *file = iocb->ki_filp;
>>  	struct inode *inode = file_inode(file);
>>  	struct page **pages;
>> -	u64 off = *poff;
>> -	int num_pages, ret;
>> +	u64 off = iocb->ki_pos;
>> +	int num_pages, ret, n;
>>  
>> -	dout("sync_read on file %p %llu~%u %s\n", file, off, len,
>> +	dout("sync_read on file %p %llu~%u %s\n", file, off,
>> +	     (unsigned)iocb->ki_left,
>>  	     (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
>> -
>> -	if (file->f_flags & O_DIRECT) {
>> -		num_pages = calc_pages_for((unsigned long)data, len);
>> -		pages = ceph_get_direct_page_vector(data, num_pages, true);
>> -	} else {
>> -		num_pages = calc_pages_for(off, len);
>> -		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
>> -	}
>> -	if (IS_ERR(pages))
>> -		return PTR_ERR(pages);
>> -
>>  	/*
>>  	 * flush any page cache pages in this range.  this
>>  	 * will make concurrent normal and sync io slow,
>>  	 * but it will at least behave sensibly when they are
>>  	 * in sequence.
>>  	 */
>> -	ret = filemap_write_and_wait(inode->i_mapping);
>> +	ret = filemap_write_and_wait_range(inode->i_mapping, off,
>> +						off + iocb->ki_left);
>>  	if (ret < 0)
>> -		goto done;
>> +		return ret;
>>  
>> -	ret = striped_read(inode, off, len, pages, num_pages, checkeof,
>> -			   file->f_flags & O_DIRECT,
>> -			   (unsigned long)data & ~PAGE_MASK);
>> +	if (file->f_flags & O_DIRECT) {
>> +		for (n = 0; n < i->nr_segs; n++) {
>> +			void __user *data = i->iov[n].iov_base;
>> +			size_t len = i->iov[n].iov_len;
>> +
>> +			if (n == 0) {
>> +				len -=  i->iov_offset;
>> +				data += i->iov_offset;
>> +			}
>> +
>> +			num_pages = calc_pages_for((unsigned long)data, len);
>> +			pages = ceph_get_direct_page_vector(data,
>> +							    num_pages, true);
>> +			if (IS_ERR(pages))
>> +				return PTR_ERR(pages);
>> +
>> +			ret = striped_read(inode, off, len,
>> +					   pages, num_pages, checkeof,
>> +					   1, (unsigned long)data & ~PAGE_MASK);
>> +			ceph_put_page_vector(pages, num_pages, true);
>> +
>> +			if (ret <= 0)
>> +				break;
>> +			off += ret;
>> +			if (ret < len)
>> +				break;
>> +		}
>>  
>> -	if (ret >= 0 && (file->f_flags & O_DIRECT) == 0)
>> -		ret = ceph_copy_page_vector_to_user(pages, data, off, ret);
>> -	if (ret >= 0)
>> -		*poff = off + ret;
>> +		if (off > iocb->ki_pos) {
>> +			ret = off - iocb->ki_pos;
>> +			iocb->ki_pos = off;
>> +			iocb->ki_left -= ret;
>> +		}
>> +	} else {
>> +		size_t len = iocb->ki_left;
>>  
>> -done:
>> -	if (file->f_flags & O_DIRECT)
>> -		ceph_put_page_vector(pages, num_pages, true);
>> -	else
>> +		num_pages = calc_pages_for(off, len);
>> +		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
>> +		if (IS_ERR(pages))
>> +			return PTR_ERR(pages);
>> +		ret = striped_read(inode, off, len, pages,
>> +					num_pages, checkeof, 0, 0);
>> +		len = ret;
>> +		if (len) {
>> +			int l, k = 0;
>> +			size_t left = len;
>> +
>> +			while (left) {
>> +				void __user *data = i->iov[0].iov_base
>> +							+ i->iov_offset;
>> +				l = min(i->iov[0].iov_len - i->iov_offset,
>> +					len);
>> +
>> +				ret = ceph_copy_page_vector_to_user(&pages[k],
>> +								    data, off,
>> +								    l);
>> +				if (ret > 0) {
>> +					iov_iter_advance(i, ret);
>> +					left -= ret;
>> +					off += ret;
>> +					k = calc_pages_for(iocb->ki_pos,
>> +							   len - left + 1) - 1;
>> +					BUG_ON(k >= num_pages && left);
>> +				} else
>> +					break;
>> +			}
>> +
>> +			len -= left;
>> +			if (len > 0) {
>> +				iocb->ki_pos += len;
>> +				iocb->ki_left -= len;
>> +				ret = len;
>> +			}
>> +		}
>>  		ceph_release_page_vector(pages, num_pages);
>> +	}
>> +
>>  	dout("sync_read result %d\n", ret);
>>  	return ret;
>>  }
>> @@ -647,55 +702,69 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
>>  {
>>  	struct file *filp = iocb->ki_filp;
>>  	struct ceph_file_info *fi = filp->private_data;
>> -	loff_t *ppos = &iocb->ki_pos;
>> -	size_t len = iov->iov_len;
>> +	size_t len = 0;
>>  	struct inode *inode = file_inode(filp);
>>  	struct ceph_inode_info *ci = ceph_inode(inode);
>> -	void __user *base = iov->iov_base;
>>  	ssize_t ret;
>>  	int want, got = 0;
>>  	int checkeof = 0, read = 0;
>>  
>> +
>>  	dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
>>  	     inode, ceph_vinop(inode), pos, (unsigned)len, inode);
>> -again:
>> +
>> +	ret = generic_segment_checks(iov, &nr_segs, &len, VERIFY_WRITE);
>> +	if (ret)
>> +		return ret;
>> +
>>  	if (fi->fmode & CEPH_FILE_MODE_LAZY)
>>  		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
>>  	else
>>  		want = CEPH_CAP_FILE_CACHE;
>>  	ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, &got, -1);
>>  	if (ret < 0)
>> -		goto out;
>> +		return ret;
>> +
>>  	dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s\n",
>>  	     inode, ceph_vinop(inode), pos, (unsigned)len,
>>  	     ceph_cap_string(got));
>>  
>>  	if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
>>  	    (iocb->ki_filp->f_flags & O_DIRECT) ||
>> -	    (fi->flags & CEPH_F_SYNC))
>> +	    (fi->flags & CEPH_F_SYNC)) {
>> +		struct iov_iter i;
>> +
>> +		iocb->ki_left = len;
>> +		iov_iter_init(&i, iov, nr_segs, len, 0);
>> +again:
>>  		/* hmm, this isn't really async... */
>> -		ret = ceph_sync_read(filp, base, len, ppos, &checkeof);
>> -	else
>> +		ret = ceph_sync_read(iocb, &i, &checkeof);
>> +
>> +		if (checkeof && ret >= 0) {
>> +			int statret = ceph_do_getattr(inode,
>> +						      CEPH_STAT_CAP_SIZE);
>> +
>> +			/* hit EOF or hole? */
>> +			if (statret == 0 && iocb->ki_pos < inode->i_size &&
>> +				iocb->ki_left) {
>> +				dout("sync_read hit hole, ppos %lld < size %lld"
>> +				     ", reading more\n", iocb->ki_pos,
>> +				     inode->i_size);
>> +
>> +				read += ret;
>> +				iov_iter_advance(&i, ret);
>
>I think this "iov_iter_advance" is superfluous. Other than this, your patch looks
>good.
>
No, i made a error.In ceph_sync_read, for direct mode, i don't use iov_iter_advance.
But for sync mode, i used.So it's error.
I'll check carefully and resend again.

Thanks!
Jianpeng Ma

>By the way, your email is base64 encoded. please make your email client use plain text instead.
>
>Regards
>Yan, Zheng
>
>
>
>> +				checkeof = 0;
>> +				goto again;
>> +			}
>> +		}
>> +
>> +	} else
>>  		ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
>>  
>> -out:
>>  	dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",
>>  	     inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
>>  	ceph_put_cap_refs(ci, got);
>>  
>> -	if (checkeof && ret >= 0) {
>> -		int statret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
>> -
>> -		/* hit EOF or hole? */
>> -		if (statret == 0 && *ppos < inode->i_size) {
>> -			dout("aio_read sync_read hit hole, ppos %lld < size %lld, reading more\n", *ppos, inode->i_size);
>> -			read += ret;
>> -			base += ret;
>> -			len -= ret;
>> -			checkeof = 0;
>> -			goto again;
>> -		}
>> -	}
>>  	if (ret >= 0)
>>  		ret += read;
>>  
>> 
>