Re: Re: [RESEND PATCH V5] ceph:Implement readv/preadv for sync operation

[majianpeng <majianpeng@gmail.com>]

>On 09/24/2013 04:54 PM, majianpeng wrote:
>>> On 09/24/2013 04:05 PM, majianpeng wrote:
>>>> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>>>> index 3de8982..5422d8e 100644
>>>> --- a/fs/ceph/file.c
>>>> +++ b/fs/ceph/file.c
>>>> @@ -408,51 +408,94 @@ 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;
>>>> +	u64 off = iocb->ki_pos;
>>>>  	int num_pages, ret;
>>>>  
>>>> -	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;
>>>> -
>>>> -	ret = striped_read(inode, off, len, pages, num_pages, checkeof,
>>>> -			   file->f_flags & O_DIRECT,
>>>> -			   (unsigned long)data & ~PAGE_MASK);
>>>> +		return ret;
>>>>  
>>>> -	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 (file->f_flags & O_DIRECT) {
>>>> +		while (iov_iter_count(i)) {
>>>> +			void __user *data = i->iov[0].iov_base + i->iov_offset;
>>>> +			size_t len = i->iov[0].iov_len - 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;
>>>> +			iov_iter_advance(i, ret);
>>>> +			if (ret < len)
>>>> +				break;
>>>> +		}
>>>> +	} 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);
>>>> +		if (ret > 0) {
>>>> +			int l, k = 0;
>>>> +			size_t left = len = ret;
>>>> +
>>>> +			while (left) {
>>>> +				void __user *data = i->iov[0].iov_base
>>>> +							+ 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) {
>>>> +					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;
>>>> +			}
>>>> +		}
>>>>  		ceph_release_page_vector(pages, num_pages);
>>>> +	}
>>>> +
>>>> +	if (off > iocb->ki_pos) {
>>>> +		ret = off - iocb->ki_pos;
>>>> +		iocb->ki_pos = off;
>>>> +		iocb->ki_left -= ret;
>>>> +	}
>>>> +
>>>>  	dout("sync_read result %d\n", ret);
>>>>  	return ret;
>>>>  }
>>>> @@ -647,17 +690,16 @@ 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;
>>>
>>> len = iocb->ki_left;
>> Yes, the dout need this.
>> 
>>>
>>>>  	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;
>>>>  
>>>
>>> I think we should put label 'again' here.
>> Ok
>> 
>>>
>>>>  	dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
>>>>  	     inode, ceph_vinop(inode), pos, (unsigned)len, inode);
>>>> +
>>>>  again:
>>>>  	if (fi->fmode & CEPH_FILE_MODE_LAZY)
>>>>  		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
>>>> @@ -665,38 +707,61 @@ again:
>>>>  		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;
>>>> +
>>>> +		if (!read) {
>>>> +			ret = generic_segment_checks(iov, &nr_segs,
>>>> +							&len, VERIFY_WRITE);
>>>> +			if (ret)
>>>> +				goto out;
>>>> +		}
>>>> +
>>>> +		iocb->ki_left = len;
>>>
>>> iocb->ki_left = len - read ?
>> Before goto again, i let 'len -= ret'.
>> len mean the left size.
>>>
>>>
>>>> +		iov_iter_init(&i, iov, nr_segs, len, read);
>>>>  		/* hmm, this isn't really async... */
>>>> -		ret = ceph_sync_read(filp, base, len, ppos, &checkeof);
>>>> -	else
>>>> +		ret = ceph_sync_read(iocb, &i, &checkeof);
>>>> +	} else {
>>>> +		/*
>>>> +		 * We can't modify the content of iov,
>>>> +		 * so we only read from beginning.
>>>> +		 */
>>>> +		if (read)
>>>> +			iocb->ki_pos = pos;
>>>
>>> forget to set 'read' to 0 ?
>> When define read, i set read = 0.
>>   >int checkeof = 0, read = 0;
>
>I mean you need to reset 'read' to 0 here, because 'read' is used for calculating the return value.
>
Yes, i see. 
by the way, dout used pos and len so i think we should put dout in different place.

>
>---
>if (read) {
>  iocb->ki_pos = pos;
>  read = 0;
>}
>
>
>>>
>>>
>>>>  		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);
>>>> +		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);
>>>> +		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;
>>>> -			base += ret;
>>>>  			len -= ret;
>>>>  			checkeof = 0;
>>>>  			goto again;
>>>>  		}
>>>>  	}
>>>> -	if (ret >= 0)
>>>> +
>>>> +	if (ret > 0)
>>>>  		ret += read;
>>>
>>> what is the purpose of this change ?
>> Sorry, i make a mistake.
>> 
>>>
>>> Regards
>>> Yan, Zheng
>>>>  
>>>>  	return ret;
>>>> -- 
>>>
>> 
>