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

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>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;
>
>
>>  		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;
>> -- 
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