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

[majianpeng <majianpeng@gmail.com>]

>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);
+				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;
 
-- 
1.8.1.2