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Commit 4af6b225 authored by Yehuda Sadeh's avatar Yehuda Sadeh Committed by Sage Weil
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ceph: refactor ceph_write_begin, fix ceph_page_mkwrite 



Originally ceph_page_mkwrite called ceph_write_begin, hoping that
the returned locked page would be the page that it was requested
to mkwrite. Factored out relevant part of ceph_page_mkwrite and
we lock the right page anyway.

Signed-off-by: default avatarYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent 972f0d3a

fs/ceph/addr.c

+51 −29
Original line number Diff line number Diff line
@@ -907,15 +907,13 @@ static int context_is_writeable_or_written(struct inode *inode, 
 * We are only allowed to write into/dirty the page if the page is

 * clean, or already dirty within the same snap context.

 */

static int ceph_write_begin(struct file *file, struct address_space *mapping,

			    loff_t pos, unsigned len, unsigned flags,

			    struct page **pagep, void **fsdata)

static int ceph_update_writeable_page(struct file *file,

			    loff_t pos, unsigned len,

			    struct page *page)

{

	struct inode *inode = file->f_dentry->d_inode;

	struct ceph_inode_info *ci = ceph_inode(inode);

	struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;

	struct page *page;

	pgoff_t index = pos >> PAGE_CACHE_SHIFT;

	loff_t page_off = pos & PAGE_CACHE_MASK;

	int pos_in_page = pos & ~PAGE_CACHE_MASK;

	int end_in_page = pos_in_page + len;
@@ -923,16 +921,6 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping, 
	struct ceph_snap_context *snapc;

	int r;



	/* get a page*/

retry:

	page = grab_cache_page_write_begin(mapping, index, 0);

	if (!page)

		return -ENOMEM;

	*pagep = page;



	dout("write_begin file %p inode %p page %p %d~%d\n", file,

	     inode, page, (int)pos, (int)len);



retry_locked:

	/* writepages currently holds page lock, but if we change that later, */

	wait_on_page_writeback(page);
@@ -964,7 +952,7 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping, 
			wait_event_interruptible(ci->i_cap_wq,

			       context_is_writeable_or_written(inode, snapc));

			ceph_put_snap_context(snapc);

			goto retry;

			return -EAGAIN;

		}



		/* yay, writeable, do it now (without dropping page lock) */
@@ -1021,6 +1009,35 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping, 
	return r;

}



/*

 * We are only allowed to write into/dirty the page if the page is

 * clean, or already dirty within the same snap context.

 */

static int ceph_write_begin(struct file *file, struct address_space *mapping,

			    loff_t pos, unsigned len, unsigned flags,

			    struct page **pagep, void **fsdata)

{

	struct inode *inode = file->f_dentry->d_inode;

	struct page *page;

	pgoff_t index = pos >> PAGE_CACHE_SHIFT;

	int r;



	do {

		/* get a page*/

		page = grab_cache_page_write_begin(mapping, index, 0);

		if (!page)

			return -ENOMEM;

		*pagep = page;



		dout("write_begin file %p inode %p page %p %d~%d\n", file,

	     	inode, page, (int)pos, (int)len);



		r = ceph_update_writeable_page(file, pos, len, page);

	} while (r == -EAGAIN);



	return r;

}



/*

 * we don't do anything in here that simple_write_end doesn't do

 * except adjust dirty page accounting and drop read lock on
@@ -1104,8 +1121,6 @@ static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) 
	struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;

	loff_t off = page->index << PAGE_CACHE_SHIFT;

	loff_t size, len;

	struct page *locked_page = NULL;

	void *fsdata = NULL;

	int ret;



	size = i_size_read(inode);
@@ -1116,23 +1131,30 @@ static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) 


	dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,

	     off, len, page, page->index);

	ret = ceph_write_begin(vma->vm_file, inode->i_mapping, off, len, 0,

			       &locked_page, &fsdata);

	WARN_ON(page != locked_page);

	if (!ret) {

		/*

		 * doing the following, instead of calling

		 * ceph_write_end. Note that we keep the

		 * page locked

		 */



	lock_page(page);



	ret = VM_FAULT_NOPAGE;

	if ((off > size) ||

	    (page->mapping != inode->i_mapping))

		goto out;



	ret = ceph_update_writeable_page(vma->vm_file, off, len, page);

	if (ret == 0) {

		/* success.  we'll keep the page locked. */

		set_page_dirty(page);

		up_read(&mdsc->snap_rwsem);

		page_cache_release(page);

		ret = VM_FAULT_LOCKED;

	} else {

		if (ret == -ENOMEM)

			ret = VM_FAULT_OOM;

		else

			ret = VM_FAULT_SIGBUS;

	}

out:

	dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);

	if (ret != VM_FAULT_LOCKED)

		unlock_page(page);

	return ret;

}