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Commit 4506cfb6 authored by Ryan Ding's avatar Ryan Ding Committed by Linus Torvalds
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ocfs2: record UNWRITTEN extents when populate write desc 



To support direct io in ocfs2_write_begin_nolock & ocfs2_write_end_nolock.

There is still one issue in the direct write procedure.

phase 1: alloc extent with UNWRITTEN flag
phase 2: submit direct data to disk, add zero page to page cache
phase 3: clear UNWRITTEN flag when data has been written to disk

When there are 2 direct write A(0~3KB),B(4~7KB) writing to the same
cluster 0~7KB (cluster size 8KB).  Write request A arrive phase 2 first,
it will zero the region (4~7KB).  Before request A enter to phase 3,
request B arrive phase 2, it will zero region (0~3KB).  This is just like
request B steps request A.

To resolve this issue, we should let request B knows this cluster is already
under zero, to prevent it from steps the previous write request.

This patch will add function ocfs2_unwritten_check() to do this job.  It
will record all clusters that are under direct write(it will be recorded
in the 'ip_unwritten_list' member of inode info), and prevent the later
direct write writing to the same cluster to do the zero work again.

Signed-off-by: default avatarRyan Ding <ryan.ding@oracle.com>
Reviewed-by: default avatarJunxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2de6a3c7

fs/ocfs2/aops.c

+99 −5
Original line number Diff line number Diff line
@@ -1201,6 +1201,13 @@ int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno, 


#define OCFS2_MAX_CLUSTERS_PER_PAGE	(PAGE_CACHE_SIZE / OCFS2_MIN_CLUSTERSIZE)



struct ocfs2_unwritten_extent {

	struct list_head	ue_node;

	struct list_head	ue_ip_node;

	u32			ue_cpos;

	u32			ue_phys;

};



/*

 * Describe the state of a single cluster to be written to.

 */
@@ -1275,6 +1282,8 @@ struct ocfs2_write_ctxt { 
	struct buffer_head		*w_di_bh;



	struct ocfs2_cached_dealloc_ctxt w_dealloc;



	struct list_head		w_unwritten_list;

};



void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
@@ -1313,8 +1322,25 @@ static void ocfs2_unlock_pages(struct ocfs2_write_ctxt *wc) 
	ocfs2_unlock_and_free_pages(wc->w_pages, wc->w_num_pages);

}



static void ocfs2_free_write_ctxt(struct ocfs2_write_ctxt *wc)

static void ocfs2_free_unwritten_list(struct inode *inode,

				 struct list_head *head)

{

	struct ocfs2_inode_info *oi = OCFS2_I(inode);

	struct ocfs2_unwritten_extent *dz = NULL, *tmp = NULL;



	list_for_each_entry_safe(dz, tmp, head, ue_node) {

		list_del(&dz->ue_node);

		spin_lock(&oi->ip_lock);

		list_del(&dz->ue_ip_node);

		spin_unlock(&oi->ip_lock);

		kfree(dz);

	}

}



static void ocfs2_free_write_ctxt(struct inode *inode,

				  struct ocfs2_write_ctxt *wc)

{

	ocfs2_free_unwritten_list(inode, &wc->w_unwritten_list);

	ocfs2_unlock_pages(wc);

	brelse(wc->w_di_bh);

	kfree(wc);
@@ -1346,6 +1372,7 @@ static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp, 
		wc->w_large_pages = 0;



	ocfs2_init_dealloc_ctxt(&wc->w_dealloc);

	INIT_LIST_HEAD(&wc->w_unwritten_list);



	*wcp = wc;
@@ -1795,6 +1822,66 @@ static void ocfs2_set_target_boundaries(struct ocfs2_super *osb, 
	}

}



/*

 * Check if this extent is marked UNWRITTEN by direct io. If so, we need not to

 * do the zero work. And should not to clear UNWRITTEN since it will be cleared

 * by the direct io procedure.

 * If this is a new extent that allocated by direct io, we should mark it in

 * the ip_unwritten_list.

 */

static int ocfs2_unwritten_check(struct inode *inode,

				 struct ocfs2_write_ctxt *wc,

				 struct ocfs2_write_cluster_desc *desc)

{

	struct ocfs2_inode_info *oi = OCFS2_I(inode);

	struct ocfs2_unwritten_extent *dz = NULL, *new = NULL;

	int ret = 0;



	if (!desc->c_needs_zero)

		return 0;



retry:

	spin_lock(&oi->ip_lock);

	/* Needs not to zero no metter buffer or direct. The one who is zero

	 * the cluster is doing zero. And he will clear unwritten after all

	 * cluster io finished. */

	list_for_each_entry(dz, &oi->ip_unwritten_list, ue_ip_node) {

		if (desc->c_cpos == dz->ue_cpos) {

			BUG_ON(desc->c_new);

			desc->c_needs_zero = 0;

			desc->c_clear_unwritten = 0;

			goto unlock;

		}

	}



	if (wc->w_type != OCFS2_WRITE_DIRECT)

		goto unlock;



	if (new == NULL) {

		spin_unlock(&oi->ip_lock);

		new = kmalloc(sizeof(struct ocfs2_unwritten_extent),

			     GFP_NOFS);

		if (new == NULL) {

			ret = -ENOMEM;

			goto out;

		}

		goto retry;

	}

	/* This direct write will doing zero. */

	new->ue_cpos = desc->c_cpos;

	new->ue_phys = desc->c_phys;

	desc->c_clear_unwritten = 0;

	list_add_tail(&new->ue_ip_node, &oi->ip_unwritten_list);

	list_add_tail(&new->ue_node, &wc->w_unwritten_list);

	new = NULL;

unlock:

	spin_unlock(&oi->ip_lock);

out:

	if (new)

		kfree(new);

	return ret;

}



/*

 * Populate each single-cluster write descriptor in the write context

 * with information about the i/o to be done.
@@ -1879,6 +1966,12 @@ static int ocfs2_populate_write_desc(struct inode *inode, 
			desc->c_needs_zero = 1;

		}



		ret = ocfs2_unwritten_check(inode, wc, desc);

		if (ret) {

			mlog_errno(ret);

			goto out;

		}



		num_clusters--;

	}
@@ -2215,9 +2308,8 @@ int ocfs2_write_begin_nolock(struct address_space *mapping, 
	 * and non-sparse clusters we just extended.  For non-sparse writes,

	 * we know zeros will only be needed in the first and/or last cluster.

	 */

	if (clusters_to_alloc || extents_to_split ||

	    (wc->w_clen && (wc->w_desc[0].c_needs_zero ||

			    wc->w_desc[wc->w_clen - 1].c_needs_zero)))

	if (wc->w_clen && (wc->w_desc[0].c_needs_zero ||

			   wc->w_desc[wc->w_clen - 1].c_needs_zero))

		cluster_of_pages = 1;

	else

		cluster_of_pages = 0;
@@ -2296,7 +2388,7 @@ int ocfs2_write_begin_nolock(struct address_space *mapping, 
	ocfs2_commit_trans(osb, handle);



out:

	ocfs2_free_write_ctxt(wc);

	ocfs2_free_write_ctxt(inode, wc);



	if (data_ac) {

		ocfs2_free_alloc_context(data_ac);
@@ -2406,6 +2498,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping, 
	handle_t *handle = wc->w_handle;

	struct page *tmppage;



	BUG_ON(!list_empty(&wc->w_unwritten_list));



	if (handle) {

		ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode),

				wc->w_di_bh, OCFS2_JOURNAL_ACCESS_WRITE);

fs/ocfs2/inode.c

+3 −0
Original line number Diff line number Diff line
@@ -1170,6 +1170,9 @@ static void ocfs2_clear_inode(struct inode *inode) 
	mlog_bug_on_msg(!list_empty(&oi->ip_io_markers),

			"Clear inode of %llu, inode has io markers\n",

			(unsigned long long)oi->ip_blkno);

	mlog_bug_on_msg(!list_empty(&oi->ip_unwritten_list),

			"Clear inode of %llu, inode has unwritten extents\n",

			(unsigned long long)oi->ip_blkno);



	ocfs2_extent_map_trunc(inode, 0);

fs/ocfs2/inode.h

+3 −0
Original line number Diff line number Diff line
@@ -57,6 +57,9 @@ struct ocfs2_inode_info 
	u32				ip_flags; /* see below */

	u32				ip_attr; /* inode attributes */



	/* Record unwritten extents during direct io. */

	struct list_head		ip_unwritten_list;



	/* protected by recovery_lock. */

	struct inode			*ip_next_orphan;

fs/ocfs2/super.c

+1 −0
Original line number Diff line number Diff line
@@ -1745,6 +1745,7 @@ static void ocfs2_inode_init_once(void *data) 
	spin_lock_init(&oi->ip_lock);

	ocfs2_extent_map_init(&oi->vfs_inode);

	INIT_LIST_HEAD(&oi->ip_io_markers);

	INIT_LIST_HEAD(&oi->ip_unwritten_list);

	oi->ip_dir_start_lookup = 0;

	mutex_init(&oi->ip_unaligned_aio);

	init_rwsem(&oi->ip_alloc_sem);