From e824f99adaaf1ed0e03eac8574599af6d992163d Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Tue, 1 Aug 2017 11:53:49 -0400
Subject: NFSv4: Use a mutex to protect the per-inode commit lists

The commit lists can get very large, so using the inode->i_lock can
end up affecting general metadata performance.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 fs/nfs/write.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

(limited to 'fs/nfs/write.c')

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 8d8fa6d4cfcc..5ab5ca24b48a 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -195,7 +195,7 @@ nfs_page_find_swap_request(struct page *page)
 	struct nfs_page *req = NULL;
 	if (!PageSwapCache(page))
 		return NULL;
-	spin_lock(&inode->i_lock);
+	mutex_lock(&nfsi->commit_mutex);
 	if (PageSwapCache(page)) {
 		req = nfs_page_search_commits_for_head_request_locked(nfsi,
 			page);
@@ -204,7 +204,7 @@ nfs_page_find_swap_request(struct page *page)
 			kref_get(&req->wb_kref);
 		}
 	}
-	spin_unlock(&inode->i_lock);
+	mutex_unlock(&nfsi->commit_mutex);
 	return req;
 }
 
@@ -856,7 +856,8 @@ nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
  * number of outstanding requests requiring a commit as well as
  * the MM page stats.
  *
- * The caller must hold cinfo->inode->i_lock, and the nfs_page lock.
+ * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
+ * nfs_page lock.
  */
 void
 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
@@ -884,9 +885,9 @@ EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 void
 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 {
-	spin_lock(&cinfo->inode->i_lock);
+	mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 	nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
-	spin_unlock(&cinfo->inode->i_lock);
+	mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 	if (req->wb_page)
 		nfs_mark_page_unstable(req->wb_page, cinfo);
 }
@@ -964,11 +965,11 @@ nfs_clear_request_commit(struct nfs_page *req)
 		struct nfs_commit_info cinfo;
 
 		nfs_init_cinfo_from_inode(&cinfo, inode);
-		spin_lock(&inode->i_lock);
+		mutex_lock(&NFS_I(inode)->commit_mutex);
 		if (!pnfs_clear_request_commit(req, &cinfo)) {
 			nfs_request_remove_commit_list(req, &cinfo);
 		}
-		spin_unlock(&inode->i_lock);
+		mutex_unlock(&NFS_I(inode)->commit_mutex);
 		nfs_clear_page_commit(req->wb_page);
 	}
 }
@@ -1027,7 +1028,7 @@ nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
 	return cinfo->mds->ncommit;
 }
 
-/* cinfo->inode->i_lock held by caller */
+/* NFS_I(cinfo->inode)->commit_mutex held by caller */
 int
 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
 		     struct nfs_commit_info *cinfo, int max)
@@ -1039,13 +1040,12 @@ nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
 		if (!nfs_lock_request(req))
 			continue;
 		kref_get(&req->wb_kref);
-		if (cond_resched_lock(&cinfo->inode->i_lock))
-			list_safe_reset_next(req, tmp, wb_list);
 		nfs_request_remove_commit_list(req, cinfo);
 		nfs_list_add_request(req, dst);
 		ret++;
 		if ((ret == max) && !cinfo->dreq)
 			break;
+		cond_resched();
 	}
 	return ret;
 }
@@ -1065,7 +1065,7 @@ nfs_scan_commit(struct inode *inode, struct list_head *dst,
 {
 	int ret = 0;
 
-	spin_lock(&cinfo->inode->i_lock);
+	mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 	if (cinfo->mds->ncommit > 0) {
 		const int max = INT_MAX;
 
@@ -1073,7 +1073,7 @@ nfs_scan_commit(struct inode *inode, struct list_head *dst,
 					   cinfo, max);
 		ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
 	}
-	spin_unlock(&cinfo->inode->i_lock);
+	mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 	return ret;
 }
 
-- 
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