[Devel] [PATCH RHEL7 COMMIT] ms/NFS: Don't call COMMIT in ->releasepage()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.11.1.vz7.39.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.11.1.vz7.39.1
------>
commit f80db0b78d067a78f5f93d605c0175c4178e0b0f
Author: Trond Myklebust <trond.myklebust at primarydata.com>
Date:   Thu Dec 7 14:03:38 2017 +0300

    ms/NFS: Don't call COMMIT in ->releasepage()
    
    While COMMIT has the potential to free up a lot of memory that is being
    taken by unstable writes, it isn't guaranteed to free up this particular
    page. Also, calling fsync() on the server is expensive and so we want to
    do it in a more controlled fashion, rather than have it triggered at
    random by the VM.
    
    Signed-off-by: Trond Myklebust <trond.myklebust at primarydata.com>
    
    https://jira.sw.ru/browse/PSBM-77949
    (cherry picked from commit 4f52b6bb8c57b9accafad526a429d6c0851cc62f)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 fs/nfs/file.c | 23 -----------------------
 1 file changed, 23 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 7ad044976fd1..24d3d0c44bc4 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -470,31 +470,8 @@ static void nfs_invalidate_page(struct page *page, unsigned int offset,
  */
 static int nfs_release_page(struct page *page, gfp_t gfp)
 {
-	struct address_space *mapping = page->mapping;
-
 	dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
 
-	/* Always try to initiate a 'commit' if relevant, but only
-	 * wait for it if __GFP_WAIT is set.  Even then, only wait 1
-	 * second and only if the 'bdi' is not congested.
-	 * Waiting indefinitely can cause deadlocks when the NFS
-	 * server is on this machine, when a new TCP connection is
-	 * needed and in other rare cases.  There is no particular
-	 * need to wait extensively here.  A short wait has the
-	 * benefit that someone else can worry about the freezer.
-	 */
-	if (mapping) {
-		struct nfs_server *nfss = NFS_SERVER(mapping->host);
-		nfs_commit_inode(mapping->host, 0);
-		if ((gfp & __GFP_WAIT) &&
-		    !bdi_write_congested(&nfss->backing_dev_info)) {
-			wait_on_page_bit_killable_timeout(page, PG_private,
-							  HZ);
-			if (PagePrivate(page))
-				set_bdi_congested(&nfss->backing_dev_info,
-						  BLK_RW_ASYNC);
-		}
-	}
 	/* If PagePrivate() is set, then the page is not freeable */
 	if (PagePrivate(page))
 		return 0;