linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Josef Bacik <josef@toxicpanda.com>
To: kernel-team@fb.com, linux-kernel@vger.kernel.org,
	hannes@cmpxchg.org, tj@kernel.org, linux-fsdevel@vger.kernel.org,
	akpm@linux-foundation.org, riel@redhat.com, linux-mm@kvack.org,
	linux-btrfs@vger.kernel.org
Subject: [PATCH 7/9] mm: add a flag to indicate we used a cached page
Date: Wed, 26 Sep 2018 17:08:54 -0400	[thread overview]
Message-ID: <20180926210856.7895-8-josef@toxicpanda.com> (raw)
In-Reply-To: <20180926210856.7895-1-josef@toxicpanda.com>

This is preparation for dropping the mmap_sem in page_mkwrite.  We need
to know if we used our cached page so we can be sure it is the page we
already did the page_mkwrite stuff on so we don't have to redo all of
that work.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 include/linux/mm.h | 6 +++++-
 mm/filemap.c       | 5 ++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4a84ec976dfc..a7305d193c71 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -318,6 +318,9 @@ extern pgprot_t protection_map[16];
 #define FAULT_FLAG_USER		0x40	/* The fault originated in userspace */
 #define FAULT_FLAG_REMOTE	0x80	/* faulting for non current tsk/mm */
 #define FAULT_FLAG_INSTRUCTION  0x100	/* The fault was during an instruction fetch */
+#define FAULT_FLAG_USED_CACHED	0x200	/* Our vmf->page was from a previous
+					 * loop through the fault handler.
+					 */
 
 #define FAULT_FLAG_TRACE \
 	{ FAULT_FLAG_WRITE,		"WRITE" }, \
@@ -328,7 +331,8 @@ extern pgprot_t protection_map[16];
 	{ FAULT_FLAG_TRIED,		"TRIED" }, \
 	{ FAULT_FLAG_USER,		"USER" }, \
 	{ FAULT_FLAG_REMOTE,		"REMOTE" }, \
-	{ FAULT_FLAG_INSTRUCTION,	"INSTRUCTION" }
+	{ FAULT_FLAG_INSTRUCTION,	"INSTRUCTION" }, \
+	{ FAULT_FLAG_USED_CACHED,	"USED_CACHED" }
 
 /*
  * vm_fault is filled by the the pagefault handler and passed to the vma's
diff --git a/mm/filemap.c b/mm/filemap.c
index 5212ab637832..e9cb44bd35aa 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2556,6 +2556,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 		if (cached_page->mapping == mapping &&
 		    cached_page->index == offset) {
 			page = cached_page;
+			vmf->flags |= FAULT_FLAG_USED_CACHED;
 			goto have_cached_page;
 		}
 		unlock_page(cached_page);
@@ -2619,8 +2620,10 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 	 * We have a locked page in the page cache, now we need to check
 	 * that it's up-to-date. If not, it is going to be due to an error.
 	 */
-	if (unlikely(!PageUptodate(page)))
+	if (unlikely(!PageUptodate(page))) {
+		vmf->flags &= ~(FAULT_FLAG_USED_CACHED);
 		goto page_not_uptodate;
+	}
 
 	/*
 	 * Found the page and have a reference on it.
-- 
2.14.3

  parent reply	other threads:[~2018-09-26 21:08 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-26 21:08 [RFC][PATCH 0/9][V2] drop the mmap_sem when doing IO in the fault path Josef Bacik
2018-09-26 21:08 ` [PATCH 1/9] mm: infrastructure for page fault page caching Josef Bacik
2018-09-27 16:24   ` Matthew Wilcox
2018-09-26 21:08 ` [PATCH 2/9] mm: drop mmap_sem for page cache read IO submission Josef Bacik
2018-09-26 21:08 ` [PATCH 3/9] mm: clean up swapcache lookup and creation function names Josef Bacik
2018-09-26 21:08 ` [PATCH 4/9] mm: drop mmap_sem for swap read IO submission Josef Bacik
2018-09-26 21:08 ` [PATCH 5/9] mm: drop the mmap_sem in all read fault cases Josef Bacik
2018-09-26 21:08 ` [PATCH 6/9] mm: use the cached page for filemap_fault Josef Bacik
2018-09-26 21:08 ` Josef Bacik [this message]
2018-09-26 21:08 ` [PATCH 8/9] mm: allow ->page_mkwrite to do retries Josef Bacik
2018-09-26 21:08 ` [PATCH 9/9] btrfs: drop mmap_sem in mkwrite for btrfs Josef Bacik

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180926210856.7895-8-josef@toxicpanda.com \
    --to=josef@toxicpanda.com \
    --cc=akpm@linux-foundation.org \
    --cc=hannes@cmpxchg.org \
    --cc=kernel-team@fb.com \
    --cc=linux-btrfs@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=riel@redhat.com \
    --cc=tj@kernel.org \
    --subject='Re: [PATCH 7/9] mm: add a flag to indicate we used a cached page' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).