From: Josef Bacik <josef@toxicpanda.com>
To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, linux-btrfs@vger.kernel.org, riel@redhat.com,
hannes@cmpxchg.org, tj@kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org
Subject: [PATCH 7/8] mm: add a flag to indicate we used a cached page
Date: Tue, 25 Sep 2018 11:30:10 -0400 [thread overview]
Message-ID: <20180925153011.15311-8-josef@toxicpanda.com> (raw)
In-Reply-To: <20180925153011.15311-1-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 724514be03b2..10a0118f5485 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 49b35293fa95..75a8b252814a 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);
@@ -2618,8 +2619,10 @@ 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
next prev parent reply other threads:[~2018-09-25 15:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 15:30 [RFC][PATCH 0/8] drop the mmap_sem when doing IO in the fault path Josef Bacik
2018-09-25 15:30 ` [PATCH 1/8] mm: push vm_fault into the page fault handlers Josef Bacik
2018-09-26 0:22 ` Dave Chinner
2018-09-26 1:33 ` Josef Bacik
2018-09-25 15:30 ` [PATCH 2/8] mm: drop mmap_sem for page cache read IO submission Josef Bacik
2018-09-25 15:30 ` [PATCH 3/8] mm: clean up swapcache lookup and creation function names Josef Bacik
2018-09-25 15:30 ` [PATCH 4/8] mm: drop mmap_sem for swap read IO submission Josef Bacik
2018-09-25 15:30 ` [PATCH 5/8] mm: drop the mmap_sem in all read fault cases Josef Bacik
2018-09-25 15:30 ` [PATCH 6/8] mm: keep the page we read for the next loop Josef Bacik
2018-09-25 15:30 ` Josef Bacik [this message]
2018-09-25 15:30 ` [PATCH 8/8] btrfs: drop mmap_sem in mkwrite for btrfs Josef Bacik
2018-09-26 0:24 ` Dave Chinner
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