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Date: Tue, 5 Mar 2019 17:52:32 +0800
From: Chao Yu <yuchao0@...wei.com>
To: <jaegeuk@...nel.org>
CC: <linux-f2fs-devel@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>, <chao@...nel.org>,
Chao Yu <yuchao0@...wei.com>
Subject: [PATCH 1/2] f2fs: fix to add refcount once page is tagged PG_private
As Gao Xiang reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=202749
f2fs may skip pageout() due to incorrect page reference count.
The problem here is that MM defined the rule [1] very clearly that
once page was set with PG_private flag, we should increment the
refcount in that page, also main flows like pageout(), migrate_page()
will assume there is one additional page reference count if
page_has_private() returns true.
But currently, f2fs won't add/del refcount when changing PG_private
flag. Anyway, f2fs should follow MM's rule to make MM's related flows
running as expected.
[1] https://lore.kernel.org/lkml/2b19b3c4-2bc4-15fa-15cc-27a13e5c7af1@aol.com/
Reported-by: Gao Xiang <gaoxiang25@...wei.com>
Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
fs/f2fs/checkpoint.c | 11 +++++++++--
fs/f2fs/data.c | 32 ++++++++++++++++++++------------
fs/f2fs/dir.c | 6 +++++-
fs/f2fs/node.c | 6 +++++-
fs/f2fs/segment.c | 23 +++++++++++++++++------
5 files changed, 56 insertions(+), 22 deletions(-)
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index c65a1e8e1e95..4e0e93af5ce0 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -406,7 +406,11 @@ static int f2fs_set_meta_page_dirty(struct page *page)
if (!PageDirty(page)) {
__set_page_dirty_nobuffers(page);
inc_page_count(F2FS_P_SB(page), F2FS_DIRTY_META);
- SetPagePrivate(page);
+
+ if (!PagePrivate(page)) {
+ get_page(page);
+ SetPagePrivate(page);
+ }
f2fs_trace_pid(page);
return 1;
}
@@ -957,7 +961,10 @@ void f2fs_update_dirty_page(struct inode *inode, struct page *page)
inode_inc_dirty_pages(inode);
spin_unlock(&sbi->inode_lock[type]);
- SetPagePrivate(page);
+ if (!PagePrivate(page)) {
+ get_page(page);
+ SetPagePrivate(page);
+ }
f2fs_trace_pid(page);
}
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 3f3becd46362..46924d4f69d0 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2715,8 +2715,11 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset,
if (IS_ATOMIC_WRITTEN_PAGE(page))
return f2fs_drop_inmem_page(inode, page);
- set_page_private(page, 0);
- ClearPagePrivate(page);
+ if (PagePrivate(page)) {
+ set_page_private(page, 0);
+ ClearPagePrivate(page);
+ f2fs_put_page(page, 0);
+ }
}
int f2fs_release_page(struct page *page, gfp_t wait)
@@ -2730,8 +2733,11 @@ int f2fs_release_page(struct page *page, gfp_t wait)
return 0;
clear_cold_data(page);
- set_page_private(page, 0);
- ClearPagePrivate(page);
+ if (PagePrivate(page)) {
+ set_page_private(page, 0);
+ ClearPagePrivate(page);
+ f2fs_put_page(page, 0);
+ }
return 1;
}
@@ -2799,12 +2805,8 @@ int f2fs_migrate_page(struct address_space *mapping,
return -EAGAIN;
}
- /*
- * A reference is expected if PagePrivate set when move mapping,
- * however F2FS breaks this for maintaining dirty page counts when
- * truncating pages. So here adjusting the 'extra_count' make it work.
- */
- extra_count = (atomic_written ? 1 : 0) - page_has_private(page);
+ /* one extra reference was held for atomic_write page */
+ extra_count = atomic_written ? 1 : 0;
rc = migrate_page_move_mapping(mapping, newpage,
page, mode, extra_count);
if (rc != MIGRATEPAGE_SUCCESS) {
@@ -2825,9 +2827,15 @@ int f2fs_migrate_page(struct address_space *mapping,
get_page(newpage);
}
- if (PagePrivate(page))
+ if (PagePrivate(page)) {
+ get_page(newpage);
SetPagePrivate(newpage);
- set_page_private(newpage, page_private(page));
+ set_page_private(newpage, page_private(page));
+
+ set_page_private(page, 0);
+ ClearPagePrivate(page);
+ f2fs_put_page(page, 0);
+ }
if (mode != MIGRATE_SYNC_NO_COPY)
migrate_page_copy(newpage, page);
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 103f3686a045..fbbafb04a431 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -728,7 +728,11 @@ void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
!f2fs_truncate_hole(dir, page->index, page->index + 1)) {
f2fs_clear_page_cache_dirty_tag(page);
clear_page_dirty_for_io(page);
- ClearPagePrivate(page);
+ if (PagePrivate(page)) {
+ set_page_private(page, 0);
+ ClearPagePrivate(page);
+ f2fs_put_page(page, 0);
+ }
ClearPageUptodate(page);
clear_cold_data(page);
inode_dec_dirty_pages(dir);
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index f6ff84e29749..ce97a9885105 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1961,7 +1961,11 @@ static int f2fs_set_node_page_dirty(struct page *page)
if (!PageDirty(page)) {
__set_page_dirty_nobuffers(page);
inc_page_count(F2FS_P_SB(page), F2FS_DIRTY_NODES);
- SetPagePrivate(page);
+
+ if (!PagePrivate(page)) {
+ get_page(page);
+ SetPagePrivate(page);
+ }
f2fs_trace_pid(page);
return 1;
}
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index e730c334abba..2d77dd133a4e 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -191,8 +191,11 @@ void f2fs_register_inmem_page(struct inode *inode, struct page *page)
f2fs_trace_pid(page);
- set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE);
- SetPagePrivate(page);
+ if (!PagePrivate(page)) {
+ get_page(page);
+ SetPagePrivate(page);
+ set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE);
+ }
new = f2fs_kmem_cache_alloc(inmem_entry_slab, GFP_NOFS);
@@ -280,8 +283,11 @@ static int __revoke_inmem_pages(struct inode *inode,
ClearPageUptodate(page);
clear_cold_data(page);
}
- set_page_private(page, 0);
- ClearPagePrivate(page);
+ if (PagePrivate(page)) {
+ set_page_private(page, 0);
+ ClearPagePrivate(page);
+ f2fs_put_page(page, 0);
+ }
f2fs_put_page(page, 1);
list_del(&cur->list);
@@ -370,8 +376,13 @@ void f2fs_drop_inmem_page(struct inode *inode, struct page *page)
kmem_cache_free(inmem_entry_slab, cur);
ClearPageUptodate(page);
- set_page_private(page, 0);
- ClearPagePrivate(page);
+
+ if (PagePrivate(page)) {
+ set_page_private(page, 0);
+ ClearPagePrivate(page);
+ f2fs_put_page(page, 0);
+ }
+
f2fs_put_page(page, 0);
trace_f2fs_commit_inmem_page(page, INMEM_INVALIDATE);
--
2.18.0.rc1
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