Re: [PATCH v2] f2fs: attach/detach private value in pair

From: Jaegeuk Kim
Date: Fri Apr 07 2023 - 16:25:53 EST


set_page_private_# increases a refcount after attaching page->private, and
clear_page_private_# decreases it.
But, f2fs_release_folio and f2fs_invalidate_folio call folio_detach_private()
which decreases the refcount again, which corrupts the page cache.

Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: b763f3bedc2d ("f2fs: restructure f2fs page.private layout")
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---

Change log from v1:
- update comment
- remove unnecessary zeroing bits in invalidate/release page

fs/f2fs/compress.c | 4 ++--
fs/f2fs/data.c | 21 -------------------
fs/f2fs/f2fs.h | 50 ++++++++++++++++------------------------------
3 files changed, 19 insertions(+), 56 deletions(-)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 11653fa79289..70b3910db413 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1854,7 +1854,7 @@ void f2fs_cache_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
return;
}

- set_page_private_data(cpage, ino);
+ set_page_private_ino(cpage, ino);

if (!f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE_READ))
goto out;
@@ -1917,7 +1917,7 @@ void f2fs_invalidate_compress_pages(struct f2fs_sb_info *sbi, nid_t ino)
continue;
}

- if (ino != get_page_private_data(&folio->page)) {
+ if (ino != get_page_private_ino(&folio->page)) {
folio_unlock(folio);
continue;
}
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index fa931fb768e7..0a5832ec4046 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3722,36 +3722,15 @@ void f2fs_invalidate_folio(struct folio *folio, size_t offset, size_t length)
f2fs_remove_dirty_inode(inode);
}
}
-
- clear_page_private_reference(&folio->page);
- clear_page_private_gcing(&folio->page);
-
- if (test_opt(sbi, COMPRESS_CACHE) &&
- inode->i_ino == F2FS_COMPRESS_INO(sbi))
- clear_page_private_data(&folio->page);
-
folio_detach_private(folio);
}

bool f2fs_release_folio(struct folio *folio, gfp_t wait)
{
- struct f2fs_sb_info *sbi;
-
/* If this is dirty folio, keep private data */
if (folio_test_dirty(folio))
return false;

- sbi = F2FS_M_SB(folio->mapping);
- if (test_opt(sbi, COMPRESS_CACHE)) {
- struct inode *inode = folio->mapping->host;
-
- if (inode->i_ino == F2FS_COMPRESS_INO(sbi))
- clear_page_private_data(&folio->page);
- }
-
- clear_page_private_reference(&folio->page);
- clear_page_private_gcing(&folio->page);
-
folio_detach_private(folio);
return true;
}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index dfead8160a51..5d025eae40b8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1384,7 +1384,7 @@ static inline void f2fs_clear_bit(unsigned int nr, char *addr);
* bit 2 PAGE_PRIVATE_ONGOING_MIGRATION
* bit 3 PAGE_PRIVATE_INLINE_INODE
* bit 4 PAGE_PRIVATE_REF_RESOURCE
- * bit 5- f2fs private data
+ * bit 5- PAGE_PRIVATE_DATA followed by additional info
*
* Layout B: lowest bit should be 0
* page.private is a wrapped pointer.
@@ -1395,6 +1395,7 @@ enum {
PAGE_PRIVATE_ONGOING_MIGRATION, /* data page which is on-going migrating */
PAGE_PRIVATE_INLINE_INODE, /* inode page contains inline data */
PAGE_PRIVATE_REF_RESOURCE, /* dirty page has referenced resources */
+ PAGE_PRIVATE_DATA, /* page has referenced data */
PAGE_PRIVATE_MAX
};

@@ -1409,73 +1410,56 @@ static inline bool page_private_##name(struct page *page) \
#define PAGE_PRIVATE_SET_FUNC(name, flagname) \
static inline void set_page_private_##name(struct page *page) \
{ \
- if (!PagePrivate(page)) { \
- get_page(page); \
- SetPagePrivate(page); \
- set_page_private(page, 0); \
- } \
+ if (!PagePrivate(page)) \
+ attach_page_private(page, 0); \
set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page)); \
set_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \
}

+/* clear private by f2fs_release_folio or f2fs_invalidate_folio */
#define PAGE_PRIVATE_CLEAR_FUNC(name, flagname) \
static inline void clear_page_private_##name(struct page *page) \
{ \
clear_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \
- if (page_private(page) == BIT(PAGE_PRIVATE_NOT_POINTER)) { \
+ if (page_private(page) == BIT(PAGE_PRIVATE_NOT_POINTER)) \
set_page_private(page, 0); \
- if (PagePrivate(page)) { \
- ClearPagePrivate(page); \
- put_page(page); \
- }\
- } \
}

PAGE_PRIVATE_GET_FUNC(nonpointer, NOT_POINTER);
PAGE_PRIVATE_GET_FUNC(inline, INLINE_INODE);
PAGE_PRIVATE_GET_FUNC(gcing, ONGOING_MIGRATION);
PAGE_PRIVATE_GET_FUNC(dummy, DUMMY_WRITE);
+PAGE_PRIVATE_GET_FUNC(data, DATA);

PAGE_PRIVATE_SET_FUNC(reference, REF_RESOURCE);
PAGE_PRIVATE_SET_FUNC(inline, INLINE_INODE);
PAGE_PRIVATE_SET_FUNC(gcing, ONGOING_MIGRATION);
PAGE_PRIVATE_SET_FUNC(dummy, DUMMY_WRITE);
+PAGE_PRIVATE_SET_FUNC(data, DATA);

PAGE_PRIVATE_CLEAR_FUNC(reference, REF_RESOURCE);
PAGE_PRIVATE_CLEAR_FUNC(inline, INLINE_INODE);
PAGE_PRIVATE_CLEAR_FUNC(gcing, ONGOING_MIGRATION);
PAGE_PRIVATE_CLEAR_FUNC(dummy, DUMMY_WRITE);
+PAGE_PRIVATE_CLEAR_FUNC(data, DATA);

-static inline unsigned long get_page_private_data(struct page *page)
+static inline nid_t get_page_private_ino(struct page *page)
{
- unsigned long data = page_private(page);
-
- if (!test_bit(PAGE_PRIVATE_NOT_POINTER, &data))
+ if (!page_private_data(page))
return 0;
- return data >> PAGE_PRIVATE_MAX;
+ return page_private(page) >> PAGE_PRIVATE_MAX;
}

-static inline void set_page_private_data(struct page *page, unsigned long data)
+static inline void set_page_private_ino(struct page *page, nid_t ino)
{
- if (!PagePrivate(page)) {
- get_page(page);
- SetPagePrivate(page);
- set_page_private(page, 0);
- }
- set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page));
- page_private(page) |= data << PAGE_PRIVATE_MAX;
+ set_page_private_data(page);
+ page_private(page) |= ino << PAGE_PRIVATE_MAX;
}

-static inline void clear_page_private_data(struct page *page)
+static inline void clear_page_private_ino(struct page *page)
{
page_private(page) &= GENMASK(PAGE_PRIVATE_MAX - 1, 0);
- if (page_private(page) == BIT(PAGE_PRIVATE_NOT_POINTER)) {
- set_page_private(page, 0);
- if (PagePrivate(page)) {
- ClearPagePrivate(page);
- put_page(page);
- }
- }
+ clear_page_private_data(page);
}

/* For compression */
--
2.40.0.577.gac1e443424-goog