Messages in this thread | | | Date | Mon, 5 Jul 2021 01:56:59 -0700 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH] f2fs: initialize page->private when using for our internal use |
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On 07/05, Chao Yu wrote: > On 2021/7/5 13:22, Jaegeuk Kim wrote: > > We need to guarantee it's initially zero. Otherwise, it'll hurt entire flag > > operations. > > Oops, I didn't get the point, shouldn't .private be zero after page was > just allocated by filesystem? What's the case we will encounter stall > private data left in page?
I'm seeing f2fs_migrate_page() has the newpage with some value without Private flag. That causes a kernel panic later due to wrong private flag used in f2fs.
> > Cc Matthew Wilcox. > > Thanks, > > > > > Fixes: b763f3bedc2d ("f2fs: restructure f2fs page.private layout") > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > --- > > fs/f2fs/data.c | 2 ++ > > fs/f2fs/f2fs.h | 5 ++++- > > 2 files changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index 3a01a1b50104..d2cf48c5a2e4 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -3819,6 +3819,8 @@ int f2fs_migrate_page(struct address_space *mapping, > > get_page(newpage); > > } > > + /* guarantee to start from no stale private field */ > > + set_page_private(newpage, 0); > > if (PagePrivate(page)) { > > set_page_private(newpage, page_private(page)); > > SetPagePrivate(newpage); > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index 65befc68d88e..ee8eb33e2c25 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -1331,7 +1331,8 @@ enum { > > #define PAGE_PRIVATE_GET_FUNC(name, flagname) \ > > static inline bool page_private_##name(struct page *page) \ > > { \ > > - return test_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page)) && \ > > + return PagePrivate(page) && \ > > + test_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page)) && \ > > test_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \ > > } > > @@ -1341,6 +1342,7 @@ static inline void set_page_private_##name(struct page *page) \ > > if (!PagePrivate(page)) { \ > > get_page(page); \ > > SetPagePrivate(page); \ > > + set_page_private(page, 0); \ > > } \ > > set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page)); \ > > set_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \ > > @@ -1392,6 +1394,7 @@ static inline void set_page_private_data(struct page *page, unsigned long data) > > 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; > >
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