From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Chao Yu <chao@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH RFC] f2fs: fix to use spinlock to avoid page.private update race
Date: Mon, 10 Apr 2023 16:25:58 -0700 [thread overview]
Message-ID: <ZDSbBk8bD8meyGel@google.com> (raw)
In-Reply-To: <20230410093912.2184557-1-chao@kernel.org>
On 04/10, Chao Yu wrote:
> There may be subtle race condition, make PagePrivate and page_private
> being inconsistent, result in decreasing page count incorrectly,
> introduce a per-inode spinlock to avoid such condition.
No...what have you found? The set/clear.. were supposed to be done in page_lock,
and checking the flag should not corrupt any memory.
>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> fs/f2fs/f2fs.h | 19 ++++++++++++++++++-
> fs/f2fs/super.c | 2 ++
> 2 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c378aedcadea..6b31bef5853e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -856,6 +856,8 @@ struct f2fs_inode_info {
>
> unsigned int atomic_write_cnt;
> loff_t original_i_size; /* original i_size before atomic write */
> +
> + spinlock_t private_lock; /* protect page->private */
> };
>
> static inline void get_read_extent_info(struct extent_info *ext,
> @@ -1413,21 +1415,28 @@ static inline bool page_private_##name(struct page *page) \
> test_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \
> }
>
> +static inline struct f2fs_inode_info *F2FS_I(struct inode *inode);
> #define PAGE_PRIVATE_SET_FUNC(name, flagname) \
> static inline void set_page_private_##name(struct page *page) \
> { \
> + unsigned long flags; \
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags); \
> if (!PagePrivate(page)) \
> attach_page_private(page, (void *)page->private); \
> set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page)); \
> set_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags); \
> }
>
> #define PAGE_PRIVATE_CLEAR_FUNC(name, flagname) \
> static inline void clear_page_private_##name(struct page *page) \
> { \
> + unsigned long flags; \
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags); \
> 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))) \
> detach_page_private(page); \
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags); \
> }
>
> PAGE_PRIVATE_GET_FUNC(nonpointer, NOT_POINTER);
> @@ -1456,17 +1465,25 @@ static inline unsigned long get_page_private_data(struct page *page)
>
> static inline void set_page_private_data(struct page *page, unsigned long data)
> {
> + unsigned long flags;
> +
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags);
> if (!PagePrivate(page))
> attach_page_private(page, 0);
> set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page));
> page_private(page) |= data << PAGE_PRIVATE_MAX;
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags);
> }
>
> static inline void clear_page_private_data(struct page *page)
> {
> + unsigned long flags;
> +
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags);
> page_private(page) &= GENMASK(PAGE_PRIVATE_MAX - 1, 0);
> if (page_private(page) == BIT(PAGE_PRIVATE_NOT_POINTER))
> detach_page_private(page);
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags);
> }
>
> /* For compression */
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index a1b570a5e50f..555424dd85fd 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1419,6 +1419,8 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
> init_f2fs_rwsem(&fi->i_gc_rwsem[WRITE]);
> init_f2fs_rwsem(&fi->i_xattr_sem);
>
> + spin_lock_init(&fi->private_lock);
> +
> /* Will be used by directory only */
> fi->i_dir_level = F2FS_SB(sb)->dir_level;
>
> --
> 2.25.1
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
WARNING: multiple messages have this Message-ID (diff)
From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Chao Yu <chao@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] f2fs: fix to use spinlock to avoid page.private update race
Date: Mon, 10 Apr 2023 16:25:58 -0700 [thread overview]
Message-ID: <ZDSbBk8bD8meyGel@google.com> (raw)
In-Reply-To: <20230410093912.2184557-1-chao@kernel.org>
On 04/10, Chao Yu wrote:
> There may be subtle race condition, make PagePrivate and page_private
> being inconsistent, result in decreasing page count incorrectly,
> introduce a per-inode spinlock to avoid such condition.
No...what have you found? The set/clear.. were supposed to be done in page_lock,
and checking the flag should not corrupt any memory.
>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> fs/f2fs/f2fs.h | 19 ++++++++++++++++++-
> fs/f2fs/super.c | 2 ++
> 2 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c378aedcadea..6b31bef5853e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -856,6 +856,8 @@ struct f2fs_inode_info {
>
> unsigned int atomic_write_cnt;
> loff_t original_i_size; /* original i_size before atomic write */
> +
> + spinlock_t private_lock; /* protect page->private */
> };
>
> static inline void get_read_extent_info(struct extent_info *ext,
> @@ -1413,21 +1415,28 @@ static inline bool page_private_##name(struct page *page) \
> test_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \
> }
>
> +static inline struct f2fs_inode_info *F2FS_I(struct inode *inode);
> #define PAGE_PRIVATE_SET_FUNC(name, flagname) \
> static inline void set_page_private_##name(struct page *page) \
> { \
> + unsigned long flags; \
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags); \
> if (!PagePrivate(page)) \
> attach_page_private(page, (void *)page->private); \
> set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page)); \
> set_bit(PAGE_PRIVATE_##flagname, &page_private(page)); \
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags); \
> }
>
> #define PAGE_PRIVATE_CLEAR_FUNC(name, flagname) \
> static inline void clear_page_private_##name(struct page *page) \
> { \
> + unsigned long flags; \
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags); \
> 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))) \
> detach_page_private(page); \
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags); \
> }
>
> PAGE_PRIVATE_GET_FUNC(nonpointer, NOT_POINTER);
> @@ -1456,17 +1465,25 @@ static inline unsigned long get_page_private_data(struct page *page)
>
> static inline void set_page_private_data(struct page *page, unsigned long data)
> {
> + unsigned long flags;
> +
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags);
> if (!PagePrivate(page))
> attach_page_private(page, 0);
> set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page));
> page_private(page) |= data << PAGE_PRIVATE_MAX;
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags);
> }
>
> static inline void clear_page_private_data(struct page *page)
> {
> + unsigned long flags;
> +
> + spin_lock_irqsave(&F2FS_I(page->mapping->host)->private_lock, flags);
> page_private(page) &= GENMASK(PAGE_PRIVATE_MAX - 1, 0);
> if (page_private(page) == BIT(PAGE_PRIVATE_NOT_POINTER))
> detach_page_private(page);
> + spin_unlock_irqrestore(&F2FS_I(page->mapping->host)->private_lock, flags);
> }
>
> /* For compression */
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index a1b570a5e50f..555424dd85fd 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1419,6 +1419,8 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
> init_f2fs_rwsem(&fi->i_gc_rwsem[WRITE]);
> init_f2fs_rwsem(&fi->i_xattr_sem);
>
> + spin_lock_init(&fi->private_lock);
> +
> /* Will be used by directory only */
> fi->i_dir_level = F2FS_SB(sb)->dir_level;
>
> --
> 2.25.1
next prev parent reply other threads:[~2023-04-10 23:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-10 9:39 [f2fs-dev] [PATCH RFC] f2fs: fix to use spinlock to avoid page.private update race Chao Yu
2023-04-10 9:39 ` Chao Yu
2023-04-10 23:25 ` Jaegeuk Kim [this message]
2023-04-10 23:25 ` Jaegeuk Kim
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=ZDSbBk8bD8meyGel@google.com \
--to=jaegeuk@kernel.org \
--cc=chao@kernel.org \
--cc=linux-f2fs-devel@lists.sourceforge.net \
--cc=linux-kernel@vger.kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.