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Date:   Tue, 27 Jun 2023 21:37:30 +0800
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Subject: Re: [f2fs-dev] [PATCH] f2fs: remove i_xattr_sem to avoid deadlock and
 fix the original issue
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To:     Jaegeuk Kim <jaegeuk@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, stable@vger.kernel.org
References: <20230613233940.3643362-1-jaegeuk@kernel.org>
 <e5788348-b547-8e10-21af-90544f3aa75c@kernel.org>
 <d0ec4a04-ab81-7e71-ad56-5b22e1815919@kernel.org>
 <ZJmOgRADvLP/4rMJ@google.com>
From:   Chao Yu <chao@kernel.org>
In-Reply-To: <ZJmOgRADvLP/4rMJ@google.com>
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On 2023/6/26 21:11, Jaegeuk Kim wrote:
> On 06/25, Chao Yu wrote:
>> On 2023/6/25 15:26, Chao Yu wrote:
>>> One concern below:
>>>
>>> Thread A:                    Thread B:
>>> - f2fs_getxattr
>>>    - lookup_all_xattrs
>>>     - read_inline_xattr
>>>      - f2fs_get_node_page(ino)
>>>      - memcpy inline xattr
>>>      - f2fs_put_page
>>>                           - f2fs_setxattr
>>>                            - __f2fs_setxattr
>>>                             - __f2fs_setxattr
>>>                              - write_all_xattrs
>>>                               - write xnode and inode
>>>     ---> inline xattr may out of update here.
>>>     - read_xattr_block
>>>      - f2fs_get_node_page(xnid)
>>>      - memcpy xnode xattr
>>>      - f2fs_put_page
>>>
>>> Do we need to keep xattr_{get,set} being atomical operation?
>>
>> It seems xfstest starts to complain w/ below message...
> 
> I don't see any failure. Which test do you see?

051, 083, ... 467, 642

Testcase doesn't fail, but kernel log shows inode has corrupted xattr.

> 
>>
>> [ 3400.856443] F2FS-fs (vdc): inode (2187) has invalid last xattr entry, entry_size: 21468
>> [ 3400.864042] F2FS-fs (vdc): inode (1595) has invalid last xattr entry, entry_size: 26580
>> [ 3400.865764] F2FS-fs (vdc): inode (2187) has invalid last xattr entry, entry_size: 21468
>> [ 3400.880067] F2FS-fs (vdc): inode (9839) has corrupted xattr
>> [ 3400.880714] F2FS-fs (vdc): inode (10855) has corrupted xattr
>>
>> Thanks,
>>
>>>
>>> Thanks,
>>>
>>>>
>>>> I think we don't need to truncate xattr pages eagerly which introduces lots of
>>>> data races without big benefits.
>>>>
>>>> Cc: <stable@vger.kernel.org>
>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>>> ---
>>>>    fs/f2fs/f2fs.h  |  1 -
>>>>    fs/f2fs/super.c |  1 -
>>>>    fs/f2fs/xattr.c | 31 ++++++++-----------------------
>>>>    3 files changed, 8 insertions(+), 25 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index 3f5b161dd743..7b9af2d51656 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -838,7 +838,6 @@ struct f2fs_inode_info {
>>>>        /* avoid racing between foreground op and gc */
>>>>        struct f2fs_rwsem i_gc_rwsem[2];
>>>> -    struct f2fs_rwsem i_xattr_sem; /* avoid racing between reading and changing EAs */
>>>>        int i_extra_isize;        /* size of extra space located in i_addr */
>>>>        kprojid_t i_projid;        /* id for project quota */
>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>>> index 1b2c788ed80d..c917fa771f0e 100644
>>>> --- a/fs/f2fs/super.c
>>>> +++ b/fs/f2fs/super.c
>>>> @@ -1418,7 +1418,6 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
>>>>        INIT_LIST_HEAD(&fi->gdirty_list);
>>>>        init_f2fs_rwsem(&fi->i_gc_rwsem[READ]);
>>>>        init_f2fs_rwsem(&fi->i_gc_rwsem[WRITE]);
>>>> -    init_f2fs_rwsem(&fi->i_xattr_sem);
>>>>        /* Will be used by directory only */
>>>>        fi->i_dir_level = F2FS_SB(sb)->dir_level;
>>>> diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
>>>> index 213805d3592c..bdc8a55085a2 100644
>>>> --- a/fs/f2fs/xattr.c
>>>> +++ b/fs/f2fs/xattr.c
>>>> @@ -433,7 +433,7 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize,
>>>>    {
>>>>        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>>>        size_t inline_size = inline_xattr_size(inode);
>>>> -    struct page *in_page = NULL;
>>>> +    struct page *in_page = ipage;
>>>>        void *xattr_addr;
>>>>        void *inline_addr = NULL;
>>>>        struct page *xpage;
>>>> @@ -446,29 +446,19 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize,
>>>>        /* write to inline xattr */
>>>>        if (inline_size) {
>>>> -        if (ipage) {
>>>> -            inline_addr = inline_xattr_addr(inode, ipage);
>>>> -        } else {
>>>> +        if (!in_page) {
>>>>                in_page = f2fs_get_node_page(sbi, inode->i_ino);
>>>>                if (IS_ERR(in_page)) {
>>>>                    f2fs_alloc_nid_failed(sbi, new_nid);
>>>>                    return PTR_ERR(in_page);
>>>>                }
>>>> -            inline_addr = inline_xattr_addr(inode, in_page);
>>>>            }
>>>> +        inline_addr = inline_xattr_addr(inode, in_page);
>>>> -        f2fs_wait_on_page_writeback(ipage ? ipage : in_page,
>>>> -                            NODE, true, true);
>>>> -        /* no need to use xattr node block */
>>>> +        f2fs_wait_on_page_writeback(in_page, NODE, true, true);
>>>>            if (hsize <= inline_size) {
>>>> -            err = f2fs_truncate_xattr_node(inode);
>>>> -            f2fs_alloc_nid_failed(sbi, new_nid);
>>>> -            if (err) {
>>>> -                f2fs_put_page(in_page, 1);
>>>> -                return err;
>>>> -            }
>>>>                memcpy(inline_addr, txattr_addr, inline_size);
>>>> -            set_page_dirty(ipage ? ipage : in_page);
>>>> +            set_page_dirty(in_page);
>>>>                goto in_page_out;
>>>>            }
>>>>        }
>>>> @@ -502,12 +492,13 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize,
>>>>        memcpy(xattr_addr, txattr_addr + inline_size, VALID_XATTR_BLOCK_SIZE);
>>>>        if (inline_size)
>>>> -        set_page_dirty(ipage ? ipage : in_page);
>>>> +        set_page_dirty(in_page);
>>>>        set_page_dirty(xpage);
>>>>        f2fs_put_page(xpage, 1);
>>>>    in_page_out:
>>>> -    f2fs_put_page(in_page, 1);
>>>> +    if (in_page != ipage)
>>>> +        f2fs_put_page(in_page, 1);
>>>>        return err;
>>>>    }
>>>> @@ -528,10 +519,8 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name,
>>>>        if (len > F2FS_NAME_LEN)
>>>>            return -ERANGE;
>>>> -    f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
>>>>        error = lookup_all_xattrs(inode, ipage, index, len, name,
>>>>                    &entry, &base_addr, &base_size, &is_inline);
>>>> -    f2fs_up_read(&F2FS_I(inode)->i_xattr_sem);
>>>>        if (error)
>>>>            return error;
>>>> @@ -565,9 +554,7 @@ ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
>>>>        int error;
>>>>        size_t rest = buffer_size;
>>>> -    f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
>>>>        error = read_all_xattrs(inode, NULL, &base_addr);
>>>> -    f2fs_up_read(&F2FS_I(inode)->i_xattr_sem);
>>>>        if (error)
>>>>            return error;
>>>> @@ -794,9 +781,7 @@ int f2fs_setxattr(struct inode *inode, int index, const char *name,
>>>>        f2fs_balance_fs(sbi, true);
>>>>        f2fs_lock_op(sbi);
>>>> -    f2fs_down_write(&F2FS_I(inode)->i_xattr_sem);
>>>>        err = __f2fs_setxattr(inode, index, name, value, size, ipage, flags);
>>>> -    f2fs_up_write(&F2FS_I(inode)->i_xattr_sem);
>>>>        f2fs_unlock_op(sbi);
>>>>        f2fs_update_time(sbi, REQ_TIME);
>>>
>>>
>>> _______________________________________________
>>> Linux-f2fs-devel mailing list
>>> Linux-f2fs-devel@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel