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Message-ID: <53df1b78-c611-6a22-88b1-74cc83a9e148@kernel.org>
Date: Fri, 30 Sep 2022 08:49:06 +0800
From: Chao Yu <chao@...nel.org>
To: Daeho Jeong <daeho43@...il.com>
Cc: linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net, kernel-team@...roid.com,
Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: introduce
F2FS_IOC_START_ATOMIC_REPLACE
On 2022/9/30 7:33, Daeho Jeong wrote:
> On Thu, Sep 29, 2022 at 3:54 PM Chao Yu <chao@...nel.org> wrote:
>>
>> On 2022/9/30 0:13, Daeho Jeong wrote:
>>> On Thu, Sep 29, 2022 at 12:36 AM Chao Yu <chao@...nel.org> wrote:
>>>>
>>>> On 2022/9/20 9:40, Daeho Jeong wrote:
>>>>> From: Daeho Jeong <daehojeong@...gle.com>
>>>>>
>>>>> introduce a new ioctl to replace the whole content of a file atomically,
>>>>> which means it induces truncate and content update at the same time.
>>>>> We can start it with F2FS_IOC_START_ATOMIC_REPLACE and complete it with
>>>>> F2FS_IOC_COMMIT_ATOMIC_WRITE. Or abort it with
>>>>> F2FS_IOC_ABORT_ATOMIC_WRITE.
>>>>>
>>>>> Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
>>>>> ---
>>>>> v2: add undefined ioctl number reported by <lkp@...el.com>
>>>>> ---
>>>>> fs/f2fs/data.c | 3 +++
>>>>> fs/f2fs/f2fs.h | 1 +
>>>>> fs/f2fs/file.c | 12 ++++++++++--
>>>>> fs/f2fs/segment.c | 14 +++++++++++++-
>>>>> include/uapi/linux/f2fs.h | 1 +
>>>>> 5 files changed, 28 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>>> index 6cd29a575105..d3d32db3a25d 100644
>>>>> --- a/fs/f2fs/data.c
>>>>> +++ b/fs/f2fs/data.c
>>>>> @@ -3438,6 +3438,9 @@ static int prepare_atomic_write_begin(struct f2fs_sb_info *sbi,
>>>>> else if (*blk_addr != NULL_ADDR)
>>>>> return 0;
>>>>>
>>>>> + if (is_inode_flag_set(inode, FI_ATOMIC_REPLACE))
>>>>> + goto reserve_block;
>>>>> +
>>>>> /* Look for the block in the original inode */
>>>>> err = __find_data_block(inode, index, &ori_blk_addr);
>>>>> if (err)
>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>> index 539da7f12cfc..2c49da12d6d8 100644
>>>>> --- a/fs/f2fs/f2fs.h
>>>>> +++ b/fs/f2fs/f2fs.h
>>>>> @@ -764,6 +764,7 @@ enum {
>>>>> FI_COMPRESS_RELEASED, /* compressed blocks were released */
>>>>> FI_ALIGNED_WRITE, /* enable aligned write */
>>>>> FI_COW_FILE, /* indicate COW file */
>>>>> + FI_ATOMIC_REPLACE, /* indicate atomic replace */
>>>>> FI_MAX, /* max flag, never be used */
>>>>> };
>>>>>
>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>> index 4f9b80c41b1e..4abd9d2a55b3 100644
>>>>> --- a/fs/f2fs/file.c
>>>>> +++ b/fs/f2fs/file.c
>>>>> @@ -1982,7 +1982,7 @@ static int f2fs_ioc_getversion(struct file *filp, unsigned long arg)
>>>>> return put_user(inode->i_generation, (int __user *)arg);
>>>>> }
>>>>>
>>>>> -static int f2fs_ioc_start_atomic_write(struct file *filp)
>>>>> +static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
>>>>> {
>>>>> struct inode *inode = file_inode(filp);
>>>>> struct user_namespace *mnt_userns = file_mnt_user_ns(filp);
>>>>> @@ -2051,6 +2051,12 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>>>>>
>>>>> isize = i_size_read(inode);
>>>>> fi->original_i_size = isize;
>>>>> + if (truncate) {
>>>>> + set_inode_flag(inode, FI_ATOMIC_REPLACE);
>>>>> + truncate_inode_pages_final(inode->i_mapping);
>>>>> + f2fs_i_size_write(inode, 0);
>>>>> + isize = 0;
>>>>> + }
>>>>
>>>> Hi Daeho,
>>>>
>>>> isize should be updated after tagging inode as atomic_write one?
>>>> otherwise f2fs_mark_inode_dirty_sync() may update isize to inode page,
>>>> latter checkpoint may persist that change? IIUC...
>>>>
>>>> Thanks,
>>>
>>> Hi Chao,
>>>
>>> The first patch of this patchset prevents the inode page from being
>>> updated as dirty for atomic file cases.
>>> Is there any other chances for the inode page to be marked as dirty?
>>
>> I mean:
>>
>> Thread A Thread B
>> - f2fs_ioc_start_atomic_write
>> - f2fs_i_size_write(inode, 0)
>> - f2fs_mark_inode_dirty_sync
>> - checkpoint
>> - persist inode with incorrect zero isize
>>
>> - set_inode_flag(inode, FI_ATOMIC_FILE)
>>
>> Am I missing something?
>>
>
> So, f2fs_mark_inode_dirty_sync() will not work for atomic files
> anymore, which means it doesn't make the inode dirty.
> Plz, refer to the first patch of this patchset. Or I might be confused
> with something. :(
I mean FI_ATOMIC_FILE was set after f2fs_i_size_write(), so inode will be set
as dirty.
Thanks,
>
> @@ -30,6 +30,9 @@ void f2fs_mark_inode_dirty_sync(struct inode *inode,
> bool sync)
> if (f2fs_inode_dirtied(inode, sync))
> return;
>
> + if (f2fs_is_atomic_file(inode))
> + return;
> +
> mark_inode_dirty_sync(inode);
> }
>
>
>
>
>
>> Thanks,
>>
>>>
>>> Thanks,
>>>
>>>>
>>>>> f2fs_i_size_write(fi->cow_inode, isize);
>>>>>
>>>>> spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
>>>>> @@ -4080,7 +4086,9 @@ static long __f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>>> case FS_IOC_GETVERSION:
>>>>> return f2fs_ioc_getversion(filp, arg);
>>>>> case F2FS_IOC_START_ATOMIC_WRITE:
>>>>> - return f2fs_ioc_start_atomic_write(filp);
>>>>> + return f2fs_ioc_start_atomic_write(filp, false);
>>>>> + case F2FS_IOC_START_ATOMIC_REPLACE:
>>>>> + return f2fs_ioc_start_atomic_write(filp, true);
>>>>> case F2FS_IOC_COMMIT_ATOMIC_WRITE:
>>>>> return f2fs_ioc_commit_atomic_write(filp);
>>>>> case F2FS_IOC_ABORT_ATOMIC_WRITE:
>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>>> index 143b7ea0fb8e..c524538a9013 100644
>>>>> --- a/fs/f2fs/segment.c
>>>>> +++ b/fs/f2fs/segment.c
>>>>> @@ -263,14 +263,26 @@ static void __complete_revoke_list(struct inode *inode, struct list_head *head,
>>>>> bool revoke)
>>>>> {
>>>>> struct revoke_entry *cur, *tmp;
>>>>> + pgoff_t start_index = 0;
>>>>> + bool truncate = is_inode_flag_set(inode, FI_ATOMIC_REPLACE);
>>>>>
>>>>> list_for_each_entry_safe(cur, tmp, head, list) {
>>>>> - if (revoke)
>>>>> + if (revoke) {
>>>>> __replace_atomic_write_block(inode, cur->index,
>>>>> cur->old_addr, NULL, true);
>>>>> + } else if (truncate) {
>>>>> + f2fs_truncate_hole(inode, start_index, cur->index);
>>>>> + start_index = cur->index + 1;
>>>>> + }
>>>>> +
>>>>> list_del(&cur->list);
>>>>> kmem_cache_free(revoke_entry_slab, cur);
>>>>> }
>>>>> +
>>>>> + if (!revoke && truncate) {
>>>>> + f2fs_do_truncate_blocks(inode, start_index * PAGE_SIZE, false);
>>>>> + clear_inode_flag(inode, FI_ATOMIC_REPLACE);
>>>>> + }
>>>>> }
>>>>>
>>>>> static int __f2fs_commit_atomic_write(struct inode *inode)
>>>>> diff --git a/include/uapi/linux/f2fs.h b/include/uapi/linux/f2fs.h
>>>>> index 3121d127d5aa..955d440be104 100644
>>>>> --- a/include/uapi/linux/f2fs.h
>>>>> +++ b/include/uapi/linux/f2fs.h
>>>>> @@ -42,6 +42,7 @@
>>>>> struct f2fs_comp_option)
>>>>> #define F2FS_IOC_DECOMPRESS_FILE _IO(F2FS_IOCTL_MAGIC, 23)
>>>>> #define F2FS_IOC_COMPRESS_FILE _IO(F2FS_IOCTL_MAGIC, 24)
>>>>> +#define F2FS_IOC_START_ATOMIC_REPLACE _IO(F2FS_IOCTL_MAGIC, 25)
>>>>>
>>>>> /*
>>>>> * should be same as XFS_IOC_GOINGDOWN.
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