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Message-ID: <4aca0d00-d3b7-975f-6b72-ccd6f07d22e5@kernel.org>
Date: Fri, 30 Sep 2022 06:54:48 +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 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?
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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