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Date: Wed, 1 Jun 2022 11:05:07 +0800
From: Chao Yu <chao@...nel.org>
To: Jaegeuk Kim <jaegeuk@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, Chao Yu <chao.yu@...o.com>
Subject: Re: [PATCH v4] f2fs: separate NOCoW and pinfile semantics
On 2022/6/1 4:18, Jaegeuk Kim wrote:
> On 05/31, Chao Yu wrote:
>> On 2022/5/18 1:21, Jaegeuk Kim wrote:
>>> On 05/17, Chao Yu wrote:
>>>> Pinning a file is heavy, because skipping pinned files make GC
>>>> running with heavy load or no effect.
>>>>
>>>> So that this patch proposes to separate nocow and pinfile semantics:
>>>> - NOCoW flag can only be set on regular file.
>>>> - NOCoW file will only trigger IPU at common writeback/flush.
>>>> - NOCow file will do OPU during GC.
>>>
>>> How about adding
>>> - NOCow file will allocate 2MB-aligned space via fallocate.
>>>
>>> So, it'd be same as file pinning except allowing GCs. wdyt?
>>
>> Well, it seems the segment-aligned allocation feature should not couple with
>> pin_file or NoCow flag, what about introducing another ioctl for that? something
>> like: F2FS_IOC_ALIGNMENT_PREALLOCATION w/ arg.alignment_start, arg.alignment_len,
>> arg.total_len?
>
> We should allocate 2MB to pin the file, since android is using it.
I mean we can use nocow + new ioctl instead of pinfile, thoughts?
Thanks,
>
>>
>> Thanks,
>>
>>>
>>>>
>>>> This flag can satisfying the demand of:
>>>> 1) avoiding fragment of file's physical block
>>>> 2) userspace doesn't want to pin file's physical address
>>>>
>>>> After commit 5d539245cb18 ("f2fs: export FS_NOCOW_FL flag to user"),
>>>> Pin_file and NOCoW flags have already been twined closely. e.g.
>>>> once we set pinfile flag in file, nocow flag will be shown; and after
>>>> clearing pinfile flag, nocow flag will disappear.
>>>>
>>>> So, in order to keep backward compatibility, let use below semantics:
>>>>
>>>> f2fs_ioc_set_pin_file/f2fs_fileattr_set logic:
>>>> pinfile nocow
>>>> set set pinfile | nocow set nocow
>>>> clear clear pinfile | nocow clear nocow
>>>>
>>>> File Behaviors:
>>>> w/ pinfile, w/ nocow: use pinfile semantics
>>>> w/ pinfile, w/o nocow: use pinfile semantics
>>>> w/o pinfile, w/ nocow: use nocow semantics
>>>> w/o pinfile, w/o nocow: no pinfile or nocow semantics
>>>>
>>>> NOCoW can also be set on directory, and it will have no effect on
>>>> directory, however, new files created in nocow directory will have the
>>>> flag set.
>>>>
>>>> Signed-off-by: Chao Yu <chao.yu@...o.com>
>>>> ---
>>>> v4:
>>>> - allow IPU only for NoCowed regular inode.
>>>> fs/f2fs/data.c | 3 +++
>>>> fs/f2fs/f2fs.h | 13 +++++++++++--
>>>> fs/f2fs/file.c | 18 +++++++++++++++++-
>>>> 3 files changed, 31 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>> index 54a7a8ad994d..42d95ac6b508 100644
>>>> --- a/fs/f2fs/data.c
>>>> +++ b/fs/f2fs/data.c
>>>> @@ -2498,6 +2498,9 @@ bool f2fs_should_update_inplace(struct inode *inode, struct f2fs_io_info *fio)
>>>> if (f2fs_is_pinned_file(inode))
>>>> return true;
>>>> + if (S_ISREG(inode->i_mode) && F2FS_I(inode)->i_flags & F2FS_NOCOW_FL)
>>>> + return true;
>>>> +
>>>> /* if this is cold file, we should overwrite to avoid fragmentation */
>>>> if (file_is_cold(inode))
>>>> return true;
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index 492af5b96de1..5c67736000a7 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -2916,13 +2916,15 @@ static inline void f2fs_change_bit(unsigned int nr, char *addr)
>>>> #define F2FS_NOCOMP_FL 0x00000400 /* Don't compress */
>>>> #define F2FS_INDEX_FL 0x00001000 /* hash-indexed directory */
>>>> #define F2FS_DIRSYNC_FL 0x00010000 /* dirsync behaviour (directories only) */
>>>> +#define F2FS_NOCOW_FL 0x00800000 /* Do not cow file */
>>>> #define F2FS_PROJINHERIT_FL 0x20000000 /* Create with parents projid */
>>>> #define F2FS_CASEFOLD_FL 0x40000000 /* Casefolded file */
>>>> /* Flags that should be inherited by new inodes from their parent. */
>>>> #define F2FS_FL_INHERITED (F2FS_SYNC_FL | F2FS_NODUMP_FL | F2FS_NOATIME_FL | \
>>>> F2FS_DIRSYNC_FL | F2FS_PROJINHERIT_FL | \
>>>> - F2FS_CASEFOLD_FL | F2FS_COMPR_FL | F2FS_NOCOMP_FL)
>>>> + F2FS_CASEFOLD_FL | F2FS_COMPR_FL | F2FS_NOCOMP_FL | \
>>>> + F2FS_NOCOW_FL)
>>>> /* Flags that are appropriate for regular files (all but dir-specific ones). */
>>>> #define F2FS_REG_FLMASK (~(F2FS_DIRSYNC_FL | F2FS_PROJINHERIT_FL | \
>>>> @@ -2954,9 +2956,16 @@ static inline void __mark_inode_dirty_flag(struct inode *inode,
>>>> fallthrough;
>>>> case FI_DATA_EXIST:
>>>> case FI_INLINE_DOTS:
>>>> - case FI_PIN_FILE:
>>>> case FI_COMPRESS_RELEASED:
>>>> f2fs_mark_inode_dirty_sync(inode, true);
>>>> + break;
>>>> + case FI_PIN_FILE:
>>>> + if (set)
>>>> + F2FS_I(inode)->i_flags |= F2FS_NOCOW_FL;
>>>> + else
>>>> + F2FS_I(inode)->i_flags &= ~F2FS_NOCOW_FL;
>>>> + f2fs_mark_inode_dirty_sync(inode, true);
>>>> + break;
>>>> }
>>>> }
>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>> index 216081ea8c81..9e71ce8601f9 100644
>>>> --- a/fs/f2fs/file.c
>>>> +++ b/fs/f2fs/file.c
>>>> @@ -1851,6 +1851,20 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
>>>> if (IS_NOQUOTA(inode))
>>>> return -EPERM;
>>>> + if ((iflags ^ masked_flags) & F2FS_NOCOW_FL) {
>>>> + int ret;
>>>> +
>>>> + if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
>>>> + return -EINVAL;
>>>> + if (S_ISREG(inode->i_mode)) {
>>>> + if (f2fs_should_update_outplace(inode, NULL))
>>>> + return -EINVAL;
>>>> + ret = f2fs_convert_inline_inode(inode);
>>>> + if (ret)
>>>> + return ret;
>>>> + }
>>>> + }
>>>> +
>>>> if ((iflags ^ masked_flags) & F2FS_CASEFOLD_FL) {
>>>> if (!f2fs_sb_has_casefold(F2FS_I_SB(inode)))
>>>> return -EOPNOTSUPP;
>>>> @@ -1926,6 +1940,7 @@ static const struct {
>>>> { F2FS_NOCOMP_FL, FS_NOCOMP_FL },
>>>> { F2FS_INDEX_FL, FS_INDEX_FL },
>>>> { F2FS_DIRSYNC_FL, FS_DIRSYNC_FL },
>>>> + { F2FS_NOCOW_FL, FS_NOCOW_FL },
>>>> { F2FS_PROJINHERIT_FL, FS_PROJINHERIT_FL },
>>>> { F2FS_CASEFOLD_FL, FS_CASEFOLD_FL },
>>>> };
>>>> @@ -1957,7 +1972,8 @@ static const struct {
>>>> FS_NOCOMP_FL | \
>>>> FS_DIRSYNC_FL | \
>>>> FS_PROJINHERIT_FL | \
>>>> - FS_CASEFOLD_FL)
>>>> + FS_CASEFOLD_FL | \
>>>> + FS_NOCOW_FL)
>>>> /* Convert f2fs on-disk i_flags to FS_IOC_{GET,SET}FLAGS flags */
>>>> static inline u32 f2fs_iflags_to_fsflags(u32 iflags)
>>>> --
>>>> 2.25.1
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