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SubjectRe: [PATCH v4] f2fs: separate NOCoW and pinfile semantics
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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?

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@oppo.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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