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    SubjectRe: [PATCH v2] f2fs: separate NOCoW and pinfile semantics
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    On 2019/7/23 10:36, Jaegeuk Kim wrote:
    > On 07/19, Chao Yu wrote:
    >> Pinning a file is heavy, because skipping pinned files make GC
    >> running with heavy load or no effect.
    >
    > Pinned file is a part of NOCOW files, so I don't think we can simply drop it
    > for backward compatibility.

    Yes,

    But what I concerned is that pin file is too heavy, so in order to satisfy below
    demand, how about introducing pin_file_2 flag to triggering IPU only during
    flush/writeback.

    >
    >>
    >> So that this patch propose 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.
    >>
    >> For the demand of 1) avoid fragment of file's physical block and
    >> 2) userspace don't care about file's specific physical address,
    >> tagging file as NOCoW will be cheaper than pinned one.

    ^^^

    Thanks,

    >>
    >> Signed-off-by: Chao Yu <yuchao0@huawei.com>
    >> ---
    >> v2:
    >> - rebase code to fix compile error.
    >> fs/f2fs/data.c | 3 ++-
    >> fs/f2fs/f2fs.h | 1 +
    >> fs/f2fs/file.c | 22 +++++++++++++++++++---
    >> 3 files changed, 22 insertions(+), 4 deletions(-)
    >>
    >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
    >> index a2a28bb269bf..15fb8954c363 100644
    >> --- a/fs/f2fs/data.c
    >> +++ b/fs/f2fs/data.c
    >> @@ -1884,7 +1884,8 @@ static inline bool check_inplace_update_policy(struct inode *inode,
    >>
    >> bool f2fs_should_update_inplace(struct inode *inode, struct f2fs_io_info *fio)
    >> {
    >> - if (f2fs_is_pinned_file(inode))
    >> + if (f2fs_is_pinned_file(inode) ||
    >> + F2FS_I(inode)->i_flags & F2FS_NOCOW_FL)
    >> return true;
    >>
    >> /* if this is cold file, we should overwrite to avoid fragmentation */
    >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
    >> index 596ab3e1dd7b..f6c5a3d2e659 100644
    >> --- a/fs/f2fs/f2fs.h
    >> +++ b/fs/f2fs/f2fs.h
    >> @@ -2374,6 +2374,7 @@ static inline void f2fs_change_bit(unsigned int nr, char *addr)
    >> #define F2FS_NOATIME_FL 0x00000080 /* do not update atime */
    >> #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 */
    >>
    >> /* Flags that should be inherited by new inodes from their parent. */
    >> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
    >> index 7ca545874060..ae0fec54cac6 100644
    >> --- a/fs/f2fs/file.c
    >> +++ b/fs/f2fs/file.c
    >> @@ -1692,6 +1692,7 @@ static const struct {
    >> { F2FS_NOATIME_FL, FS_NOATIME_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 },
    >> };
    >>
    >> @@ -1715,7 +1716,8 @@ static const struct {
    >> FS_NODUMP_FL | \
    >> FS_NOATIME_FL | \
    >> FS_DIRSYNC_FL | \
    >> - FS_PROJINHERIT_FL)
    >> + FS_PROJINHERIT_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)
    >> @@ -1753,8 +1755,6 @@ static int f2fs_ioc_getflags(struct file *filp, unsigned long arg)
    >> fsflags |= FS_ENCRYPT_FL;
    >> if (f2fs_has_inline_data(inode) || f2fs_has_inline_dentry(inode))
    >> fsflags |= FS_INLINE_DATA_FL;
    >> - if (is_inode_flag_set(inode, FI_PIN_FILE))
    >> - fsflags |= FS_NOCOW_FL;
    >>
    >> fsflags &= F2FS_GETTABLE_FS_FL;
    >>
    >> @@ -1794,6 +1794,22 @@ static int f2fs_ioc_setflags(struct file *filp, unsigned long arg)
    >> if (ret)
    >> goto out;
    >>
    >> + if ((fsflags ^ old_fsflags) & FS_NOCOW_FL) {
    >> + if (!S_ISREG(inode->i_mode)) {
    >> + ret = -EINVAL;
    >> + goto out;
    >> + }
    >> +
    >> + if (f2fs_should_update_outplace(inode, NULL)) {
    >> + ret = -EINVAL;
    >> + goto out;
    >> + }
    >> +
    >> + ret = f2fs_convert_inline_inode(inode);
    >> + if (ret)
    >> + goto out;
    >> + }
    >> +
    >> ret = f2fs_setflags_common(inode, iflags,
    >> f2fs_fsflags_to_iflags(F2FS_SETTABLE_FS_FL));
    >> out:
    >> --
    >> 2.18.0.rc1
    > .
    >

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