On 2022/5/13 5:57, Jaegeuk Kim wrote:
On 05/12, 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.

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

Signed-off-by: Chao Yu <[email protected]>
---
  fs/f2fs/data.c |  3 ++-
  fs/f2fs/f2fs.h |  1 +
  fs/f2fs/file.c | 25 ++++++++++++++++++++++++-
  3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 54a7a8ad994d..c8eab78f7d89 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2495,7 +2495,8 @@ bool f2fs_should_update_inplace(struct inode *inode, 
struct f2fs_io_info *fio)
        if (is_inode_flag_set(inode, FI_ALIGNED_WRITE))
                return false;
- 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 492af5b96de1..e91ece55f5e8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2916,6 +2916,7 @@ 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 */
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 09287876dbb7..7f92a3a157f7 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))
+                       return -EINVAL;
+               if (f2fs_should_update_outplace(inode, NULL))
+                       return -EINVAL;
+               if (f2fs_is_pinned_file(inode))
+                       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)
@@ -3081,6 +3097,13 @@ static int f2fs_ioc_set_pin_file(struct file *filp, 
unsigned long arg)
inode_lock(inode); + if (F2FS_I(inode)->i_flags & F2FS_NOCOW_FL) {
+               f2fs_info(F2FS_I_SB(inode), "inode (%lu) is already NOCOW one",
+                       inode->i_ino);
+               ret = -EINVAL;

Why rejecting this? We can pin the file to get 2MB-aligned allocation on the
NOCOW file.

I try to separate these two flag completely, but, seems it can't, because after
commit 5d539245cb18 ("f2fs: export FS_NOCOW_FL flag to user"), these two flags
have already been twined closely....

@@ -1651,6 +1651,8 @@ static int f2fs_ioc_getflags(struct file *filp, unsigned 
long arg)
                flags |= F2FS_ENCRYPT_FL;
        if (f2fs_has_inline_data(inode) || f2fs_has_inline_dentry(inode))
                flags |= F2FS_INLINE_DATA_FL;
+       if (is_inode_flag_set(inode, FI_PIN_FILE))
+               flags |= F2FS_NOCOW_FL;

How about:

f2fs_ioc_set_pin_file/f2fs_fileattr_set logic:
                pinfile                 nocow
set             set pinfile | nocow     set nocow
clear           clear pinfile | nocow   clear nocow

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

Thanks,


+               goto out;
+       }
+
        if (!pin) {
                clear_inode_flag(inode, FI_PIN_FILE);
                f2fs_i_gc_failures_write(inode, 0);
--
2.25.1


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