linux-kernel - [PATCH v2] f2fs: separate NOCoW and pinfile semantics

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Date:   Sun, 15 May 2022 18:39:34 +0800
From:   Chao Yu <chao@...nel.org>
To:     jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <chao@...nel.org>,
        Chao Yu <chao.yu@...o.com>
Subject: [PATCH v2] f2fs: separate NOCoW and pinfile semantics

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

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

Signed-off-by: Chao Yu <chao.yu@...o.com>
---
v2:
- keep compatibility in between pinfile and nocow flags
 fs/f2fs/data.c |  3 ++-
 fs/f2fs/f2fs.h |  8 +++++++-
 fs/f2fs/file.c | 16 +++++++++++++++-
 3 files changed, 24 insertions(+), 3 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 18a0335799ad..d9445fc62bd7 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2929,6 +2929,7 @@ 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 */
 
@@ -2965,9 +2966,14 @@ static inline void __mark_inode_dirty_flag(struct inode *inode,
 		if (set)
 			return;
 		fallthrough;
+	case FI_PIN_FILE:
+		if (set)
+			F2FS_I(inode)->i_flags |= F2FS_NOCOW_FL;
+		else
+			F2FS_I(inode)->i_flags &= ~F2FS_NOCOW_FL;
+		fallthrough;
 	case FI_DATA_EXIST:
 	case FI_INLINE_DOTS:
-	case FI_PIN_FILE:
 	case FI_COMPRESS_RELEASED:
 		f2fs_mark_inode_dirty_sync(inode, true);
 	}
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index b857384ccd12..da635a904e69 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1854,6 +1854,18 @@ 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;
+		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;
@@ -1929,6 +1941,7 @@ 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 },
 };
@@ -1960,7 +1973,8 @@ 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)
-- 
2.32.0