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From:   Chao Yu <chao@kernel.org>
To:     jaegeuk@kernel.org
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, Chao Yu <chao@kernel.org>,
        Chao Yu <chao.yu@oppo.com>
Subject: [PATCH v4] f2fs: separate NOCoW and pinfile semantics
Date:   Tue, 17 May 2022 11:24:10 +0800
Message-Id: <20220517032410.3564033-1-chao@kernel.org>
MIME-Version: 1.0
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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

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