[PATCH] f2fs: support F2FS_NOLINEAR_LOOKUP_FL

[Chao Yu]

This patch introduces a new flag F2FS_NOLINEAR_LOOKUP_FL, so that we can
tag casefolded directory w/ it to disable linear lookup functionality,
it can be used for QA.

Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
 fs/f2fs/dir.c             |  3 ++-
 fs/f2fs/f2fs.h            |  2 ++
 fs/f2fs/file.c            | 36 +++++++++++++++++++++++-------------
 include/uapi/linux/f2fs.h |  5 +++++
 4 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 54dd52de7269..4c74f29a2c73 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -366,7 +366,8 @@ struct f2fs_dir_entry *__f2fs_find_entry(struct inode *dir,
 
 out:
 #if IS_ENABLED(CONFIG_UNICODE)
-	if (IS_CASEFOLDED(dir) && !de && use_hash) {
+	if (IS_CASEFOLDED(dir) && !de && use_hash &&
+				!IS_NOLINEAR_LOOKUP(dir)) {
 		use_hash = false;
 		goto start_find_entry;
 	}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 05879c6dc4d6..787f1e5a52d7 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3047,6 +3047,7 @@ 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_NOLINEAR_LOOKUP_FL		0x08000000 /* do not use linear lookup */
 #define F2FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
 #define F2FS_CASEFOLD_FL		0x40000000 /* Casefolded file */
 #define F2FS_DEVICE_ALIAS_FL		0x80000000 /* File for aliasing a device */
@@ -3066,6 +3067,7 @@ static inline void f2fs_change_bit(unsigned int nr, char *addr)
 #define F2FS_OTHER_FLMASK	(F2FS_NODUMP_FL | F2FS_NOATIME_FL)
 
 #define IS_DEVICE_ALIASING(inode)	(F2FS_I(inode)->i_flags & F2FS_DEVICE_ALIAS_FL)
+#define IS_NOLINEAR_LOOKUP(inode)	(F2FS_I(inode)->i_flags & F2FS_NOLINEAR_LOOKUP_FL)
 
 static inline __u32 f2fs_mask_flags(umode_t mode, __u32 flags)
 {
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 014cb7660a9a..1acddc4d11e4 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2062,6 +2062,11 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
 		}
 	}
 
+	if ((iflags ^ masked_flags) & F2FS_NOLINEAR_LOOKUP_FLAG) {
+		if (!S_ISDIR(inode->i_mode) || !IS_CASEFOLDED(inode))
+			return -EINVAL;
+	}
+
 	fi->i_flags = iflags | (fi->i_flags & ~mask);
 	f2fs_bug_on(F2FS_I_SB(inode), (fi->i_flags & F2FS_COMPR_FL) &&
 					(fi->i_flags & F2FS_NOCOMP_FL));
@@ -2093,17 +2098,18 @@ static const struct {
 	u32 iflag;
 	u32 fsflag;
 } f2fs_fsflags_map[] = {
-	{ F2FS_COMPR_FL,	FS_COMPR_FL },
-	{ F2FS_SYNC_FL,		FS_SYNC_FL },
-	{ F2FS_IMMUTABLE_FL,	FS_IMMUTABLE_FL },
-	{ F2FS_APPEND_FL,	FS_APPEND_FL },
-	{ F2FS_NODUMP_FL,	FS_NODUMP_FL },
-	{ F2FS_NOATIME_FL,	FS_NOATIME_FL },
-	{ F2FS_NOCOMP_FL,	FS_NOCOMP_FL },
-	{ F2FS_INDEX_FL,	FS_INDEX_FL },
-	{ F2FS_DIRSYNC_FL,	FS_DIRSYNC_FL },
-	{ F2FS_PROJINHERIT_FL,	FS_PROJINHERIT_FL },
-	{ F2FS_CASEFOLD_FL,	FS_CASEFOLD_FL },
+	{ F2FS_COMPR_FL,		FS_COMPR_FL },
+	{ F2FS_SYNC_FL,			FS_SYNC_FL },
+	{ F2FS_IMMUTABLE_FL,		FS_IMMUTABLE_FL },
+	{ F2FS_APPEND_FL,		FS_APPEND_FL },
+	{ F2FS_NODUMP_FL,		FS_NODUMP_FL },
+	{ F2FS_NOATIME_FL,		FS_NOATIME_FL },
+	{ F2FS_NOCOMP_FL,		FS_NOCOMP_FL },
+	{ F2FS_INDEX_FL,		FS_INDEX_FL },
+	{ F2FS_DIRSYNC_FL,		FS_DIRSYNC_FL },
+	{ F2FS_PROJINHERIT_FL,		FS_PROJINHERIT_FL },
+	{ F2FS_CASEFOLD_FL,		FS_CASEFOLD_FL },
+	{ F2FS_NOLINEAR_LOOKUP_FL,	F2FS_NOLINEAR_LOOKUP_FL },
 };
 
 #define F2FS_GETTABLE_FS_FL (		\
@@ -2121,7 +2127,8 @@ static const struct {
 		FS_INLINE_DATA_FL |	\
 		FS_NOCOW_FL |		\
 		FS_VERITY_FL |		\
-		FS_CASEFOLD_FL)
+		FS_CASEFOLD_FL |	\
+		F2FS_NOLINEAR_LOOKUP_FL)
 
 #define F2FS_SETTABLE_FS_FL (		\
 		FS_COMPR_FL |		\
@@ -2133,7 +2140,8 @@ static const struct {
 		FS_NOCOMP_FL |		\
 		FS_DIRSYNC_FL |		\
 		FS_PROJINHERIT_FL |	\
-		FS_CASEFOLD_FL)
+		FS_CASEFOLD_FL |	\
+		F2FS_NOLINEAR_LOOKUP_FL)
 
 /* Convert f2fs on-disk i_flags to FS_IOC_{GET,SET}FLAGS flags */
 static inline u32 f2fs_iflags_to_fsflags(u32 iflags)
@@ -3344,6 +3352,8 @@ int f2fs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 		fsflags |= FS_INLINE_DATA_FL;
 	if (is_inode_flag_set(inode, FI_PIN_FILE))
 		fsflags |= FS_NOCOW_FL;
+	if (IS_NOLINEAR_LOOKUP(inode))
+		fsflags |= F2FS_NOLINEAR_LOOKUP_FL;
 
 	fileattr_fill_flags(fa, fsflags & F2FS_GETTABLE_FS_FL);
 
diff --git a/include/uapi/linux/f2fs.h b/include/uapi/linux/f2fs.h
index 795e26258355..a03626fdcf35 100644
--- a/include/uapi/linux/f2fs.h
+++ b/include/uapi/linux/f2fs.h
@@ -104,4 +104,9 @@ struct f2fs_comp_option {
 	__u8 log_cluster_size;
 };
 
+/* used for FS_IOC_GETFLAGS and FS_IOC_SETFLAGS */
+enum {
+	F2FS_NOLINEAR_LOOKUP_FLAG = 0x08000000,
+};
+
 #endif /* _UAPI_LINUX_F2FS_H */
-- 
2.48.1