[v4,1/5] fs, block: refactor enum rw_hint

Commit Message

Kanchan Joshi Aug. 26, 2024, 5:06 p.m. UTC

Rename enum rw_hint to rw_life_hint.
Change i_write_hint (in inode), bi_write_hint (in bio) and write_hint
(in request) to use u8 data-type rather than this enum.

This is in preparation to introduce a new write hint type.

Signed-off-by: Kanchan Joshi <[e-mail]>
---
 fs/buffer.c               | 4 ++--
 fs/f2fs/f2fs.h            | 4 ++--
 fs/f2fs/segment.c         | 4 ++--
 include/linux/blk-mq.h    | 2 +-
 include/linux/blk_types.h | 2 +-
 include/linux/fs.h        | 2 +-
 include/linux/rw_hint.h   | 9 ++-------
 7 files changed, 11 insertions(+), 16 deletions(-)

Comments

Bart Van Assche Aug. 26, 2024, 5:44 p.m. UTC | #1

On 8/26/24 10:06 AM, Kanchan Joshi wrote:
> Change i_write_hint (in inode), bi_write_hint (in bio) and write_hint
> (in request) to use u8 data-type rather than this enum.

That sounds fishy to me. Why to increase the size of this enum? Why to
reduce the ability of the compiler to perform type checking? I think
this needs to be motivated clearly in the patch description.

Bart.

Kanchan Joshi Aug. 27, 2024, 5:12 a.m. UTC | #2

On 8/26/2024 11:14 PM, Bart Van Assche wrote:
> On 8/26/24 10:06 AM, Kanchan Joshi wrote:
>> Change i_write_hint (in inode), bi_write_hint (in bio) and write_hint
>> (in request) to use u8 data-type rather than this enum.
> 
> That sounds fishy to me. Why to increase the size of this enum? Why to
> reduce the ability of the compiler to perform type checking? I think
> this needs to be motivated clearly in the patch description.

Since inode/bio/request stopped using this, the __packed annotation did 
not seem to serve much purpose. But sure, I can retain the size/checks 
on the renamed enum (rw_life_hint) too.

Motivation for keeping u8 in inode/bio/request is to represent another 
hint type. This is similar to ioprio where multiple io priority 
classes/values are expressed within an int type.

Bart Van Assche Aug. 30, 2024, 12:17 p.m. UTC | #3

On 8/26/24 1:06 PM, Kanchan Joshi wrote:
>   /* Block storage write lifetime hint values. */
> -enum rw_hint {
> +enum rw_life_hint {

The name "rw_life_hint" seems confusing to me. I think that the
name "rw_lifetime_hint" would be a better name.

Thanks,

Bart.

Kanchan Joshi Sept. 2, 2024, 5:18 a.m. UTC | #4

On 8/30/2024 5:47 PM, Bart Van Assche wrote:
> On 8/26/24 1:06 PM, Kanchan Joshi wrote:
>>   /* Block storage write lifetime hint values. */
>> -enum rw_hint {
>> +enum rw_life_hint {
> 
> The name "rw_life_hint" seems confusing to me. I think that the
> name "rw_lifetime_hint" would be a better name.
> 

I can change to that in next iteration.
This change needs to be consistent in all the places. But more important 
in patch #3 (as we expose TYPE_RW_LIFE_HINT to userspace). Do you have 
comments on the other parts?

Patch

diff --git a/fs/buffer.c b/fs/buffer.c
index e55ad471c530..0c6bc9b7d4ad 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -55,7 +55,7 @@ 
 
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
 static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
-			  enum rw_hint hint, struct writeback_control *wbc);
+			  u8 hint, struct writeback_control *wbc);
 
 #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
 
@@ -2778,7 +2778,7 @@  static void end_bio_bh_io_sync(struct bio *bio)
 }
 
 static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
-			  enum rw_hint write_hint,
+			  u8 write_hint,
 			  struct writeback_control *wbc)
 {
 	const enum req_op op = opf & REQ_OP_MASK;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index ac19c61f0c3e..b3022dc94a1f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3756,8 +3756,8 @@  int f2fs_build_segment_manager(struct f2fs_sb_info *sbi);
 void f2fs_destroy_segment_manager(struct f2fs_sb_info *sbi);
 int __init f2fs_create_segment_manager_caches(void);
 void f2fs_destroy_segment_manager_caches(void);
-int f2fs_rw_hint_to_seg_type(struct f2fs_sb_info *sbi, enum rw_hint hint);
-enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
+int f2fs_rw_hint_to_seg_type(struct f2fs_sb_info *sbi, enum rw_life_hint hint);
+enum rw_life_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
 			enum page_type type, enum temp_type temp);
 unsigned int f2fs_usable_segs_in_sec(struct f2fs_sb_info *sbi,
 			unsigned int segno);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 78c3198a6308..794050f4cdbf 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3381,7 +3381,7 @@  int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
 	return err;
 }
 
-int f2fs_rw_hint_to_seg_type(struct f2fs_sb_info *sbi, enum rw_hint hint)
+int f2fs_rw_hint_to_seg_type(struct f2fs_sb_info *sbi, enum rw_life_hint hint)
 {
 	if (F2FS_OPTION(sbi).active_logs == 2)
 		return CURSEG_HOT_DATA;
@@ -3425,7 +3425,7 @@  int f2fs_rw_hint_to_seg_type(struct f2fs_sb_info *sbi, enum rw_hint hint)
  * WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM
  * WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG
  */
-enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
+enum rw_life_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
 				enum page_type type, enum temp_type temp)
 {
 	switch (type) {
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 8d304b1d16b1..1e5ce84ccf0a 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -159,7 +159,7 @@  struct request {
 	struct blk_crypto_keyslot *crypt_keyslot;
 #endif
 
-	enum rw_hint write_hint;
+	u8 write_hint;
 	unsigned short ioprio;
 
 	enum mq_rq_state state;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 36ed96133217..446c847bb3b3 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -216,7 +216,7 @@  struct bio {
 						 */
 	unsigned short		bi_flags;	/* BIO_* below */
 	unsigned short		bi_ioprio;
-	enum rw_hint		bi_write_hint;
+	u8			bi_write_hint;
 	blk_status_t		bi_status;
 	atomic_t		__bi_remaining;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fb0426f349fc..f9a7a2a80661 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -674,7 +674,7 @@  struct inode {
 	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
 	unsigned short          i_bytes;
 	u8			i_blkbits;
-	enum rw_hint		i_write_hint;
+	u8			i_write_hint;
 	blkcnt_t		i_blocks;
 
 #ifdef __NEED_I_SIZE_ORDERED
diff --git a/include/linux/rw_hint.h b/include/linux/rw_hint.h
index 309ca72f2dfb..e17fd9fa65d4 100644
--- a/include/linux/rw_hint.h
+++ b/include/linux/rw_hint.h
@@ -7,18 +7,13 @@ 
 #include <uapi/linux/fcntl.h>
 
 /* Block storage write lifetime hint values. */
-enum rw_hint {
+enum rw_life_hint {
 	WRITE_LIFE_NOT_SET	= RWH_WRITE_LIFE_NOT_SET,
 	WRITE_LIFE_NONE		= RWH_WRITE_LIFE_NONE,
 	WRITE_LIFE_SHORT	= RWH_WRITE_LIFE_SHORT,
 	WRITE_LIFE_MEDIUM	= RWH_WRITE_LIFE_MEDIUM,
 	WRITE_LIFE_LONG		= RWH_WRITE_LIFE_LONG,
 	WRITE_LIFE_EXTREME	= RWH_WRITE_LIFE_EXTREME,
-} __packed;
-
-/* Sparse ignores __packed annotations on enums, hence the #ifndef below. */
-#ifndef __CHECKER__
-static_assert(sizeof(enum rw_hint) == 1);
-#endif
+};
 
 #endif /* _LINUX_RW_HINT_H */