linux-kernel - [RFC PATCH] vfat:avoid unnecessary check

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Message-ID: <tencent_C19E4D9448D8514A505A9FE439D01C333B08@qq.com>
Date: Fri,  5 Sep 2025 00:17:54 +0800
From: zhoumin <teczm@...mail.com>
To: hirofumi@...l.parknet.co.jp
Cc: linux-kernel@...r.kernel.org,
	zhoumin <teczm@...mail.com>
Subject: [RFC PATCH] vfat:avoid unnecessary check

Remove redundant and unreachable name check code in dir.c.

Remove flags check in fat_update_time since fat does not support
inode version.

Optimize fat_truncate_time to return a meaningful value, allowing
the removal of redundant inode checks in fat_update_time. This
ensures non-root inodes are validated only once.

Signed-off-by: zhoumin <teczm@...mail.com>
---
 fs/fat/dir.c  | 12 ++++--------
 fs/fat/misc.c | 11 ++++-------
 2 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index acbec5bdd521..4f1be9939292 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -337,11 +337,11 @@ static int fat_parse_long(struct inode *dir, loff_t *pos,
 		if (ds->alias_checksum != alias_checksum)
 			goto parse_long;
 	}
-	if ((*de)->name[0] == DELETED_FLAG)
+	if (IS_FREE((*de)->name))
 		return PARSE_INVALID;
 	if ((*de)->attr == ATTR_EXT)
 		goto parse_long;
-	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
+	if ((*de)->attr & ATTR_VOLUME)
 		return PARSE_INVALID;
 	if (fat_checksum((*de)->name) != alias_checksum)
 		*nr_slots = 0;
@@ -491,12 +491,10 @@ int fat_search_long(struct inode *inode, const unsigned char *name,
 			goto end_of_dir;
 parse_record:
 		nr_slots = 0;
-		if (de->name[0] == DELETED_FLAG)
+		if (IS_FREE(de->name))
 			continue;
 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
 			continue;
-		if (de->attr != ATTR_EXT && IS_FREE(de->name))
-			continue;
 		if (de->attr == ATTR_EXT) {
 			int status = fat_parse_long(inode, &cpos, &bh, &de,
 						    &unicode, &nr_slots);
@@ -608,12 +606,10 @@ static int __fat_readdir(struct inode *inode, struct file *file,
 	 * need to parse long filename.
 	 */
 	if (isvfat && !short_only) {
-		if (de->name[0] == DELETED_FLAG)
+		if (IS_FREE(de->name))
 			goto record_end;
 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
 			goto record_end;
-		if (de->attr != ATTR_EXT && IS_FREE(de->name))
-			goto record_end;
 	} else {
 		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
 			goto record_end;
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index c7a2d27120ba..41f6362a0428 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -335,7 +335,7 @@ int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
 		inode_set_mtime_to_ts(inode,
 				      inode_set_ctime_to_ts(inode, fat_truncate_mtime(sbi, now)));
 
-	return 0;
+	return 1;
 }
 EXPORT_SYMBOL_GPL(fat_truncate_time);
 
@@ -343,18 +343,15 @@ int fat_update_time(struct inode *inode, int flags)
 {
 	int dirty_flags = 0;
 
-	if (inode->i_ino == MSDOS_ROOT_INO)
-		return 0;
-
-	if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
-		fat_truncate_time(inode, NULL, flags);
+	if (fat_truncate_time(inode, NULL, flags)) {
 		if (inode->i_sb->s_flags & SB_LAZYTIME)
 			dirty_flags |= I_DIRTY_TIME;
 		else
 			dirty_flags |= I_DIRTY_SYNC;
+
+		__mark_inode_dirty(inode, dirty_flags);
 	}
 
-	__mark_inode_dirty(inode, dirty_flags);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(fat_update_time);
-- 
2.43.0