[PATCH v2 3/5] exfat: move exfat_entry_set_cache from heap to stack

[Yuezhang.Mo@xxxxxxxx]

The size of struct exfat_entry_set_cache is only 56 bytes on
64-bit system, and allocating from stack is more efficient than
allocating from heap.

Signed-off-by: Yuezhang Mo <Yuezhang.Mo@xxxxxxxx>
Reviewed-by: Andy Wu <Andy.Wu@xxxxxxxx>
Reviewed-by: Aoyama Wataru <wataru.aoyama@xxxxxxxx>
---
 fs/exfat/dir.c      | 35 +++++++++++++++--------------------
 fs/exfat/exfat_fs.h |  5 +++--
 fs/exfat/inode.c    | 13 ++++++-------
 fs/exfat/namei.c    | 11 +++++------
 4 files changed, 29 insertions(+), 35 deletions(-)

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index 03e9c9e3966e..a3fb609dd129 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -33,10 +33,9 @@ static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
 		struct exfat_chain *p_dir, int entry, unsigned short *uniname)
 {
 	int i;
-	struct exfat_entry_set_cache *es;
+	struct exfat_entry_set_cache es;
 
-	es = exfat_get_dentry_set(sb, p_dir, entry, ES_ALL_ENTRIES);
-	if (!es)
+	if (exfat_get_dentry_set(&es, sb, p_dir, entry, ES_ALL_ENTRIES))
 		return;
 
 	/*
@@ -45,8 +44,8 @@ static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
 	 * Third entry  : first file-name entry
 	 * So, the index of first file-name dentry should start from 2.
 	 */
-	for (i = 2; i < es->num_entries; i++) {
-		struct exfat_dentry *ep = exfat_get_dentry_cached(es, i);
+	for (i = 2; i < es.num_entries; i++) {
+		struct exfat_dentry *ep = exfat_get_dentry_cached(&es, i);
 
 		/* end of name entry */
 		if (exfat_get_entry_type(ep) != TYPE_EXTEND)
@@ -56,7 +55,7 @@ static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
 		uniname += EXFAT_FILE_NAME_LEN;
 	}
 
-	exfat_free_dentry_set(es, false);
+	exfat_free_dentry_set(&es, false);
 }
 
 /* read a directory entry from the opened directory */
@@ -619,7 +618,6 @@ int exfat_free_dentry_set(struct exfat_entry_set_cache *es, int sync)
 	if (IS_DYNAMIC_ES(es))
 		kfree(es->bh);
 
-	kfree(es);
 	return err;
 }
 
@@ -816,14 +814,14 @@ struct exfat_dentry *exfat_get_dentry_cached(
  *   pointer of entry set on success,
  *   NULL on failure.
  */
-struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
-		struct exfat_chain *p_dir, int entry, unsigned int type)
+int exfat_get_dentry_set(struct exfat_entry_set_cache *es,
+		struct super_block *sb, struct exfat_chain *p_dir, int entry,
+		unsigned int type)
 {
 	int ret, i, num_bh;
 	unsigned int off, byte_offset, clu = 0;
 	sector_t sec;
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
-	struct exfat_entry_set_cache *es;
 	struct exfat_dentry *ep;
 	int num_entries;
 	enum exfat_validate_dentry_mode mode = ES_MODE_STARTED;
@@ -831,17 +829,15 @@ struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
 
 	if (p_dir->dir == DIR_DELETED) {
 		exfat_err(sb, "access to deleted dentry");
-		return NULL;
+		return -EIO;
 	}
 
 	byte_offset = EXFAT_DEN_TO_B(entry);
 	ret = exfat_walk_fat_chain(sb, p_dir, byte_offset, &clu);
 	if (ret)
-		return NULL;
+		return ret;
 
-	es = kzalloc(sizeof(*es), GFP_KERNEL);
-	if (!es)
-		return NULL;
+	memset(es, 0, sizeof(*es));
 	es->sb = sb;
 	es->modified = false;
 
@@ -859,7 +855,7 @@ struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
 
 	bh = sb_bread(sb, sec);
 	if (!bh)
-		goto free_es;
+		return -EIO;
 	es->bh[es->num_bh++] = bh;
 
 	ep = exfat_get_dentry_cached(es, 0);
@@ -875,8 +871,7 @@ struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
 		es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
 		if (!es->bh) {
 			brelse(bh);
-			kfree(es);
-			return NULL;
+			return -ENOMEM;
 		}
 		es->bh[0] = bh;
 	}
@@ -905,11 +900,11 @@ struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
 		if (!exfat_validate_entry(exfat_get_entry_type(ep), &mode))
 			goto free_es;
 	}
-	return es;
+	return 0;
 
 free_es:
 	exfat_free_dentry_set(es, false);
-	return NULL;
+	return -EIO;
 }
 
 static inline void exfat_reset_empty_hint(struct exfat_hint_femp *hint_femp)
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 82395ae80dba..2ffe5792b1a9 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -490,8 +490,9 @@ struct exfat_dentry *exfat_get_dentry(struct super_block *sb,
 		struct exfat_chain *p_dir, int entry, struct buffer_head **bh);
 struct exfat_dentry *exfat_get_dentry_cached(struct exfat_entry_set_cache *es,
 		int num);
-struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
-		struct exfat_chain *p_dir, int entry, unsigned int type);
+int exfat_get_dentry_set(struct exfat_entry_set_cache *es,
+		struct super_block *sb, struct exfat_chain *p_dir, int entry,
+		unsigned int type);
 int exfat_free_dentry_set(struct exfat_entry_set_cache *es, int sync);
 int exfat_count_dir_entries(struct super_block *sb, struct exfat_chain *p_dir);
 
diff --git a/fs/exfat/inode.c b/fs/exfat/inode.c
index 5590a1e83126..cdcf037a304f 100644
--- a/fs/exfat/inode.c
+++ b/fs/exfat/inode.c
@@ -21,7 +21,7 @@ int __exfat_write_inode(struct inode *inode, int sync)
 {
 	unsigned long long on_disk_size;
 	struct exfat_dentry *ep, *ep2;
-	struct exfat_entry_set_cache *es = NULL;
+	struct exfat_entry_set_cache es;
 	struct super_block *sb = inode->i_sb;
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 	struct exfat_inode_info *ei = EXFAT_I(inode);
@@ -42,11 +42,10 @@ int __exfat_write_inode(struct inode *inode, int sync)
 	exfat_set_volume_dirty(sb);
 
 	/* get the directory entry of given file or directory */
-	es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry, ES_ALL_ENTRIES);
-	if (!es)
+	if (exfat_get_dentry_set(&es, sb, &(ei->dir), ei->entry, ES_ALL_ENTRIES))
 		return -EIO;
-	ep = exfat_get_dentry_cached(es, 0);
-	ep2 = exfat_get_dentry_cached(es, 1);
+	ep = exfat_get_dentry_cached(&es, 0);
+	ep2 = exfat_get_dentry_cached(&es, 1);
 
 	ep->dentry.file.attr = cpu_to_le16(exfat_make_attr(inode));
 
@@ -83,8 +82,8 @@ int __exfat_write_inode(struct inode *inode, int sync)
 		ep2->dentry.stream.start_clu = EXFAT_FREE_CLUSTER;
 	}
 
-	exfat_update_dir_chksum_with_entry_set(es);
-	return exfat_free_dentry_set(es, sync);
+	exfat_update_dir_chksum_with_entry_set(&es);
+	return exfat_free_dentry_set(&es, sync);
 }
 
 int exfat_write_inode(struct inode *inode, struct writeback_control *wbc)
diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index 99e00a36c029..8d72527dfb78 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -604,7 +604,7 @@ static int exfat_find(struct inode *dir, struct qstr *qname,
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 	struct exfat_inode_info *ei = EXFAT_I(dir);
 	struct exfat_dentry *ep, *ep2;
-	struct exfat_entry_set_cache *es;
+	struct exfat_entry_set_cache es;
 	/* for optimized dir & entry to prevent long traverse of cluster chain */
 	struct exfat_hint hint_opt;
 
@@ -644,11 +644,10 @@ static int exfat_find(struct inode *dir, struct qstr *qname,
 	if (cdir.flags & ALLOC_NO_FAT_CHAIN)
 		cdir.size -= dentry / sbi->dentries_per_clu;
 	dentry = hint_opt.eidx;
-	es = exfat_get_dentry_set(sb, &cdir, dentry, ES_2_ENTRIES);
-	if (!es)
+	if (exfat_get_dentry_set(&es, sb, &cdir, dentry, ES_2_ENTRIES))
 		return -EIO;
-	ep = exfat_get_dentry_cached(es, 0);
-	ep2 = exfat_get_dentry_cached(es, 1);
+	ep = exfat_get_dentry_cached(&es, 0);
+	ep2 = exfat_get_dentry_cached(&es, 1);
 
 	info->type = exfat_get_entry_type(ep);
 	info->attr = le16_to_cpu(ep->dentry.file.attr);
@@ -677,7 +676,7 @@ static int exfat_find(struct inode *dir, struct qstr *qname,
 			     ep->dentry.file.access_time,
 			     ep->dentry.file.access_date,
 			     0);
-	exfat_free_dentry_set(es, false);
+	exfat_free_dentry_set(&es, false);
 
 	if (ei->start_clu == EXFAT_FREE_CLUSTER) {
 		exfat_fs_error(sb,
-- 
2.25.1