exfat: optimize dir-cache

Optimize directory access based on exfat_entry_set_cache.
 - Hold bh instead of copied d-entry.
 - Modify bh->data directly instead of the copied d-entry.
 - Write back the retained bh instead of rescanning the d-entry-set.
And
 - Remove unused cache related definitions.

Signed-off-by: Tetsuhiro Kohada <kohada.tetsuhiro@dc.mitsubishielectric.co.jp>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

1 files changed, 22 insertions, 31 deletions

diff --git a/fs/exfat/inode.c b/fs/exfat/inode.c
index 3f367d081cd6..ef7cf7a6d187 100644
--- a/fs/exfat/inode.c
+++ b/fs/exfat/inode.c
@@ -19,7 +19,6 @@
 
 static int __exfat_write_inode(struct inode *inode, int sync)
 {
-	int ret = -EIO;
 	unsigned long long on_disk_size;
 	struct exfat_dentry *ep, *ep2;
 	struct exfat_entry_set_cache *es = NULL;
@@ -43,11 +42,11 @@ static int __exfat_write_inode(struct inode *inode, int sync)
 	exfat_set_vol_flags(sb, VOL_DIRTY);
 
 	/* get the directory entry of given file or directory */
-	es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry, ES_ALL_ENTRIES,
-		&ep);
+	es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry, ES_ALL_ENTRIES);
 	if (!es)
 		return -EIO;
-	ep2 = ep + 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));
 
@@ -77,9 +76,9 @@ static int __exfat_write_inode(struct inode *inode, int sync)
 	ep2->dentry.stream.valid_size = cpu_to_le64(on_disk_size);
 	ep2->dentry.stream.size = ep2->dentry.stream.valid_size;
 
-	ret = exfat_update_dir_chksum_with_entry_set(sb, es, sync);
-	kfree(es);
-	return ret;
+	exfat_update_dir_chksum_with_entry_set(es);
+	exfat_free_dentry_set(es, sync);
+	return 0;
 }
 
 int exfat_write_inode(struct inode *inode, struct writeback_control *wbc)
@@ -110,8 +109,6 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
 	int ret, modified = false;
 	unsigned int last_clu;
 	struct exfat_chain new_clu;
-	struct exfat_dentry *ep;
-	struct exfat_entry_set_cache *es = NULL;
 	struct super_block *sb = inode->i_sb;
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 	struct exfat_inode_info *ei = EXFAT_I(inode);
@@ -222,34 +219,28 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
 		num_clusters += num_to_be_allocated;
 		*clu = new_clu.dir;
 
-		if (ei->dir.dir != DIR_DELETED) {
+		if (ei->dir.dir != DIR_DELETED && modified) {
+			struct exfat_dentry *ep;
+			struct exfat_entry_set_cache *es;
+
 			es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry,
-				ES_ALL_ENTRIES, &ep);
+				ES_ALL_ENTRIES);
 			if (!es)
 				return -EIO;
 			/* get stream entry */
-			ep++;
+			ep = exfat_get_dentry_cached(es, 1);
 
 			/* update directory entry */
-			if (modified) {
-				if (ep->dentry.stream.flags != ei->flags)
-					ep->dentry.stream.flags = ei->flags;
-
-				if (le32_to_cpu(ep->dentry.stream.start_clu) !=
-						ei->start_clu)
-					ep->dentry.stream.start_clu =
-						cpu_to_le32(ei->start_clu);
-
-				ep->dentry.stream.valid_size =
-					cpu_to_le64(i_size_read(inode));
-				ep->dentry.stream.size =
-					ep->dentry.stream.valid_size;
-			}
-
-			if (exfat_update_dir_chksum_with_entry_set(sb, es,
-			    inode_needs_sync(inode)))
-				return -EIO;
-			kfree(es);
+			ep->dentry.stream.flags = ei->flags;
+			ep->dentry.stream.start_clu =
+				cpu_to_le32(ei->start_clu);
+			ep->dentry.stream.valid_size =
+				cpu_to_le64(i_size_read(inode));
+			ep->dentry.stream.size =
+				ep->dentry.stream.valid_size;
+
+			exfat_update_dir_chksum_with_entry_set(es);
+			exfat_free_dentry_set(es, inode_needs_sync(inode));
 
 		} /* end of if != DIR_DELETED */