1 files changed, 52 insertions, 11 deletions

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index 561fd2349218..500094c60c13 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -470,32 +470,70 @@ static void exfat_free_benign_secondary_clusters(struct inode *inode,
 	exfat_free_cluster(inode, &dir);
 }
 
+/*
+ * exfat_init_ext_entry - initialize extension entries in a directory entry set
+ * @es:          target entry set
+ * @num_entries: number of entries excluding benign secondary entries
+ * @p_uniname:   filename to store
+ * @old_es:      optional source entry set with benign secondary entries, or NULL
+ * @num_extra:   number of benign secondary entries to copy from @old_es
+ *
+ * Set up the file, stream extension, and filename entries in @es, optionally
+ * preserving @num_extra benign secondary entries from @old_es.  @es and @old_es
+ * may refer to the same entry set; excess entries are marked as deleted.
+ */
 void exfat_init_ext_entry(struct exfat_entry_set_cache *es, int num_entries,
-		struct exfat_uni_name *p_uniname)
+		struct exfat_uni_name *p_uniname,
+		struct exfat_entry_set_cache *old_es, int num_extra)
 {
-	int i;
+	int i, src_start = 0, old_num;
 	unsigned short *uniname = p_uniname->name;
 	struct exfat_dentry *ep;
 
-	es->num_entries = num_entries;
+	if (WARN_ON(num_extra < 0 || (num_extra && (!old_es ||
+		    old_es->num_entries < ES_IDX_FIRST_FILENAME + num_extra))))
+		num_extra = 0;
+
+	/*
+	 * Save old entry count and source position before modifying
+	 * es->num_entries, since old_es and es may point to the same
+	 * entry set.
+	 */
+	old_num = es->num_entries;
+	if (old_es && num_extra > 0)
+		src_start = old_es->num_entries - num_extra;
+
+	es->num_entries = num_entries + num_extra;
 	ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
-	ep->dentry.file.num_ext = (unsigned char)(num_entries - 1);
+	ep->dentry.file.num_ext = (unsigned char)(num_entries - 1 + num_extra);
 
 	ep = exfat_get_dentry_cached(es, ES_IDX_STREAM);
 	ep->dentry.stream.name_len = p_uniname->name_len;
 	ep->dentry.stream.name_hash = cpu_to_le16(p_uniname->name_hash);
 
+	if (old_es && num_extra > 0) {
+		for (i = 0; i < num_extra; i++)
+			*exfat_get_dentry_cached(es, num_entries + i) =
+				*exfat_get_dentry_cached(old_es, src_start + i);
+	}
+
 	for (i = ES_IDX_FIRST_FILENAME; i < num_entries; i++) {
 		ep = exfat_get_dentry_cached(es, i);
 		exfat_init_name_entry(ep, uniname);
 		uniname += EXFAT_FILE_NAME_LEN;
 	}
 
+	/* Mark excess old entries as deleted (in-place shrink) */
+	for (i = num_entries + num_extra; i < old_num; i++) {
+		ep = exfat_get_dentry_cached(es, i);
+		exfat_set_entry_type(ep, TYPE_DELETED);
+	}
+
 	exfat_update_dir_chksum(es);
 }
 
 void exfat_remove_entries(struct inode *inode, struct exfat_entry_set_cache *es,
-		int order)
+		int order, bool free_benign)
 {
 	int i;
 	struct exfat_dentry *ep;
@@ -503,7 +541,7 @@ void exfat_remove_entries(struct inode *inode, struct exfat_entry_set_cache *es,
 	for (i = order; i < es->num_entries; i++) {
 		ep = exfat_get_dentry_cached(es, i);
 
-		if (exfat_get_entry_type(ep) & TYPE_BENIGN_SEC)
+		if (free_benign && (exfat_get_entry_type(ep) & TYPE_BENIGN_SEC))
 			exfat_free_benign_secondary_clusters(inode, ep);
 
 		exfat_set_entry_type(ep, TYPE_DELETED);
@@ -1029,6 +1067,7 @@ rewind:
 
 			if (entry_type == TYPE_EXTEND) {
 				unsigned short entry_uniname[16], unichar;
+				unsigned int offset;
 
 				if (step != DIRENT_STEP_NAME ||
 				    name_len >= MAX_NAME_LENGTH) {
@@ -1037,13 +1076,15 @@ rewind:
 					continue;
 				}
 
-				if (++order == 2)
-					uniname = p_uniname->name;
-				else
-					uniname += EXFAT_FILE_NAME_LEN;
-
+				offset = (++order - 2) * EXFAT_FILE_NAME_LEN;
 				len = exfat_extract_uni_name(ep, entry_uniname);
 				brelse(bh);
+				if (offset > MAX_NAME_LENGTH ||
+				    len > MAX_NAME_LENGTH - offset) {
+					step = DIRENT_STEP_FILE;
+					continue;
+				}
+				uniname = p_uniname->name + offset;
 				name_len += len;
 
 				unichar = *(uniname+len);