udf: Move handling of uniqueID into a helper function and protect it by a s_alloc_mutex

uniqueID handling has been duplicated in three places. Move it into a common
helper. Since we modify an LVID buffer with uniqueID update, we take
sbi->s_alloc_mutex to protect agaist other modifications of the structure.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 27 insertions, 0 deletions

diff --git a/fs/udf/super.c b/fs/udf/super.c
index f99ff5dbd741..948e1aca0f34 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1823,6 +1823,33 @@ static void udf_close_lvid(struct super_block *sb)
 	sbi->s_lvid_dirty = 0;
 }
 
+u64 lvid_get_unique_id(struct super_block *sb)
+{
+	struct buffer_head *bh;
+	struct udf_sb_info *sbi = UDF_SB(sb);
+	struct logicalVolIntegrityDesc *lvid;
+	struct logicalVolHeaderDesc *lvhd;
+	u64 uniqueID;
+	u64 ret;
+
+	bh = sbi->s_lvid_bh;
+	if (!bh)
+		return 0;
+
+	lvid = (struct logicalVolIntegrityDesc *)bh->b_data;
+	lvhd = (struct logicalVolHeaderDesc *)lvid->logicalVolContentsUse;
+
+	mutex_lock(&sbi->s_alloc_mutex);
+	ret = uniqueID = le64_to_cpu(lvhd->uniqueID);
+	if (!(++uniqueID & 0xFFFFFFFF))
+		uniqueID += 16;
+	lvhd->uniqueID = cpu_to_le64(uniqueID);
+	mutex_unlock(&sbi->s_alloc_mutex);
+	mark_buffer_dirty(bh);
+
+	return ret;
+}
+
 static void udf_sb_free_bitmap(struct udf_bitmap *bitmap)
 {
 	int i;