udf: Fix unalloc space handling in udf_update_inode

Writing of inode holding unallocated space info was broken because we first
cleared the buffer and after that checked whether it contains a tag meaning the
block holds unallocated space information.  Fix the problem by checking
appropriate in memory flag instead.

Also cleanup the function a bit along the way - most importantly lock buffer
when modifying its contents, check for buffer_write_io_error instead of
!buffer_uptodate, etc..
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/inode.c

@@ -1412,16 +1412,16 @@ static int udf_update_inode(struct inode *inode, int do_sync)
 			udf_get_lb_pblock(inode->i_sb,
 					  &iinfo->i_location, 0));
 	if (!bh) {
-		udf_debug("bread failure\n");
-		return -EIO;
+		udf_debug("getblk failure\n");
+		return -ENOMEM;
 	}
 
-	memset(bh->b_data, 0x00, inode->i_sb->s_blocksize);
-
+	lock_buffer(bh);
+	memset(bh->b_data, 0, inode->i_sb->s_blocksize);
 	fe = (struct fileEntry *)bh->b_data;
 	efe = (struct extendedFileEntry *)bh->b_data;
 
-	if (fe->descTag.tagIdent == cpu_to_le16(TAG_IDENT_USE)) {
+	if (iinfo->i_use) {
 		struct unallocSpaceEntry *use =
 			(struct unallocSpaceEntry *)bh->b_data;
 
@@ -1429,20 +1429,18 @@ static int udf_update_inode(struct inode *inode, int do_sync)
 		memcpy(bh->b_data + sizeof(struct unallocSpaceEntry),
 		       iinfo->i_ext.i_data, inode->i_sb->s_blocksize -
 					sizeof(struct unallocSpaceEntry));
+		use->descTag.tagIdent = cpu_to_le16(TAG_IDENT_USE);
+		use->descTag.tagLocation =
+				cpu_to_le32(iinfo->i_location.logicalBlockNum);
 		crclen = sizeof(struct unallocSpaceEntry) +
 				iinfo->i_lenAlloc - sizeof(struct tag);
-		use->descTag.tagLocation = cpu_to_le32(
-						iinfo->i_location.
-							logicalBlockNum);
 		use->descTag.descCRCLength = cpu_to_le16(crclen);
 		use->descTag.descCRC = cpu_to_le16(crc_itu_t(0, (char *)use +
 							   sizeof(struct tag),
 							   crclen));
 		use->descTag.tagChecksum = udf_tag_checksum(&use->descTag);
 
-		mark_buffer_dirty(bh);
-		brelse(bh);
-		return err;
+		goto out;
 	}
 
 	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_UID_FORGET))
@@ -1597,18 +1595,20 @@ static int udf_update_inode(struct inode *inode, int do_sync)
 	fe->descTag.tagSerialNum = cpu_to_le16(sbi->s_serial_number);
 	fe->descTag.tagLocation = cpu_to_le32(
 					iinfo->i_location.logicalBlockNum);
-	crclen += iinfo->i_lenEAttr + iinfo->i_lenAlloc -
-								sizeof(struct tag);
+	crclen += iinfo->i_lenEAttr + iinfo->i_lenAlloc - sizeof(struct tag);
 	fe->descTag.descCRCLength = cpu_to_le16(crclen);
 	fe->descTag.descCRC = cpu_to_le16(crc_itu_t(0, (char *)fe + sizeof(struct tag),
 						  crclen));
 	fe->descTag.tagChecksum = udf_tag_checksum(&fe->descTag);
 
+out:
+	unlock_buffer(bh);
+
 	/* write the data blocks */
 	mark_buffer_dirty(bh);
 	if (do_sync) {
 		sync_dirty_buffer(bh);
-		if (buffer_req(bh) && !buffer_uptodate(bh)) {
+		if (buffer_write_io_error(bh)) {
 			printk(KERN_WARNING "IO error syncing udf inode "
 				"[%s:%08lx]\n", inode->i_sb->s_id,
 				inode->i_ino);