From: Jiang Yi <jiangyilism@gmail.com>
Date: Fri, 11 Aug 2017 03:29:44 +0000 (+0800)
Subject: target/file: Do not return error for UNMAP if length is zero
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=594e25e73440863981032d76c9b1e33409ceff6e;p=openwrt%2Fstaging%2Fblogic.git

target/file: Do not return error for UNMAP if length is zero

The function fd_execute_unmap() in target_core_file.c calles

ret = file->f_op->fallocate(file, mode, pos, len);

Some filesystems implement fallocate() to return error if
length is zero (e.g. btrfs) but according to SCSI Block
Commands spec UNMAP should return success for zero length.

Signed-off-by: Jiang Yi <jiangyilism@gmail.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index c629817a8854..9b2c0c773022 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -482,6 +482,10 @@ fd_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb)
 	struct inode *inode = file->f_mapping->host;
 	int ret;
 
+	if (!nolb) {
+		return 0;
+	}
+
 	if (cmd->se_dev->dev_attrib.pi_prot_type) {
 		ret = fd_do_prot_unmap(cmd, lba, nolb);
 		if (ret)