4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiang Yi <jiangyilism@xxxxxxxxx> [ Upstream commit 594e25e73440863981032d76c9b1e33409ceff6e ] 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@xxxxxxxxx> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/target/target_core_file.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/target/target_core_file.c +++ b/drivers/target/target_core_file.c @@ -466,6 +466,10 @@ fd_execute_unmap(struct se_cmd *cmd, sec 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)