[PATCH 3/3] target/file: Fix UNMAP with DIF protection support

[Akinobu Mita <akinobu.mita@gmail.com>]

When UNMAP command is issued with DIF protection support enabled,
the protection info for the unmapped region is remain unchanged.
So READ command for the region causes data integrity failure.

This fixes it by invalidating protection info for the unmapped region
by filling with 0xff pattern.  This change also adds helper function
fd_do_prot_fill() in order to reduce code duplication with existing
fd_format_prot().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: target-devel@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
---
 drivers/target/target_core_file.c | 86 +++++++++++++++++++++++++++------------
 1 file changed, 61 insertions(+), 25 deletions(-)

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 4c7a6c8..cbb0cc2 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -541,6 +541,56 @@ fd_execute_write_same(struct se_cmd *cmd)
 	return 0;
 }
 
+static int
+fd_do_prot_fill(struct se_device *se_dev, sector_t lba, sector_t nolb,
+		void *buf, size_t bufsize)
+{
+	struct fd_dev *fd_dev = FD_DEV(se_dev);
+	struct file *prot_fd = fd_dev->fd_prot_file;
+	sector_t prot_length, prot;
+	loff_t pos = lba * se_dev->prot_length;
+
+	if (!prot_fd) {
+		pr_err("Unable to locate fd_dev->fd_prot_file\n");
+		return -ENODEV;
+	}
+
+	prot_length = nolb * se_dev->prot_length;
+
+	for (prot = 0; prot < prot_length;) {
+		sector_t len = min_t(sector_t, bufsize, prot_length - prot);
+		ssize_t ret = kernel_write(prot_fd, buf, len, pos + prot);
+
+		if (ret != len) {
+			pr_err("vfs_write to prot file failed: %zd\n", ret);
+			return ret < 0 ? ret : -ENODEV;
+		}
+		prot += ret;
+	}
+
+	return 0;
+}
+
+static int
+fd_do_prot_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb)
+{
+	void *buf;
+	int rc;
+
+	buf = (void *)__get_free_page(GFP_KERNEL);
+	if (!buf) {
+		pr_err("Unable to allocate FILEIO prot buf\n");
+		return -ENOMEM;
+	}
+	memset(buf, 0xff, PAGE_SIZE);
+
+	rc = fd_do_prot_fill(cmd->se_dev, lba, nolb, buf, PAGE_SIZE);
+
+	free_page((unsigned long)buf);
+
+	return rc;
+}
+
 static sense_reason_t
 fd_do_unmap(struct se_cmd *cmd, void *priv, sector_t lba, sector_t nolb)
 {
@@ -548,6 +598,12 @@ fd_do_unmap(struct se_cmd *cmd, void *priv, sector_t lba, sector_t nolb)
 	struct inode *inode = file->f_mapping->host;
 	int ret;
 
+	if (cmd->se_dev->dev_attrib.pi_prot_type) {
+		ret = fd_do_prot_unmap(cmd, lba, nolb);
+		if (ret)
+			return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+	}
+
 	if (S_ISBLK(inode->i_mode)) {
 		/* The backend is block device, use discard */
 		struct block_device *bdev = inode->i_bdev;
@@ -870,48 +926,28 @@ static int fd_init_prot(struct se_device *dev)
 
 static int fd_format_prot(struct se_device *dev)
 {
-	struct fd_dev *fd_dev = FD_DEV(dev);
-	struct file *prot_fd = fd_dev->fd_prot_file;
-	sector_t prot_length, prot;
 	unsigned char *buf;
-	loff_t pos = 0;
 	int unit_size = FDBD_FORMAT_UNIT_SIZE * dev->dev_attrib.block_size;
-	int rc, ret = 0, size, len;
+	int ret;
 
 	if (!dev->dev_attrib.pi_prot_type) {
 		pr_err("Unable to format_prot while pi_prot_type == 0\n");
 		return -ENODEV;
 	}
-	if (!prot_fd) {
-		pr_err("Unable to locate fd_dev->fd_prot_file\n");
-		return -ENODEV;
-	}
 
 	buf = vzalloc(unit_size);
 	if (!buf) {
 		pr_err("Unable to allocate FILEIO prot buf\n");
 		return -ENOMEM;
 	}
-	prot_length = (dev->transport->get_blocks(dev) + 1) * dev->prot_length;
-	size = prot_length;
 
 	pr_debug("Using FILEIO prot_length: %llu\n",
-		 (unsigned long long)prot_length);
+		 (unsigned long long)(dev->transport->get_blocks(dev) + 1) *
+					dev->prot_length);
 
 	memset(buf, 0xff, unit_size);
-	for (prot = 0; prot < prot_length; prot += unit_size) {
-		len = min(unit_size, size);
-		rc = kernel_write(prot_fd, buf, len, pos);
-		if (rc != len) {
-			pr_err("vfs_write to prot file failed: %d\n", rc);
-			ret = -ENODEV;
-			goto out;
-		}
-		pos += len;
-		size -= len;
-	}
-
-out:
+	ret = fd_do_prot_fill(dev, 0, dev->transport->get_blocks(dev) + 1,
+			      buf, unit_size);
 	vfree(buf);
 	return ret;
 }
-- 
1.9.1