Re: [PATCH-v2 12/17] target/file: Add DIF protection init/formatsupport

From: Sagi Grimberg
Date: Wed Jan 22 2014 - 05:12:34 EST

On 1/22/2014 12:28 AM, Nicholas A. Bellinger wrote:
On Sun, 2014-01-19 at 14:31 +0200, Sagi Grimberg wrote:
On 1/19/2014 4:44 AM, Nicholas A. Bellinger wrote:
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

This patch adds support for DIF protection init/format support into
the FILEIO backend.

It involves using a seperate $FILE.protection for storing PI that is
opened via fd_init_prot() using the common pi_prot_type attribute.
The actual formatting of the protection is done via fd_format_prot()
using the common pi_prot_format attribute, that will populate the
initial PI data based upon the currently configured pi_prot_type.

Based on original FILEIO code from Sagi.
Nice! see comments below...

v1 changes:
- Fix sparse warnings in fd_init_format_buf (Fengguang)

Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_file.c | 137 +++++++++++++++++++++++++++++++++++++
drivers/target/target_core_file.h | 4 ++
2 files changed, 141 insertions(+)

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 0e34cda..119d519 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -700,6 +700,140 @@ static sector_t fd_get_blocks(struct se_device *dev)
dev->dev_attrib.block_size);
}
+static int fd_init_prot(struct se_device *dev)
+{
+ struct fd_dev *fd_dev = FD_DEV(dev);
+ struct file *prot_file, *file = fd_dev->fd_file;
+ struct inode *inode;
+ int ret, flags = O_RDWR | O_CREAT | O_LARGEFILE | O_DSYNC;
+ char buf[FD_MAX_DEV_PROT_NAME];
+
+ if (!file) {
+ pr_err("Unable to locate fd_dev->fd_file\n");
+ return -ENODEV;
+ }
+
+ inode = file->f_mapping->host;
+ if (S_ISBLK(inode->i_mode)) {
+ pr_err("FILEIO Protection emulation only supported on"
+ " !S_ISBLK\n");
+ return -ENOSYS;
+ }
+
+ if (fd_dev->fbd_flags & FDBD_HAS_BUFFERED_IO_WCE)
+ flags &= ~O_DSYNC;
+
+ snprintf(buf, FD_MAX_DEV_PROT_NAME, "%s.protection",
+ fd_dev->fd_dev_name);
+
+ prot_file = filp_open(buf, flags, 0600);
+ if (IS_ERR(prot_file)) {
+ pr_err("filp_open(%s) failed\n", buf);
+ ret = PTR_ERR(prot_file);
+ return ret;
+ }
+ fd_dev->fd_prot_file = prot_file;
+
+ return 0;
+}
+
+static void fd_init_format_buf(struct se_device *dev, unsigned char *buf,
+ u32 unit_size, u32 *ref_tag, u16 app_tag,
+ bool inc_reftag)
+{
+ unsigned char *p = buf;
+ int i;
+
+ for (i = 0; i < unit_size; i += dev->prot_length) {
+ *((u16 *)&p[0]) = 0xffff;
+ *((__be16 *)&p[2]) = cpu_to_be16(app_tag);
+ *((__be32 *)&p[4]) = cpu_to_be32(*ref_tag);
+
+ if (inc_reftag)
+ (*ref_tag)++;
+
+ p += dev->prot_length;
+ }
+}
+
+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;
+ u32 ref_tag = 0;
+ int unit_size = FDBD_FORMAT_UNIT_SIZE * dev->dev_attrib.block_size;
+ int rc, ret = 0, size, len;
+ bool inc_reftag = false;
+
+ 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;
+ }
+
+ switch (dev->dev_attrib.pi_prot_type) {
redundant - see below.
+ case TARGET_DIF_TYPE3_PROT:
+ ref_tag = 0xffffffff;
+ break;
+ case TARGET_DIF_TYPE2_PROT:
+ case TARGET_DIF_TYPE1_PROT:
+ inc_reftag = true;
+ break;
+ default:
+ break;
+ }
+
+ 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);
+
+ for (prot = 0; prot < prot_length; prot += unit_size) {
+
+ fd_init_format_buf(dev, buf, unit_size, &ref_tag, 0xffff,
+ inc_reftag);
I didn't send you my latest patches (my fault...).T10-PI format should
only place
escape values throughout the protection file (fill it with 0xff). so I
guess in this case
fd_init_formast_buf() boils down to memset(buf, 0xff, unit_size) once
before the loop
and just loop until prot_length writing buf, no need to address
apptag/reftag...
Yeah, was thinking about just formatting with escape values as mentioned
above, but thought it might be useful to keep around for pre-populating
values apptag + reftag values for testing purposes.

--nab


OK, but maybe it is better to do that under some debug configuration rather then always do that.

Sagi.
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