linux-kernel - [PATCH v2 2/2] ubi: expose the volume CRC check skip flag

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Message-Id: <c439cfe60b003c8b0158a0f57a95057ab7e93b90.1530099128.git-series.quentin.schulz@bootlin.com>
Date:   Wed, 27 Jun 2018 13:33:20 +0200
From:   Quentin Schulz <quentin.schulz@...tlin.com>
To:     dedekind1@...il.com, richard@....at, dwmw2@...radead.org,
        computersforpeace@...il.com, boris.brezillon@...tlin.com,
        marek.vasut@...il.com
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        thomas.petazzoni@...tlin.com,
        Quentin Schulz <quentin.schulz@...tlin.com>
Subject: [PATCH v2 2/2] ubi: expose the volume CRC check skip flag

Now that we have the logic for skipping CRC check for static UBI volumes
in the core, let's expose it to users.

This makes use of a padding byte in the volume description data
structure as a flag. This flag only tell for now whether we should skip
the CRC check of a volume.

This checks the UBI volume for which we are trying to skip the CRC check
is static.

Suggested-by: Boris Brezillon <boris.brezillon@...tlin.com>
Signed-off-by: Quentin Schulz <quentin.schulz@...tlin.com>
---
 drivers/mtd/ubi/cdev.c      |  4 ++++
 drivers/mtd/ubi/vmt.c       |  3 +++
 include/uapi/mtd/ubi-user.h | 16 ++++++++++++++--
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 45c3296..3eea1df 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -622,6 +622,10 @@ static int verify_mkvol_req(const struct ubi_device *ubi,
 	    req->vol_type != UBI_STATIC_VOLUME)
 		goto bad;
 
+	if (req->flags & UBI_VOL_SKIP_CRC_CHECK_FLG &&
+	    req->vol_type != UBI_STATIC_VOLUME)
+		goto bad;
+
 	if (req->alignment > ubi->leb_size)
 		goto bad;
 
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index e2606a4..729588b 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -174,6 +174,9 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
 	vol->dev.class = &ubi_class;
 	vol->dev.groups = volume_dev_groups;
 
+	if (req->flags & UBI_VOL_SKIP_CRC_CHECK_FLG)
+		vol->skip_check = 1;
+
 	spin_lock(&ubi->volumes_lock);
 	if (vol_id == UBI_VOL_NUM_AUTO) {
 		/* Find unused volume ID */
diff --git a/include/uapi/mtd/ubi-user.h b/include/uapi/mtd/ubi-user.h
index 5b04a49..ce76766 100644
--- a/include/uapi/mtd/ubi-user.h
+++ b/include/uapi/mtd/ubi-user.h
@@ -285,6 +285,18 @@ struct ubi_attach_req {
 	__s8 padding[10];
 };
 
+/*
+ * UBI volume flags.
+ *
+ * @UBI_VOL_SKIP_CRC_CHECK_FLG: skip the CRC check done on static volumes at
+ *				open time. Only valid for static volumes and
+ *				should only be used if the volume user has a
+ *				way to verify data integrity
+ */
+enum {
+	UBI_VOL_SKIP_CRC_CHECK_FLG = 0x1,
+};
+
 /**
  * struct ubi_mkvol_req - volume description data structure used in
  *                        volume creation requests.
@@ -292,7 +304,7 @@ struct ubi_attach_req {
  * @alignment: volume alignment
  * @bytes: volume size in bytes
  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
- * @padding1: reserved for future, not used, has to be zeroed
+ * @flags: volume flags (%UBI_VOL_SKIP_CRC_CHECK_FLG)
  * @name_len: volume name length
  * @padding2: reserved for future, not used, has to be zeroed
  * @name: volume name
@@ -321,7 +333,7 @@ struct ubi_mkvol_req {
 	__s32 alignment;
 	__s64 bytes;
 	__s8 vol_type;
-	__s8 padding1;
+	__u8 flags;
 	__s16 name_len;
 	__s8 padding2[4];
 	char name[UBI_MAX_VOLUME_NAME + 1];
-- 
git-series 0.9.1