[PATCH v3 11/15] block: introduce BLKREPORTZONESV2 ioctl

[Damien Le Moal <dlemoal@kernel.org>]

Introduce the new BLKREPORTZONESV2 ioctl command to allow user
applications access to the fast zone report implemented by
blkdev_report_zones_cached(). This new ioctl is defined as number 142
and is documented in include/uapi/linux/fs.h.

Unlike the existing BLKREPORTZONES ioctl, this new ioctl uses the flags
field of struct blk_zone_report also as an input. If the user sets the
BLK_ZONE_REP_CACHED flag as an input, then blkdev_report_zones_cached()
is used to generate the zone report using cached zone information. If
this flag is not set, then BLKREPORTZONESV2 behaves in the same manner
as BLKREPORTZONES and the zone report is generated by accessing the
zoned device.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-zoned.c             | 25 ++++++++++++++++++++++---
 block/ioctl.c                 |  1 +
 include/uapi/linux/blkzoned.h | 32 +++++++++++++++++++++++++++-----
 include/uapi/linux/fs.h       |  2 +-
 4 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index fc96cad083fd..ea61ad7905c0 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -357,7 +357,12 @@ static int blkdev_copy_zone_to_user(struct blk_zone *zone, unsigned int idx,
 }
 
 /*
- * BLKREPORTZONE ioctl processing.
+ * Mask of valid input flags for BLKREPORTZONEV2 ioctl.
+ */
+#define BLK_ZONE_REPV2_INPUT_FLAGS	BLK_ZONE_REP_CACHED
+
+/*
+ * BLKREPORTZONE and BLKREPORTZONEV2 ioctl processing.
  * Called from blkdev_ioctl.
  */
 int blkdev_report_zones_ioctl(struct block_device *bdev, unsigned int cmd,
@@ -381,8 +386,22 @@ int blkdev_report_zones_ioctl(struct block_device *bdev, unsigned int cmd,
 		return -EINVAL;
 
 	args.zones = argp + sizeof(struct blk_zone_report);
-	ret = blkdev_report_zones(bdev, rep.sector, rep.nr_zones,
-				  blkdev_copy_zone_to_user, &args);
+
+	switch (cmd) {
+	case BLKREPORTZONE:
+		ret = blkdev_report_zones(bdev, rep.sector, rep.nr_zones,
+					  blkdev_copy_zone_to_user, &args);
+		break;
+	case BLKREPORTZONEV2:
+		if (rep.flags & ~BLK_ZONE_REPV2_INPUT_FLAGS)
+			return -EINVAL;
+		ret = blkdev_report_zones_cached(bdev, rep.sector, rep.nr_zones,
+					 blkdev_copy_zone_to_user, &args);
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	if (ret < 0)
 		return ret;
 
diff --git a/block/ioctl.c b/block/ioctl.c
index f99b9291a84d..2b3ab9bfc413 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -581,6 +581,7 @@ static int blkdev_common_ioctl(struct block_device *bdev, blk_mode_t mode,
 	case BLKGETDISKSEQ:
 		return put_u64(argp, bdev->bd_disk->diskseq);
 	case BLKREPORTZONE:
+	case BLKREPORTZONEV2:
 		return blkdev_report_zones_ioctl(bdev, cmd, arg);
 	case BLKRESETZONE:
 	case BLKOPENZONE:
diff --git a/include/uapi/linux/blkzoned.h b/include/uapi/linux/blkzoned.h
index 1b9599411f71..52cd5b7ffc4a 100644
--- a/include/uapi/linux/blkzoned.h
+++ b/include/uapi/linux/blkzoned.h
@@ -85,10 +85,20 @@ enum blk_zone_cond {
 /**
  * enum blk_zone_report_flags - Feature flags of reported zone descriptors.
  *
- * @BLK_ZONE_REP_CAPACITY: Zone descriptor has capacity field.
+ * @BLK_ZONE_REP_CAPACITY: Output only. Indicates that zone descriptors in a
+ *			   zone report have a valid capacity field.
+ * @BLK_ZONE_REP_CACHED: Input only. Indicates that the zone report should be
+ *			 generated using cached zone information. In this case,
+ *			 the implicit open, explicit open and closed zone
+ *			 conditions are all reported with the
+ *			 BLK_ZONE_COND_ACTIVE condition.
  */
 enum blk_zone_report_flags {
-	BLK_ZONE_REP_CAPACITY	= (1 << 0),
+	/* Output flags */
+	BLK_ZONE_REP_CAPACITY	= (1U << 0),
+
+	/* Input flags */
+	BLK_ZONE_REP_CACHED	= (1U << 31),
 };
 
 /**
@@ -131,6 +141,10 @@ struct blk_zone {
  * @sector: starting sector of report
  * @nr_zones: IN maximum / OUT actual
  * @flags: one or more flags as defined by enum blk_zone_report_flags.
+ * @flags: one or more flags as defined by enum blk_zone_report_flags.
+ *	   With BLKREPORTZONE, this field is ignored as an input and is valid
+ *	   only as an output. Using BLKREPORTZONEV2, this field is used as both
+ *	   input and output.
  * @zones: Space to hold @nr_zones @zones entries on reply.
  *
  * The array of at most @nr_zones must follow this structure in memory.
@@ -157,9 +171,16 @@ struct blk_zone_range {
 /**
  * Zoned block device ioctl's:
  *
- * @BLKREPORTZONE: Get zone information. Takes a zone report as argument.
- *                 The zone report will start from the zone containing the
- *                 sector specified in the report request structure.
+ * @BLKREPORTZONE: Get zone information from a zoned device. Takes a zone report
+ *		   as argument. The zone report will start from the zone
+ *		   containing the sector specified in struct blk_zone_report.
+ *		   The flags field of struct blk_zone_report is used as an
+ *		   output only and ignored as an input.
+ *		   DEPRECATED, use BLKREPORTZONEV2 instead.
+ * @BLKREPORTZONEV2: Same as @BLKREPORTZONE but uses the flags field of
+ *		     struct blk_zone_report as an input, allowing to get a zone
+ *		     report using cached zone information if BLK_ZONE_REP_CACHED
+ *		     is set.
  * @BLKRESETZONE: Reset the write pointer of the zones in the specified
  *                sector range. The sector range must be zone aligned.
  * @BLKGETZONESZ: Get the device zone size in number of 512 B sectors.
@@ -178,5 +199,6 @@ struct blk_zone_range {
 #define BLKOPENZONE	_IOW(0x12, 134, struct blk_zone_range)
 #define BLKCLOSEZONE	_IOW(0x12, 135, struct blk_zone_range)
 #define BLKFINISHZONE	_IOW(0x12, 136, struct blk_zone_range)
+#define BLKREPORTZONEV2	_IOWR(0x12, 142, struct blk_zone_report)
 
 #endif /* _UAPI_BLKZONED_H */
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 957ce3343a4f..66ca526cf786 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -298,7 +298,7 @@ struct file_attr {
 #define BLKROTATIONAL _IO(0x12,126)
 #define BLKZEROOUT _IO(0x12,127)
 #define BLKGETDISKSEQ _IOR(0x12,128,__u64)
-/* 130-136 are used by zoned block device ioctls (uapi/linux/blkzoned.h) */
+/* 130-136 and 142 are used by zoned block device ioctls (uapi/linux/blkzoned.h) */
 /* 137-141 are used by blk-crypto ioctls (uapi/linux/blk-crypto.h) */
 #define BLKTRACESETUP2 _IOWR(0x12, 142, struct blk_user_trace_setup2)
 
-- 
2.51.0