For UBLK_F_AUTO_BUF_REG, buffer is registered to uring_cmd context
automatically with the provided buffer index. User may provide one wrong
buffer index, or the specified buffer is registered by application already.
Add UBLK_AUTO_BUF_REG_FALLBACK for supporting to auto buffer registering
fallback by completing the uring_cmd and telling ublk server the
register failure via UBLK_AUTO_BUF_REG_FALLBACK, then ublk server still
can register the buffer from userspace.
So we can provide reliable way for supporting auto buffer register.
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
drivers/block/ublk_drv.c | 16 ++++++++++++++++
include/uapi/linux/ublk_cmd.h | 32 +++++++++++++++++++++++++++++---
2 files changed, 45 insertions(+), 3 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 0c8c18ea25bc..9bff2f8183d9 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1182,6 +1182,16 @@ static inline void __ublk_abort_rq(struct ublk_queue *ubq,
blk_mq_end_request(rq, BLK_STS_IOERR);
}
+static void ublk_auto_buf_reg_fallback(struct request *req, struct ublk_io *io)
+{
+ const struct ublk_queue *ubq = req->mq_hctx->driver_data;
+ struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
+ struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
+
+ iod->op_flags |= UBLK_IO_F_NEED_REG_BUF;
+ refcount_set(&data->ref, 1);
+}
+
static bool ublk_auto_buf_reg(struct request *req, struct ublk_io *io,
unsigned int issue_flags)
{
@@ -1192,6 +1202,10 @@ static bool ublk_auto_buf_reg(struct request *req, struct ublk_io *io,
ret = io_buffer_register_bvec(io->cmd, req, ublk_io_release,
pdu->buf.index, issue_flags);
if (ret) {
+ if (pdu->buf.flags & UBLK_AUTO_BUF_REG_FALLBACK) {
+ ublk_auto_buf_reg_fallback(req, io);
+ return true;
+ }
blk_mq_end_request(req, BLK_STS_IOERR);
return false;
}
@@ -1971,6 +1985,8 @@ static inline bool ublk_set_auto_buf_reg(struct io_uring_cmd *cmd)
if (pdu->buf.reserved0 || pdu->buf.reserved1)
return false;
+ if (pdu->buf.flags & ~UBLK_AUTO_BUF_REG_F_MASK)
+ return false;
return true;
}
diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 663187cdfa52..637e302544db 100644
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h
@@ -328,6 +328,17 @@ struct ublksrv_ctrl_dev_info {
#define UBLK_IO_F_FUA (1U << 13)
#define UBLK_IO_F_NOUNMAP (1U << 15)
#define UBLK_IO_F_SWAP (1U << 16)
+/*
+ * For UBLK_F_AUTO_BUF_REG & UBLK_AUTO_BUF_REG_FALLBACK only.
+ *
+ * This flag is set if auto buffer register is failed & ublk server passes
+ * UBLK_AUTO_BUF_REG_FALLBACK, and ublk server need to register buffer
+ * manually for handling the delivered IO command if this flag is observed
+ *
+ * ublk server has to check this flag if UBLK_AUTO_BUF_REG_FALLBACK is
+ * passed in.
+ */
+#define UBLK_IO_F_NEED_REG_BUF (1U << 17)
/*
* io cmd is described by this structure, and stored in share memory, indexed
@@ -362,10 +373,23 @@ static inline __u32 ublksrv_get_flags(const struct ublksrv_io_desc *iod)
return iod->op_flags >> 8;
}
+/*
+ * If this flag is set, fallback by completing the uring_cmd and setting
+ * `UBLK_IO_F_NEED_REG_BUF` in case of auto-buf-register failure;
+ * otherwise the client ublk request is failed silently
+ *
+ * If ublk server passes this flag, it has to check if UBLK_IO_F_NEED_REG_BUF
+ * is set in `ublksrv_io_desc.op_flags`. If UBLK_IO_F_NEED_REG_BUF is set,
+ * ublk server needs to register io buffer manually for handling IO command.
+ */
+#define UBLK_AUTO_BUF_REG_FALLBACK (1 << 0)
+#define UBLK_AUTO_BUF_REG_F_MASK UBLK_AUTO_BUF_REG_FALLBACK
+
struct ublk_auto_buf_reg {
/* index for registering the delivered request buffer */
__u16 index;
- __u16 reserved0;
+ __u8 flags;
+ __u8 reserved0;
/*
* io_ring FD can be passed via the reserve field in future for
@@ -379,6 +403,7 @@ struct ublk_auto_buf_reg {
* uring_cmd's sqe->addr:
*
* - bit0 ~ bit15: buffer index
+ * - bit16 ~ bit23: flags
* - bit24 ~ bit31: reserved0
* - bit32 ~ bit63: reserved1
*/
@@ -387,7 +412,8 @@ static inline struct ublk_auto_buf_reg ublk_sqe_addr_to_auto_buf_reg(
{
struct ublk_auto_buf_reg reg = {
.index = sqe_addr & 0xffff,
- .reserved0 = (sqe_addr >> 16) & 0xffff,
+ .flags = (sqe_addr >> 16) & 0xff,
+ .reserved0 = (sqe_addr >> 24) & 0xff,
.reserved1 = sqe_addr >> 32,
};
@@ -397,7 +423,7 @@ static inline struct ublk_auto_buf_reg ublk_sqe_addr_to_auto_buf_reg(
static inline __u64
ublk_auto_buf_reg_to_sqe_addr(const struct ublk_auto_buf_reg *buf)
{
- __u64 addr = buf->index | (__u64)buf->reserved0 << 16 |
+ __u64 addr = buf->index | (__u64)buf->flags << 16 | (__u64)buf->reserved0 << 24 |
(__u64)buf->reserved1 << 32;
return addr;
--
2.47.0
