From: Adam Manzanares <adam.manzana...@wdc.com>

This is the per-I/O equivalent of the ioprio_set system call.

When IOCB_FLAG_IOPRIO is set on the iocb aio_flags field, then we set the
newly added kiocb ki_ioprio field to the value in the iocb aio_reqprio field.

When a bio is created for an aio request by the block dev we set the priority
value of the bio to the user supplied value.

This patch depends on block: add ioprio_check_cap function

Signed-off-by: Adam Manzanares <adam.manzana...@wdc.com>
---
 fs/aio.c                     | 16 ++++++++++++++++
 fs/block_dev.c               |  2 ++
 include/linux/fs.h           |  2 ++
 include/uapi/linux/aio_abi.h |  1 +
 4 files changed, 21 insertions(+)

diff --git a/fs/aio.c b/fs/aio.c
index f3eae5d5771b..ff3107aa82d5 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1451,6 +1451,22 @@ static int aio_prep_rw(struct kiocb *req, struct iocb 
*iocb)
        if (iocb->aio_flags & IOCB_FLAG_RESFD)
                req->ki_flags |= IOCB_EVENTFD;
        req->ki_hint = file_write_hint(req->ki_filp);
+       if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
+               /*
+                * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
+                * aio_reqprio is interpreted as an I/O scheduling
+                * class and priority.
+                */
+               ret = ioprio_check_cap(iocb->aio_reqprio);
+               if (ret) {
+                       pr_debug("aio ioprio check cap error\n");
+                       return -EINVAL;
+               }
+
+               req->ki_ioprio = iocb->aio_reqprio;
+               req->ki_flags |= IOCB_IOPRIO;
+       }
+
        ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
        if (unlikely(ret))
                fput(req->ki_filp);
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 7ec920e27065..970bef79caa6 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -355,6 +355,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter 
*iter, int nr_pages)
                bio->bi_write_hint = iocb->ki_hint;
                bio->bi_private = dio;
                bio->bi_end_io = blkdev_bio_end_io;
+               if (iocb->ki_flags & IOCB_IOPRIO)
+                       bio->bi_ioprio = iocb->ki_ioprio;
 
                ret = bio_iov_iter_get_pages(bio, iter);
                if (unlikely(ret)) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7a90ce387e00..3415e83f6350 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -294,6 +294,7 @@ enum rw_hint {
 #define IOCB_SYNC              (1 << 5)
 #define IOCB_WRITE             (1 << 6)
 #define IOCB_NOWAIT            (1 << 7)
+#define IOCB_IOPRIO            (1 << 8)
 
 struct kiocb {
        struct file             *ki_filp;
@@ -302,6 +303,7 @@ struct kiocb {
        void                    *private;
        int                     ki_flags;
        u16                     ki_hint;
+       u16                     ki_ioprio; /* See linux/ioprio.h */
 } __randomize_layout;
 
 static inline bool is_sync_kiocb(struct kiocb *kiocb)
diff --git a/include/uapi/linux/aio_abi.h b/include/uapi/linux/aio_abi.h
index 2c0a3415beee..d4e768d55d14 100644
--- a/include/uapi/linux/aio_abi.h
+++ b/include/uapi/linux/aio_abi.h
@@ -55,6 +55,7 @@ enum {
  *                   is valid.
  */
 #define IOCB_FLAG_RESFD                (1 << 0)
+#define IOCB_FLAG_IOPRIO       (1 << 1)
 
 /* read() from /dev/aio returns these structures. */
 struct io_event {
-- 
2.15.1

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