io_uring: avoid touching inode in rw prep

If we use fixed files, we can be sure (almost) that REQ_F_ISREG is set.
However, for non-reg files io_prep_rw() still will look into inode to
double check, and that's expensive and can be avoided.

The only caveat is that it only currently works with 64+ bit
architectures, see FFS_ISREG, so we should consider that.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0a62780c491ca2522cd52db4ae3f16e03aafed0f.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 7027c7e1f5627aae6aee608dd91dd5607b34bca4..69e5a2102f943be5a9d72c73c815adc2f6447179 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1231,6 +1231,20 @@ static bool req_need_defer(struct io_kiocb *req, u32 seq)
        return false;
 }
 
+#define FFS_ASYNC_READ         0x1UL
+#define FFS_ASYNC_WRITE                0x2UL
+#ifdef CONFIG_64BIT
+#define FFS_ISREG              0x4UL
+#else
+#define FFS_ISREG              0x0UL
+#endif
+#define FFS_MASK               ~(FFS_ASYNC_READ|FFS_ASYNC_WRITE|FFS_ISREG)
+
+static inline bool io_req_ffs_set(struct io_kiocb *req)
+{
+       return IS_ENABLED(CONFIG_64BIT) && (req->flags & REQ_F_FIXED_FILE);
+}
+
 static void io_req_track_inflight(struct io_kiocb *req)
 {
        if (!(req->flags & REQ_F_INFLIGHT)) {
@@ -2682,7 +2696,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
        unsigned ioprio;
        int ret;
 
-       if (!(req->flags & REQ_F_ISREG) && S_ISREG(file_inode(file)->i_mode))
+       if (!io_req_ffs_set(req) && S_ISREG(file_inode(file)->i_mode))
                req->flags |= REQ_F_ISREG;
 
        kiocb->ki_pos = READ_ONCE(sqe->off);
@@ -6319,15 +6333,6 @@ static void io_wq_submit_work(struct io_wq_work *work)
        }
 }
 
-#define FFS_ASYNC_READ         0x1UL
-#define FFS_ASYNC_WRITE                0x2UL
-#ifdef CONFIG_64BIT
-#define FFS_ISREG              0x4UL
-#else
-#define FFS_ISREG              0x0UL
-#endif
-#define FFS_MASK               ~(FFS_ASYNC_READ|FFS_ASYNC_WRITE|FFS_ISREG)
-
 static inline struct io_fixed_file *io_fixed_file_slot(struct io_file_table *table,
                                                       unsigned i)
 {