io_uring: encapsulate fixed files into struct

Add struct io_fixed_file representing a single registered file, first to
hide ugly struct file **, which may be misleading, and secondly to
retype it to unsigned long as conversions to it and back to file * for
handling and masking FFS_* flags are getting nasty.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/78669731a605a7614c577c3de552631cfaf0869a.1617287883.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 663e1cf..4e5f930 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -207,6 +207,11 @@ struct io_overflow_cqe {
        struct list_head list;
 };
 
+struct io_fixed_file {
+       /* file * with additional FFS_* flags */
+       unsigned long file_ptr;
+};
+
 struct io_rsrc_put {
        struct list_head list;
        union {
@@ -216,7 +221,7 @@ struct io_rsrc_put {
 };
 
 struct fixed_rsrc_table {
-       struct file             **files;
+       struct io_fixed_file *files;
 };
 
 struct io_rsrc_node {
@@ -6275,8 +6280,8 @@ static void io_wq_submit_work(struct io_wq_work *work)
 #endif
 #define FFS_MASK               ~(FFS_ASYNC_READ|FFS_ASYNC_WRITE|FFS_ISREG)
 
-static inline struct file **io_fixed_file_slot(struct io_rsrc_data *file_data,
-                                              unsigned i)
+static inline struct io_fixed_file *io_fixed_file_slot(struct io_rsrc_data *file_data,
+                                                     unsigned i)
 {
        struct fixed_rsrc_table *table;
 
@@ -6287,12 +6292,12 @@ static inline struct file **io_fixed_file_slot(struct io_rsrc_data *file_data,
 static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
                                              int index)
 {
-       struct file **file_slot = io_fixed_file_slot(ctx->file_data, index);
+       struct io_fixed_file *slot = io_fixed_file_slot(ctx->file_data, index);
 
-       return (struct file *) ((unsigned long) *file_slot & FFS_MASK);
+       return (struct file *) (slot->file_ptr & FFS_MASK);
 }
 
-static void io_fixed_file_set(struct file **file_slot, struct file *file)
+static void io_fixed_file_set(struct io_fixed_file *file_slot, struct file *file)
 {
        unsigned long file_ptr = (unsigned long) file;
 
@@ -6302,7 +6307,7 @@ static void io_fixed_file_set(struct file **file_slot, struct file *file)
                file_ptr |= FFS_ASYNC_WRITE;
        if (S_ISREG(file_inode(file)->i_mode))
                file_ptr |= FFS_ISREG;
-       *file_slot = (struct file *)file_ptr;
+       file_slot->file_ptr = file_ptr;
 }
 
 static struct file *io_file_get(struct io_submit_state *state,
@@ -6317,7 +6322,7 @@ static struct file *io_file_get(struct io_submit_state *state,
                if (unlikely((unsigned int)fd >= ctx->nr_user_files))
                        return NULL;
                fd = array_index_nospec(fd, ctx->nr_user_files);
-               file_ptr = (unsigned long) *io_fixed_file_slot(ctx->file_data, fd);
+               file_ptr = io_fixed_file_slot(ctx->file_data, fd)->file_ptr;
                file = (struct file *) (file_ptr & FFS_MASK);
                file_ptr &= ~FFS_MASK;
                /* mask in overlapping REQ_F and FFS bits */
@@ -7756,7 +7761,8 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
                                 unsigned nr_args)
 {
        struct io_rsrc_data *data = ctx->file_data;
-       struct file *file, **file_slot;
+       struct io_fixed_file *file_slot;
+       struct file *file;
        __s32 __user *fds;
        int fd, i, err;
        __u32 done;
@@ -7783,12 +7789,12 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
                i = array_index_nospec(up->offset + done, ctx->nr_user_files);
                file_slot = io_fixed_file_slot(ctx->file_data, i);
 
-               if (*file_slot) {
-                       file = (struct file *) ((unsigned long) *file_slot & FFS_MASK);
+               if (file_slot->file_ptr) {
+                       file = (struct file *)(file_slot->file_ptr & FFS_MASK);
                        err = io_queue_rsrc_removal(data, ctx->rsrc_node, file);
                        if (err)
                                break;
-                       *file_slot = NULL;
+                       file_slot->file_ptr = 0;
                        needs_switch = true;
                }
                if (fd != -1) {
@@ -7813,7 +7819,7 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
                        io_fixed_file_set(file_slot, file);
                        err = io_sqe_file_register(ctx, file, i);
                        if (err) {
-                               *file_slot = NULL;
+                               file_slot->file_ptr = 0;
                                fput(file);
                                break;
                        }