io_uring: add helpers for 2 level table alloc

Some parts like fixed file table use 2 level tables, factor out helpers
for allocating/deallocating them as more users are to come.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1709212359cd82eb416d395f86fc78431ccfc0aa.1623634181.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 55e449d..0fbf194 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7059,14 +7059,36 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
        return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
 }
 
-static void io_free_file_tables(struct io_file_table *table, unsigned nr_files)
+static void io_free_page_table(void **table, size_t size)
 {
-       unsigned i, nr_tables = DIV_ROUND_UP(nr_files, IORING_MAX_FILES_TABLE);
+       unsigned i, nr_tables = DIV_ROUND_UP(size, PAGE_SIZE);
 
        for (i = 0; i < nr_tables; i++)
-               kfree(table->files[i]);
-       kfree(table->files);
-       table->files = NULL;
+               kfree(table[i]);
+       kfree(table);
+}
+
+static void **io_alloc_page_table(size_t size)
+{
+       unsigned i, nr_tables = DIV_ROUND_UP(size, PAGE_SIZE);
+       size_t init_size = size;
+       void **table;
+
+       table = kcalloc(nr_tables, sizeof(*table), GFP_KERNEL);
+       if (!table)
+               return NULL;
+
+       for (i = 0; i < nr_tables; i++) {
+               unsigned int this_size = min(size, PAGE_SIZE);
+
+               table[i] = kzalloc(this_size, GFP_KERNEL);
+               if (!table[i]) {
+                       io_free_page_table(table, init_size);
+                       return NULL;
+               }
+               size -= this_size;
+       }
+       return table;
 }
 
 static inline void io_rsrc_ref_lock(struct io_ring_ctx *ctx)
@@ -7195,6 +7217,22 @@ static int io_rsrc_data_alloc(struct io_ring_ctx *ctx, rsrc_put_fn *do_put,
        return 0;
 }
 
+static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
+{
+       size_t size = nr_files * sizeof(struct io_fixed_file);
+
+       table->files = (struct io_fixed_file **)io_alloc_page_table(size);
+       return !!table->files;
+}
+
+static void io_free_file_tables(struct io_file_table *table, unsigned nr_files)
+{
+       size_t size = nr_files * sizeof(struct io_fixed_file);
+
+       io_free_page_table((void **)table->files, size);
+       table->files = NULL;
+}
+
 static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
 {
 #if defined(CONFIG_UNIX)
@@ -7456,31 +7494,6 @@ static int io_sqe_files_scm(struct io_ring_ctx *ctx)
 }
 #endif
 
-static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
-{
-       unsigned i, nr_tables = DIV_ROUND_UP(nr_files, IORING_MAX_FILES_TABLE);
-
-       table->files = kcalloc(nr_tables, sizeof(*table->files), GFP_KERNEL);
-       if (!table->files)
-               return false;
-
-       for (i = 0; i < nr_tables; i++) {
-               unsigned int this_files = min(nr_files, IORING_MAX_FILES_TABLE);
-
-               table->files[i] = kcalloc(this_files, sizeof(*table->files[i]),
-                                       GFP_KERNEL);
-               if (!table->files[i])
-                       break;
-               nr_files -= this_files;
-       }
-
-       if (i == nr_tables)
-               return true;
-
-       io_free_file_tables(table, nr_tables * IORING_MAX_FILES_TABLE);
-       return false;
-}
-
 static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
 {
        struct file *file = prsrc->file;