io_uring: defer alloc_hint update to io_file_bitmap_set()

io_file_bitmap_get() returns a free bitmap slot, but if it isn't
used later, such as io_queue_rsrc_removal() returns error, in this
case, we should not update alloc_hint at all, which still should
be considered as a valid candidate for next io_file_bitmap_get()
calls.

To fix this issue, only update alloc_hint in io_file_bitmap_set().

Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220528015109.48039-1-xiaoguang.wang@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1e5726b07b654c12e9b22136c184bee445fe8fab..11524ea86f1f34a82010e5a917295295048424f1 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5419,15 +5419,11 @@ static int io_file_bitmap_get(struct io_ring_ctx *ctx)
        unsigned long nr = ctx->nr_user_files;
        int ret;
 
-       if (table->alloc_hint >= nr)
-               table->alloc_hint = 0;
-
        do {
                ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint);
-               if (ret != nr) {
-                       table->alloc_hint = ret + 1;
+               if (ret != nr)
                        return ret;
-               }
+
                if (!table->alloc_hint)
                        break;
 
@@ -9682,8 +9678,7 @@ static inline void io_file_bitmap_set(struct io_file_table *table, int bit)
 {
        WARN_ON_ONCE(test_bit(bit, table->bitmap));
        __set_bit(bit, table->bitmap);
-       if (bit == table->alloc_hint)
-               table->alloc_hint++;
+       table->alloc_hint = bit + 1;
 }
 
 static inline void io_file_bitmap_clear(struct io_file_table *table, int bit)