@@ -68,7 +68,6 @@ struct loop_device {
struct list_head idle_worker_list;
struct rb_root worker_tree;
struct timer_list timer;
- bool use_dio;
bool sysfs_inited;
struct request_queue *lo_queue;
@@ -196,32 +195,30 @@ static bool lo_can_use_dio(struct loop_device *lo)
return true;
}
+/*
+ * Direct I/O can be enabled either by using an O_DIRECT file descriptor, or by
+ * passing in the LO_FLAGS_DIRECT_IO flag from userspace. It will be silently
+ * disabled when the device block size is too small or the offset is unaligned.
+ *
+ * loop_get_status will always report the effective LO_FLAGS_DIRECT_IO flag and
+ * not the originally passed in one.
+ */
static inline void loop_update_dio(struct loop_device *lo)
{
- bool dio = lo->use_dio || (lo->lo_backing_file->f_flags & O_DIRECT);
- bool use_dio = dio && lo_can_use_dio(lo);
+ bool dio_in_use = lo->lo_flags & LO_FLAGS_DIRECT_IO;
lockdep_assert_held(&lo->lo_mutex);
WARN_ON_ONCE(lo->lo_state == Lo_bound &&
lo->lo_queue->mq_freeze_depth == 0);
- if (lo->use_dio == use_dio)
- return;
-
- /* flush dirty pages before starting to use direct I/O */
- if (use_dio)
- vfs_fsync(lo->lo_backing_file, 0);
-
- /*
- * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
- * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
- * will get updated by ioctl(LOOP_GET_STATUS)
- */
- lo->use_dio = use_dio;
- if (use_dio)
+ if (lo->lo_backing_file->f_flags & O_DIRECT)
lo->lo_flags |= LO_FLAGS_DIRECT_IO;
- else
+ if ((lo->lo_flags & LO_FLAGS_DIRECT_IO) && !lo_can_use_dio(lo))
lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
+
+ /* flush dirty pages before starting to issue direct I/O */
+ if ((lo->lo_flags & LO_FLAGS_DIRECT_IO) && !dio_in_use)
+ vfs_fsync(lo->lo_backing_file, 0);
}
/**
@@ -1089,7 +1086,6 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
disk_force_media_change(lo->lo_disk);
set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
- lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
lo->lo_device = bdev;
lo->lo_backing_file = file;
lo->old_gfp_mask = mapping_gfp_mask(mapping);
@@ -1454,7 +1450,7 @@ static int loop_set_dio(struct loop_device *lo, unsigned long arg)
if (lo->lo_state != Lo_bound)
return -ENXIO;
- if (use_dio == lo->use_dio)
+ if (use_dio == !!(lo->lo_flags & LO_FLAGS_DIRECT_IO))
return 0;
if (use_dio) {
@@ -1465,7 +1461,6 @@ static int loop_set_dio(struct loop_device *lo, unsigned long arg)
}
blk_mq_freeze_queue(lo->lo_queue);
- lo->use_dio = use_dio;
if (use_dio)
lo->lo_flags |= LO_FLAGS_DIRECT_IO;
else
@@ -1876,7 +1871,7 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
cmd->use_aio = false;
break;
default:
- cmd->use_aio = lo->use_dio;
+ cmd->use_aio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
break;
}
This field duplicate the LO_FLAGS_DIRECT_IO flag in lo_flags. Remove it to have a single source of truth about using direct I/O. Signed-off-by: Christoph Hellwig <hch@lst.de> --- drivers/block/loop.c | 39 +++++++++++++++++---------------------- 1 file changed, 17 insertions(+), 22 deletions(-)