diff options
| -rw-r--r-- | drivers/block/loop.c | 77 | ||||
| -rw-r--r-- | drivers/block/loop.h | 1 | ||||
| -rw-r--r-- | include/uapi/linux/loop.h | 1 |
3 files changed, 79 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 1875aadb31b0..06cad7edc0d3 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -164,6 +164,62 @@ static loff_t get_loop_size(struct loop_device *lo, struct file *file) return get_size(lo->lo_offset, lo->lo_sizelimit, file); } +static void __loop_update_dio(struct loop_device *lo, bool dio) +{ + struct file *file = lo->lo_backing_file; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + unsigned short sb_bsize = 0; + unsigned dio_align = 0; + bool use_dio; + + if (inode->i_sb->s_bdev) { + sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); + dio_align = sb_bsize - 1; + } + + /* + * We support direct I/O only if lo_offset is aligned with the + * logical I/O size of backing device, and the logical block + * size of loop is bigger than the backing device's and the loop + * needn't transform transfer. + * + * TODO: the above condition may be loosed in the future, and + * direct I/O may be switched runtime at that time because most + * of requests in sane appplications should be PAGE_SIZE algined + */ + if (dio) { + if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && + !(lo->lo_offset & dio_align) && + mapping->a_ops->direct_IO && + !lo->transfer) + use_dio = true; + else + use_dio = false; + } else { + use_dio = false; + } + + if (lo->use_dio == use_dio) + return; + + /* flush dirty pages before changing direct IO */ + vfs_fsync(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) + */ + blk_mq_freeze_queue(lo->lo_queue); + lo->use_dio = use_dio; + if (use_dio) + lo->lo_flags |= LO_FLAGS_DIRECT_IO; + else + lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; + blk_mq_unfreeze_queue(lo->lo_queue); +} + static int figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit) { @@ -421,6 +477,12 @@ struct switch_request { struct completion wait; }; +static inline void loop_update_dio(struct loop_device *lo) +{ + __loop_update_dio(lo, io_is_direct(lo->lo_backing_file) | + lo->use_dio); +} + /* * Do the actual switch; called from the BIO completion routine */ @@ -441,6 +503,7 @@ static void do_loop_switch(struct loop_device *lo, struct switch_request *p) mapping->host->i_bdev->bd_block_size : PAGE_SIZE; lo->old_gfp_mask = mapping_gfp_mask(mapping); mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); + loop_update_dio(lo); } /* @@ -627,11 +690,19 @@ static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) return sprintf(buf, "%s\n", partscan ? "1" : "0"); } +static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) +{ + int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); + + return sprintf(buf, "%s\n", dio ? "1" : "0"); +} + LOOP_ATTR_RO(backing_file); LOOP_ATTR_RO(offset); LOOP_ATTR_RO(sizelimit); LOOP_ATTR_RO(autoclear); LOOP_ATTR_RO(partscan); +LOOP_ATTR_RO(dio); static struct attribute *loop_attrs[] = { &loop_attr_backing_file.attr, @@ -639,6 +710,7 @@ static struct attribute *loop_attrs[] = { &loop_attr_sizelimit.attr, &loop_attr_autoclear.attr, &loop_attr_partscan.attr, + &loop_attr_dio.attr, NULL, }; @@ -770,6 +842,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); + lo->use_dio = false; lo->lo_blocksize = lo_blocksize; lo->lo_device = bdev; lo->lo_flags = lo_flags; @@ -783,6 +856,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) blk_queue_flush(lo->lo_queue, REQ_FLUSH); + loop_update_dio(lo); set_capacity(lo->lo_disk, size); bd_set_size(bdev, size << 9); loop_sysfs_init(lo); @@ -1001,6 +1075,9 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) lo->lo_key_owner = uid; } + /* update dio if lo_offset or transfer is changed */ + __loop_update_dio(lo, lo->use_dio); + return 0; } diff --git a/drivers/block/loop.h b/drivers/block/loop.h index b6c7d21a453a..d1de2217c09a 100644 --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -58,6 +58,7 @@ struct loop_device { struct mutex lo_ctl_mutex; struct kthread_worker worker; struct task_struct *worker_task; + bool use_dio; struct request_queue *lo_queue; struct blk_mq_tag_set tag_set; diff --git a/include/uapi/linux/loop.h b/include/uapi/linux/loop.h index e0cecd2eabdc..949851ce681f 100644 --- a/include/uapi/linux/loop.h +++ b/include/uapi/linux/loop.h @@ -21,6 +21,7 @@ enum { LO_FLAGS_READ_ONLY = 1, LO_FLAGS_AUTOCLEAR = 4, LO_FLAGS_PARTSCAN = 8, + LO_FLAGS_DIRECT_IO = 16, }; #include <asm/posix_types.h> /* for __kernel_old_dev_t */ |