From bbab37ddc20bae4709bca8745c128c4f46fe63c5 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 3 Jul 2015 10:40:42 -0400 Subject: block: Add support for DAX reads/writes to block devices If a block device supports the ->direct_access methods, bypass the normal DIO path and use DAX to go straight to memcpy() instead of allocating a DIO and a BIO. Includes support for the DIO_SKIP_DIO_COUNT flag in DAX, as is done in do_blockdev_direct_IO(). Signed-off-by: Matthew Wilcox Signed-off-by: Al Viro --- fs/block_dev.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index c7e4163ede87..5dde6dff4940 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -151,6 +151,9 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset) struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host; + if (IS_DAX(inode)) + return dax_do_io(iocb, inode, iter, offset, blkdev_get_block, + NULL, DIO_SKIP_DIO_COUNT); return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset, blkdev_get_block, NULL, NULL, DIO_SKIP_DIO_COUNT); @@ -1173,6 +1176,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) bdev->bd_disk = disk; bdev->bd_queue = disk->queue; bdev->bd_contains = bdev; + bdev->bd_inode->i_flags = disk->fops->direct_access ? S_DAX : 0; if (!partno) { ret = -ENXIO; bdev->bd_part = disk_get_part(disk, partno); -- cgit v1.2.3 From 43c3dd08da890e458f670b4fc0630513fb405620 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 3 Jul 2015 10:40:43 -0400 Subject: dax: bdev_direct_access() may sleep The brd driver is the only in-tree driver that may sleep currently. After some discussion on linux-fsdevel, we decided that any driver may choose to sleep in its ->direct_access method. To ensure that all callers of bdev_direct_access() are prepared for this, add a call to might_sleep(). Signed-off-by: Matthew Wilcox Signed-off-by: Al Viro --- fs/block_dev.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index 5dde6dff4940..12b22ddb22ef 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -445,6 +445,12 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector, long avail; const struct block_device_operations *ops = bdev->bd_disk->fops; + /* + * The device driver is allowed to sleep, in order to make the + * memory directly accessible. + */ + might_sleep(); + if (size < 0) return size; if (!ops->direct_access) -- cgit v1.2.3