Commit 5a5f79b5 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: allow unaligned DIO 



In order to support DIO that isn't aligned to the filesystem blocksize,
we fall back to buffered for any unaligned DIOs.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 933b585f

fs/btrfs/inode.c

+35 −3
Original line number Diff line number Diff line
@@ -5722,6 +5722,32 @@ static void btrfs_submit_direct(int rw, struct bio *bio, struct inode *inode, 
	bio_endio(bio, ret);

}



static ssize_t check_direct_IO(struct btrfs_root *root, int rw, struct kiocb *iocb,

			const struct iovec *iov, loff_t offset,

			unsigned long nr_segs)

{

	int seg;

	size_t size;

	unsigned long addr;

	unsigned blocksize_mask = root->sectorsize - 1;

	ssize_t retval = -EINVAL;

	loff_t end = offset;



	if (offset & blocksize_mask)

		goto out;



	/* Check the memory alignment.  Blocks cannot straddle pages */

	for (seg = 0; seg < nr_segs; seg++) {

		addr = (unsigned long)iov[seg].iov_base;

		size = iov[seg].iov_len;

		end += size;

		if ((addr & blocksize_mask) || (size & blocksize_mask)) 

			goto out;

	}

	retval = 0;

out:

	return retval;

}

static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,

			const struct iovec *iov, loff_t offset,

			unsigned long nr_segs)
@@ -5736,6 +5762,11 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb, 
	int write_bits = 0;

	size_t count = iov_length(iov, nr_segs);



	if (check_direct_IO(BTRFS_I(inode)->root, rw, iocb, iov,

			    offset, nr_segs)) {

		return 0;

	}



	lockstart = offset;

	lockend = offset + count - 1;
@@ -5784,8 +5815,9 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb, 
	free_extent_state(cached_state);

	cached_state = NULL;



	ret = __blockdev_direct_IO(rw, iocb, inode, NULL, iov, offset, nr_segs,

				   btrfs_get_blocks_direct, NULL,

	ret = __blockdev_direct_IO(rw, iocb, inode,

		   BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev,

		   iov, offset, nr_segs, btrfs_get_blocks_direct, NULL,

		   btrfs_submit_direct, 0);



	if (ret < 0 && ret != -EIOCBQUEUED) {