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: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5ab120d5..6866c36 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5722,6 +5722,32 @@
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 @@
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;
@@ -5784,9 +5815,10 @@
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,
- btrfs_submit_direct, 0);
+ 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) {
clear_extent_bit(&BTRFS_I(inode)->io_tree, offset,
