Commit 4a001071 authored Jun 07, 2010 by Miao Xie Committed by Chris Mason Jun 11, 2010

Btrfs: fix loop device on top of btrfs



We cannot use the loop device which has been connected to a file in the btrf

The reproduce steps is following:
 # dd if=/dev/zero of=vdev0 bs=1M count=1024
 # losetup /dev/loop0 vdev0
 # mkfs.btrfs /dev/loop0
 ...
 failed to zero device start -5

The reason is that the btrfs don't implement either ->write_begin or ->write
the VFS API, so we fix it by setting ->write to do_sync_write().

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

parent 9aeead73

fs/btrfs/file.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1197,6 +1197,7 @@ static int btrfs_file_mmap(struct file filp, struct vm_area_struct vma)
		const struct file_operations btrfs_file_operations = {
		.llseek = generic_file_llseek,
		.read = do_sync_read,
		.write = do_sync_write,
		.aio_read = generic_file_aio_read,
		.splice_read = generic_file_splice_read,
		.aio_write = btrfs_file_aio_write,

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