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Commit fbf19087 authored by Josef Bacik's avatar Josef Bacik Committed by Chris Mason
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Btrfs: fix data space leak fix 



There is a problem where page_mkwrite can be called on a dirtied page that
already has a delalloc range associated with it.  The fix is to clear any
delalloc bits for the range we are dirtying so the space accounting gets
handled properly.  This is the same thing we do in the normal write case, so we
are consistent across the board.  With this patch we no longer leak reserved
space.

Signed-off-by: default avatarJosef Bacik <jbacik@redhat.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent ab93dbec

fs/btrfs/inode.c

+11 −0
Original line number Diff line number Diff line
@@ -4909,10 +4909,21 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) 
		goto again;

	}



	/*

	 * XXX - page_mkwrite gets called every time the page is dirtied, even

	 * if it was already dirty, so for space accounting reasons we need to

	 * clear any delalloc bits for the range we are fixing to save.  There

	 * is probably a better way to do this, but for now keep consistent with

	 * prepare_pages in the normal write path.

	 */

	clear_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end,

			  EXTENT_DIRTY | EXTENT_DELALLOC, GFP_NOFS);



	ret = btrfs_set_extent_delalloc(inode, page_start, page_end);

	if (ret) {

		unlock_extent(io_tree, page_start, page_end, GFP_NOFS);

		ret = VM_FAULT_SIGBUS;

		btrfs_free_reserved_data_space(root, inode, PAGE_CACHE_SIZE);

		goto out_unlock;

	}

	ret = 0;