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Commit 48ddc6f4 authored by Chris Mason's avatar Chris Mason Committed by David Woodhouse
Browse files

Btrfs: cow file extents before writing 



Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent d0dbc624

fs/btrfs/super.c

+18 −2
Original line number Diff line number Diff line
@@ -1020,7 +1020,7 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock, 


	ret = btrfs_lookup_file_extent(trans, root, path,

				       inode->i_ino,

				       iblock << inode->i_blkbits, 0);

				       iblock << inode->i_blkbits, 1);

	if (ret < 0) {

		err = ret;

		goto out;
@@ -1040,9 +1040,25 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock, 
	blocknr = btrfs_file_extent_disk_blocknr(item);

	blocknr += btrfs_file_extent_offset(item);



	/* exact match found, use it */

	/* exact match found, use it, FIXME, deal with extents

	 * other than the page size

	 */

	if (ret == 0) {

		err = 0;

		BUG_ON(btrfs_file_extent_disk_num_blocks(item) != 1);

		if (btrfs_file_extent_generation(item) != trans->transid) {

			struct btrfs_key ins;

			ret = btrfs_alloc_extent(trans, root, 1,

						 blocknr, (u64)-1, &ins);

			BUG_ON(ret);

			btrfs_set_file_extent_disk_blocknr(item, ins.objectid);

			mark_buffer_dirty(path->nodes[0]);

			ret = btrfs_free_extent(trans, root,

						blocknr, 1, 0);

			BUG_ON(ret);

			blocknr = ins.objectid;



		}

		map_bh(result, inode->i_sb, blocknr);

		goto out;

	}