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Commit 211f96c2 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: make sure we don't overflow the free space cache crc page 



The free space cache uses only one page for crcs right now,
which means we can't have a cache file bigger than the
crcs we can fit in the first page.  This adds a check to
enforce that restriction.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 17aca1c9

fs/btrfs/free-space-cache.c

+19 −8
Original line number Diff line number Diff line
@@ -590,10 +590,25 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode, 


	num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>

		PAGE_CACHE_SHIFT;



	/* Since the first page has all of our checksums and our generation we

	 * need to calculate the offset into the page that we can start writing

	 * our entries.

	 */

	first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);



	filemap_write_and_wait(inode->i_mapping);

	btrfs_wait_ordered_range(inode, inode->i_size &

				 ~(root->sectorsize - 1), (u64)-1);



	/* make sure we don't overflow that first page */

	if (first_page_offset + sizeof(struct btrfs_free_space_entry) >= PAGE_CACHE_SIZE) {

		/* this is really the same as running out of space, where we also return 0 */

		printk(KERN_CRIT "Btrfs: free space cache was too big for the crc page\n");

		ret = 0;

		goto out_update;

	}



	/* We need a checksum per page. */

	crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);

	if (!crc)
@@ -605,12 +620,6 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode, 
		return -1;

	}



	/* Since the first page has all of our checksums and our generation we

	 * need to calculate the offset into the page that we can start writing

	 * our entries.

	 */

	first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);



	/* Get the cluster for this block_group if it exists */

	if (block_group && !list_empty(&block_group->cluster_list))

		cluster = list_entry(block_group->cluster_list.next,
@@ -872,12 +881,14 @@ int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode, 
	ret = 1;



out_free:

	kfree(checksums);

	kfree(pages);



out_update:

	if (ret != 1) {

		invalidate_inode_pages2_range(inode->i_mapping, 0, index);

		BTRFS_I(inode)->generation = 0;

	}

	kfree(checksums);

	kfree(pages);

	btrfs_update_inode(trans, root, inode);

	return ret;

}