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Commit edd1400b authored by Miao Xie's avatar Miao Xie Committed by Josef Bacik
Browse files

Btrfs: fix several potential problems in copy_nocow_pages_for_inode 



- It makes no sense that we deal with a inode in the dead tree.
- fix the race between dio and page copy by waiting the dio completion
- avoid the page copy vs truncate/punch hole
- check if the page is in the page cache or not

Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
parent 826aa0a8

fs/btrfs/scrub.c

+22 −1
Original line number Diff line number Diff line
@@ -3224,6 +3224,11 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx) 
		return PTR_ERR(local_root);

	}



	if (btrfs_root_refs(&local_root->root_item) == 0) {

		srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);

		return -ENOENT;

	}



	key.type = BTRFS_INODE_ITEM_KEY;

	key.objectid = inum;

	key.offset = 0;
@@ -3232,12 +3237,16 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx) 
	if (IS_ERR(inode))

		return PTR_ERR(inode);



	/* Avoid truncate/dio/punch hole.. */

	mutex_lock(&inode->i_mutex);

	inode_dio_wait(inode);



	ret = 0;

	physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;

	len = nocow_ctx->len;

	while (len >= PAGE_CACHE_SIZE) {

		index = offset >> PAGE_CACHE_SHIFT;



again:

		page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);

		if (!page) {

			pr_err("find_or_create_page() failed\n");
@@ -3258,7 +3267,18 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx) 
				ret = err;

				goto next_page;

			}



			lock_page(page);

			/*

			 * If the page has been remove from the page cache,

			 * the data on it is meaningless, because it may be

			 * old one, the new data may be written into the new

			 * page in the page cache.

			 */

			if (page->mapping != inode->i_mapping) {

				page_cache_release(page);

				goto again;

			}

			if (!PageUptodate(page)) {

				ret = -EIO;

				goto next_page;
@@ -3280,6 +3300,7 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx) 
		len -= PAGE_CACHE_SIZE;

	}

out:

	mutex_unlock(&inode->i_mutex);

	iput(inode);

	return ret;

}