The following commit has been merged in the linux branch: commit 5d5e103a70f74ae98e3965a4add1ab951d0651d1 Author: Josef Bacik josef@redhat.com Date: Tue Oct 13 16:46:49 2009 -0400

Btrfs: fix possible ENOSPC problems with truncate

There's a problem where we don't do any space reservation for truncates, which can cause you to OOPs because you will be allowed to go off in the weeds a bit since we don't account for the delalloc bytes that are created as a result of the truncate.

Signed-off-by: Josef Bacik jbacik@redhat.com Signed-off-by: Chris Mason chris.mason@oracle.com

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 5b9567c..78139ef 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3032,12 +3032,22 @@ static int btrfs_truncate_page(struct address_space *mapping, loff_t from)

if ((offset & (blocksize - 1)) == 0) goto out; + ret = btrfs_check_data_free_space(root, inode, PAGE_CACHE_SIZE); + if (ret) + goto out; + + ret = btrfs_reserve_metadata_for_delalloc(root, inode, 1); + if (ret) + goto out;

ret = -ENOMEM; again: page = grab_cache_page(mapping, index); - if (!page) + if (!page) { + btrfs_free_reserved_data_space(root, inode, PAGE_CACHE_SIZE); + btrfs_unreserve_metadata_for_delalloc(root, inode, 1); goto out; + }

page_start = page_offset(page); page_end = page_start + PAGE_CACHE_SIZE - 1; @@ -3070,6 +3080,10 @@ again: goto again; }

+ clear_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end, + EXTENT_DIRTY | EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING, + GFP_NOFS); + ret = btrfs_set_extent_delalloc(inode, page_start, page_end); if (ret) { unlock_extent(io_tree, page_start, page_end, GFP_NOFS); @@ -3088,6 +3102,9 @@ again: unlock_extent(io_tree, page_start, page_end, GFP_NOFS);

out_unlock: + if (ret) + btrfs_free_reserved_data_space(root, inode, PAGE_CACHE_SIZE); + btrfs_unreserve_metadata_for_delalloc(root, inode, 1); unlock_page(page); page_cache_release(page); out: @@ -3111,7 +3128,9 @@ int btrfs_cont_expand(struct inode *inode, loff_t size) if (size <= hole_start) return 0;

- btrfs_truncate_page(inode->i_mapping, inode->i_size); + err = btrfs_truncate_page(inode->i_mapping, inode->i_size); + if (err) + return err;

while (1) { struct btrfs_ordered_extent *ordered; @@ -5008,7 +5027,9 @@ static void btrfs_truncate(struct inode *inode) if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) return;

- btrfs_truncate_page(inode->i_mapping, inode->i_size); + ret = btrfs_truncate_page(inode->i_mapping, inode->i_size); + if (ret) + return; btrfs_wait_ordered_range(inode, inode->i_size & (~mask), (u64)-1);

trans = btrfs_start_transaction(root, 1);