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 (file)
--- 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);