1 files changed, 23 insertions, 9 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 6e953de83f08..75533adef998 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4728,16 +4728,16 @@ err:
 }
 
 struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
-                                                u64 start)
+                                                u64 start, u32 nodesize)
 {
         unsigned long len;
 
         if (!fs_info) {
                 /*
                  * Called only from tests that don't always have a fs_info
-                 * available, but we know that nodesize is 4096
+                 * available
                  */
-                len = 4096;
+                len = nodesize;
         } else {
                 len = fs_info->tree_root->nodesize;
         }
@@ -4833,7 +4833,7 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
 
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
-                                               u64 start)
+                                        u64 start, u32 nodesize)
 {
         struct extent_buffer *eb, *exists = NULL;
         int ret;
@@ -4841,7 +4841,7 @@ struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
         eb = find_extent_buffer(fs_info, start);
         if (eb)
                 return eb;
-        eb = alloc_dummy_extent_buffer(fs_info, start);
+        eb = alloc_dummy_extent_buffer(fs_info, start, nodesize);
         if (!eb)
                 return NULL;
         eb->fs_info = fs_info;
@@ -4892,18 +4892,25 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
         int uptodate = 1;
         int ret;
 
+        if (!IS_ALIGNED(start, fs_info->tree_root->sectorsize)) {
+                btrfs_err(fs_info, "bad tree block start %llu", start);
+                return ERR_PTR(-EINVAL);
+        }
+
         eb = find_extent_buffer(fs_info, start);
         if (eb)
                 return eb;
 
         eb = __alloc_extent_buffer(fs_info, start, len);
         if (!eb)
-                return NULL;
+                return ERR_PTR(-ENOMEM);
 
         for (i = 0; i < num_pages; i++, index++) {
                 p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL);
-                if (!p)
+                if (!p) {
+                        exists = ERR_PTR(-ENOMEM);
                         goto free_eb;
+                }
 
                 spin_lock(&mapping->private_lock);
                 if (PagePrivate(p)) {
@@ -4948,8 +4955,10 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
                 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
 again:
         ret = radix_tree_preload(GFP_NOFS);
-        if (ret)
+        if (ret) {
+                exists = ERR_PTR(ret);
                 goto free_eb;
+        }
 
         spin_lock(&fs_info->buffer_lock);
         ret = radix_tree_insert(&fs_info->buffer_radix,
@@ -5333,6 +5342,11 @@ int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
         return ret;
 }
 
+/*
+ * return 0 if the item is found within a page.
+ * return 1 if the item spans two pages.
+ * return -EINVAL otherwise.
+ */
 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
                                unsigned long min_len, char **map,
                                unsigned long *map_start,
@@ -5347,7 +5361,7 @@ int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
                 PAGE_SHIFT;
 
         if (i != end_i)
-                return -EINVAL;
+                return 1;
 
         if (i == 0) {
                 offset = start_offset;