Btrfs: Fix an off by one in the extent_map prepare write code

Signed-off-by: Chris Mason <chris.mason@oracle.com>

2 files changed, 3 insertions, 3 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 2b92f1070274..f53d8c976219 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -2270,7 +2270,7 @@ int extent_prepare_write(struct extent_map_tree *tree,
                         kunmap_atomic(kaddr, KM_USER0);
                 }
                 if ((em->block_start != EXTENT_MAP_HOLE &&
-                     em->block_start != EXTENT_MAP_INLINE) && 
+                     em->block_start != EXTENT_MAP_INLINE) &&
                     !isnew && !PageUptodate(page) &&
                     (block_off_end > to || block_off_start < from) &&
                     !test_range_bit(tree, block_start, cur_end,
@@ -2279,7 +2279,7 @@ int extent_prepare_write(struct extent_map_tree *tree,
                         u64 extent_offset = block_start - em->start;
                         size_t iosize;
                         sector = (em->block_start + extent_offset) >> 9;
-                        iosize = (cur_end - block_start + blocksize - 1) &
+                        iosize = (cur_end - block_start + blocksize) &
                                 ~((u64)blocksize - 1);
                         /*
                          * we've already got the extent locked, but we
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a9f5d6d417f0..5f5b7b89b144 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1956,7 +1956,7 @@ static int btrfs_prepare_write(struct file *file, struct page *page,
 
         mutex_lock(&root->fs_info->fs_mutex);
         err = btrfs_check_free_space(root, PAGE_CACHE_SIZE, 0);
-        mutex_lock(&root->fs_info->fs_mutex);
+        mutex_unlock(&root->fs_info->fs_mutex);
         if (err)
                 return -ENOSPC;