Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux...

[firefly-linux-kernel-4.4.55.git] / fs / btrfs / extent_io.c

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index f25a9092b946758af5f063591011ff30acf8a623..a389820d158b5b7ae64a2c6dfecabbb6ed3ed9bb 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2354,7 +2354,7 @@ int end_extent_writepage(struct page *page, int err, u64 start, u64 end)
 {
        int uptodate = (err == 0);
        struct extent_io_tree *tree;
-       int ret;
+       int ret = 0;
 
        tree = &BTRFS_I(page->mapping->host)->io_tree;
 
@@ -5068,6 +5068,43 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
        }
 }
 
+int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
+                       unsigned long start,
+                       unsigned long len)
+{
+       size_t cur;
+       size_t offset;
+       struct page *page;
+       char *kaddr;
+       char __user *dst = (char __user *)dstv;
+       size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+       unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
+       int ret = 0;
+
+       WARN_ON(start > eb->len);
+       WARN_ON(start + len > eb->start + eb->len);
+
+       offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
+
+       while (len > 0) {
+               page = extent_buffer_page(eb, i);
+
+               cur = min(len, (PAGE_CACHE_SIZE - offset));
+               kaddr = page_address(page);
+               if (copy_to_user(dst, kaddr + offset, cur)) {
+                       ret = -EFAULT;
+                       break;
+               }
+
+               dst += cur;
+               len -= cur;
+               offset = 0;
+               i++;
+       }
+
+       return ret;
+}
+
 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
                               unsigned long min_len, char **map,
                               unsigned long *map_start,