btrfs: zero out left over bytes after processing compression streams

[cascardo/linux.git] / fs / btrfs / zlib.c

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 759fa4e..fb22fd8 100644 (file)
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -299,6 +299,8 @@ done:
        zlib_inflateEnd(&workspace->strm);
        if (data_in)
                kunmap(pages_in[page_in_index]);
+       if (!ret)
+               btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
        return ret;
 }
 
@@ -310,10 +312,14 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
        struct workspace *workspace = list_entry(ws, struct workspace, list);
        int ret = 0;
        int wbits = MAX_WBITS;
-       unsigned long bytes_left = destlen;
+       unsigned long bytes_left;
        unsigned long total_out = 0;
+       unsigned long pg_offset = 0;
        char *kaddr;
 
+       destlen = min_t(unsigned long, destlen, PAGE_SIZE);
+       bytes_left = destlen;
+
        workspace->strm.next_in = data_in;
        workspace->strm.avail_in = srclen;
        workspace->strm.total_in = 0;
@@ -341,7 +347,6 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
                unsigned long buf_start;
                unsigned long buf_offset;
                unsigned long bytes;
-               unsigned long pg_offset = 0;
 
                ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
                if (ret != Z_OK && ret != Z_STREAM_END)
@@ -384,6 +389,17 @@ next:
                ret = 0;
 
        zlib_inflateEnd(&workspace->strm);
+
+       /*
+        * this should only happen if zlib returned fewer bytes than we
+        * expected.  btrfs_get_block is responsible for zeroing from the
+        * end of the inline extent (destlen) to the end of the page
+        */
+       if (pg_offset < destlen) {
+               kaddr = kmap_atomic(dest_page);
+               memset(kaddr + pg_offset, 0, destlen - pg_offset);
+               kunmap_atomic(kaddr);
+       }
        return ret;
 }