Btrfs: correct error-handling zlib error handling

find_zlib_workspace returns an ERR_PTR value in an error case instead of NULL.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@match exists@
expression x, E;
statement S1, S2;
@@

x = find_zlib_workspace(...)
... when != x = E
(
*  if (x == NULL || ...) S1 else S2
|
*  if (x == NULL && ...) S1 else S2
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index ecfbce8..3e2b90e 100644 (file)
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -208,7 +208,7 @@ int btrfs_zlib_compress_pages(struct address_space *mapping,
        *total_in = 0;
 
        workspace = find_zlib_workspace();
-       if (!workspace)
+       if (IS_ERR(workspace))
                return -1;
 
        if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
@@ -366,7 +366,7 @@ int btrfs_zlib_decompress_biovec(struct page **pages_in,
        char *kaddr;
 
        workspace = find_zlib_workspace();
-       if (!workspace)
+       if (IS_ERR(workspace))
                return -ENOMEM;
 
        data_in = kmap(pages_in[page_in_index]);
@@ -547,7 +547,7 @@ int btrfs_zlib_decompress(unsigned char *data_in,
                return -ENOMEM;
 
        workspace = find_zlib_workspace();
-       if (!workspace)
+       if (IS_ERR(workspace))
                return -ENOMEM;
 
        workspace->inf_strm.next_in = data_in;