[patch v2 5/5] ntfs: remove dependency on __GFP_NOFAIL

[David Rientjes]

Reimplement ntfs_malloc_nofs_nofail() to loop forever calling
ntfs_malloc_nofs() until the allocation succeeds.

If the first allocation attempt fails because the page allocator doesn't
implicitly loop, a warning will be emitted, including a call trace.
Subsequent failures will suppress this warning.

This was added as a helper function for documentation and auditability.
No future callers should be added.

Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
 fs/ntfs/malloc.h |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/ntfs/malloc.h b/fs/ntfs/malloc.h
--- a/fs/ntfs/malloc.h
+++ b/fs/ntfs/malloc.h
@@ -76,11 +76,19 @@ static inline void *ntfs_malloc_nofs(unsigned long size)
  * This function guarantees that the allocation will succeed.  It will sleep
  * for as long as it takes to complete the allocation.
  *
- * If there was insufficient memory to complete the request, return NULL.
+ * NOTE: no new callers of this function should be implemented!
+ * All memory allocations should be failable whenever possible.
  */
 static inline void *ntfs_malloc_nofs_nofail(unsigned long size)
 {
-	return __ntfs_malloc(size, GFP_NOFS | __GFP_HIGHMEM | __GFP_NOFAIL);
+	void *ret;
+
+	for (;;) {
+		ret = ntfs_malloc_nofs(size);
+		if (ret)
+			return ret;
+		WARN_ON_ONCE(get_order(size) > PAGE_ALLOC_COSTLY_ORDER);
+	}
 }
 
 static inline void ntfs_free(void *addr)
--
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