iomap: fix integer truncation issues in the zeroing and dirtying helpers

Christoph Hellwig · djwong · commit e28ae8e428fe · 2017-08-11T16:56:33.000-07:00
Fix the min_t calls in the zeroing and dirtying helpers to perform the
comparisms on 64-bit types, which prevents them from incorrectly
being truncated, and larger zeroing operations being stuck in a never
ending loop.

Special thanks to Markus Stockhausen for spotting the bug.

Reported-by: Paul Menzel &lt;pmenzel@molgen.mpg.de&gt;
Tested-by: Paul Menzel &lt;pmenzel@molgen.mpg.de&gt;
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
diff --git a/fs/iomap.c b/fs/iomap.c
@@ -278,7 +278,7 @@ iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		unsigned long bytes;	/* Bytes to write to page */
 
 		offset = (pos & (PAGE_SIZE - 1));
-		bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
+		bytes = min_t(loff_t, PAGE_SIZE - offset, length);
 
 		rpage = __iomap_read_page(inode, pos);
 		if (IS_ERR(rpage))
@@ -373,7 +373,7 @@ iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
 		unsigned offset, bytes;
 
 		offset = pos & (PAGE_SIZE - 1); /* Within page */
-		bytes = min_t(unsigned, PAGE_SIZE - offset, count);
+		bytes = min_t(loff_t, PAGE_SIZE - offset, count);
 
 		if (IS_DAX(inode))
 			status = iomap_dax_zero(pos, offset, bytes, iomap);
