scatterlist: do not disable IRQs in sg_copy_buffer

Commit 50bed2e2862a ("sg: disable interrupts inside sg_copy_buffer")
introduced disabling interrupts in sg_copy_buffer() since atomic uses of
miter required it due to use of kmap_atomic().

However, as commit 8290e2d2dcbf ("scatterlist: atomic sg_mapping_iter()
no longer needs disabled IRQs") acknowledges disabling interrupts is no
longer needed for calls to kmap_atomic() and therefore unneeded for
miter ops either, so remove it from sg_copy_buffer().

Link: http://lkml.kernel.org/r/1486040150-14109-3-git-send-email-gilad@benyossef.com
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <ofir.drang@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/scatterlist.c

@@ -651,7 +651,6 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 {
 	unsigned int offset = 0;
 	struct sg_mapping_iter miter;
-	unsigned long flags;
 	unsigned int sg_flags = SG_MITER_ATOMIC;
 
 	if (to_buffer)
@@ -664,8 +663,6 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 	if (!sg_miter_skip(&miter, skip))
 		return false;
 
-	local_irq_save(flags);
-
 	while ((offset < buflen) && sg_miter_next(&miter)) {
 		unsigned int len;
 
@@ -681,7 +678,6 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 
 	sg_miter_stop(&miter);
 
-	local_irq_restore(flags);
 	return offset;
 }
 EXPORT_SYMBOL(sg_copy_buffer);