[PATCH v4 2/7] iomap: remove pos+len BUG_ON() to after folio lookup

[Brian Foster <bfoster@redhat.com>]

The bug checks at the top of iomap_write_begin() assume the pos/len
reflect exactly the next range to process. This may no longer be the
case once the get folio path is able to process a folio batch from
the filesystem. On top of that, len is already trimmed to within the
iomap/srcmap by iomap_length(), so these checks aren't terribly
useful. Remove the unnecessary BUG_ON() checks.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
---
 fs/iomap/buffered-io.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index fd827398afd2..01721f10cf6e 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -812,15 +812,12 @@ static int iomap_write_begin(struct iomap_iter *iter,
 		size_t *poffset, u64 *plen)
 {
 	const struct iomap *srcmap = iomap_iter_srcmap(iter);
-	loff_t pos = iter->pos;
+	loff_t pos;
 	u64 len = min_t(u64, SIZE_MAX, iomap_length(iter));
 	struct folio *folio;
 	int status = 0;
 
 	len = min_not_zero(len, *plen);
-	BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
-	if (srcmap != &iter->iomap)
-		BUG_ON(pos + len > srcmap->offset + srcmap->length);
 
 	if (fatal_signal_pending(current))
 		return -EINTR;
-- 
2.50.1