[PATCH] block: do not warn when doing greedy allocation in folio_alloc_greedy()

[WARNING]
During one of my local btrfs fstests runs, folio_alloc() inside
folio_alloc_greedy() triggered an allocation failure report when trying
to allocate an order-4 folio.

The kernel is from the latest development branch, which is utilizing
the IOMAP_DIO_BOUNCE flag for direct writes when the inode requires
checksum.

Unfortunately I didn't save the full log, only the function and the
order.

[CAUSE]
When the IOMAP_DIO_BOUNCE flag is utilized, we will hit the following call
chain:

 bio_iov_iter_bounce_write()
 |- folio_alloc_greedy()
    |- folio_alloc(gfp | __GFP_NORETRY, get_order(*size));

However __GFP_NORETRY will still emit an allocation failure report
when it fails.

And folio_alloc_greedy() will retry with a smaller order anyway, there
is no point in emitting that allocation failure report.

[FIX]
Append the __GFP_NOWARN flag to folio_alloc() for the larger-order folio
attempts.

Fixes: 8dd5e7c75d7b ("block: add helpers to bounce buffer an iov_iter into bios")
Signed-off-by: Qu Wenruo <[email protected]>
---
 block/bio.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index f2a5f4d0a967..5ac954c70dd0 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1285,7 +1285,8 @@ static struct folio *folio_alloc_greedy(gfp_t gfp, size_t *size,
 	struct folio *folio;
 
 	while (*size > minsize) {
-		folio = folio_alloc(gfp | __GFP_NORETRY, get_order(*size));
+		folio = folio_alloc(gfp | __GFP_NORETRY | __GFP_NOWARN,
+				    get_order(*size));
 		if (folio)
 			return folio;
 		*size = rounddown_pow_of_two(*size - 1);
-- 
2.54.0