+ fat-avoid-oops-when-bdi-io_pages==0.patch added to -mm tree

+ fat-avoid-oops-when-bdi-io_pages==0.patch added to -mm tree

[akpm]

The patch titled
     Subject: fat: avoid oops when bdi->io_pages==0
has been added to the -mm tree.  Its filename is
     fat-avoid-oops-when-bdi-io_pages==0.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/fat-avoid-oops-when-bdi-io_pages%3D%3D0.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/fat-avoid-oops-when-bdi-io_pages%3D%3D0.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Subject: fat: avoid oops when bdi->io_pages==0

On one system, there was bdi->io_pages==0.  This seems to be the bug of a
driver somewhere, which perhaps failed to initialize io_pages.  We should
fix it though - it is better to avoid the divide-by-zero Oops.

So add a check for this.

Link: http://lkml.kernel.org/r/87ft85osn6.fsf@mail.parknet.co.jp
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>		[5.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/fat/fatent.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/fat/fatent.c~fat-avoid-oops-when-bdi-io_pages==0
+++ a/fs/fat/fatent.c
@@ -660,7 +660,7 @@ static void fat_ra_init(struct super_blo
 	if (fatent->entry >= ent_limit)
 		return;
 
-	if (ra_pages > sb->s_bdi->io_pages)
+	if (sb->s_bdi->io_pages && ra_pages > sb->s_bdi->io_pages)
 		ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages);
 	reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1);
 
_

Patches currently in -mm which might be from hirofumi@mail.parknet.co.jp are

fat-avoid-oops-when-bdi-io_pages==0.patch