linux-kernel - [PATCH 0/7] Fix a pile of 4GB file problems on 32-bit

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Date:   Sun,  4 Oct 2020 19:04:21 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>, ericvh@...il.com,
        lucho@...kov.net, viro@...iv.linux.org.uk, jlayton@...nel.org,
        idryomov@...il.com, mark@...heh.com, jlbec@...lplan.org,
        joseph.qi@...ux.alibaba.com, v9fs-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, ceph-devel@...r.kernel.org,
        ocfs2-devel@....oracle.com, linux-btrfs@...r.kernel.org,
        clm@...com, josef@...icpanda.com, dsterba@...e.com
Subject: [PATCH 0/7] Fix a pile of 4GB file problems on 32-bit

I caught a bug in my own code where I forgot to cast to loff_t before
shifting.  So I thought I'd grep around and see if I could find any
other occurrences.  I found a few that were clearly bugs, and they're
fixed below.  There are other places where we don't cast, and I think
they're OK.  For example, some places we have a 'nr_pages' being shifted
by PAGE_SHIFT, and that's probably OK because it's probably a single I/O.

Also, I didn't touch AFFS or ROMFS or some other filesystems which
probably have never seen a 4GB file in their lives.  Might be worth
fixing to be sure nobody copies bad code from them, but not worth cc'ing
stable for.

I didn't look for SECTOR_SHIFT or SECTOR_SIZE (or bare 9/512), just
PAGE_SIZE and PAGE_SHIFT.

I can't find a GCC warning to enable for this pattern, so I filed
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97287

Matthew Wilcox (Oracle) (7):
  9P: Cast to loff_t before multiplying
  buffer: Promote to unsigned long long before shifting
  ceph: Promote to unsigned long long before shifting
  ocfs2: Promote to unsigned long long before shifting
  btrfs: Promote to unsigned long long before shifting
  btrfs: Promote to unsigned long long before shifting
  btrfs: Promote to unsigned long long before multiplying

 fs/9p/vfs_file.c  |  4 ++--
 fs/btrfs/ioctl.c  |  6 +++---
 fs/btrfs/raid56.c |  2 +-
 fs/btrfs/scrub.c  | 25 ++++++++++++++++---------
 fs/buffer.c       |  2 +-
 fs/ceph/addr.c    |  2 +-
 fs/ocfs2/alloc.c  |  2 +-
 7 files changed, 25 insertions(+), 18 deletions(-)

-- 
2.28.0