linux-kernel - Re: [PATCH] ceph: Fix file open flags on ppc64

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Date:   Fri, 21 Apr 2017 09:46:01 -0400
From:   Jeff Layton <jlayton@...hat.com>
To:     Alexander Graf <agraf@...e.de>, ceph-devel@...r.kernel.org
Cc:     zyan@...hat.com, Sage Weil <sage@...hat.com>,
        Ilya Dryomov <idryomov@...il.com>,
        linux-kernel@...r.kernel.org, Jan.Fajerski@...e.com
Subject: Re: [PATCH] ceph: Fix file open flags on ppc64

On Thu, 2017-04-20 at 14:40 +0200, Alexander Graf wrote:
> The file open flags (O_foo) are platform specific and should never go
> out to an interface that is not local to the system.
> 
> Unfortunately these flags have leaked out onto the wire in the cephfs
> implementation. That lead to bogus flags getting transmitted on ppc64.
> 
> This patch converts the kernel view of flags to the ceph view of file
> open flags. On x86 systems, the new function should get optimized out
> by smart compilers. On systems where the flags differ, it should adapt
> them accordingly.
> 
> Fixes: 124e68e74 ("ceph: file operations")
> Signed-off-by: Alexander Graf <agraf@...e.de>
> ---
>  fs/ceph/file.c               | 45 +++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/ceph/ceph_fs.h | 24 +++++++++++++++++++++++
>  2 files changed, 68 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 26cc954..0ed6392 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -103,6 +103,49 @@ static size_t dio_get_pagev_size(const struct iov_iter *it)
>  	return ERR_PTR(ret);
>  }
>  
> +static u32 ceph_flags_sys2wire(u32 flags)
> +{
> +	u32 wire_flags = 0;
> +
> +	switch (flags & O_ACCMODE) {
> +	case O_RDONLY:
> +		wire_flags |= CEPH_O_RDONLY;
> +		break;
> +	case O_WRONLY:
> +		wire_flags |= CEPH_O_WRONLY;
> +		break;
> +	case O_RDWR:
> +		wire_flags |= CEPH_O_RDWR;
> +		break;
> +	}
> +	flags &= ~O_ACCMODE;
> +
> +#define ceph_sys2wire(a) if (flags & a) { wire_flags |= CEPH_##a; flags &= ~a; }
> +
> +	ceph_sys2wire(O_CREAT);
> +	ceph_sys2wire(O_NOCTTY);
> +	ceph_sys2wire(O_TRUNC);
> +	ceph_sys2wire(O_APPEND);
> +	ceph_sys2wire(O_NONBLOCK);
> +	ceph_sys2wire(O_DSYNC);
> +	ceph_sys2wire(FASYNC);
> +	ceph_sys2wire(O_DIRECT);
> +	ceph_sys2wire(O_LARGEFILE);
> +	ceph_sys2wire(O_DIRECTORY);
> +	ceph_sys2wire(O_NOFOLLOW);
> +	ceph_sys2wire(O_NOATIME);
> +	ceph_sys2wire(O_CLOEXEC);
> +	ceph_sys2wire(__O_SYNC);
> +	ceph_sys2wire(O_PATH);
> +	ceph_sys2wire(__O_TMPFILE);
> +
> +#undef ceph_sys2wire
> +
> +	WARN_ONCE(flags, "Found unknown open flags: %x", flags);
> +
> +	return wire_flags;
> +}
> +
>  /*
>   * Prepare an open request.  Preallocate ceph_cap to avoid an
>   * inopportune ENOMEM later.
> @@ -123,7 +166,7 @@ static size_t dio_get_pagev_size(const struct iov_iter *it)
>  	if (IS_ERR(req))
>  		goto out;
>  	req->r_fmode = ceph_flags_to_mode(flags);
> -	req->r_args.open.flags = cpu_to_le32(flags);
> +	req->r_args.open.flags = ceph_flags_sys2wire(cpu_to_le32(flags));

Shouldn't that be:

    req->r_args.open.flags = cpu_to_le32(ceph_flags_sys2wire(flags));

It might be best though to move the cpu_to_le32 conversion into
ceph_flags_sys2wire instead.

>  	req->r_args.open.mode = cpu_to_le32(create_mode);
>  out:
>  	return req;
> diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h
> index f4b2ee1..d254b48 100644
> --- a/include/linux/ceph/ceph_fs.h
> +++ b/include/linux/ceph/ceph_fs.h
> @@ -366,6 +366,30 @@ enum {
>  #define CEPH_READDIR_FRAG_COMPLETE	(1<<8)
>  #define CEPH_READDIR_HASH_ORDER		(1<<9)
>  
> +/*
> + * open request flags
> + */
> +#define CEPH_O_RDONLY		00000000
> +#define CEPH_O_WRONLY		00000001
> +#define CEPH_O_RDWR		00000002
> +#define CEPH_O_CREAT		00000100
> +#define CEPH_O_EXCL		00000200
> +#define CEPH_O_NOCTTY		00000400
> +#define CEPH_O_TRUNC		00001000
> +#define CEPH_O_APPEND		00002000
> +#define CEPH_O_NONBLOCK		00004000
> +#define CEPH_O_DSYNC		00010000
> +#define CEPH_FASYNC		00020000
> +#define CEPH_O_DIRECT		00040000
> +#define CEPH_O_LARGEFILE	00100000
> +#define CEPH_O_DIRECTORY	00200000
> +#define CEPH_O_NOFOLLOW		00400000
> +#define CEPH_O_NOATIME		01000000
> +#define CEPH_O_CLOEXEC		02000000
> +#define CEPH___O_SYNC		04000000
> +#define CEPH_O_PATH		010000000
> +#define CEPH___O_TMPFILE	020000000
> +
>  union ceph_mds_request_args {
>  	struct {
>  		__le32 mask;                 /* CEPH_CAP_* */

-- 
Jeff Layton <jlayton@...hat.com>