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

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Message-Id: <33BF9A5A-2B46-48B7-914C-10197BACA0E0@suse.de>
Date:   Fri, 21 Apr 2017 09:25:26 +0200
From:   Alexander Graf <agraf@...e.de>
To:     Jan Fajerski <jfajerski@...e.com>
Cc:     "Yan, Zheng" <zyan@...hat.com>,
        ceph-devel <ceph-devel@...r.kernel.org>,
        Sage Weil <sage@...hat.com>, Ilya Dryomov <idryomov@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jan.Fajerski@...e.com
Subject: Re: [PATCH] ceph: Fix file open flags on ppc64



> Am 21.04.2017 um 08:59 schrieb Jan Fajerski <jfajerski@...e.com>:
> 
>> On Fri, Apr 21, 2017 at 10:22:16AM +0800, Yan, Zheng wrote:
>> 
>>> On 20 Apr 2017, at 20:40, Alexander Graf <agraf@...e.de> 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));
>> 
>> cpu_to_le32(ceph_flags_sys2wire(flags)) ?
>> 
>>>    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
>>> +
>> 
>> RDONLY, WRONLY, RDWR, CREAT, EXCL, TRUNC, DIRECTORY, NOFOLLOW  are used by mds, no need to define the rest.
>> 
>>> union ceph_mds_request_args {
>>>    struct {
>>>        __le32 mask;                 /* CEPH_CAP_* */
>> 
>> Besides, the ceph mds server requires the fix too. Do you have patch for that?
> If the wire format is normalized like this, the mds can remain unchanged, can it not?

I think he means the case when mds is running on a ppc64 host.

Alex