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    Subject[PATCH 3.4 12/92] NFSv4: don't set SETATTR for O_RDONLY|O_EXCL
    Date
    From: NeilBrown <neilb@suse.com>

    3.4.112-rc1 review patch. If anyone has any objections, please let me know.

    ------------------


    commit efcbc04e16dfa95fef76309f89710dd1d99a5453 upstream.

    It is unusual to combine the open flags O_RDONLY and O_EXCL, but
    it appears that libre-office does just that.

    [pid 3250] stat("/home/USER/.config", {st_mode=S_IFDIR|0700, st_size=8192, ...}) = 0
    [pid 3250] open("/home/USER/.config/libreoffice/4-suse/user/extensions/buildid", O_RDONLY|O_EXCL <unfinished ...>

    NFSv4 takes O_EXCL as a sign that a setattr command should be sent,
    probably to reset the timestamps.

    When it was an O_RDONLY open, the SETATTR command does not
    identify any actual attributes to change.
    If no delegation was provided to the open, the SETATTR uses the
    all-zeros stateid and the request is accepted (at least by the
    Linux NFS server - no harm, no foul).

    If a read-delegation was provided, this is used in the SETATTR
    request, and a Netapp filer will justifiably claim
    NFS4ERR_BAD_STATEID, which the Linux client takes as a sign
    to retry - indefinitely.

    So only treat O_EXCL specially if O_CREAT was also given.

    Signed-off-by: NeilBrown <neilb@suse.com>
    Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
    [lizf: Backported to 3.4: adjust context]
    Signed-off-by: Zefan Li <lizefan@huawei.com>
    ---
    fs/nfs/nfs4proc.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
    index 3d344ab..92eff4d 100644
    --- a/fs/nfs/nfs4proc.c
    +++ b/fs/nfs/nfs4proc.c
    @@ -1851,7 +1851,7 @@ static int _nfs4_do_open(struct inode *dir, struct dentry *dentry, fmode_t fmode
    if (server->caps & NFS_CAP_POSIX_LOCK)
    set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);

    - if (opendata->o_arg.open_flags & O_EXCL) {
    + if ((opendata->o_arg.open_flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)) {
    nfs4_exclusive_attrset(opendata, sattr);

    nfs_fattr_init(opendata->o_res.f_attr);
    --
    1.9.1
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