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    SubjectRe: [Bisected] commit 71574865 (vfs: do_last(): common slow lookup) breaks CUPS printing
    On Mon, Jul 30, 2012 at 09:10:23AM +0200, Markus Trippelsdorf wrote:
    > Looks like you're right. The first warning happens during startup. The last one
    > when I print a test page (which now succeeds).
    > Thanks Al.

    > WTF: open("/dev/input/mice", 34946)
    > WTF: open("/dev/usblp0", 32898)
    > WTF: open("/dev/usb/lp0", 32898)

    Ahhh... OK, yes - it's the case we had missed (and where the manpage
    needs correction, BTW). O_EXCL for *devices* has additional semantics;
    it's not "fail if exists", it's "fail if already opened by somebody".
    No need to pester CUPS folks (except that I really hope that this
    open of /dev/input/mice does *not* come from them)...

    All right, the proper fix is *not* removing O_EXCL from flags; we want
    it to reach ->f_flags, so that device open would work correctly. I think
    we need this, but I wonder if that's all; ->atomic_open() instances
    might need to be corrected as well. I've pushed this into for-next/for-linus
    for now:

    commit f8310c59201b183ebee2e3fe0c7242f5729be0af
    Author: Al Viro <>
    Date: Mon Jul 30 11:50:30 2012 +0400

    fix O_EXCL handling for devices

    O_EXCL without O_CREAT has different semantics; it's "fail if already opened",
    not "fail if already exists". commit 71574865 broke that...

    Signed-off-by: Al Viro <>

    diff --git a/fs/namei.c b/fs/namei.c
    index 618d353..e133bf3 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -2418,7 +2418,7 @@ static int atomic_open(struct nameidata *nd, struct dentry *dentry,
    if ((open_flag & O_CREAT) && !IS_POSIXACL(dir))
    mode &= ~current_umask();

    - if (open_flag & O_EXCL) {
    + if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) {
    open_flag &= ~O_TRUNC;
    *opened |= FILE_CREATED;
    @@ -2742,7 +2742,7 @@ retry_lookup:

    error = -EEXIST;
    - if (open_flag & O_EXCL)
    + if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))
    goto exit_dput;

    error = follow_managed(path, nd->flags);

     \ /
      Last update: 2012-07-30 10:21    [W:0.023 / U:32.556 seconds]
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