Eric Lee / smarc-ti-linux-kernel

02 Apr, 2014

1 commit

  • f2ebb3a92   smarter propagate_mnt() ... Browse Code »
    10

    The current mainline has copies propagated to *all* nodes, then
    tears down the copies we made for nodes that do not contain
    counterparts of the desired mountpoint. That sets the right
    propagation graph for the copies (at teardown time we move
    the slaves of removed node to a surviving peer or directly
    to master), but we end up paying a fairly steep price in
    useless allocations. It's fairly easy to create a situation
    where N calls of mount(2) create exactly N bindings, with
    O(N^2) vfsmounts allocated and freed in process.

    Fortunately, it is possible to avoid those allocations/freeings.
    The trick is to create copies in the right order and find which
    one would've eventually become a master with the current algorithm.
    It turns out to be possible in O(nodes getting propagation) time
    and with no extra allocations at all.

    One part is that we need to make sure that eventual master will be
    created before its slaves, so we need to walk the propagation
    tree in a different order - by peer groups. And iterate through
    the peers before dealing with the next group.

    Another thing is finding the (earlier) copy that will be a master
    of one we are about to create; to do that we are (temporary) marking
    the masters of mountpoints we are attaching the copies to.

    Either we are in a peer of the last mountpoint we'd dealt with,
    or we have the following situation: we are attaching to mountpoint M,
    the last copy S_0 had been attached to M_0 and there are sequences
    S_0...S_n, M_0...M_n such that S_{i+1} is a master of S_{i},
    S_{i} mounted on M{i} and we need to create a slave of the first S_{k}
    such that M is getting propagation from M_{k}. It means that the master
    of M_{k} will be among the sequence of masters of M. On the
    other hand, the nearest marked node in that sequence will either
    be the master of M_{k} or the master of M_{k-1} (the latter -
    in the case if M_{k-1} is a slave of something M gets propagation
    from, but in a wrong peer group).

    So we go through the sequence of masters of M until we find
    a marked one (P). Let N be the one before it. Then we go through
    the sequence of masters of S_0 until we find one (say, S) mounted
    on a node D that has P as master and check if D is a peer of N.
    If it is, S will be the master of new copy, if not - the master of S
    will be.

    That's it for the hard part; the rest is fairly simple. Iterator
    is in next_group(), handling of one prospective mountpoint is
    propagate_one().

    It seems to survive all tests and gives a noticably better performance
    than the current mainline for setups that are seriously using shared
    subtrees.

    Cc: stable@vger.kernel.org
    Signed-off-by: Al Viro

    Al Viro
     

31 Mar, 2014

1 commit

  • 38129a13e   switch mnt_hash to hlist ... Browse Code »
    32

    fixes RCU bug - walking through hlist is safe in face of element moves,
    since it's self-terminating. Cyclic lists are not - if we end up jumping
    to another hash chain, we'll loop infinitely without ever hitting the
    original list head.

    [fix for dumb braino folded]

    Spotted by: Max Kellermann
    Cc: stable@vger.kernel.org
    Signed-off-by: Al Viro

    Al Viro
     

25 Oct, 2013

3 commits

01 Jun, 2013

1 commit

  • 5d477b607   vfs: Fix invalid ida_remove() call ... Browse Code »

    When the group id of a shared mount is not allocated, the umount still
    tries to call mnt_release_group_id(), which eventually hits a kernel
    warning at ida_remove() spewing a message like:
    ida_remove called for id=0 which is not allocated.

    This patch fixes the bug simply checking the group id in the caller.

    Reported-by: Cristian Rodríguez
    Signed-off-by: Takashi Iwai
    Signed-off-by: Al Viro

    Takashi Iwai
     

02 May, 2013

1 commit

  • 20b4fb485   Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs ... Browse Code »

    Pull VFS updates from Al Viro,

    Misc cleanups all over the place, mainly wrt /proc interfaces (switch
    create_proc_entry to proc_create(), get rid of the deprecated
    create_proc_read_entry() in favor of using proc_create_data() and
    seq_file etc).

    7kloc removed.

    * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (204 commits)
    don't bother with deferred freeing of fdtables
    proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h
    proc: Make the PROC_I() and PDE() macros internal to procfs
    proc: Supply a function to remove a proc entry by PDE
    take cgroup_open() and cpuset_open() to fs/proc/base.c
    ppc: Clean up scanlog
    ppc: Clean up rtas_flash driver somewhat
    hostap: proc: Use remove_proc_subtree()
    drm: proc: Use remove_proc_subtree()
    drm: proc: Use minor->index to label things, not PDE->name
    drm: Constify drm_proc_list[]
    zoran: Don't print proc_dir_entry data in debug
    reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show()
    proc: Supply an accessor for getting the data from a PDE's parent
    airo: Use remove_proc_subtree()
    rtl8192u: Don't need to save device proc dir PDE
    rtl8187se: Use a dir under /proc/net/r8180/
    proc: Add proc_mkdir_data()
    proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h}
    proc: Move PDE_NET() to fs/proc/proc_net.c
    ...

    Linus Torvalds
     

10 Apr, 2013

2 commits

27 Mar, 2013

1 commit

  • 132c94e31   vfs: Carefully propogate mounts across user namespaces ... Browse Code »

    As a matter of policy MNT_READONLY should not be changable if the
    original mounter had more privileges than creator of the mount
    namespace.

    Add the flag CL_UNPRIVILEGED to note when we are copying a mount from
    a mount namespace that requires more privileges to a mount namespace
    that requires fewer privileges.

    When the CL_UNPRIVILEGED flag is set cause clone_mnt to set MNT_NO_REMOUNT
    if any of the mnt flags that should never be changed are set.

    This protects both mount propagation and the initial creation of a less
    privileged mount namespace.

    Cc: stable@vger.kernel.org
    Acked-by: Serge Hallyn
    Reported-by: Andy Lutomirski
    Signed-off-by: "Eric W. Biederman"

    Eric W. Biederman
     

14 Jul, 2012

1 commit

  • be34d1a3b   VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors ... Browse Code »

    copy_tree() can theoretically fail in a case other than ENOMEM, but always
    returns NULL which is interpreted by callers as -ENOMEM. Change it to return
    an explicit error.

    Also change clone_mnt() for consistency and because union mounts will add new
    error cases.

    Thanks to Andreas Gruenbacher for a bug fix.
    [AV: folded braino fix by Dan Carpenter]

    Original-author: Valerie Aurora
    Signed-off-by: David Howells
    Cc: Valerie Aurora
    Cc: Andreas Gruenbacher
    Signed-off-by: Al Viro

    David Howells
     

30 May, 2012

1 commit

  • 962830df3   brlocks/lglocks: API cleanups ... Browse Code »

    lglocks and brlocks are currently generated with some complicated macros
    in lglock.h. But there's no reason to not just use common utility
    functions and put all the data into a common data structure.

    In preparation, this patch changes the API to look more like normal
    function calls with pointers, not magic macros.

    The patch is rather large because I move over all users in one go to keep
    it bisectable. This impacts the VFS somewhat in terms of lines changed.
    But no actual behaviour change.

    [akpm@linux-foundation.org: checkpatch fixes]
    Signed-off-by: Andi Kleen
    Cc: Al Viro
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Rusty Russell
    Signed-off-by: Al Viro

    Andi Kleen
     

04 Jan, 2012

28 commits