OpenAFS Master Repository branch, master, updated. BP--openafs-stable-1_6_x-1565-g597de25

[Gerrit Code Review]

The following commit has been merged in the master branch:
commit 597de25969ebdeaafb7390984b5ce2c8782fd557
Author: Andrew Deason <adeason@sinenomine.net>
Date:   Wed Aug 24 12:48:19 2011 -0500

    ihandle: Fix IH_REALLYCLOSE for positional I/O
    
    Currently, ih_fdclose (which is called by IH_REALLYCLOSE), goes
    through every FD_HANDLE_OPEN FdHandle_t and closes it. If it finds
    handles that are FD_HANDLE_INUSE, it skips those and sets a flag on
    the parent IHandle_t. For non-positional I/O, any future opens cannot
    use these _INUSE handles, since _INUSE handles cannot be reused, and
    the handle will be actually closed when it is FDH_CLOSE'd.
    
    For positional I/O, the situation is different. Multiple threads can
    use the same _INUSE FdHandle_t, and so there is nothing currently
    stopping a thread from IH_OPEN'ing an ihandle that has been
    IH_REALLYCLOSE'd, and getting back an FdHandle_t that existed before
    the IH_REALLYCLOSE was issued. This is important, since IH_REALLYCLOSE
    is used on files that are deleted, and future IH_OPENs for the same
    inode must not use the cached file descriptor. Getting this wrong can
    cause data loss, since it can cause us to read from or write to a file
    descriptor referring to a deleted file, when we instead should open a
    new copy of that file.
    
    To fix this, we create a new FdHandle_t state called
    FD_HANDLE_CLOSING, which is set in IH_REALLYCLOSE if we encounter an
    FD_HANDLE_INUSE FdHandle_t. In IH_OPEN, we always skip
    FD_HANDLE_CLOSING handles, so we can never get back a cached file
    descriptor from before an IH_REALLYCLOSE call.
    
    Change-Id: I3188a18f7833950cf5454b3ffe4a4ce0c69e234f
    Reviewed-on: http://gerrit.openafs.org/5308
    Tested-by: BuildBot <buildbot@rampaginggeek.com>
    Reviewed-by: Derrick Brashear <shadow@dementix.org>

 src/vol/ihandle.c |   18 ++++++++++++++----
 src/vol/ihandle.h |    3 +++
 2 files changed, 17 insertions(+), 4 deletions(-)

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