git: sbin/hammer: Don't ioctl(SET_PFS) before attempt to destroy PFS

[Tomohiro Kusumi]

commit 9376f71b677e9fcde9af7c16cd3f31cfcdb43121
Author: Tomohiro Kusumi <kusumi.tomohiro at gmail.com>
Date:   Thu Aug 18 23:00:44 2016 +0900

    sbin/hammer: Don't ioctl(SET_PFS) before attempt to destroy PFS
    
    This is part 1/2 of what's mentioned in below post.
    Two ondisk PFS data (deleted PFS followed by undeleted PFS data) will
    still appear with this commit, like what's mentioned in below post.
    (This comes from HAMMER's flushing mechanism, so it's basically a bad
    idea to try to fix it unless it's possible without touching core part
    of HAMMER's flusher code, provided that this extra ondisk PFS data
    does nothing bad. This may be fixed in the future as part 2/2 patch.)
    
    http://lists.dragonflybsd.org/pipermail/users/2016-August/313004.html
    
    This part 1/2 patch alone is still effective even without part 2/2.
    
    If the PFS is successfully destroyed, the ondisk PFS data written by
    ioctl(HAMMERIOC_SET_PSEUDOFS) prior to destroying (which is the code
    removed by this commit) gets shadowed by the one with deleted flag,
    so no one is to (or no one needs to) access that.
    
    If failed to destroy the PFS, the original ondisk PFS data is restored
    using a copy of the original data, so ioctl(HAMMERIOC_SET_PSEUDOFS)
    prior to destroying is still unnecessary. Also see 750beaef.
    Restoring part by 750beaef could be removed too since the PFS is not
    downgraded or updated anymore.

Summary of changes:
 sbin/hammer/cmd_pfs.c | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/9376f71b677e9fcde9af7c16cd3f31cfcdb43121


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