• Steven Whitehouse's avatar
    [GFS2] Make journaled data files identical to normal files on disk · 18ec7d5c
    Steven Whitehouse authored
    This is a very large patch, with a few still to be resolved issues
    so you might want to check out the previous head of the tree since
    this is known to be unstable. Fixes for the various bugs will be
    forthcoming shortly.
    This patch removes the special data format which has been used
    up till now for journaled data files. Directories still retain the
    old format so that they will remain on disk compatible with earlier
    releases. As a result you can now do the following with journaled
    data files:
     1) mmap them
     2) export them over NFS
     3) convert to/from normal files whenever you want to (the zero length
        restriction is gone)
    In addition the level at which GFS' locking is done has changed for all
    files (since they all now use the page cache) such that the locking is
    done at the page cache level rather than the level of the fs operations.
    This should mean that things like loopback mounts and other things which
    touch the page cache directly should now work.
    Current known issues:
     1. There is a lock mode inversion problem related to the resource
        group hold function which needs to be resolved.
     2. Any significant amount of I/O causes an oops with an offset of hex 320
        (NULL pointer dereference) which appears to be related to a journaled data
        buffer appearing on a list where it shouldn't be.
     3. Direct I/O writes are disabled for the time being (will reappear later)
     4. There is probably a deadlock between the page lock and GFS' locks under
        certain combinations of mmap and fs operation I/O.
     5. Issue relating to ref counting on internally used inodes causes a hang
        on umount (discovered before this patch, and not fixed by it)
     6. One part of the directory metadata is different from GFS1 and will need
        to be resolved before next release.
    Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
trans.h 1.2 KB