Eric Lee / smarc-fsl-linux-kernel

14 Jul, 2007

2 commits

  • 3a59c94c4   [XFS] Clean up function name handling in tracing code ... Browse Code »

    Remove the hardcoded "fnames" for tracing, and just embed them in tracing
    macros via __FUNCTION__. Kills a lot of #ifdefs too.

    SGI-PV: 967353
    SGI-Modid: xfs-linux-melb:xfs-kern:29099a

    Signed-off-by: Eric Sandeen
    Signed-off-by: David Chinner
    Signed-off-by: Tim Shimmin

    Eric Sandeen
     
  • 92821e2ba   [XFS] Lazy Superblock Counters ... Browse Code »

    When we have a couple of hundred transactions on the fly at once, they all
    typically modify the on disk superblock in some way.
    create/unclink/mkdir/rmdir modify inode counts, allocation/freeing modify
    free block counts.

    When these counts are modified in a transaction, they must eventually lock
    the superblock buffer and apply the mods. The buffer then remains locked
    until the transaction is committed into the incore log buffer. The result
    of this is that with enough transactions on the fly the incore superblock
    buffer becomes a bottleneck.

    The result of contention on the incore superblock buffer is that
    transaction rates fall - the more pressure that is put on the superblock
    buffer, the slower things go.

    The key to removing the contention is to not require the superblock fields
    in question to be locked. We do that by not marking the superblock dirty
    in the transaction. IOWs, we modify the incore superblock but do not
    modify the cached superblock buffer. In short, we do not log superblock
    modifications to critical fields in the superblock on every transaction.
    In fact we only do it just before we write the superblock to disk every
    sync period or just before unmount.

    This creates an interesting problem - if we don't log or write out the
    fields in every transaction, then how do the values get recovered after a
    crash? the answer is simple - we keep enough duplicate, logged information
    in other structures that we can reconstruct the correct count after log
    recovery has been performed.

    It is the AGF and AGI structures that contain the duplicate information;
    after recovery, we walk every AGI and AGF and sum their individual
    counters to get the correct value, and we do a transaction into the log to
    correct them. An optimisation of this is that if we have a clean unmount
    record, we know the value in the superblock is correct, so we can avoid
    the summation walk under normal conditions and so mount/recovery times do
    not change under normal operation.

    One wrinkle that was discovered during development was that the blocks
    used in the freespace btrees are never accounted for in the AGF counters.
    This was once a valid optimisation to make; when the filesystem is full,
    the free space btrees are empty and consume no space. Hence when it
    matters, the "accounting" is correct. But that means the when we do the
    AGF summations, we would not have a correct count and xfs_check would
    complain. Hence a new counter was added to track the number of blocks used
    by the free space btrees. This is an *on-disk format change*.

    As a result of this, lazy superblock counters are a mkfs option and at the
    moment on linux there is no way to convert an old filesystem. This is
    possible - xfs_db can be used to twiddle the right bits and then
    xfs_repair will do the format conversion for you. Similarly, you can
    convert backwards as well. At some point we'll add functionality to
    xfs_admin to do the bit twiddling easily....

    SGI-PV: 964999
    SGI-Modid: xfs-linux-melb:xfs-kern:28652a

    Signed-off-by: David Chinner
    Signed-off-by: Christoph Hellwig
    Signed-off-by: Tim Shimmin

    David Chinner
     

08 May, 2007

1 commit

28 Sep, 2006

2 commits

10 Aug, 2006

1 commit

  • 0e1edbd99   [XFS] Fix xfs_free_extent related NULL pointer dereference. ... Browse Code »

    We recently fixed an out-of-space deadlock in XFS, and part of that fix
    involved the addition of the XFS_ALLOC_FLAG_FREEING flag to some of the
    space allocator calls to indicate they're freeing space, not allocating
    it. There was a missed xfs_alloc_fix_freelist condition test that did not
    correctly test "flags". The same test would also test an uninitialised
    structure field (args->userdata) and depending on its value either would
    or would not return early with a critical buffer pointer set to NULL.

    This fixes that up, adds asserts to several places to catch future botches
    of this nature, and skips sections of xfs_alloc_fix_freelist that are
    irrelevent for the space-freeing case.

    SGI-PV: 955303
    SGI-Modid: xfs-linux-melb:xfs-kern:26743a

    Signed-off-by: Nathan Scott

    Nathan Scott
     

20 Jun, 2006

1 commit

09 Jun, 2006

1 commit

  • d210a28cd   [XFS] In actual allocation of file system blocks and freeing extents, the ... Browse Code »

    transaction within each such operation may involve multiple locking of AGF
    buffer. While the freeing extent function has sorted the extents based on
    AGF number before entering into transaction, however, when the file system
    space is very limited, the allocation of space would try every AGF to get
    space allocated, this could potentially cause out-of-order locking, thus
    deadlock could happen. This fix mitigates the scarce space for allocation
    by setting aside a few blocks without reservation, and avoid deadlock by
    maintaining ascending order of AGF locking.

    SGI-PV: 947395
    SGI-Modid: xfs-linux-melb:xfs-kern:210801a

    Signed-off-by: Yingping Lu
    Signed-off-by: Nathan Scott

    Yingping Lu
     

08 May, 2006

1 commit

29 Mar, 2006

1 commit

02 Nov, 2005

3 commits

21 Jun, 2005

1 commit

17 Apr, 2005

1 commit

  • 1da177e4c   Linux-2.6.12-rc2 ... Browse Code »

    Initial git repository build. I'm not bothering with the full history,
    even though we have it. We can create a separate "historical" git
    archive of that later if we want to, and in the meantime it's about
    3.2GB when imported into git - space that would just make the early
    git days unnecessarily complicated, when we don't have a lot of good
    infrastructure for it.

    Let it rip!

    Linus Torvalds