Doug / smarc-fsl-linux-kernel

02 May, 2011

1 commit

30 Oct, 2010

1 commit

  • 559af8211   Btrfs: cleanup warnings from gcc 4.6 (nonbugs) ... Browse Code »

    These are all the cases where a variable is set, but not read which are
    not bugs as far as I can see, but simply leftovers.

    Still needs more review.

    Found by gcc 4.6's new warnings

    Signed-off-by: Andi Kleen
    Cc: Chris Mason
    Signed-off-by: Andrew Morton
    Signed-off-by: Chris Mason

    Andi Kleen
     

25 May, 2010

1 commit

25 Mar, 2009

1 commit

  • 56bec294d   Btrfs: do extent allocation and reference count updates in the background ... Browse Code »

    The extent allocation tree maintains a reference count and full
    back reference information for every extent allocated in the
    filesystem. For subvolume and snapshot trees, every time
    a block goes through COW, the new copy of the block adds a reference
    on every block it points to.

    If a btree node points to 150 leaves, then the COW code needs to go
    and add backrefs on 150 different extents, which might be spread all
    over the extent allocation tree.

    These updates currently happen during btrfs_cow_block, and most COWs
    happen during btrfs_search_slot. btrfs_search_slot has locks held
    on both the parent and the node we are COWing, and so we really want
    to avoid IO during the COW if we can.

    This commit adds an rbtree of pending reference count updates and extent
    allocations. The tree is ordered by byte number of the extent and byte number
    of the parent for the back reference. The tree allows us to:

    1) Modify back references in something close to disk order, reducing seeks
    2) Significantly reduce the number of modifications made as block pointers
    are balanced around
    3) Do all of the extent insertion and back reference modifications outside
    of the performance critical btrfs_search_slot code.

    #3 has the added benefit of greatly reducing the btrfs stack footprint.
    The extent allocation tree modifications are done without the deep
    (and somewhat recursive) call chains used in the past.

    These delayed back reference updates must be done before the transaction
    commits, and so the rbtree is tied to the transaction. Throttling is
    implemented to help keep the queue of backrefs at a reasonable size.

    Since there was a similar mechanism in place for the extent tree
    extents, that is removed and replaced by the delayed reference tree.

    Yan Zheng helped review and fixup this code.

    Signed-off-by: Chris Mason

    Chris Mason
     

04 Feb, 2009

1 commit

  • b4ce94de9   Btrfs: Change btree locking to use explicit blocking points ... Browse Code »

    Most of the btrfs metadata operations can be protected by a spinlock,
    but some operations still need to schedule.

    So far, btrfs has been using a mutex along with a trylock loop,
    most of the time it is able to avoid going for the full mutex, so
    the trylock loop is a big performance gain.

    This commit is step one for getting rid of the blocking locks entirely.
    btrfs_tree_lock takes a spinlock, and the code explicitly switches
    to a blocking lock when it starts an operation that can schedule.

    We'll be able get rid of the blocking locks in smaller pieces over time.
    Tracing allows us to find the most common cause of blocking, so we
    can start with the hot spots first.

    The basic idea is:

    btrfs_tree_lock() returns with the spin lock held

    btrfs_set_lock_blocking() sets the EXTENT_BUFFER_BLOCKING bit in
    the extent buffer flags, and then drops the spin lock. The buffer is
    still considered locked by all of the btrfs code.

    If btrfs_tree_lock gets the spinlock but finds the blocking bit set, it drops
    the spin lock and waits on a wait queue for the blocking bit to go away.

    Much of the code that needs to set the blocking bit finishes without actually
    blocking a good percentage of the time. So, an adaptive spin is still
    used against the blocking bit to avoid very high context switch rates.

    btrfs_clear_lock_blocking() clears the blocking bit and returns
    with the spinlock held again.

    btrfs_tree_unlock() can be called on either blocking or spinning locks,
    it does the right thing based on the blocking bit.

    ctree.c has a helper function to set/clear all the locked buffers in a
    path as blocking.

    Signed-off-by: Chris Mason

    Chris Mason
     

06 Jan, 2009

1 commit

30 Oct, 2008

1 commit

  • 251792013   Btrfs: nuke fs wide allocation mutex V2 ... Browse Code »

    This patch removes the giant fs_info->alloc_mutex and replaces it with a bunch
    of little locks.

    There is now a pinned_mutex, which is used when messing with the pinned_extents
    extent io tree, and the extent_ins_mutex which is used with the pending_del and
    extent_ins extent io trees.

    The locking for the extent tree stuff was inspired by a patch that Yan Zheng
    wrote to fix a race condition, I cleaned it up some and changed the locking
    around a little bit, but the idea remains the same. Basically instead of
    holding the extent_ins_mutex throughout the processing of an extent on the
    extent_ins or pending_del trees, we just hold it while we're searching and when
    we clear the bits on those trees, and lock the extent for the duration of the
    operations on the extent.

    Also to keep from getting hung up waiting to lock an extent, I've added a
    try_lock_extent so if we cannot lock the extent, move on to the next one in the
    tree and we'll come back to that one. I have tested this heavily and it does
    not appear to break anything. This has to be applied on top of my
    find_free_extent redo patch.

    I tested this patch on top of Yan's space reblancing code and it worked fine.
    The only thing that has changed since the last version is I pulled out all my
    debugging stuff, apparently I forgot to run guilt refresh before I sent the
    last patch out. Thank you,

    Signed-off-by: Josef Bacik

    Josef Bacik
     

30 Sep, 2008

1 commit

  • d352ac681   Btrfs: add and improve comments ... Browse Code »

    This improves the comments at the top of many functions. It didn't
    dive into the guts of functions because I was trying to
    avoid merging problems with the new allocator and back reference work.

    extent-tree.c and volumes.c were both skipped, and there is definitely
    more work todo in cleaning and commenting the code.

    Signed-off-by: Chris Mason

    Chris Mason
     

25 Sep, 2008

23 commits

11 Sep, 2007

1 commit

11 Aug, 2007

2 commits

09 Aug, 2007

1 commit

08 Aug, 2007

1 commit