09 Oct, 2012

1 commit


29 Aug, 2012

1 commit


26 Jul, 2012

1 commit

  • This patch introduces uuids for subvolumes. Each
    subvolume has it's own uuid. In case it was snapshotted,
    it also contains parent_uuid. In case it was received,
    it also contains received_uuid.

    It also introduces subvolume ctime/otime/stime/rtime. The
    first two are comparable to the times found in inodes. otime
    is the origin/creation time and ctime is the change time.
    stime/rtime are only valid on received subvolumes.
    stime is the time of the subvolume when it was
    sent. rtime is the time of the subvolume when it was
    received.

    Additionally to the times, we have a transid for each
    time. They are updated at the same place as the times.

    btrfs receive uses stransid and rtransid to find out
    if a received subvolume changed in the meantime.

    If an older kernel mounts a filesystem with the
    extented fields, all fields become invalid. The next
    mount with a new kernel will detect this and reset the
    fields.

    Signed-off-by: Alexander Block
    Reviewed-by: David Sterba
    Reviewed-by: Arne Jansen
    Reviewed-by: Jan Schmidt
    Reviewed-by: Alex Lyakas

    Alexander Block
     

22 Mar, 2012

3 commits


02 Aug, 2011

1 commit

  • This is fairly trivial - btrfs_set_root_node() - always returns zero so we
    can just make it void. All callers ignore the return code now anyway. I
    also made sure to check that none of the functions that
    btrfs_set_root_node() calls returns an error that we might have needed to
    catch and pass back.

    Signed-off-by: Mark Fasheh
    Signed-off-by: Chris Mason

    Mark Fasheh
     

24 May, 2011

2 commits


06 May, 2011

1 commit

  • Remove static and global declarations and/or definitions. Reduces size
    of btrfs.ko by ~3.4kB.

    text data bss dec hex filename
    402081 7464 200 409745 64091 btrfs.ko.base
    398620 7144 200 405964 631cc btrfs.ko.remove-all

    Signed-off-by: David Sterba

    David Sterba
     

02 May, 2011

1 commit


05 Apr, 2011

1 commit

  • root_item->flags and root_item->byte_limit are not initialized when
    a subvolume is created. This bug is not revealed until we added
    readonly snapshot support - now you mount a btrfs filesystem and you
    may find the subvolumes in it are readonly.

    To work around this problem, we steal a bit from root_item->inode_item->flags,
    and use it to indicate if those fields have been properly initialized.
    When we read a tree root from disk, we check if the bit is set, and if
    not we'll set the flag and initialize the two fields of the root item.

    Reported-by: Andreas Philipp
    Signed-off-by: Li Zefan
    Tested-by: Andreas Philipp
    cc: stable@kernel.org
    Signed-off-by: Chris Mason

    Li Zefan
     

28 Mar, 2011

1 commit


30 Oct, 2010

1 commit

  • 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
     

12 Jun, 2010

1 commit

  • If btrfs_ioctl_snap_destroy() deletes a snapshot but finishes
    with end_transaction(), the cleaner kthread may come in and
    drop the root in the same transaction. If that's the case, the
    root's refs still == 1 in the tree when btrfs_del_root() deletes
    the item, because commit_fs_roots() hasn't updated it yet (that
    happens during the commit).

    This wasn't a problem before only because
    btrfs_ioctl_snap_destroy() would commit the transaction before dropping
    the dentry reference, so the dead root wouldn't get queued up until
    after the fs root item was updated in the btree.

    Since it is not an error to drop the root reference and the root in the
    same transaction, just drop the BUG_ON() in btrfs_del_root().

    Signed-off-by: Sage Weil
    Signed-off-by: Chris Mason

    Sage Weil
     

25 May, 2010

1 commit


12 Nov, 2009

1 commit


22 Sep, 2009

2 commits

  • This patch adds snapshot/subvolume destroy ioctl. A subvolume that isn't being
    used and doesn't contains links to other subvolumes can be destroyed.

    Signed-off-by: Yan Zheng
    Signed-off-by: Chris Mason

    Yan, Zheng
     
  • btrfs allows subvolumes and snapshots anywhere in the directory tree.
    If we snapshot a subvolume that contains a link to other subvolume
    called subvolA, subvolA can be accessed through both the original
    subvolume and the snapshot. This is similar to creating hard link to
    directory, and has the very similar problems.

    The aim of this patch is enforcing there is only one access point to
    each subvolume. Only the first directory entry (the one added when
    the subvolume/snapshot was created) is treated as valid access point.
    The first directory entry is distinguished by checking root forward
    reference. If the corresponding root forward reference is missing,
    we know the entry is not the first one.

    This patch also adds snapshot/subvolume rename support, the code
    allows rename subvolume link across subvolumes.

    Signed-off-by: Yan Zheng
    Signed-off-by: Chris Mason

    Yan, Zheng
     

10 Jun, 2009

1 commit

  • This commit introduces a new kind of back reference for btrfs metadata.
    Once a filesystem has been mounted with this commit, IT WILL NO LONGER
    BE MOUNTABLE BY OLDER KERNELS.

    When a tree block in subvolume tree is cow'd, the reference counts of all
    extents it points to are increased by one. At transaction commit time,
    the old root of the subvolume is recorded in a "dead root" data structure,
    and the btree it points to is later walked, dropping reference counts
    and freeing any blocks where the reference count goes to 0.

    The increments done during cow and decrements done after commit cancel out,
    and the walk is a very expensive way to go about freeing the blocks that
    are no longer referenced by the new btree root. This commit reduces the
    transaction overhead by avoiding the need for dead root records.

    When a non-shared tree block is cow'd, we free the old block at once, and the
    new block inherits old block's references. When a tree block with reference
    count > 1 is cow'd, we increase the reference counts of all extents
    the new block points to by one, and decrease the old block's reference count by
    one.

    This dead tree avoidance code removes the need to modify the reference
    counts of lower level extents when a non-shared tree block is cow'd.
    But we still need to update back ref for all pointers in the block.
    This is because the location of the block is recorded in the back ref
    item.

    We can solve this by introducing a new type of back ref. The new
    back ref provides information about pointer's key, level and in which
    tree the pointer lives. This information allow us to find the pointer
    by searching the tree. The shortcoming of the new back ref is that it
    only works for pointers in tree blocks referenced by their owner trees.

    This is mostly a problem for snapshots, where resolving one of these
    fuzzy back references would be O(number_of_snapshots) and quite slow.
    The solution used here is to use the fuzzy back references in the common
    case where a given tree block is only referenced by one root,
    and use the full back references when multiple roots have a reference
    on a given block.

    This commit adds per subvolume red-black tree to keep trace of cached
    inodes. The red-black tree helps the balancing code to find cached
    inodes whose inode numbers within a given range.

    This commit improves the balancing code by introducing several data
    structures to keep the state of balancing. The most important one
    is the back ref cache. It caches how the upper level tree blocks are
    referenced. This greatly reduce the overhead of checking back ref.

    The improved balancing code scales significantly better with a large
    number of snapshots.

    This is a very large commit and was written in a number of
    pieces. But, they depend heavily on the disk format change and were
    squashed together to make sure git bisect didn't end up in a
    bad state wrt space balancing or the format change.

    Signed-off-by: Yan Zheng
    Signed-off-by: Chris Mason

    Yan Zheng
     

06 Jan, 2009

1 commit


02 Dec, 2008

1 commit


18 Nov, 2008

2 commits

  • For a directory tree:

    /mnt/subvolA/subvolB

    btrfsctl -s /mnt/subvolA/subvolB /mnt

    Will create a directory loop with subvolA under subvolB. This
    commit uses the forward refs for each subvol and snapshot to error out
    before creating the loop.

    Signed-off-by: Chris Mason

    Chris Mason
     
  • Subvols and snapshots can now be referenced from any point in the directory
    tree. We need to maintain back refs for them so we can find lost
    subvols.

    Forward refs are added so that we know all of the subvols and
    snapshots referenced anywhere in the directory tree of a single subvol. This
    can be used to do recursive snapshotting (but they aren't yet) and it is
    also used to detect and prevent directory loops when creating new snapshots.

    Signed-off-by: Chris Mason

    Chris Mason
     

30 Sep, 2008

1 commit

  • 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
     

26 Sep, 2008

1 commit

  • This patch updates the space balancing code to utilize the new
    backref format. Before, btrfs-vol -b would break any COW links
    on data blocks or metadata. This was slow and caused the amount
    of space used to explode if a large number of snapshots were present.

    The new code can keeps the sharing of all data extents and
    most of the tree blocks.

    To maintain the sharing of data extents, the space balance code uses
    a seperate inode hold data extent pointers, then updates the references
    to point to the new location.

    To maintain the sharing of tree blocks, the space balance code uses
    reloc trees to relocate tree blocks in reference counted roots.
    There is one reloc tree for each subvol, and all reloc trees share
    same root key objectid. Reloc trees are snapshots of the latest
    committed roots of subvols (root->commit_root).

    To relocate a tree block referenced by a subvol, there are two steps.
    COW the block through subvol's reloc tree, then update block pointer in
    the subvol to point to the new block. Since all reloc trees share
    same root key objectid, doing special handing for tree blocks
    owned by them is easy. Once a tree block has been COWed in one
    reloc tree, we can use the resulting new block directly when the
    same block is required to COW again through other reloc trees.
    In this way, relocated tree blocks are shared between reloc trees,
    so they are also shared between subvols.

    Signed-off-by: Chris Mason

    Zheng Yan
     

25 Sep, 2008

7 commits


11 Sep, 2007

1 commit

  • Dead roots are trees left over after a crash, and they were either in the
    process of being removed or were waiting to be removed when the box crashed.
    Before, a search of the entire tree of root pointers was done on mount
    looking for dead roots. Now, the search is done the first time we load
    a root.

    This makes mount faster when there are a large number of snapshots, and it
    enables the block accounting code to properly update the block counts on
    the latest root as old versions of the root are reaped after a crash.

    Signed-off-by: Chris Mason

    Chris Mason
     

11 Jul, 2007

2 commits


23 Jun, 2007

3 commits


14 Jun, 2007

1 commit

  • Attaching below is some of the code cleanups that i came across while
    reading the code.

    a) alloc_path already calls init_path.
    b) Mention that btrfs_inode is the in memory copy.Ext4 have ext4_inode_info as
    the in memory copy ext4_inode as the disk copy

    Signed-off-by: Chris Mason

    Aneesh