linux-toradex.git/fs/btrfs/tree-defrag.c, branch v4.3.1

Btrfs: cleanup: remove unnecessary check before btrfs_free_path is called

2015-08-31T18:46:41+00:00

We need not check path before btrfs_free_path() is called because
path is checked in btrfs_free_path().

Signed-off-by: Tsutomu Itoh 
Reviewed-by: Qu Wenruo 
Signed-off-by: Chris Mason

btrfs: let tree defrag work in SSD mode

2015-06-03T02:34:33+00:00

Long time ago (2008) the defrag was automatic for new b-tree writes but
has been disabled after performance problems. There was a leftover in
tree-defrag.c that effectively stops any defragmentation on b-trees.
This is a bit unexpected and IMHO undesired. The SSD mode is an
optimization and defrag is supposed to work if the users asks for it.

Related commits:

6702ed490ca0bb44e17131818a5a18b773957c5a
Btrfs: Add run time btree defrag, and an ioctl to force btree defrag

e18e4809b10e6c9efb5fe10c1ddcb4ebb690d517
Btrfs: Add mount -o ssd, which includes optimizations for seek free
storage

b3236e68bf86b3ae87f58984a1822369225211cb
Btrfs: Leave on the tree defragger in mount -o ssd, it still helps there

9afbb0b752ef30a429c45b9de6706e28ad1a36e1
Btrfs: Disable tree defrag in SSD mode

The last three commits switch the defrag+ssd off/on/off and the last one

3f157a2fd2ad731e1ed9964fecdc5f459f04a4a4
Btrfs: Online btree defragmentation fixes

misses the bits from tree-defrag.c to revert to the behaviour introduced
in e18e4809b10e.

Signed-off-by: David Sterba 
Signed-off-by: Chris Mason

Btrfs: use bitfield instead of integer data type for the some variants in btrfs_root

2014-06-10T00:20:40+00:00

Signed-off-by: Miao Xie 
Signed-off-by: Wang Shilong 
Signed-off-by: Chris Mason

Btrfs: cleanup dead code of defragment

2013-11-12T02:59:45+00:00

@is_extent is no more needed since we don't defrag extent root.

Signed-off-by: Liu Bo 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: remove unused max_key arg from btrfs_search_forward

2013-11-12T02:54:57+00:00

It is not used for anything.

Signed-off-by: Filipe David Borba Manana 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

btrfs: remove cache only arguments from defrag path

2013-02-20T17:59:36+00:00

The entry point at the defrag ioctl always sets "cache only" to 0;
the codepaths haven't run for a long time as far as I can
tell.  Chris says they're dead code, so remove them.

Signed-off-by: Eric Sandeen 
Signed-off-by: Josef Bacik

btrfs: drop unused parameter from btrfs_release_path

2011-05-02T11:57:22+00:00

parameter tree root it's not used since commit
5f39d397dfbe140a14edecd4e73c34ce23c4f9ee ("Btrfs: Create extent_buffer
interface for large blocksizes")

Signed-off-by: David Sterba

Btrfs: cleanup warnings from gcc 4.6 (nonbugs)

2010-10-29T19:14:37+00:00

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

Btrfs: Introduce global metadata reservation

2010-05-25T14:34:52+00:00

Reserve metadata space for extent tree, checksum tree and root tree

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

Btrfs: do extent allocation and reference count updates in the background

2009-03-24T20:14:25+00:00

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