linux

Btrfs: Add backing store, memory management Signed-off-by: Chris Mason <chris.mason@oracle.com>

2007-02-02 09:18:22 -05:00

Btrfs: Fix makefile for builing btrfs static This fixes the btrfs makefile for building in the tree and out of the tree both as a module and static. Signed-off-by: Chris Mason <chris.mason@oracle.com>

2008-10-09 11:52:35 -04:00

Btrfs: simplify makefile Get rid of the hacks for building out of tree, and always use += for assigning to the object lists. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Chris Mason <chris.mason@oracle.com>

2009-04-13 15:32:28 +02:00

Switch btrfs_name_hash() to crc32c Date: Tue, 19 Aug 2008 19:21:57 +0100 Using a 64-bit hash as the readdir cookie is just asking for trouble. And gets it, when we try to export the file system by NFS. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>

2008-08-19 19:21:57 +01:00

Btrfs: add and improve comments 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@oracle.com>

2008-09-29 15:18:18 -04:00

Btrfs: Split the extent_map code into two parts There is now extent_map for mapping offsets in the file to disk and extent_io for state tracking, IO submission and extent_bufers. The new extent_map code shifts from [start,end] pairs to [start,len], and pushes the locking out into the caller. This allows a few performance optimizations and is easier to use. A number of extent_map usage bugs were fixed, mostly with failing to remove extent_map entries when changing the file. Signed-off-by: Chris Mason <chris.mason@oracle.com>

2008-01-24 16:13:08 -05:00

Btrfs: Add a leaf reference cache Much of the IO done while dropping snapshots is done looking up leaves in the filesystem trees to see if they point to any extents and to drop the references on any extents found. This creates a cache so that IO isn't required. Signed-off-by: Chris Mason <chris.mason@oracle.com>

2008-07-28 15:32:19 -04:00

Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE) 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 <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>

2009-06-10 10:45:14 -04:00

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10 lines

455 B

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