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* Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE)Yan Zheng2009-06-101-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Btrfs: simplify makefileChristoph Hellwig2009-04-241-17/+2
| | | | | | | | 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>
* Btrfs: do extent allocation and reference count updates in the backgroundChris Mason2009-03-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <yan.zheng@oracle.com> helped review and fixup this code. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add zlib compression supportChris Mason2008-10-291-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a large change for adding compression on reading and writing, both for inline and regular extents. It does some fairly large surgery to the writeback paths. Compression is off by default and enabled by mount -o compress. Even when the -o compress mount option is not used, it is possible to read compressed extents off the disk. If compression for a given set of pages fails to make them smaller, the file is flagged to avoid future compression attempts later. * While finding delalloc extents, the pages are locked before being sent down to the delalloc handler. This allows the delalloc handler to do complex things such as cleaning the pages, marking them writeback and starting IO on their behalf. * Inline extents are inserted at delalloc time now. This allows us to compress the data before inserting the inline extent, and it allows us to insert an inline extent that spans multiple pages. * All of the in-memory extent representations (extent_map.c, ordered-data.c etc) are changed to record both an in-memory size and an on disk size, as well as a flag for compression. From a disk format point of view, the extent pointers in the file are changed to record the on disk size of a given extent and some encoding flags. Space in the disk format is allocated for compression encoding, as well as encryption and a generic 'other' field. Neither the encryption or the 'other' field are currently used. In order to limit the amount of data read for a single random read in the file, the size of a compressed extent is limited to 128k. This is a software only limit, the disk format supports u64 sized compressed extents. In order to limit the ram consumed while processing extents, the uncompressed size of a compressed extent is limited to 256k. This is a software only limit and will be subject to tuning later. Checksumming is still done on compressed extents, and it is done on the uncompressed version of the data. This way additional encodings can be layered on without having to figure out which encoding to checksum. Compression happens at delalloc time, which is basically singled threaded because it is usually done by a single pdflush thread. This makes it tricky to spread the compression load across all the cpus on the box. We'll have to look at parallel pdflush walks of dirty inodes at a later time. Decompression is hooked into readpages and it does spread across CPUs nicely. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Fix makefile for builing btrfs staticSage Weil2008-10-091-2/+2
| | | | | | | | 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>
* Btrfs: add and improve commentsChris Mason2008-09-291-1/+1
| | | | | | | | | | | 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>
* Update Btrfs files for in-kernel usageChris Mason2008-09-251-6/+1
| | | | | | | | btrfs had magic to put the chagneset id into a printk on module load. This removes that from the Makefile and hardcodes the printk to print "Btrfs" Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: free space accounting redoJosef Bacik2008-09-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1) replace the per fs_info extent_io_tree that tracked free space with two rb-trees per block group to track free space areas via offset and size. The reason to do this is because most allocations come with a hint byte where to start, so we can usually find a chunk of free space at that hint byte to satisfy the allocation and get good space packing. If we cannot find free space at or after the given offset we fall back on looking for a chunk of the given size as close to that given offset as possible. When we fall back on the size search we also try to find a slot as close to the size we want as possible, to avoid breaking small chunks off of huge areas if possible. 2) remove the extent_io_tree that tracked the block group cache from fs_info and replaced it with an rb-tree thats tracks block group cache via offset. also added a per space_info list that tracks the block group cache for the particular space so we can lookup related block groups easily. 3) cleaned up the allocation code to make it a little easier to read and a little less complicated. Basically there are 3 steps, first look from our provided hint. If we couldn't find from that given hint, start back at our original search start and look for space from there. If that fails try to allocate space if we can and start looking again. If not we're screwed and need to start over again. 4) small fixes. there were some issues in volumes.c where we wouldn't allocate the rest of the disk. fixed cow_file_range to actually pass the alloc_hint, which has helped a good bit in making the fs_mark test I run have semi-normal results as we run out of space. Generally with data allocations we don't track where we last allocated from, so everytime we did a data allocation we'd search through every block group that we have looking for free space. Now searching a block group with no free space isn't terribly time consuming, it was causing a slight degradation as we got more data block groups. The alloc_hint has fixed this slight degredation and made things semi-normal. There is still one nagging problem I'm working on where we will get ENOSPC when there is definitely plenty of space. This only happens with metadata allocations, and only when we are almost full. So you generally hit the 85% mark first, but sometimes you'll hit the BUG before you hit the 85% wall. I'm still tracking it down, but until then this seems to be pretty stable and make a significant performance gain. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add a write ahead tree log to optimize synchronous operationsChris Mason2008-09-251-2/+1
| | | | | | | | | | | File syncs and directory syncs are optimized by copying their items into a special (copy-on-write) log tree. There is one log tree per subvolume and the btrfs super block points to a tree of log tree roots. After a crash, items are copied out of the log tree and back into the subvolume. See tree-log.c for all the details. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: compile when posix acl's are disabledJosef Bacik2008-09-251-2/+1
| | | | | | | This patch makes btrfs so it will compile properly when acls are disabled. I tested this and it worked with CONFIG_FS_POSIX_ACL off and on. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Switch btrfs_name_hash() to crc32cDavid Woodhouse2008-09-251-1/+1
| | | | | | | | | 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>
* NFS support for btrfs - v3Balaji Rao2008-09-251-1/+1
| | | | | | | | | | | | | | | | Date: Mon, 21 Jul 2008 02:01:56 +0530 Here's an implementation of NFS support for btrfs. It relies on the fixes which are going in to 2.6.28 for the NFS readdir/lookup deadlock. This uses the btrfs_iget helper introduced previously. [dwmw2: Tidy up a little, switch to d_obtain_alias() w/compat routine, change fh_type, store parent's root object ID where needed, fix some get_parent() and fs_to_dentry() bugs] Signed-off-by: Balaji Rao <balajirrao@gmail.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add a leaf reference cacheYan Zheng2008-09-251-1/+2
| | | | | | | | | | 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>
* Btrfs: Create orphan inode records to prevent lost files after a crashJosef Bacik2008-09-251-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add version strings on module loadChris Mason2008-09-251-1/+5
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Start btree concurrency work.Chris Mason2008-09-251-1/+1
| | | | | | | | | | | | | | | The allocation trees and the chunk trees are serialized via their own dedicated mutexes. This means allocation location is still not very fine grained. The main FS btree is protected by locks on each block in the btree. Locks are taken top / down, and as processing finishes on a given level of the tree, the lock is released after locking the lower level. The end result of a search is now a path where only the lowest level is locked. Releasing or freeing the path drops any locks held. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: split out ioctl.cChristoph Hellwig2008-09-251-1/+1
| | | | | | | | Split the ioctl handling out of inode.c into a file of it's own. Also fix up checkpatch.pl warnings for the moved code. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add async worker threads for pre and post IO checksummingChris Mason2008-09-251-1/+1
| | | | | | | | | | | | | | | | | | | | Btrfs has been using workqueues to spread the checksumming load across other CPUs in the system. But, workqueues only schedule work on the same CPU that queued the work, giving them a limited benefit for systems with higher CPU counts. This code adds a generic facility to schedule work with pools of kthreads, and changes the bio submission code to queue bios up. The queueing is important to make sure large numbers of procs on the system don't turn streaming workloads into random workloads by sending IO down concurrently. The end result of all of this is much higher performance (and CPU usage) when doing checksumming on large machines. Two worker pools are created, one for writes and one for endio processing. The two could deadlock if we tried to service both from a single pool. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* btrfs: tiny makefile cleanupChristoph Hellwig2008-09-251-7/+1
| | | | | | | | use normal kbuild syntax to build acl.o conditinally and remove comment out lines. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add support for multiple devices per filesystemChris Mason2008-09-251-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Split the extent_map code into two partsChris Mason2008-09-251-1/+2
| | | | | | | | | | | | | | 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>
* Btrfs: Fix compile on kernel without ACLs enabledYan2008-09-251-1/+4
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add data=ordered supportChris Mason2008-09-251-1/+1
| | | | | | | | This forces file data extents down the disk along with the metadata that references them. The current implementation is fairly simple, and just writes out all of the dirty pages in an inode before the commit. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* xattr support for btrfsJosef Bacik2008-09-251-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Breakout BTRFS_SETGET_FUNCS into a separate C file, the inlines were too big.Chris Mason2008-09-251-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Create extent_buffer interface for large blocksizesChris Mason2008-09-251-0/+2
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Simplify makefileJan Engelhardt2007-09-141-3/+4
| | | | | | Single-colons will do here. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: add modules_install targetChris Mason2007-09-141-0/+2
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add per-root block accounting and sysfs entriesJosef Bacik2007-08-291-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Extent based page cache code. This uses an rbtree of extents and testsChris Mason2007-08-271-1/+2
| | | | | | instead of buffer heads. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add run time btree defrag, and an ioctl to force btree defragChris Mason2007-08-071-1/+1
| | | | | | | | | | | This adds two types of btree defrag, a run time form that tries to defrag recently allocated blocks in the btree when they are still in ram, and an ioctl that forces defrag of all btree blocks. File data blocks are not defragged yet, but this can make a huge difference in sequential btree reads. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: cleaner make cleanJoel Becker2007-07-251-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: split up super.cChris Mason2007-06-121-2/+2
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: add a radix back bit treeChris Mason2007-03-261-1/+2
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: transaction reworkChris Mason2007-03-221-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Mountable btrfs, with readdirChris Mason2007-03-221-2/+3
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: initial move to kernel module landChris Mason2007-03-211-35/+15
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Better block record keeping, real mkfsChris Mason2007-03-201-2/+5
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Add inode map, and the start of file extent itemsChris Mason2007-03-201-1/+2
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: add transaction.h to the MakefileChris Mason2007-03-201-1/+2
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: transaction handles everywhereChris Mason2007-03-161-2/+2
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: add inode itemChris Mason2007-03-151-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: directory testing code and dir item fixesChris Mason2007-03-151-2/+3
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Use a chunk of the key flags to record the item type.Chris Mason2007-03-151-1/+1
| | | | | | | | Add (untested and simple) directory item code Fix comp_keys to use the new key ordering Add btrfs_insert_empty_item Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Change the super to point to a tree of trees to enable persistent ↵Chris Mason2007-03-131-1/+2
| | | | | | snapshots Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: get/set for struct header fieldsChris Mason2007-03-121-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Fixup last found extent cachingChris Mason2007-03-071-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: get rid of add recursionChris Mason2007-03-071-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Fixup reference counting on cowsChris Mason2007-03-061-1/+1
| | | | Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: Fixup the code to merge during path walksChris Mason2007-03-011-1/+4
| | | | | | | Add a bulk insert/remove test to random-test Add the quick-test code back as another regression test Signed-off-by: Chris Mason <chris.mason@oracle.com>
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