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path: root/fs/btrfs/extent_io.c
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2009-02-12Btrfs: remove unused code in split_state()Qinghuang Feng
These two lines are not used, remove them. Signed-off-by: Qinghuang Feng <qhfeng.kernel@gmail.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-02-04Btrfs: don't return congestion in write_cache_pages as oftenChris Mason
On fast devices that go from congested to uncongested very quickly, pdflush is waiting too often in congestion_wait, and the FS is backing off to easily in write_cache_pages. For now, fix this on the btrfs side by only checking congestion after some bios have already gone down. Longer term a real fix is needed for pdflush, but that is a larger project. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-02-04Btrfs: Change btree locking to use explicit blocking pointsChris Mason
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@oracle.com>
2009-02-04Btrfs: disable leak debugging checks in extent_io.cChris Mason
extent_io.c has debugging code to report and free leaked extent_state and extent_buffer objects at rmmod time. This helps track down leaks and it saves you from rebooting just to properly remove the kmem_cache object. But, the code runs under a fairly expensive spinlock and the checks to see if it is currently enabled are not entirely consistent. Some use #ifdef and some #if. This changes everything to #if and disables the leak checking. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-01-21Btrfs: fiemap supportYehuda Sadeh
Now that bmap support is gone, this is the only way to get extent mappings for userland. These are still not valid for IO, but they can tell us if a file has holes or how much fragmentation there is. Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
2009-01-21Btrfs: removed unused #include <version.h>'sHuang Weiyi
Removed unused #include <version.h>'s in btrfs Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-01-05Btrfs: drop EXPORT symbols from extent_io.cChris Mason
They should stay out until this is turned into generic code. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-01-05Btrfs: Fix checkpatch.pl warningsChris Mason
There were many, most are fixed now. struct-funcs.c generates some warnings but these are bogus. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-01-05Btrfs: Fix typo in clear_state_cbLiu Hui
In clear_state_cb, we should check 'tree->ops->clear_bit_hook' instead of 'tree->ops->set_bit_hook'. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-12-17Btrfs: shift all end_io work to thread poolsChris Mason
bio_end_io for reads without checksumming on and btree writes were happening without using async thread pools. This means the extent_io.c code had to use spin_lock_irq and friends on the rb tree locks for extent state. There were some irq safe vs unsafe lock inversions between the delallock lock and the extent state locks. This patch gets rid of them by moving all end_io code into the thread pools. To avoid contention and deadlocks between the data end_io processing and the metadata end_io processing yet another thread pool is added to finish off metadata writes. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-12-08Btrfs: Use map_private_extent_buffer during generic_bin_searchChris Mason
It is possible that generic_bin_search will be called on a tree block that has not been locked. This happens because cache_block_block skips locking on the tree blocks. Since the tree block isn't locked, we aren't allowed to change the extent_buffer->map_token field. Using map_private_extent_buffer avoids any changes to the internal extent buffer fields. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-12-08Btrfs: move data checksumming into a dedicated treeChris Mason
Btrfs stores checksums for each data block. Until now, they have been stored in the subvolume trees, indexed by the inode that is referencing the data block. This means that when we read the inode, we've probably read in at least some checksums as well. But, this has a few problems: * The checksums are indexed by logical offset in the file. When compression is on, this means we have to do the expensive checksumming on the uncompressed data. It would be faster if we could checksum the compressed data instead. * If we implement encryption, we'll be checksumming the plain text and storing that on disk. This is significantly less secure. * For either compression or encryption, we have to get the plain text back before we can verify the checksum as correct. This makes the raid layer balancing and extent moving much more expensive. * It makes the front end caching code more complex, as we have touch the subvolume and inodes as we cache extents. * There is potentitally one copy of the checksum in each subvolume referencing an extent. The solution used here is to store the extent checksums in a dedicated tree. This allows us to index the checksums by phyiscal extent start and length. It means: * The checksum is against the data stored on disk, after any compression or encryption is done. * The checksum is stored in a central location, and can be verified without following back references, or reading inodes. This makes compression significantly faster by reducing the amount of data that needs to be checksummed. It will also allow much faster raid management code in general. The checksums are indexed by a key with a fixed objectid (a magic value in ctree.h) and offset set to the starting byte of the extent. This allows us to copy the checksum items into the fsync log tree directly (or any other tree), without having to invent a second format for them. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-12-02Btrfs: make things static and include the right headersChristoph Hellwig
Shut up various sparse warnings about symbols that should be either static or have their declarations in scope. Signed-off-by: Christoph Hellwig <hch@lst.de>
2008-12-02Btrfs: sparse lock verification annotations for wait_on_stateChristoph Hellwig
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-20Btrfs: only flush down bios for writeback pagesChris Mason
The btrfs write_cache_pages call has a flush function so that it submits the bio it has been building before it waits on any writeback pages. This adds a check so that flush only happens on writeback pages. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-19Btrfs: Fixes for 2.6.28-rc API changesChris Mason
* open/close_bdev_excl -> open/close_bdev_exclusive * blkdev_issue_discard takes a GFP mask now * Fix blkdev_issue_discard usage now that it is enabled Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-19Btrfs: Avoid writeback stallsChris Mason
While building large bios in writepages, btrfs may end up waiting for other page writeback to finish if WB_SYNC_ALL is used. While it is waiting, the bio it is building has a number of pages with the writeback bit set and they aren't getting to the disk any time soon. This lowers the latencies of writeback in general by sending down the bio being built before waiting for other pages. The bio submission code tries to limit the total number of async bios in flight by waiting when we're over a certain number of async bios. But, the waits are happening while writepages is building bios, and this can easily lead to stalls and other problems for people calling wait_on_page_writeback. The current fix is to let the congestion tests take care of waiting. sync() and others make sure to drain the current async requests to make sure that everything that was pending when the sync was started really get to disk. The code would drain pending requests both before and after submitting a new request. But, if one of the requests is waiting for page writeback to finish, the draining waits might block that page writeback. This changes the draining code to only wait after submitting the bio being processed. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-11Btrfs: Fix compile warnings on 32 bit machinesChris Mason
Simple casting here and there to fix things up. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-10Btrfs: Turn off extent state leak debuggingChris Mason
The extent_io.c code has a #define to find and cleanup extent state leaks on module unmount. This adds a very highly contended spinlock to a hot path for most FS operations. Turn it off by default. A later changeset will add a .config option for it. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-10Btrfs: Use invalidatepage when writepage finds a page outside of i_sizeChris Mason
With all the recent fixes to the delalloc locking, it is now safe again to use invalidatepage inside the writepage code for pages outside of i_size. This used to deadlock against some of the code to write locked ranges of pages, but all of that has been fixed. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-10Btrfs: Make sure pages are dirty before doing delalloc for themChris Mason
This adds a PageDirty check to the writeback path that locks pages for delalloc. If a page wasn't dirty at this point, it is in the process of being truncated away. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-06Btrfs: enforce metadata allocation clusteringChris Mason
The allocator uses the last allocation as a starting point for metadata allocations, and tries to allocate in clusters of at least 256k. If the search for a free block fails to find the expected block, this patch forces a new cluster to be found in the free list. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-06Btrfs: Optimize compressed writeback and readsChris Mason
When reading compressed extents, try to put pages into the page cache for any pages covered by the compressed extent that readpages didn't already preload. Add an async work queue to handle transformations at delayed allocation processing time. Right now this is just compression. The workflow is: 1) Find offsets in the file marked for delayed allocation 2) Lock the pages 3) Lock the state bits 4) Call the async delalloc code The async delalloc code clears the state lock bits and delalloc bits. It is important this happens before the range goes into the work queue because otherwise it might deadlock with other work queue items that try to lock those extent bits. The file pages are compressed, and if the compression doesn't work the pages are written back directly. An ordered work queue is used to make sure the inodes are written in the same order that pdflush or writepages sent them down. This changes extent_write_cache_pages to let the writepage function update the wbc nr_written count. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-10-31Btrfs: Compression corner fixesChris Mason
Make sure we keep page->mapping NULL on the pages we're getting via alloc_page. It gets set so a few of the callbacks can do the right thing, but in general these pages don't have a mapping. Don't try to truncate compressed inline items in btrfs_drop_extents. The whole compressed item must be preserved. Don't try to create multipage inline compressed items. When we try to overwrite just the first page of the file, we would have to read in and recow all the pages after it in the same compressed inline items. For now, only create single page inline items. Make sure we lock pages in the correct order during delalloc. The search into the state tree for delalloc bytes can return bytes before the page we already have locked. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-10-30Btrfs: Add fallocate support v2Yan Zheng
This patch updates btrfs-progs for fallocate support. fallocate is a little different in Btrfs because we need to tell the COW system that a given preallocated extent doesn't need to be cow'd as long as there are no snapshots of it. This leverages the -o nodatacow checks. Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-10-30Btrfs: Fix bookend extent race v2Yan Zheng
When dropping middle part of an extent, btrfs_drop_extents truncates the extent at first, then inserts a bookend extent. Since truncation and insertion can't be done atomically, there is a small period that the bookend extent isn't in the tree. This causes problem for functions that search the tree for file extent item. The way to fix this is lock the range of the bookend extent before truncation. Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-10-29Btrfs: nuke fs wide allocation mutex V2Josef Bacik
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 <jbacik@redhat.com>
2008-10-29Btrfs: Add zlib compression supportChris Mason
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>
2008-09-29Btrfs: add and improve commentsChris Mason
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>
2008-09-26Btrfs: extent_map and data=ordered fixes for space balancingZheng Yan
* Add an EXTENT_BOUNDARY state bit to keep the writepage code from merging data extents that are in the process of being relocated. This allows us to do accounting for them properly. * The balancing code relocates data extents indepdent of the underlying inode. The extent_map code was modified to properly account for things moving around (invalidating extent_map caches in the inode). * Don't take the drop_mutex in the create_subvol ioctl. It isn't required. * Fix walking of the ordered extent list to avoid races with sys_unlink * Change the lock ordering rules. Transaction start goes outside the drop_mutex. This allows btrfs_commit_transaction to directly drop the relocation trees. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Remove Btrfs compat code for older kernelsChris Mason
Btrfs had compatibility code for kernels back to 2.6.18. These have been removed, and will be maintained in a separate backport git tree from now on. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Full back reference supportZheng Yan
This patch makes the back reference system to explicit record the location of parent node for all types of extents. The location of parent node is placed into the offset field of backref key. Every time a tree block is balanced, the back references for the affected lower level extents are updated. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: free space accounting redoJosef Bacik
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>
2008-09-25Btrfs: Tree logging fixesChris Mason
* Pin down data blocks to prevent them from being reallocated like so: trans 1: allocate file extent trans 2: free file extent trans 3: free file extent during old snapshot deletion trans 3: allocate file extent to new file trans 3: fsync new file Before the tree logging code, this was legal because the fsync would commit the transation that did the final data extent free and the transaction that allocated the extent to the new file at the same time. With the tree logging code, the tree log subtransaction can commit before the transaction that freed the extent. If we crash, we're left with two different files using the extent. * Don't wait in start_transaction if log replay is going on. This avoids deadlocks from iput while we're cleaning up link counts in the replay code. * Don't deadlock in replay_one_name by trying to read an inode off the disk while holding paths for the directory * Hold the buffer lock while we mark a buffer as written. This closes a race where someone is changing a buffer while we write it. They are supposed to mark it dirty again after they change it, but this violates the cow rules. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: trivial sparse fixesChristoph Hellwig
Fix a bunch of trivial sparse complaints. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Add debugging checks to track down corrupted metadataChris Mason
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Remove broken optimisations in end_bio functions.David Woodhouse
These ended up freeing objects while they were still using them. Under guidance from Chris, just rip out the 'clever' bits and do things the simple way. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Change TestSetPageLocked() to trylock_page()David Woodhouse
Add backwards compatibility in compat.h Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> --- compat.h | 3 +++ extent_io.c | 3 ++- 2 files changed, 5 insertions(+), 1 deletions(-) Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Add compatibility for kernels >= 2.6.27-rc1Sven Wegener
Add a couple of #if's to follow API changes. Signed-off-by: Sven Wegener <sven.wegener@stealer.net> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: implement memory reclaim for leaf reference cacheYan
The memory reclaiming issue happens when snapshot exists. In that case, some cache entries may not be used during old snapshot dropping, so they will remain in the cache until umount. The patch adds a field to struct btrfs_leaf_ref to record create time. Besides, the patch makes all dead roots of a given snapshot linked together in order of create time. After a old snapshot was completely dropped, we check the dead root list and remove all cache entries created before the oldest dead root in the list. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Fix verify_parent_transidChris Mason
It was incorrectly clearing the up to date flag on the buffer even when the buffer properly verified. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Search data ordered extents first for checksums on readChris Mason
Checksum items are not inserted into the tree until all of the io from a given extent is complete. This means one dirty page from an extent may be written, freed, and then read again before the entire extent is on disk and the checksum item is inserted. The checksums themselves are stored in the ordered extent so they can be inserted in bulk when IO is complete. On read, if a checksum item isn't found, the ordered extents were being searched for a checksum record. This all worked most of the time, but the checksum insertion code tries to reduce the number of tree operations by pre-inserting checksum items based on i_size and a few other factors. This means the read code might find a checksum item that hasn't yet really been filled in. This commit changes things to check the ordered extents first and only dive into the btree if nothing was found. This removes the need for extra locking and is more reliable. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Fix some data=ordered related data corruptionsChris Mason
Stress testing was showing data checksum errors, most of which were caused by a lookup bug in the extent_map tree. The tree was caching the last pointer returned, and searches would check the last pointer first. But, search callers also expect the search to return the very first matching extent in the range, which wasn't always true with the last pointer usage. For now, the code to cache the last return value is just removed. It is easy to fix, but I think lookups are rare enough that it isn't required anymore. This commit also replaces do_sync_mapping_range with a local copy of the related functions. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Use a mutex in the extent buffer for tree block lockingChris Mason
This replaces the use of the page cache lock bit for locking, which wasn't suitable for block size < page size and couldn't be used recursively. The mutexes alone don't fix either problem, but they are the first step. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Index extent buffers in an rbtreeChris Mason
Before, extent buffers were a temporary object, meant to map a number of pages at once and collect operations on them. But, a few extra fields have crept in, and they are also the best place to store a per-tree block lock field as well. This commit puts the extent buffers into an rbtree, and ensures a single extent buffer for each tree block. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Keep extent mappings in ram until pending ordered extents are doneChris Mason
It was possible for stale mappings from disk to be used instead of the new pending ordered extent. This adds a flag to the extent map struct to keep it pinned until the pending ordered extent is actually on disk. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Don't allow releasepage to succeed if EXTENT_ORDERED is setChris Mason
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Use async helpers to deal with pages that have been improperly dirtiedChris Mason
Higher layers sometimes call set_page_dirty without asking the filesystem to help. This causes many problems for the data=ordered and cow code. This commit detects pages that haven't been properly setup for IO and kicks off an async helper to deal with them. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: New data=ordered implementationChris Mason
The old data=ordered code would force commit to wait until all the data extents from the transaction were fully on disk. This introduced large latencies into the commit and stalled new writers in the transaction for a long time. The new code changes the way data allocations and extents work: * When delayed allocation is filled, data extents are reserved, and the extent bit EXTENT_ORDERED is set on the entire range of the extent. A struct btrfs_ordered_extent is allocated an inserted into a per-inode rbtree to track the pending extents. * As each page is written EXTENT_ORDERED is cleared on the bytes corresponding to that page. * When all of the bytes corresponding to a single struct btrfs_ordered_extent are written, The previously reserved extent is inserted into the FS btree and into the extent allocation trees. The checksums for the file data are also updated. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25Btrfs: Change find_extent_buffer to use TestSetPageLockedChris Mason
This makes it possible for callers to check for extent_buffers in cache without deadlocking against any btree locks held. Signed-off-by: Chris Mason <chris.mason@oracle.com>