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linux/fs/btrfs/transaction.h

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Btrfs: add GPLv2 Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-06-12 17:07:21 +04:00
/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
Btrfs: Add data=ordered support 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>
2008-01-08 23:46:30 +03:00
#ifndef __BTRFS_TRANSACTION__
#define __BTRFS_TRANSACTION__
Btrfs: allocator improvements, inode block groups Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-04-30 23:25:45 +04:00
#include "btrfs_inode.h"
Btrfs: do extent allocation and reference count updates in the background 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>
2009-03-13 17:10:06 +03:00
#include "delayed-ref.h"
Btrfs: transaction handles everywhere Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-16 23:20:31 +03:00
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
struct btrfs_transaction {
u64 transid;
Btrfs: reduce stalls during transaction commit To avoid deadlocks and reduce latencies during some critical operations, some transaction writers are allowed to jump into the running transaction and make it run a little longer, while others sit around and wait for the commit to finish. This is a bit unfair, especially when the callers that jump in do a bunch of IO that makes all the others procs on the box wait. This commit reduces the stalls this produces by pre-reading file extent pointers during btrfs_finish_ordered_io before the transaction is joined. It also tunes the drop_snapshot code to politely wait for transactions that have started writing out their delayed refs to finish. This avoids new delayed refs being flooded into the queue while we're trying to close off the transaction. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-03-13 03:12:45 +03:00
/*
* total writers in this transaction, it must be zero before the
* transaction can end
*/
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
unsigned long num_writers;
Btrfs: reduce stalls during transaction commit To avoid deadlocks and reduce latencies during some critical operations, some transaction writers are allowed to jump into the running transaction and make it run a little longer, while others sit around and wait for the commit to finish. This is a bit unfair, especially when the callers that jump in do a bunch of IO that makes all the others procs on the box wait. This commit reduces the stalls this produces by pre-reading file extent pointers during btrfs_finish_ordered_io before the transaction is joined. It also tunes the drop_snapshot code to politely wait for transactions that have started writing out their delayed refs to finish. This avoids new delayed refs being flooded into the queue while we're trying to close off the transaction. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-03-13 03:12:45 +03:00
Btrfs: delay commits during fsync to allow more writers Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-08-11 00:22:09 +04:00
unsigned long num_joined;
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
int in_commit;
int use_count;
int commit_done;
btrfs_start_transaction: wait for commits in progress to finish btrfs_commit_transaction has to loop waiting for any writers in the transaction to finish before it can proceed. btrfs_start_transaction should be polite and not join a transaction that is in the process of being finished off. There are a few places that can't wait, basically the ones doing IO that might be needed to finish the transaction. For them, btrfs_join_transaction is added. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-07-17 20:54:14 +04:00
int blocked;
Btrfs: early fsync support Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-04-20 05:01:03 +04:00
struct list_head list;
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>
2008-01-25 00:13:08 +03:00
struct extent_io_tree dirty_pages;
Btrfs: add compat ioctl Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-06-08 23:33:54 +04:00
unsigned long start_time;
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
wait_queue_head_t writer_wait;
wait_queue_head_t commit_wait;
Btrfs: Move snapshot creation to commit time It is very difficult to create a consistent snapshot of the btree when other writers may update the btree before the commit is done. This changes the snapshot creation to happen during the commit, while no other updates are possible. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-01-08 23:46:30 +03:00
struct list_head pending_snapshots;
Btrfs: do extent allocation and reference count updates in the background 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>
2009-03-13 17:10:06 +03:00
struct btrfs_delayed_ref_root delayed_refs;
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
};
Btrfs: transaction handles everywhere Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-16 23:20:31 +03:00
struct btrfs_trans_handle {
u64 transid;
Btrfs: Introduce contexts for metadata reservation Introducing metadata reseravtion contexts has two major advantages. First, it makes metadata reseravtion more traceable. Second, it can reclaim freed space and re-add them to the itself after transaction committed. Besides add btrfs_block_rsv structure and related helper functions, This patch contains following changes: Move code that decides if freed tree block should be pinned into btrfs_free_tree_block(). Make space accounting more accurate, mainly for handling read only block groups. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:46:25 +04:00
u64 block_group;
u64 bytes_reserved;
Btrfs: transaction handles everywhere Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-16 23:20:31 +03:00
unsigned long blocks_reserved;
unsigned long blocks_used;
Btrfs: do extent allocation and reference count updates in the background 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>
2009-03-13 17:10:06 +03:00
unsigned long delayed_ref_updates;
Btrfs: Introduce contexts for metadata reservation Introducing metadata reseravtion contexts has two major advantages. First, it makes metadata reseravtion more traceable. Second, it can reclaim freed space and re-add them to the itself after transaction committed. Besides add btrfs_block_rsv structure and related helper functions, This patch contains following changes: Move code that decides if freed tree block should be pinned into btrfs_free_tree_block(). Make space accounting more accurate, mainly for handling read only block groups. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:46:25 +04:00
struct btrfs_transaction *transaction;
struct btrfs_block_rsv *block_rsv;
Btrfs: transaction handles everywhere Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-16 23:20:31 +03:00
};
Btrfs: Move snapshot creation to commit time It is very difficult to create a consistent snapshot of the btree when other writers may update the btree before the commit is done. This changes the snapshot creation to happen during the commit, while no other updates are possible. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-01-08 23:46:30 +03:00
struct btrfs_pending_snapshot {
Btrfs: Allow subvolumes and snapshots anywhere in the directory tree Before, all snapshots and subvolumes lived in a single flat directory. This was awkward and confusing because the single flat directory was only writable with the ioctls. This commit changes the ioctls to create subvols and snapshots at any point in the directory tree. This requires making separate ioctls for snapshot and subvol creation instead of a combining them into one. The subvol ioctl does: btrfsctl -S subvol_name parent_dir After the ioctl is done subvol_name lives inside parent_dir. The snapshot ioctl does: btrfsctl -s path_for_snapshot root_to_snapshot path_for_snapshot can be an absolute or relative path. btrfsctl breaks it up into directory and basename components. root_to_snapshot can be any file or directory in the FS. The snapshot is taken of the entire root where that file lives. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-18 05:02:50 +03:00
struct dentry *dentry;
Btrfs: Move snapshot creation to commit time It is very difficult to create a consistent snapshot of the btree when other writers may update the btree before the commit is done. This changes the snapshot creation to happen during the commit, while no other updates are possible. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-01-08 23:46:30 +03:00
struct btrfs_root *root;
Btrfs: Integrate metadata reservation with start_transaction Besides simplify the code, this change makes sure all metadata reservation for normal metadata operations are released after committing transaction. Changes since V1: Add code that check if unlink and rmdir will free space. Add ENOSPC handling for clone ioctl. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:48:46 +04:00
struct btrfs_root *snap;
/* block reservation for the operation */
struct btrfs_block_rsv block_rsv;
/* extra metadata reseration for relocation */
int error;
Btrfs: Add readonly snapshots support Usage: Set BTRFS_SUBVOL_RDONLY of btrfs_ioctl_vol_arg_v2->flags, and call ioctl(BTRFS_I0CTL_SNAP_CREATE_V2). Implementation: - Set readonly bit of btrfs_root_item->flags. - Add readonly checks in btrfs_permission (inode_permission), btrfs_setattr, btrfs_set/remove_xattr and some ioctls. Changelog for v3: - Eliminate btrfs_root->readonly, but check btrfs_root->root_item.flags. - Rename BTRFS_ROOT_SNAP_RDONLY to BTRFS_ROOT_SUBVOL_RDONLY. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2010-12-20 11:04:08 +03:00
bool readonly;
Btrfs: Move snapshot creation to commit time It is very difficult to create a consistent snapshot of the btree when other writers may update the btree before the commit is done. This changes the snapshot creation to happen during the commit, while no other updates are possible. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-01-08 23:46:30 +03:00
struct list_head list;
};
Btrfs: allocator improvements, inode block groups Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-04-30 23:25:45 +04:00
static inline void btrfs_set_trans_block_group(struct btrfs_trans_handle *trans,
struct inode *inode)
{
trans->block_group = BTRFS_I(inode)->block_group;
}
Btrfs: Fix checkpatch.pl warnings 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>
2009-01-06 05:25:51 +03:00
static inline void btrfs_update_inode_block_group(
struct btrfs_trans_handle *trans,
struct inode *inode)
Btrfs: allocator improvements, inode block groups Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-04-30 23:25:45 +04:00
{
BTRFS_I(inode)->block_group = trans->block_group;
}
Btrfs: delay commits during fsync to allow more writers Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-08-11 00:22:09 +04:00
static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
struct inode *inode)
{
BTRFS_I(inode)->last_trans = trans->transaction->transid;
Btrfs: avoid tree log commit when there are no changes rpm has a habit of running fdatasync when the file hasn't changed. We already detect if a file hasn't been changed in the current transaction but it might have been sent to the tree-log in this transaction and not changed since the last call to fsync. In this case, we want to avoid a tree log sync, which includes a number of synchronous writes and barriers. This commit extends the existing tracking of the last transaction to change a file to also track the last sub-transaction. The end result is that rpm -ivh and -Uvh are roughly twice as fast, and on par with ext3. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-10-13 21:21:08 +04:00
BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;
Btrfs: delay commits during fsync to allow more writers Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-08-11 00:22:09 +04:00
}
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
int btrfs_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
Btrfs: create special free space cache inode In order to save free space cache, we need an inode to hold the data, and we need a special item to point at the right inode for the right block group. So first, create a special item that will point to the right inode, and the number of extent entries we will have and the number of bitmaps we will have. We truncate and pre-allocate space everytime to make sure it's uptodate. This feature will be turned on as soon as you mount with -o space_cache, however it is safe to boot into old kernels, they will just generate the cache the old fashion way. When you boot back into a newer kernel we will notice that we modified and not the cache and automatically discard the cache. Signed-off-by: Josef Bacik <josef@redhat.com>
2010-06-21 22:48:16 +04:00
int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
Btrfs: Integrate metadata reservation with start_transaction Besides simplify the code, this change makes sure all metadata reservation for normal metadata operations are released after committing transaction. Changes since V1: Add code that check if unlink and rmdir will free space. Add ENOSPC handling for clone ioctl. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:48:46 +04:00
int num_items);
btrfs_start_transaction: wait for commits in progress to finish btrfs_commit_transaction has to loop waiting for any writers in the transaction to finish before it can proceed. btrfs_start_transaction should be polite and not join a transaction that is in the process of being finished off. There are a few places that can't wait, basically the ones doing IO that might be needed to finish the transaction. For them, btrfs_join_transaction is added. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-07-17 20:54:14 +04:00
struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
Btrfs: Integrate metadata reservation with start_transaction Besides simplify the code, this change makes sure all metadata reservation for normal metadata operations are released after committing transaction. Changes since V1: Add code that check if unlink and rmdir will free space. Add ENOSPC handling for clone ioctl. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:48:46 +04:00
int num_blocks);
Btrfs: create special free space cache inode In order to save free space cache, we need an inode to hold the data, and we need a special item to point at the right inode for the right block group. So first, create a special item that will point to the right inode, and the number of extent entries we will have and the number of bitmaps we will have. We truncate and pre-allocate space everytime to make sure it's uptodate. This feature will be turned on as soon as you mount with -o space_cache, however it is safe to boot into old kernels, they will just generate the cache the old fashion way. When you boot back into a newer kernel we will notice that we modified and not the cache and automatically discard the cache. Signed-off-by: Josef Bacik <josef@redhat.com>
2010-06-21 22:48:16 +04:00
struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
int num_blocks);
Btrfs: fix ioctl-initiated transactions vs wait_current_trans() Commit 597:466b27332893 (btrfs_start_transaction: wait for commits in progress) breaks the transaction start/stop ioctls by making btrfs_start_transaction conditionally wait for the next transaction to start. If an application artificially is holding a transaction open, things deadlock. This workaround maintains a count of open ioctl-initiated transactions in fs_info, and avoids wait_current_trans() if any are currently open (in start_transaction() and btrfs_throttle()). The start transaction ioctl uses a new btrfs_start_ioctl_transaction() that _does_ call wait_current_trans(), effectively pushing the join/wait decision to the outer ioctl-initiated transaction. This more or less neuters btrfs_throttle() when ioctl-initiated transactions are in use, but that seems like a pretty fundamental consequence of wrapping lots of write()'s in a transaction. Btrfs has no way to tell if the application considers a given operation as part of it's transaction. Obviously, if the transaction start/stop ioctls aren't being used, there is no effect on current behavior. Signed-off-by: Sage Weil <sage@newdream.net> --- ctree.h | 1 + ioctl.c | 12 +++++++++++- transaction.c | 18 +++++++++++++----- transaction.h | 2 ++ 4 files changed, 27 insertions(+), 6 deletions(-) Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-08-04 18:41:27 +04:00
struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
Btrfs: Integrate metadata reservation with start_transaction Besides simplify the code, this change makes sure all metadata reservation for normal metadata operations are released after committing transaction. Changes since V1: Add code that check if unlink and rmdir will free space. Add ENOSPC handling for clone ioctl. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:48:46 +04:00
int num_blocks);
Btrfs: add START_SYNC, WAIT_SYNC ioctls START_SYNC will start a sync/commit, but not wait for it to complete. Any modification started after the ioctl returns is guaranteed not to be included in the commit. If a non-NULL pointer is passed, the transaction id will be returned to userspace. WAIT_SYNC will wait for any in-progress commit to complete. If a transaction id is specified, the ioctl will block and then return (success) when the specified transaction has committed. If it has already committed when we call the ioctl, it returns immediately. If the specified transaction doesn't exist, it returns EINVAL. If no transaction id is specified, WAIT_SYNC will wait for the currently committing transaction to finish it's commit to disk. If there is no currently committing transaction, it returns success. These ioctls are useful for applications which want to impose an ordering on when fs modifications reach disk, but do not want to wait for the full (slow) commit process to do so. Picky callers can take the transid returned by START_SYNC and feed it to WAIT_SYNC, and be certain to wait only as long as necessary for the transaction _they_ started to reach disk. Sloppy callers can START_SYNC and WAIT_SYNC without a transid, and provided they didn't wait too long between the calls, they will get the same result. However, if a second commit starts before they call WAIT_SYNC, they may end up waiting longer for it to commit as well. Even so, a START_SYNC+WAIT_SYNC still guarantees that any operation completed before the START_SYNC reaches disk. Signed-off-by: Sage Weil <sage@newdream.net> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-10-29 23:41:32 +04:00
int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid);
Btrfs: transaction rework Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-22 22:59:16 +03:00
int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
Btrfs: add compat ioctl Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-06-08 23:33:54 +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 18:45:14 +04:00
int btrfs_add_dead_root(struct btrfs_root *root);
int btrfs_drop_dead_root(struct btrfs_root *root);
Btrfs: Btree defrag on the extent-mapping tree as well Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-08-10 22:06:19 +04:00
int btrfs_defrag_root(struct btrfs_root *root, int cacheonly);
int btrfs_clean_old_snapshots(struct btrfs_root *root);
Btrfs: Create extent_buffer interface for large blocksizes Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-10-16 00:14:19 +04:00
int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
Btrfs: async transaction commit Add support for an async transaction commit that is ordered such that any subsequent operations will join the following transaction, but does not wait until the current commit is fully on disk. This avoids much of the latency associated with the btrfs_commit_transaction for callers concerned with serialization and not safety. The wait_for_unblock flag controls whether we wait for the 'middle' portion of commit_transaction to complete, which is necessary if the caller expects some of the modifications contained in the commit to be available (this is the case for subvol/snapshot creation). Signed-off-by: Sage Weil <sage@newdream.net> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-10-29 23:37:34 +04:00
int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
int wait_for_unblock);
Add btrfs_end_transaction_throttle to force writers to wait for pending commits The existing throttle mechanism was often not sufficient to prevent new writers from coming in and making a given transaction run forever. This adds an explicit wait at the end of most operations so they will allow the current transaction to close. There is no wait inside file_write, inode updates, or cow filling, all which have different deadlock possibilities. This is a temporary measure until better asynchronous commit support is added. This code leads to stalls as it waits for data=ordered writeback, and it really needs to be fixed. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-06-26 00:01:31 +04:00
int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
Btrfs: Introduce global metadata reservation Reserve metadata space for extent tree, checksum tree and root tree Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:49:58 +04:00
int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
Btrfs: Throttle operations if the reference cache gets too large A large reference cache is directly related to a lot of work pending for the cleaner thread. This throttles back new operations based on the size of the reference cache so the cleaner thread will be able to keep up. Overall, this actually makes the FS faster because the cleaner thread will be more likely to find things in cache. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-07-30 00:15:18 +04:00
void btrfs_throttle(struct btrfs_root *root);
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 18:45:14 +04:00
int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
Btrfs: Record dirty pages tree-log pages in an extent_io tree This is the same way the transaction code makes sure that all the other tree blocks are safely on disk. There's an extent_io tree for each root, and any blocks allocated to the tree logs are recorded in that tree. At tree-log sync, the extent_io tree is walked to flush down the dirty pages and wait for them. The main benefit is less time spent walking the tree log and skipping clean pages, and getting sequential IO down to the drive. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-12 00:17:57 +04:00
int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
Btrfs: Avoid superfluous tree-log writeout We allow two log transactions at a time, but use same flag to mark dirty tree-log btree blocks. So we may flush dirty blocks belonging to newer log transaction when committing a log transaction. This patch fixes the issue by using two flags to mark dirty tree-log btree blocks. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-11-12 12:33:26 +03:00
struct extent_io_tree *dirty_pages, int mark);
Btrfs: streamline tree-log btree block writeout Syncing the tree log is a 3 phase operation. 1) write and wait for all the tree log blocks for a given root. 2) write and wait for all the tree log blocks for the tree of tree log roots. 3) write and wait for the super blocks (barriers here) This isn't as efficient as it could be because there is no requirement to wait for the blocks from step one to hit the disk before we start writing the blocks from step two. This commit changes the sequence so that we don't start waiting until all the tree blocks from both steps one and two have been sent to disk. We do this by breaking up btrfs_write_wait_marked_extents into two functions, which is trivial because it was already broken up into two parts. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-10-13 21:29:19 +04:00
int btrfs_write_marked_extents(struct btrfs_root *root,
Btrfs: Avoid superfluous tree-log writeout We allow two log transactions at a time, but use same flag to mark dirty tree-log btree blocks. So we may flush dirty blocks belonging to newer log transaction when committing a log transaction. This patch fixes the issue by using two flags to mark dirty tree-log btree blocks. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-11-12 12:33:26 +03:00
struct extent_io_tree *dirty_pages, int mark);
Btrfs: streamline tree-log btree block writeout Syncing the tree log is a 3 phase operation. 1) write and wait for all the tree log blocks for a given root. 2) write and wait for all the tree log blocks for the tree of tree log roots. 3) write and wait for the super blocks (barriers here) This isn't as efficient as it could be because there is no requirement to wait for the blocks from step one to hit the disk before we start writing the blocks from step two. This commit changes the sequence so that we don't start waiting until all the tree blocks from both steps one and two have been sent to disk. We do this by breaking up btrfs_write_wait_marked_extents into two functions, which is trivial because it was already broken up into two parts. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-10-13 21:29:19 +04:00
int btrfs_wait_marked_extents(struct btrfs_root *root,
Btrfs: Avoid superfluous tree-log writeout We allow two log transactions at a time, but use same flag to mark dirty tree-log btree blocks. So we may flush dirty blocks belonging to newer log transaction when committing a log transaction. This patch fixes the issue by using two flags to mark dirty tree-log btree blocks. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-11-12 12:33:26 +03:00
struct extent_io_tree *dirty_pages, int mark);
Btrfs: Introduce global metadata reservation Reserve metadata space for extent tree, checksum tree and root tree Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-05-16 18:49:58 +04:00
int btrfs_transaction_blocked(struct btrfs_fs_info *info);
Btrfs: be more polite in the async caching threads The semaphore used by the async caching threads can prevent a transaction commit, which can make the FS appear to stall. This releases the semaphore more often when a transaction commit is in progress. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-07-30 18:04:48 +04:00
int btrfs_transaction_in_commit(struct btrfs_fs_info *info);
Btrfs: transaction handles everywhere Signed-off-by: Chris Mason <chris.mason@oracle.com>
2007-03-16 23:20:31 +03:00
#endif
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