btrfs_record_root_in_trans needs the trans_mutex held to make sure two
callers don't race to setup the root in a given transaction. This adds
it to all the places that were missing it.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Btrfs is currently using spin_lock_nested with a nested value based
on the tree depth of the block. But, this doesn't quite work because
the max tree depth is bigger than what spin_lock_nested can deal with,
and because locks are sometimes taken before the level field is filled in.
The solution here is to use lockdep_set_class_and_name instead, and to
set the class before unlocking the pages when the block is read from the
disk and just after init of a freshly allocated tree block.
btrfs_clear_path_blocking is also changed to take the locks in the proper
order, and it also makes sure all the locks currently held are properly
set to blocking before it tries to retake the spinlocks. Otherwise, lockdep
gets upset about bad lock orderin.
The lockdep magic cam from Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Larger metadata clusters can significantly improve writeback performance
on ssd drives with large erasure blocks. The larger clusters make it
more likely a given IO will completely overwrite the ssd block, so it
doesn't have to do an internal rwm cycle.
On spinning media, lager metadata clusters end up spreading out the
metadata more over time, which makes fsck slower, so we don't want this
to be the default.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Theres a slight problem with finish_current_insert, if we set all to 1 and then
go through and don't actually skip any of the extents on the pending list, we
could exit right after we've added new extents.
This is a problem because by inserting the new extents we could have gotten new
COW's to happen and such, so we may have some pending updates to do or even
more inserts to do after that.
So this patch will only exit if we have never skipped any of the extents in the
pending list, and we have no extents to insert, this will make sure that all of
the pending work is truly done before we return. I've been running with this
patch for a few days with all of my other testing and have not seen issues.
Thanks,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Every transaction in btrfs creates a new snapshot, and then schedules the
snapshot from the last transaction for deletion. Snapshot deletion
works by walking down the btree and dropping the reference counts
on each btree block during the walk.
If if a given leaf or node has a reference count greater than one,
the reference count is decremented and the subtree pointed to by that
node is ignored.
If the reference count is one, walking continues down into that node
or leaf, and the references of everything it points to are decremented.
The old code would try to work in small pieces, walking down the tree
until it found the lowest leaf or node to free and then returning. This
was very friendly to the rest of the FS because it didn't have a huge
impact on other operations.
But it wouldn't always keep up with the rate that new commits added new
snapshots for deletion, and it wasn't very optimal for the extent
allocation tree because it wasn't finding leaves that were close together
on disk and processing them at the same time.
This changes things to walk down to a level 1 node and then process it
in bulk. All the leaf pointers are sorted and the leaves are dropped
in order based on their extent number.
The extent allocation tree and commit code are now fast enough for
this kind of bulk processing to work without slowing the rest of the FS
down. Overall it does less IO and is better able to keep up with
snapshot deletions under high load.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
When a block goes through cow, we update the reference counts of
everything that block points to. The internal pointers of the block
can be in just about any order, and it is likely to have clusters of
things that are close together and clusters of things that are not.
To help reduce the seeks that come with updating all of these reference
counts, sort them by byte number before actual updates are done.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
To improve performance, btrfs_sync_log merges tree log sync
requests. But it wrongly merges sync requests for different
tree logs. If multiple tree logs are synced at the same time,
only one of them actually gets synced.
This patch has following changes to fix the bug:
Move most tree log related fields in btrfs_fs_info to
btrfs_root. This allows merging sync requests separately
for each tree log.
Don't insert root item into the log root tree immediately
after log tree is allocated. Root item for log tree is
inserted when log tree get synced for the first time. This
allows syncing the log root tree without first syncing all
log trees.
At tree-log sync, btrfs_sync_log first sync the log tree;
then updates corresponding root item in the log root tree;
sync the log root tree; then update the super block.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
replace_one_extent searches tree leaves for references to a given extent. It
stops searching if it goes beyond the last possible position.
The last possible position is computed by adding the starting offset of a found
file extent to the full size of the extent. The code uses physical size of the
extent as the full size. This is incorrect when compression is used.
The fix is get the full size from ram_bytes field of file extent item.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
btrfs_extent_post_op calls finish_current_insert and del_pending_extents. They
both may enter infinite loops.
finish_current_insert enters infinite loop if it only finds some backrefs to
update. The fix is to check for pending backref updates before restarting the
loop.
The infinite loop in del_pending_extents is due to a the skipped variable
not being properly reset before looping around.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch contains following things.
1) Limit the max size of btrfs_ordered_sum structure to PAGE_SIZE. This
struct is kmalloced so we want to keep it reasonable.
2) Replace copy_extent_csums by btrfs_lookup_csums_range. This was
duplicated code in tree-log.c
3) Remove replay_one_csum. csum items are replayed at the same time as
replaying file extents. This guarantees we only replay useful csums.
4) nbytes accounting fix.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This is a patch to fix discard semantic to make Btrfs work with FTL and SSD.
We can improve FTL's performance by telling it which sectors are freed by file
system. But if we don't tell FTL the information of free sectors in proper
time, the transaction mechanism of Btrfs will be destroyed and Btrfs could not
roll back the previous transaction under the power loss condition.
There are some problems in the old implementation:
1, In __free_extent(), the pinned down extents should not be discarded.
2, In free_extents(), the free extents are all pinned, so they need to
be discarded in transaction committing time instead of free_extents().
3, The reserved extent used by log tree should be discard too.
This patch change discard behavior as follows:
1, For the extents which need to be free at once,
we discard them in update_block_group().
2, Delay discarding the pinned extent in btrfs_finish_extent_commit()
when committing transaction.
3, Remove discarding from free_extents() and __free_extent()
4, Add discard interface into btrfs_free_reserved_extent()
5, Discard sectors before updating the free space cache, otherwise,
FTL will destroy file system data.
There is a race in relocate_inode_pages, it happens when
find_delalloc_range finds the delalloc extent before the
boundary bit is set. Thank you,
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This adds the missing block accounting code to finish_current_insert and makes
block accounting for root item properly protected by the delalloc spin lock.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Btrfs maintains a cache of blocks available for allocation in ram. The
code that frees extents was marking the extents free and then deleting
the checksum items.
This meant it was possible the extent would be reallocated before the
checksum item was actually deleted, leading to races and other
problems as the checksums were updated for the newly allocated extent.
The fix is to delete the checksum before marking the extent free.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The delalloc lock doesn't need to have irqs disabled, nobody that
changes the number of delalloc bytes in the FS is running with irqs off.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Checksums on data can be disabled by mount option, so it's
possible some data extents don't have checksums or have
invalid checksums. This causes trouble for data relocation.
This patch contains following things to make data relocation
work.
1) make nodatasum/nodatacow mount option only affects new
files. Checksums and COW on data are only controlled by the
inode flags.
2) check the existence of checksum in the nodatacow checker.
If checksums exist, force COW the data extent. This ensure that
checksum for a given block is either valid or does not exist.
3) update data relocation code to properly handle the case
of checksum missing.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch makes seed device possible to be shared by
multiple mounted file systems. The sharing is achieved
by cloning seed device's btrfs_fs_devices structure.
Thanks you,
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Yan Zheng
Chris Mason
Josef Bacik
Huang Weiyi
Qinghuang Feng
Liu Hui