Sometimes we end up freeing a reserved extent because we don't need it, however
this means that its possible for transaction->last_alloc to point to the middle
of a free area.
When we search for free space in find_free_space we do a tree_search_offset
with contains set to 0, because we want it to find the next best free area if
we do not have an offset starting on the given offset.
Unfortunately that currently means that if the offset we were given as a hint
points to the middle of a free area, we won't find anything. This is especially
bad if we happened to last allocate from the big huge chunk of a newly formed
block group, since we won't find anything and have to go back and search the
long way around.
This fixes this problem by making it so that we return the free space area
regardless of the contains variable. This made cache missing happen _alot_
less, and speeds things up considerably.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Subvol creation already requires privs, and security_inode_mkdir isn't
exported. For now we don't need it.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Creating a subvolume is in many ways like a normal VFS ->mkdir, and we
really need to play with the VFS topology locking rules. So instead of
just creating the snapshot on disk and then later getting rid of
confliting aliases do it correctly from the start. This will become
especially important once we allow for subvolumes anywhere in the tree,
and not just below a hidden root.
Note that snapshots will need the same treatment, but do to the delay
in creating them we can't do it currently. Chris promised to fix that
issue, so I'll wait on that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
Due to the optimization for truncate, tree leaves only containing
checksum items can be deleted without being COW'ed first. This causes
reference cache misses. The way to fix the miss is create cache
entries for tree leaves only contain checksum.
This patch also fixes a -EEXIST issue in shared reference cache.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
The offset field in struct btrfs_extent_ref records the position
inside file that file extent is referenced by. In the new back
reference system, tree leaves holding references to file extent
are recorded explicitly. We can scan these tree leaves very quickly, so the
offset field is not required.
This patch also makes the back reference system check the objectid
when extents are in deleting.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch makes btrfs count space allocated to file in bytes instead
of 512 byte sectors.
Everything else in btrfs uses a byte count instead of sector sizes or
blocks sizes, so this fits better.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
On 32 bit machines without CONFIG_LBD, the bi_sector field is only 32 bits.
Btrfs needs to cast it before shifting up, or we end up doing IO into
the wrong place.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The tree logging code was trying to separate tree log allocations
from normal metadata allocations to improve writeback patterns during
an fsync.
But, the code was not effective and ended up just mixing tree log
blocks with regular metadata. That seems to be working fairly well,
so the last_log_alloc code can be removed.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This reworks the btrfs O_DIRECT write code a bit. It had always fallen
back to buffered IO and done an invalidate, but needed to be updated
for the data=ordered code. The invalidate wasn't actually removing pages
because they were still inside an ordered extent.
This also combines the O_DIRECT/O_SYNC paths where possible, and kicks
off IO in the main btrfs_file_write loop to keep the pipe down the the
disk full as we process long writes.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Checksum items take up a significant portion of the metadata for large files.
It is possible to avoid reading them during truncates by checking the keys in
the higher level nodes.
If a given leaf is followed by another leaf where the lowest key is a checksum
item from the same file, we know we can safely delete the leaf without
reading it.
For a 32GB file on a 6 drive raid0 array, Btrfs needs 8s to delete
the file with a cold cache. It is read bound during the run.
With this change, Btrfs is able to delete the file in 0.5s
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This fixes a deadlock that happens between the alloc_mutex and chunk_mutex.
Process A comes in, decides to do a do_chunk_alloc, which takes the
chunk_mutex, and is holding the alloc_mutex because the only way you get to
do_chunk_alloc is by holding the alloc_mutex. btrfs_alloc_chunk does its thing
and goes to insert a new item, which results in a cow of the block.
We get into del_pending_extents from there, where if we need to be rescheduled
we drop the alloc_mutex and schedule. At this point process B comes in to do
an allocation and gets the alloc_mutex, and because process A did not do the
chunk allocation completely it thinks its a good time to do a chunk allocation
as well, and hangs on the chunk_mutex.
Process A wakes up and tries to take the alloc_mutex and cannot. The way to
fix this is do a mutex_trylock() on chunk_mutex. If we return 0 we didn't get
the lock, and if this is just a "hey it may be a good time to allocate a chunk"
then we just exit. If we are trying to force an allocation then we reschedule
and keep trying to acquire the chunk_mutex. If once we acquire it the space is
already full then we can just exit, otherwise we can continue with the chunk
allocation. Thank you,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
When reading in block groups, a global mask of the available raid policies
should be adjusted based on the types of block groups found on disk. This
global mask is then used to decide which raid policy to use for new
block groups.
The recent allocator changes dropped the call that updated the global
mask, making all the block groups allocated at run time single striped
onto a single drive.
This also fixes the async worker threads to set any thread that uses
the requeue mechanism as busy. This allows us to avoid blocking
on get_request_wait for the async bio submission threads.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch fixes a problem where we end up seeking too much when *last_ptr is
valid. This happens because btrfs_lookup_first_block_group only returns a
block group that starts on or after the given search start, so if the
search_start is in the middle of a block group it will return the block group
after the given search_start, which is suboptimal.
This patch fixes that by doing a btrfs_lookup_block_group, which will return
the block group that contains the given search start. If we fail to find a
block group, we fall back on btrfs_lookup_first_block_group so we can find the
next block group, not sure if this is absolutely needed, but better safe than
sorry.
Also if we can't find the block group that we need, or it happens to not be of
the right type, we need to add empty_cluster since *last_ptr could point to a
mismatched block group, which means we need to start over with empty_cluster
added to total needed. Thank you,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
btrfs_add_leaf_ref was doing checks on the objects it found in the
rbtree to make sure they were properly linked into the tree. But, the field
it was checking can be safely changed outside of the tree spin lock.
The WARN_ON was for debugging the initial implementation and can be
safely removed.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs-vol -a /dev/xxx will zero the first and last two MB of the device.
The kernel code needs to wait for this IO to finish before it adds
the device.
btrfs metadata IO does not happen through the block device inode. A
separate address space is used, allowing the zero filled buffer heads in
the block device inode to be written to disk after FS metadata starts
going down to the disk via the btrfs metadata inode.
The end result is zero filled metadata blocks after adding new devices
into the filesystem.
The fix is a simple filemap_write_and_wait on the block device inode
before actually inserting it into the pool of available devices.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch updates the space balancing code to utilize the new
backref format. Before, btrfs-vol -b would break any COW links
on data blocks or metadata. This was slow and caused the amount
of space used to explode if a large number of snapshots were present.
The new code can keeps the sharing of all data extents and
most of the tree blocks.
To maintain the sharing of data extents, the space balance code uses
a seperate inode hold data extent pointers, then updates the references
to point to the new location.
To maintain the sharing of tree blocks, the space balance code uses
reloc trees to relocate tree blocks in reference counted roots.
There is one reloc tree for each subvol, and all reloc trees share
same root key objectid. Reloc trees are snapshots of the latest
committed roots of subvols (root->commit_root).
To relocate a tree block referenced by a subvol, there are two steps.
COW the block through subvol's reloc tree, then update block pointer in
the subvol to point to the new block. Since all reloc trees share
same root key objectid, doing special handing for tree blocks
owned by them is easy. Once a tree block has been COWed in one
reloc tree, we can use the resulting new block directly when the
same block is required to COW again through other reloc trees.
In this way, relocated tree blocks are shared between reloc trees,
so they are also shared between subvols.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
* 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>
Btrfs has a cache of reference counts in leaves, allowing it to
avoid reading tree leaves while deleting snapshots. To reduce
contention with multiple subvolumes, this cache is private to each
subvolume.
This patch adds shared reference cache support. The new space
balancing code plays with multiple subvols at the same time, So
the old per-subvol reference cache is not well suited.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Reserved extent accounting: reserved extents have been
allocated in the rbtrees that track free space but have not
been allocated on disk. They were never properly accounted for
in the past, making it hard to know how much space was really free.
* btrfs_find_block_group used to return NULL for block groups that
had been removed by the space balancing code. This made it hard
to account for space during the final stages of a balance run.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Btrfs metadata writeback is fairly expensive. Once a tree block is written
it must be cowed before it can be changed again. The btree writepages
code has a threshold based on a count of dirty btree bytes which is
updated as IO is sent out.
This changes btree_writepages to skip the writeout if there are less
than 32MB of dirty bytes from the btrees, improving performance
across many workloads.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The code to free block groups needs to drop the space info spin lock
before calling btrfs_remove_free_space_cache (which can schedule).
This is safe because at unmount time, nobody else is going to play
with the block groups.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
After a crash, the tree log code uses btrfs_alloc_logged_extent to
record allocations of data extents that it finds in the log tree. These
come in basically random order, which does not fit how
btrfs_remove_free_space() expects to be called.
btrfs_remove_free_space was changed to support recording an extent
allocation in the middle of a region of free space.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
The code to update the on disk i_size happens before the
ordered_extent record is removed. So, it is possible for multiple
ordered_extent completion routines to run at the same time, and to
find each other in the ordered tree.
The end result is they both decide not to update disk_i_size, leaving
it too small. This temporary fix just puts the updates inside
the extent_mutex. A real solution would be stronger ordering of
disk_i_size updates against removing the ordered extent from the tree.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
Tree log blocks are only reserved, and should not ever get fully
allocated on disk. This check makes sure they stay out of the
extent tree.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Tree blocks were using async bio submission, but the sum was still
being done directly during writepage. This moves the checksumming
into the worker thread.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
cache block group had a few bugs in the error handling code,
this makes sure paths get properly released and the correct return value
goes out.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
This changes the log tree copy code to use btrfs_insert_items and
to work in larger batches where possible.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Since tree log blocks get freed every transaction, they never really
need to be written to disk. This skips the step where we update
metadata to record they were allocated.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Drop i_mutex during the commit
Don't bother doing the fsync at all unless the dir is marked as dirtied
and needing fsync in this transaction. For directories, this means
that someone has unlinked a file from the dir without fsyncing the
file.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
* 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>
Orphan items use BTRFS_ORPHAN_OBJECTID (-5UUL) as key objectid. This
affects the find free objectid functions, inode objectid can easily
overflow after orphan file cleanup.
---
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs_ilookup is unused, which is good because a normal filesystem
should never have to use ilookup anyway. Remove it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Add two missing endianess conversions in this function, found by sparse.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
d_obtain_alias is intended as a tailcall that can pass in errors encoded
in the inode pointer if needed, so use it that way instead of
duplicating the error handling.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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 actually stores the whole xattr name, including the prefix ondisk,
so using the generic resolver that strips off the prefix is not very
helpful. Instead do the real ondisk xattrs manually and only use the
generic resolver for synthetic xattrs like ACLs.
(Sorry Josef for guiding you towards the wrong direction here intially)
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The ->list handler is really not useful at all, because we always call
btrfs_xattr_generic_list anyway. After this is done
find_btrfs_xattr_handler becomes unused, and it becomes obvious that the
temporary name buffer allocation isn't needed but we can directly copy
into the supplied buffer.
Tested with various getfattr -d calls on varying xattr lists.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
The current code waits for the count of async bio submits to get below
a given threshold if it is too high right after adding the latest bio
to the work queue. This isn't optimal because the caller may have
sequential adjacent bios pending they are waiting to send down the pipe.
This changeset requires the caller to wait on the async bio count,
and changes the async checksumming submits to wait for async bios any
time they self throttle.
The end result is much higher sequential throughput.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Date: Tue, 19 Aug 2008 22:20:17 +0100
btrfs_lookup_fs_root() only finds subvol roots which have already been
seen and put into the cache. For btrfs_get_dentry() we actually have to
go to the medium -- so use btrfs_read_fs_root_no_name() instead.
In btrfs_get_parent(), notice when we've hit the root of the
subvolume and return the real root instead.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
Date: Tue, 19 Aug 2008 16:49:35 +0100
This disappeared when I removed the special case for '.' in btrfs_lookup()
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Date: Mon, 18 Aug 2008 13:10:20 +0100
This means that subvolumes get a different fsid, and NFS exporting them
works properly.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Date: Sun, 17 Aug 2008 15:14:48 +0100
We never get asked by the VFS to lookup either of them, and we can
handle the readdir() case a lot more simply, too.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
Date: Mon, 21 Jul 2008 02:01:04 +0530
This patch introduces a btrfs_iget helper to be used in NFS support.
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>
Before, the btrfs bdi congestion function was used to test for too many
async bios. This keeps that check to throttle pdflush, but also
adds a check while queuing bios.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This optimization had been removed because I thought it was triggering
csum errors. The real cause of the errors was elsewhere, and so
this optimization is back.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
add_extent_mapping was allowing the insertion of overlapping extents.
This never used to happen because it only inserted the extents from disk
and those were never overlapping.
But, with the data=ordered code, the disk and memory representations of the
file are not the same. add_extent_mapping needs to ensure a new extent
does not overlap before it inserts.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
Before this change, btrfs would use a bdi congestion function to make
sure there weren't too many pending async checksum work items.
This change makes the process creating async work items wait instead,
leading to fewer congestion returns from the bdi. This improves
pdflush background_writeout scanning.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
After writing out all the remaining btree blocks in the transaction,
the commit code would use filemap_fdatawait to make sure it was all
on disk. This means it would wait for blocks written by other procs
as well.
The new code walks the list of blocks for this transaction again
and waits only for those required by this transaction.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The writeback_index field is used by write_cache_pages to pick up where
writeback on a given inode left off. But, it is never set to a sane
value, so writeback can often start at a random offset in the file.
Kernels 2.6.28 and higher will have this fixed, but for everyone else,
we also fill in the value in btrfs.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Newer RHEL5 kernels define both ClearPageFSMisc and
ClearPageChecked, so test for both before redefining.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
Signed-off-by: Chris Mason <chris.mason@oracle.com>
rename and link don't always have a lock on the source inode, and
our use of a per-inode index variable was racy. This changes things to
store the index in a local variable instead.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The multi-bio code is responsible for duplicating blocks in raid1 and
single spindle duplication. It has counters to make sure all of
the locations for a given extent are properly written before io completion
is returned to the higher layers.
But, it didn't always complete the same bio it was given, sometimes a
clone was completed instead. This lead to problems with the async
work queues because they saved a pointer to the bio in a struct off
bi_private.
The fix is to remember the original bio and only complete that one.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Far from the perfect fix, but these structs are small. TODO for the
next release. The block group cache structs are referenced in many
different places, and it isn't safe to just free them while resizing.
A real fix will be a larger change to the allocator so that it doesn't
have to carry about the block group cache structs to find good places
to search for free blocks.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
Intel doesn't yet ship hardware to the public with this enabled, but when they
do, they will be ready. Original code from:
Austin Zhang <austin_zhang@linux.intel.com>
It is currently disabled, but edit crc32c.h to turn it on.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Make walk_down_tree wake up throttled tasks more often
* Make walk_down_tree call cond_resched during long loops
* As the size of the ref cache grows, wait longer in throttle
* Get rid of the reada code in walk_down_tree, the leaves don't get
read anymore, thanks to the ref cache.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
A btree block cow has two parts, the first is to allocate a destination
block and the second is to copy the old bock over.
The first part needs locks in the extent allocation tree, and may need to
do IO. This changeset splits that into a separate function that can be
called without any tree locks held.
btrfs_search_slot is changed to drop its path and start over if it has
to COW a contended block. This often means that many writers will
pre-alloc a new destination for a the same contended block, but they
cache their prealloc for later use on lower levels in the tree.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
While dropping snapshots, walk_down_tree does most of the work of checking
reference counts and limiting tree traversal to just the blocks that
we are freeing.
It dropped and held the allocation mutex in strange and confusing ways,
this commit changes it to only hold the mutex while actually freeing a block.
The rest of the checks around reference counts should be safe without the lock
because we only allow one process in btrfs_drop_snapshot at a time. Other
processes dropping reference counts should not drop it to 1 because
their tree roots already have an extra ref on the block.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Large streaming reads make for large bios, which means each entry on the
list async work queues represents a large amount of data. IO
congestion throttling on the device was kicking in before the async
worker threads decided a single thread was busy and needed some help.
The end result was that a streaming read would result in a single CPU
running at 100% instead of balancing the work off to other CPUs.
This patch also changes the pre-IO checksum lookup done by reads to
work on a per-bio basis instead of a per-page. This results in many
extra btree lookups on large streaming reads. Doing the checksum lookup
right before bio submit allows us to reuse searches while processing
adjacent offsets.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This avoids waiting for transactions with pages locked by breaking out
the code to wait for the current transaction to close into a function
called by btrfs_throttle.
It also lowers the limits for where we start throttling.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
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>
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>
To check whether a given file extent is referenced by multiple snapshots, the
checker walks down the fs tree through dead root and checks all tree blocks in
the path.
We can easily detect whether a given tree block is directly referenced by other
snapshot. We can also detect any indirect reference from other snapshot by
checking reference's generation. The checker can always detect multiple
references, but can't reliably detect cases of single reference. So btrfs may
do file data cow even there is only one reference.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When kthread_run() returns failure, this worker hasn't been
added to the list, so btrfs_stop_workers() won't free it.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
This changes the reference cache to make a single cache per root
instead of one cache per transaction, and to key by the byte number
of the disk block instead of the keys inside.
This makes it much less likely to have cache misses if a snapshot
or something has an extra reference on a higher node or a leaf while
the first transaction that added the leaf into the cache is dropping.
Some throttling is added to functions that free blocks heavily so they
wait for old transactions to drop.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
The 'char name[BTRFS_PATH_NAME_MAX]' member of struct btrfs_ioctl_vol_args
is passed directly to strlen() after being copied from user. I haven't
verified this, but in theory a userspace program could pass in an
unterminated string and cause a kernel crash as strlen walks off the end of
the array.
This patch terminates the ->name string in all btrfs ioctl functions which
currently use a 'struct btrfs_ioctl_vol_args'. Since the string is now
properly terminated, it's length will never be longer than
BTRFS_PATH_NAME_MAX so that error check has been removed.
By the way, it might be better overall to just have the ioctl pass an
unterminated string + length structure but I didn't bother with that since
it'd change the kernel/user interface.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
We should decrease the found slot by one as btrfs_search_slot does
when bin_search return 1 and node level > 0.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Remove a unused variable 'path' in fixup_tree_root_location.
Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Before setting an extent to delalloc, the code needs to wait for
pending ordered extents.
Also, the relocation code needs to wait for ordered IO before scanning
the block group again. This is because the extents are not removed
until the IO for the new extents is finished
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
This releases the alloc_mutex in a few places that hold it for over long
operations. btrfs_lookup_block_group is changed so that it doesn't need
the mutex at all.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Lockdep has the notion of locking subclasses so that you can identify
locks you expect to be taken after other locks of the same class. This
changes the per-extent buffer btree locking routines to use a subclass based
on the level in the tree.
Unfortunately, lockdep can only handle 8 total subclasses, and the btrfs
max level is also 8. So when lockdep is on, use a lower max level.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
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>
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>
* In btrfs_delete_inode, wait for ordered extents after calling
truncate_inode_pages. This is much faster, and more correct
* Properly clear our the PageChecked bit everywhere we redirty the page.
* Change the writepage fixup handler to lock the page range and check to
see if an ordered extent had been inserted since the improperly dirtied
page was discovered
* Wait for ordered extents outside the transaction. This isn't required
for locking rules but does improve transaction latencies
* Reduce contention on the alloc_mutex by dropping it while incrementing
refs on a node/leaf and while dropping refs on a leaf.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
Data checksumming is done right before the bio is sent down the IO stack,
which means a single bio might span more than one ordered extent. In
this case, the checksumming data is split between two ordered extents.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
