This patch gives us the space we will need in order to have different csum
algorithims at some point in the future. We save the csum algorithim type
in the superblock, and use those instead of define's.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
This needs to be applied on top of my previous patches, but is needed for more
than just my new stuff. We're going to the wrong label when we have an error,
we try to stop the workers, but they are started below all of this code. This
fixes it so we go to the right error label and not panic when we fail one of
these cases.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
This adds the necessary disk format for handling compatibility flags
in the future to handle disk format changes. We have a compat_flags,
compat_ro_flags and incompat_flags set for the super block. Compat
flags will be to hold the features that are compatible with older
versions of btrfs, compat_ro flags have features that are compatible
with older versions of btrfs if the fs is mounted read only, and
incompat_flags has features that are incompatible with older versions
of btrfs. This also axes the compat_flags field for the inode and
just makes the flags field a 64bit field, and changes the root item
flags field to 64bit.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Cleans the code up a little and also avoids a sparse warning due to the
incorrect cast in the current version of the code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Provide a void __user *argp pointer so that we can avoid duplicating
the cast for various sub-command calls.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Shut up various sparse warnings about symbols that should be either
static or have their declarations in scope.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Remove unneeded debugging sanity check. It gets corrupted anyway when
multiple btrfs file systems are mounted, throwing bad warnings along the
way.
Signed-off-by: Sage Weil <sage@newdream.net>
This the lockdep complaint by having a different mutex to gaurd caching the
block group, so you don't end up with this backwards dependancy. Thank you,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
The btrfs write_cache_pages call has a flush function so that it submits
the bio it has been building before it waits on any writeback pages.
This adds a check so that flush only happens on writeback pages.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The log replay produces dirty roots. These dirty roots
should be dropped immediately if the fs is mounted as
ro. Otherwise they can be added to the dirty root list
again when remounting the fs as rw. Thank you,
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
The btrfs git kernel trees is used to build a standalone tree for
compiling against older kernels. This commit makes the standalone tree
work with 2.6.27
Signed-off-by: Chris Mason <chris.mason@oracle.com>
* open/close_bdev_excl -> open/close_bdev_exclusive
* blkdev_issue_discard takes a GFP mask now
* Fix blkdev_issue_discard usage now that it is enabled
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch fixes what I hope is the last early ENOSPC bug left. I did not know
that pinned extents would merge into one big extent when inserted on to the
pinned extent tree, so I was adding free space to a block group that could
possibly span multiple block groups.
This is a big issue because first that space doesn't exist in that block group,
and second we won't actually use that space because there are a bunch of other
checks to make sure we're allocating within the constraints of the block group.
This patch fixes the problem by adding the btrfs_add_free_space to
btrfs_update_pinned_extents which makes sure we are adding the appropriate
amount of free space to the appropriate block group. Thanks much to Lee Trager
for running my myriad of debug patches to help me track this problem down.
Thank you,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
fsync log replay can change the filesystem, so it cannot be delayed until
mount -o rw,remount, and it can't be forgotten entirely. So, this patch
changes btrfs to do with reiserfs, ext3 and xfs do, which is to do the
log replay even when mounted readonly.
On a readonly device if log replay is required, the mount is aborted.
Getting all of this right had required fixing up some of the error
handling in open_ctree.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
While building large bios in writepages, btrfs may end up waiting
for other page writeback to finish if WB_SYNC_ALL is used.
While it is waiting, the bio it is building has a number of pages with the
writeback bit set and they aren't getting to the disk any time soon. This
lowers the latencies of writeback in general by sending down the bio being
built before waiting for other pages.
The bio submission code tries to limit the total number of async bios in
flight by waiting when we're over a certain number of async bios. But,
the waits are happening while writepages is building bios, and this can easily
lead to stalls and other problems for people calling wait_on_page_writeback.
The current fix is to let the congestion tests take care of waiting.
sync() and others make sure to drain the current async requests to make
sure that everything that was pending when the sync was started really get
to disk. The code would drain pending requests both before and after
submitting a new request.
But, if one of the requests is waiting for page writeback to finish,
the draining waits might block that page writeback. This changes the
draining code to only wait after submitting the bio being processed.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The extent based waiting was using more CPU, and other fixes have helped
with the unplug storm problems.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
For larger multi-device filesystems, there was logic to limit the
number of devices unplugged to just the page that was sent to our sync_page
function.
But, the code wasn't always unplugging the right device. Since this was
just an optimization, disable it for now.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
In insert_extents(), when ret==1 and last is not zero, it should
check if the current inserted item is the last item in this batching
inserts. If so, it should just break from loop. If not, 'cur =
insert_list->next' will make no sense because the list is empty now,
and 'op' will point to an unexpectable place.
There are also some trivial fixs in this patch including one comment
typo error and deleting two redundant lines.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
For a directory tree:
/mnt/subvolA/subvolB
btrfsctl -s /mnt/subvolA/subvolB /mnt
Will create a directory loop with subvolA under subvolB. This
commit uses the forward refs for each subvol and snapshot to error out
before creating the loop.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Subvols and snapshots can now be referenced from any point in the directory
tree. We need to maintain back refs for them so we can find lost
subvols.
Forward refs are added so that we know all of the subvols and
snapshots referenced anywhere in the directory tree of a single subvol. This
can be used to do recursive snapshotting (but they aren't yet) and it is
also used to detect and prevent directory loops when creating new snapshots.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Each subvolume has its own private inode number space, and so we need
to fill in different device numbers for each subvolume to avoid confusing
applications.
This commit puts a struct super_block into struct btrfs_root so it can
call set_anon_super() and get a different device number generated for
each root.
btrfs_rename is changed to prevent renames across subvols.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
In my batch delete/update/insert patch I introduced a free space leak. The
extent that we do the original search on in free_extents is never pinned, so we
always update the block saying that it has free space, but the free space never
actually gets added to the free space tree, since op->del will always be 0 and
it's never actually added to the pinned extents tree.
This patch fixes this problem by making sure we call pin_down_bytes on the
pending extent op and set op->del to the return value of pin_down_bytes so
update_block_group is called with the right value. This seems to fix the case
where we were getting ENOSPC when there was plenty of space available.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
In worker_loop(), the func should check whether it has been requested to stop
before it decides to schedule out.
Otherwise if the stop request(also the last wake_up()) sent by
btrfs_stop_workers() happens when worker_loop() running after the "while"
judgement and before schedule(), woker_loop() will schedule away and never be
woken up, which will also cause btrfs_stop_workers() wait forever.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When extent needs to be split, btrfs_mark_extent_written truncates the extent
first, then inserts a new extent and increases the reference count.
The race happens if someone else deletes the old extent before the new extent
is inserted. The fix here is increase the reference count in advance. This race
is similar to the race in btrfs_drop_extents that was recently fixed.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Seed device is a special btrfs with SEEDING super flag
set and can only be mounted in read-only mode. Seed
devices allow people to create new btrfs on top of it.
The new FS contains the same contents as the seed device,
but it can be mounted in read-write mode.
This patch does the following:
1) split code in btrfs_alloc_chunk into two parts. The first part does makes
the newly allocated chunk usable, but does not do any operation that modifies
the chunk tree. The second part does the the chunk tree modifications. This
division is for the bootstrap step of adding storage to the seed device.
2) Update device management code to handle seed device.
The basic idea is: For an FS grown from seed devices, its
seed devices are put into a list. Seed devices are
opened on demand at mounting time. If any seed device is
missing or has been changed, btrfs kernel module will
refuse to mount the FS.
3) make btrfs_find_block_group not return NULL when all
block groups are read-only.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch adds mount ro and remount support. The main
changes in patch are: adding btrfs_remount and related
helper function; splitting the transaction related code
out of close_ctree into btrfs_commit_super; updating
allocator to properly handle read only block group.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
While profiling the allocator I noticed a good amount of time was being spent in
finish_current_insert and del_pending_extents, and as the filesystem filled up
more and more time was being spent in those functions. This patch aims to try
and reduce that problem. This happens two ways
1) track if we tried to delete an extent that we are going to update or insert.
Once we get into finish_current_insert we discard any of the extents that were
marked for deletion. This saves us from doing unnecessary work almost every
time finish_current_insert runs.
2) Batch insertion/updates/deletions. Instead of doing a btrfs_search_slot for
each individual extent and doing the needed operation, we instead keep the leaf
around and see if there is anything else we can do on that leaf. On the insert
case I introduced a btrfs_insert_some_items, which will take an array of keys
with an array of data_sizes and try and squeeze in as many of those keys as
possible, and then return how many keys it was able to insert. In the update
case we search for an extent ref, update the ref and then loop through the leaf
to see if any of the other refs we are looking to update are on that leaf, and
then once we are done we release the path and search for the next ref we need to
update. And finally for the deletion we try and delete the extent+ref in pairs,
so we will try to find extent+ref pairs next to the extent we are trying to free
and free them in bulk if possible.
This along with the other cluster fix that Chris pushed out a bit ago helps make
the allocator preform more uniformly as it fills up the disk. There is still a
slight drop as we fill up the disk since we start having to stick new blocks in
odd places which results in more COW's than on a empty fs, but the drop is not
nearly as severe as it was before.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
This patch adds an additional CLONE_RANGE ioctl to clone an arbitrary
(block-aligned) file range to another file. The original CLONE ioctl
becomes a special case of cloning the entire file range. The logic is a
bit more complex now since ranges may be cloned to different offsets, and
because we may only be cloning the beginning or end of a particular extent
or checksum item.
An additional sanity check ensures the source and destination files aren't
the same (which would previously deadlock), although eventually this could
be extended to allow the duplication of file data at a different offset
within the same file.
Any extents within the destination range in the target file are dropped.
We currently do not cope with the case where a compressed inline extent
needs to be split. This will probably require decompressing the extent
into a temporary address_space, and inserting just the cloned portion as a
new compressed inline extent. For now, just return -EINVAL in this case.
Note that this never comes up in the more common case of cloning an entire
file.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When we fail to allocate a new block group, we should still do the
checks to make sure allocations try again with the minimum requested
allocation size.
This also fixes a deadlock that come from a missed down_read in
the chunk allocation failure handling.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This fixes latency problems on metadata reads by making sure they
don't go through the async submit queue, and by tuning down the amount
of readahead done during btree searches.
Also, the btrfs bdi congestion function is tuned to ignore the
number of pending async bios and checksums pending. There is additional
code that throttles new async bios now and the congestion function
doesn't need to worry about it anymore.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs_drop_extents will drop paths and search again when it needs to
force COW of higher nodes. It was using the key it found during the last
search as the offset for the next search.
But, this wasn't always correct. The key could be from before our desired
range, and because we're dropping the path, it is possible for file's items
to change while we do the search again.
The fix here is to make sure we don't search for something smaller than
the offset btrfs_drop_extents was called with.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The allocator wasn't catching all of the cases where it needed to do
extra loops because the check to enforce them wasn't happening early
enough.
When the allocator decided to increase the size of the allocation
for metadata clustering, it wasn't always setting the empty_size to
include the extra (optional) bytes. This also fixes the empty_size field
to be correct.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When btrfs unplugs, it tries to find the correct device to unplug
via search through the extent_map tree. This avoids unplugging
a device that doesn't need it, but is a waste of time for filesystems
with a small number of devices.
This patch checks the total number of devices before doing the
search.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The extent_io.c code has a #define to find and cleanup extent state leaks
on module unmount. This adds a very highly contended spinlock to a
hot path for most FS operations.
Turn it off by default. A later changeset will add a .config option
for it.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This makes sure the orig_start field in struct extent_map gets set
everywhere the extent_map structs are created or modified.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
With all the recent fixes to the delalloc locking, it is now safe
again to use invalidatepage inside the writepage code for
pages outside of i_size. This used to deadlock against some of the
code to write locked ranges of pages, but all of that has been fixed.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The loop searching for free space would exit out too soon when
metadata clustering was trying to allocate a large extent. This makes
sure a full scan of the free space is done searching for only the
minimum extent size requested by the higher layers.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Yan's fix to use the correct file offset during compressed reads used the
extent_map struct pointer after it had been freed. This saves the
fields we want for later use instead.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The decompress code doesn't take the logical offset in extent
pointer into account. If the logical offset isn't zero, data
will be decompressed into wrong pages.
The solution used here is to record the starting offset of the extent
in the file separately from the logical start of the extent_map struct.
This allows us to avoid problems inserting overlapping extents.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This adds a PageDirty check to the writeback path that locks pages
for delalloc. If a page wasn't dirty at this point, it is in the
process of being truncated away.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When metadata allocation clustering has to fall back to unclustered
allocs because large free areas could not be found, it was sometimes
substracting too much from the total bytes to allocate. This would
make it wrap below zero.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
While doing a commit, btrfs makes sure all the metadata blocks
were properly written to disk, calling wait_on_page_writeback for
each page. This writeback happens after allowing another transaction
to start, so it competes for the disk with other processes in the FS.
If the page writeback bit is still set, each wait_on_page_writeback might
trigger an unplug, even though the page might be waiting for checksumming
to finish or might be waiting for the async work queue to submit the
bio.
This trades wait_on_page_writeback for waiting on the extent writeback
bits. It won't trigger any unplugs and substantially improves performance
in a number of workloads.
This also changes the async bio submission to avoid requeueing if there
is only one device. The requeue just wastes CPU time because there are
no other devices to service.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
In comes cases the empty cluster was added twice to the total number of
bytes the allocator was trying to find.
With empty clustering on, the hint byte was sometimes outside of the
block group. Add an extra goto to find the correct block group.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When writing a compressed extent, a number of bios are created that
point to a single struct compressed_bio. At end_io time an atomic counter in
the compressed_bio struct makes sure that all of the bios have finished
before final end_io processing is done.
But when multiple bios are needed to write a compressed extent, the
counter was being incremented after the first bio was sent to submit_bio.
It is possible the bio will complete before the counter is incremented,
making the end_io handler free the compressed_bio struct before
processing is finished.
The fix is to increment the atomic counter before bio submission,
both for compressed reads and writes.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This lowers the empty cluster target for metadata allocations. The lower
target makes it easier to do allocations and still seems to perform well.
It also fixes the allocator loop to drop the empty cluster when things
start getting difficult, avoiding false enospc warnings.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The allocator uses the last allocation as a starting point for metadata
allocations, and tries to allocate in clusters of at least 256k.
If the search for a free block fails to find the expected block, this patch
forces a new cluster to be found in the free list.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When reading compressed extents, try to put pages into the page cache
for any pages covered by the compressed extent that readpages didn't already
preload.
Add an async work queue to handle transformations at delayed allocation processing
time. Right now this is just compression. The workflow is:
1) Find offsets in the file marked for delayed allocation
2) Lock the pages
3) Lock the state bits
4) Call the async delalloc code
The async delalloc code clears the state lock bits and delalloc bits. It is
important this happens before the range goes into the work queue because
otherwise it might deadlock with other work queue items that try to lock
those extent bits.
The file pages are compressed, and if the compression doesn't work the
pages are written back directly.
An ordered work queue is used to make sure the inodes are written in the same
order that pdflush or writepages sent them down.
This changes extent_write_cache_pages to let the writepage function
update the wbc nr_written count.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Btrfs uses kernel threads to create async work queues for cpu intensive
operations such as checksumming and decompression. These work well,
but they make it difficult to keep IO order intact.
A single writepages call from pdflush or fsync will turn into a number
of bios, and each bio is checksummed in parallel. Once the checksum is
computed, the bio is sent down to the disk, and since we don't control
the order in which the parallel operations happen, they might go down to
the disk in almost any order.
The code deals with this somewhat by having deep work queues for a single
kernel thread, making it very likely that a single thread will process all
the bios for a single inode.
This patch introduces an explicitly ordered work queue. As work structs
are placed into the queue they are put onto the tail of a list. They have
three callbacks:
->func (cpu intensive processing here)
->ordered_func (order sensitive processing here)
->ordered_free (free the work struct, all processing is done)
The work struct has three callbacks. The func callback does the cpu intensive
work, and when it completes the work struct is marked as done.
Every time a work struct completes, the list is checked to see if the head
is marked as done. If so the ordered_func callback is used to do the
order sensitive processing and the ordered_free callback is used to do
any cleanup. Then we loop back and check the head of the list again.
This patch also changes the checksumming code to use the ordered workqueues.
One a 4 drive array, it increases streaming writes from 280MB/s to 350MB/s.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Make sure we keep page->mapping NULL on the pages we're getting
via alloc_page. It gets set so a few of the callbacks can do the right
thing, but in general these pages don't have a mapping.
Don't try to truncate compressed inline items in btrfs_drop_extents.
The whole compressed item must be preserved.
Don't try to create multipage inline compressed items. When we try to
overwrite just the first page of the file, we would have to read in and recow
all the pages after it in the same compressed inline items. For now, only
create single page inline items.
Make sure we lock pages in the correct order during delalloc. The
search into the state tree for delalloc bytes can return bytes before
the page we already have locked.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch updates btrfs-progs for fallocate support.
fallocate is a little different in Btrfs because we need to tell the
COW system that a given preallocated extent doesn't need to be
cow'd as long as there are no snapshots of it. This leverages the
-o nodatacow checks.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch simplifies the nodatacow checker. If all references
were created after the latest snapshot, then we can avoid COW
safely. This patch also updates run_delalloc_nocow to do more
fine-grained checking.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
When dropping middle part of an extent, btrfs_drop_extents truncates
the extent at first, then inserts a bookend extent.
Since truncation and insertion can't be done atomically, there is a small
period that the bookend extent isn't in the tree. This causes problem for
functions that search the tree for file extent item. The way to fix this is
lock the range of the bookend extent before truncation.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch splits the hole insertion code out of btrfs_setattr
into btrfs_cont_expand and updates btrfs_get_extent to properly
handle the case that file extent items are not continuous.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
When compression was on, we were improperly ignoring -o nodatasum. This
reworks the logic a bit to properly honor all the flags.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The byte walk counting was awkward and error prone. This uses the
number of pages sent the higher layer to build bios.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
finish_current_insert and del_pending_extents process extent tree modifications
that build up while we are changing the extent tree. It is a confusing
bit of code that prevents recursion.
Both functions run through a list of pending operations and both funcs
add to the list of pending operations. If you have two procs in either
one of them, they can end up looping forever making more work for each other.
This patch makes them walk forward through the list of pending changes instead
of always trying to process the entire list. At transaction commit
time, we catch any changes that were left over.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch adds transaction IDs to root tree pointers.
Transaction IDs in tree pointers are compared with the
generation numbers in block headers when reading root
blocks of trees. This can detect some types of IO errors.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch removes the giant fs_info->alloc_mutex and replaces it with a bunch
of little locks.
There is now a pinned_mutex, which is used when messing with the pinned_extents
extent io tree, and the extent_ins_mutex which is used with the pending_del and
extent_ins extent io trees.
The locking for the extent tree stuff was inspired by a patch that Yan Zheng
wrote to fix a race condition, I cleaned it up some and changed the locking
around a little bit, but the idea remains the same. Basically instead of
holding the extent_ins_mutex throughout the processing of an extent on the
extent_ins or pending_del trees, we just hold it while we're searching and when
we clear the bits on those trees, and lock the extent for the duration of the
operations on the extent.
Also to keep from getting hung up waiting to lock an extent, I've added a
try_lock_extent so if we cannot lock the extent, move on to the next one in the
tree and we'll come back to that one. I have tested this heavily and it does
not appear to break anything. This has to be applied on top of my
find_free_extent redo patch.
I tested this patch on top of Yan's space reblancing code and it worked fine.
The only thing that has changed since the last version is I pulled out all my
debugging stuff, apparently I forgot to run guilt refresh before I sent the
last patch out. Thank you,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
So there is an odd case where we can possibly return -ENOSPC when there is in
fact space to be had. It only happens with Metadata writes, and happens _very_
infrequently. What has to happen is we have to allocate have allocated out of
the first logical byte on the disk, which would set last_alloc to
first_logical_byte(root, 0), so search_start == orig_search_start. We then
need to allocate for normal metadata, so BTRFS_BLOCK_GROUP_METADATA |
BTRFS_BLOCK_GROUP_DUP. We will do a block lookup for the given search_start,
block_group_bits() won't match and we'll go to choose another block group.
However because search_start matches orig_search_start we go to see if we can
allocate a chunk.
If we are in the situation that we cannot allocate a chunk, we fail and ENOSPC.
This is kind of a big flaw of the way find_free_extent works, as it along with
find_free_space loop through _all_ of the block groups, not just the ones that
we want to allocate out of. This patch completely kills find_free_space and
rolls it into find_free_extent. I've introduced a sort of state machine into
this, which will make it easier to get cache miss information out of the
allocator, and will work well with my locking changes.
The basic flow is this: We have the variable loop which is 0, meaning we are
in the hint phase. We lookup the block group for the hint, and lookup the
space_info for what we want to allocate out of. If the block group we were
pointed at by the hint either isn't of the correct type, or just doesn't have
the space we need, we set head to space_info->block_groups, so we start at the
beginning of the block groups for this particular space info, and loop through.
This is also where we add the empty_cluster to total_needed. At this point
loop is set to 1 and we just loop through all of the block groups for this
particular space_info looking for the space we need, just as find_free_space
would have done, except we only hit the block groups we want and not _all_ of
the block groups. If we come full circle we see if we can allocate a chunk.
If we cannot of course we exit with -ENOSPC and we are good. If not we start
over at space_info->block_groups and loop through again, with loop == 2. If we
come full circle and haven't found what we need then we exit with -ENOSPC.
I've been running this for a couple of days now and it seems stable, and I
haven't yet hit a -ENOSPC when there was plenty of space left.
Also I've made a groups_sem to handle the group list for the space_info. This
is part of my locking changes, but is relatively safe and seems better than
holding the space_info spinlock over that entire search time. Thanks,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
This patch improves the space balancing code to keep more sharing
of tree blocks. The only case that breaks sharing of tree blocks is
data extents get fragmented during balancing. The main changes in
this patch are:
Add a 'drop sub-tree' function. This solves the problem in old code
that BTRFS_HEADER_FLAG_WRITTEN check breaks sharing of tree block.
Remove relocation mapping tree. Relocation mappings are stored in
struct btrfs_ref_path and updated dynamically during walking up/down
the reference path. This reduces CPU usage and simplifies code.
This patch also fixes a bug. Root items for reloc trees should be
updated in btrfs_free_reloc_root.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This is a large change for adding compression on reading and writing,
both for inline and regular extents. It does some fairly large
surgery to the writeback paths.
Compression is off by default and enabled by mount -o compress. Even
when the -o compress mount option is not used, it is possible to read
compressed extents off the disk.
If compression for a given set of pages fails to make them smaller, the
file is flagged to avoid future compression attempts later.
* While finding delalloc extents, the pages are locked before being sent down
to the delalloc handler. This allows the delalloc handler to do complex things
such as cleaning the pages, marking them writeback and starting IO on their
behalf.
* Inline extents are inserted at delalloc time now. This allows us to compress
the data before inserting the inline extent, and it allows us to insert
an inline extent that spans multiple pages.
* All of the in-memory extent representations (extent_map.c, ordered-data.c etc)
are changed to record both an in-memory size and an on disk size, as well
as a flag for compression.
From a disk format point of view, the extent pointers in the file are changed
to record the on disk size of a given extent and some encoding flags.
Space in the disk format is allocated for compression encoding, as well
as encryption and a generic 'other' field. Neither the encryption or the
'other' field are currently used.
In order to limit the amount of data read for a single random read in the
file, the size of a compressed extent is limited to 128k. This is a
software only limit, the disk format supports u64 sized compressed extents.
In order to limit the ram consumed while processing extents, the uncompressed
size of a compressed extent is limited to 256k. This is a software only limit
and will be subject to tuning later.
Checksumming is still done on compressed extents, and it is done on the
uncompressed version of the data. This way additional encodings can be
layered on without having to figure out which encoding to checksum.
Compression happens at delalloc time, which is basically singled threaded because
it is usually done by a single pdflush thread. This makes it tricky to
spread the compression load across all the cpus on the box. We'll have to
look at parallel pdflush walks of dirty inodes at a later time.
Decompression is hooked into readpages and it does spread across CPUs nicely.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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>
