btrfs_block_rsv_add{, _noflush}() have similar code, so abstract that code.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
People have been reporting ENOSPC crashes in finish_ordered_io. This is because
we try to steal from the delalloc block rsv to satisfy a reservation to update
the inode. The problem with this is we don't explicitly save space for updating
the inode when doing delalloc. This is kind of a problem and we've gotten away
with this because way back when we just stole from the delalloc reserve without
any questions, and this worked out fine because generally speaking the leaf had
been modified either by the mtime update when we did the original write or
because we just updated the leaf when we inserted the file extent item, only on
rare occasions had the leaf not actually been modified, and that was still ok
because we'd just use a block or two out of the over-reservation that is
delalloc.
Then came the delayed inode stuff. This is amazing, except it wants a full
reservation for updating the inode since it may do it at some point down the
road after we've written the blocks and we have to recow everything again. This
worked out because the delayed inode stuff just stole from the global reserve,
that is until recently when I changed that because it caused other problems.
So here we are, we're doing everything right and being screwed for it. So take
an extra reservation for the inode at delalloc reservation time and carry it
through the life of the delalloc reservation. If we need it we can steal it in
the delayed inode stuff. If we have already stolen it try and do a normal
metadata reservation. If that fails try to steal from the delalloc reservation.
If _that_ fails we'll get a WARN_ON() so I can start thinking of a better way to
solve this and in the meantime we'll steal from the global reserve.
With this patch I ran xfstests 13 in a loop for a couple of hours and didn't see
any problems.
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
We all keep getting those stupid warnings from use_block_rsv when running
stress.sh, and it's because the delayed insertion stuff is being stupid. It's
not the delayed insertion stuffs fault, it's all just stupid. When marking an
inode dirty for oh say updating the time on it, we just do a
btrfs_join_transaction, which doesn't reserve any space. This is stupid because
we're going to have to have space reserve to make this change, but we do it
because it's fast because chances are we're going to call it over and over again
and it doesn't matter. Well thanks to the delayed insertion stuff this is
mostly the case, so we do actually need to make this reservation. So if
trans->bytes_reserved is 0 then try to do a normal reservation. If not return
ENOSPC which will make the btrfs_dirty_inode start a proper transaction which
will let it do the whole ENOSPC dance and reserve enough space for the delayed
insertion to steal the reservation from the transaction.
The other stupid thing we do is not reserve space for the inode when writing to
the thing. Usually this is ok since we have to update the time so we'd have
already done all this work before we get to the endio stuff, so it doesn't
matter. But this is stupid because we could write the data after the
transaction commits where we changed the mtime of the inode so we have to cow
all the way down to the inode anyway. This used to be masked by the delalloc
reservation stuff, but because we delay the update it doesn't get masked in this
case. So again the delayed insertion stuff bites us in the ass. So if our
trans->block_rsv is delalloc, just steal the reservation from the delalloc
reserve. Hopefully this won't bite us in the ass, but I've said that before.
With this patch stress.sh no longer spits out those stupid warnings (famous last
words). Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Because of the overcommit stuff I had to make it so that we committed the
transaction all the time in reserve_metadata_bytes in case we had overcommitted
because of delayed items. This was because previously we had no way of knowing
how much space was reserved for delayed items. Now that we have the
delayed_block_rsv we can check it to see if committing the transaction would get
us anywhere. This patch breaks out the committing logic into a helper function
that will check to see if committing the transaction would free enough space for
us to get anything done. With this patch xfstests 83 goes from taking 445
seconds to taking 28 seconds on my box. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
I've been hitting warnings in use_block_rsv when running the delayed insertion
stuff. It's because we will readjust global block rsv based on what is in use,
which means we could end up discarding reservations that are for the delayed
insertion stuff. So instead create a seperate block rsv for the delayed
insertion stuff. This will also make it easier to debug problems with the
delayed insertion reservations since we will know that only the delayed
insertion code touches this block_rsv. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
fs_info has now ~9kb, more than fits into one page. This will cause
mount failure when memory is too fragmented. Top space consumers are
super block structures super_copy and super_for_commit, ~2.8kb each.
Allocate them dynamically. fs_info will be ~3.5kb. (measured on x86_64)
Add a wrapper for freeing fs_info and all of it's dynamically allocated
members.
Signed-off-by: David Sterba <dsterba@suse.cz>
The tree log had two important bugs that could cause corruptions after a
crash. Sometimes we were allowing tree log blocks to be reused after
the tree log was committed but before the transaction commit was done.
This allowed a future metadata write to overwrite the tree log data. It
is fixed by adding a new variant of freeing reserved extents that always
pins them. Credit goes to Stefan Behrens and Arne Jansen for many many
hours spent tracking this bug down.
During tree log replay, we do a pass through the tree log and pin all
the extents we find. This makes sure the replay code won't go in and
use any of those blocks for new allocations during replay. The problem
is the free space cache isn't honoring these pinned extents. So the
allocator can end up handing them out, leading to all kinds of problems
during replay.
The fix here is to force any free space cache to load while we pin the
extents, and then to make sure we remove the pinned extents from the
free space rbtree.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Reported-by: Stefan Behrens <sbehrens@giantdisaster.de>
The WARN_ON under some circumstances heavily polute log and slow down
the machine. This is just a safety, as the warning should be fixed by
another patch, nevertheless, it still pops up during testing.
Signed-off-by: David Sterba <dsterba@suse.cz>
The task may fail to get free space though it is enough when multi-task
space allocation and caching space happen at the same time.
Task1 Caching Thread Task2
------------------------------------------------------------------------
find_free_extent
The space has not
be cached, and start
caching thread. And
wait for it.
cache space, if
the space is > 2MB
wake up Task1
find_free_extent
get all the space that
is cached.
try to allocate space,
but there is no space
now.
trigger BUG_ON()
The message is following:
btrfs allocation failed flags 1, wanted 4096
space_info has 1040187392 free, is not full
space_info total=1082130432, used=4096, pinned=41938944, reserved=0, may_use=40828928, readonly=0
block group 12582912 has 8388608 bytes, 0 used 8388608 pinned 0 reserved
block group has cluster?: no
0 blocks of free space at or bigger than bytes is
block group 1103101952 has 1073741824 bytes, 4096 used 33550336 pinned 0 reserved
block group has cluster?: no
0 blocks of free space at or bigger than bytes is
------------[ cut here ]------------
kernel BUG at fs/btrfs/inode.c:835!
[<ffffffffa031261b>] __extent_writepage+0x1bf/0x5ce [btrfs]
[<ffffffff810cbcb8>] ? __set_page_dirty_nobuffers+0xfe/0x108
[<ffffffffa02f8ada>] ? wait_current_trans+0x23/0xec [btrfs]
[<ffffffff810c3fbf>] ? find_get_pages_tag+0x73/0xe2
[<ffffffffa0312d12>] extent_write_cache_pages.clone.0+0x176/0x29a [btrfs]
[<ffffffffa0312e74>] extent_writepages+0x3e/0x53 [btrfs]
[<ffffffff8110ad2c>] ? do_sync_write+0xc6/0x103
[<ffffffffa0302d6e>] ? btrfs_submit_direct+0x414/0x414 [btrfs]
[<ffffffff811380fa>] ? fsnotify+0x236/0x266
[<ffffffffa02fc930>] btrfs_writepages+0x22/0x24 [btrfs]
[<ffffffff810cc215>] do_writepages+0x1c/0x25
[<ffffffff810c4958>] __filemap_fdatawrite_range+0x4e/0x50
[<ffffffff810c4982>] filemap_write_and_wait_range+0x28/0x51
[<ffffffffa0306b2e>] btrfs_sync_file+0x7d/0x198 [btrfs]
[<ffffffff8110aa26>] ? fsnotify_modify+0x5d/0x65
[<ffffffff8112d150>] vfs_fsync_range+0x18/0x21
[<ffffffff8112d170>] vfs_fsync+0x17/0x19
[<ffffffff8112d316>] do_fsync+0x29/0x3e
[<ffffffff8112d348>] sys_fsync+0xb/0xf
[<ffffffff81468352>] system_call_fastpath+0x16/0x1b
[SNIP]
RIP [<ffffffffa02fe08c>] cow_file_range+0x1c4/0x32b [btrfs]
We fix this bug by trying to allocate the space again if there are block groups
in caching.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Free space items are located in tree of tree roots, not in the extent
tree. It didn't pop up because lookup_free_space_inode() grabs the
inode all the time instead of actually searching the tree.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Mitch kept hitting a panic because he was getting ENOSPC. One of my previous
patches makes it so we are much better at not allocating new metadata chunks.
Unfortunately coupled with the overcommit patch this works us into a bit of a
problem if we are removing a bunch of space and end up chewing up all of our
space with pinned extents. We can allocate chunks fine and overflow is ok, but
the only way to reclaim this space is to commit the transaction. So if we go to
overcommit, first check and see how much pinned space we have. If we have more
than 80% of the free space chewed up with pinned extents, just commit the
transaction, this will free up enough space for our reservation and we won't
have this problem anymore. With this patch Mitch's test doesn't blow up
anymore. Thanks,
Reported-and-tested-by: Mitch Harder <mitch.harder@sabayonlinux.org>
Signed-off-by: Josef Bacik <josef@redhat.com>
Currently btrfs_block_rsv_check does 2 things, it will either refill a block
reserve like in the truncate or refill case, or it will check to see if there is
enough space in the global reserve and possibly refill it. However because of
overcommit we could be well overcommitting ourselves just to try and refill the
global reserve, when really we should just be committing the transaction. So
breack this out into btrfs_block_rsv_refill and btrfs_block_rsv_check. Refill
will try to reserve more metadata if it can and btrfs_block_rsv_check will not,
it will only tell you if the factor of the total space is still reserved.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
We started setting trans->block_rsv = NULL to allow the delayed refs flushing
stuff to use the right block_rsv and then just made
btrfs_trans_release_metadata() unconditionally use the trans block rsv. The
problem with this is we need to reserve some space in the transaction and then
migrate it to the global block rsv, so we need to be able to free that out
properly. So instead just move btrfs_trans_release_metadata() before the
delayed ref flushing and use trans->block_rsv for the freeing. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Currently we only allow a maximum of 2 megabytes of pages to be flushed at a
time. This was ok before, but now we have overcommit which will screw us in a
heartbeat if we are quickly filling the disk. So instead pick either 2
megabytes or the number of pages we need to reclaim to be safe again, which ever
is larger. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
The only way we actually reclaim delalloc space is waiting for the IO to
completely finish. Usually we kick off a bunch of IO and wait for a little bit
and hope we can make our reservation, and usually this works out pretty well.
With overcommit however we can get seriously underwater if we're filling up the
disk quickly, so we need to be able to force the delalloc shrinker to wait for
the ordered IO to finish to give us a better chance of actually reclaiming
enough space to get our reservation. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Before the only reason to commit the transaction to recover space in
reserve_metadata_bytes() was if there were enough pinned_bytes to satisfy our
reservation. But now we have the delayed inode stuff which will hold it's
reservations until we commit the transaction. So say we max out our reservation
by creating a bunch of files but don't have any pinned bytes we will ENOSPC out
early even though we could commit the transaction and get that space back. So
now just unconditionally commit the transaction since currently there is no way
to know how much metadata space is being reserved by delayed inode stuff.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
I noticed recently that my overcommit patch was causing one of my enospc tests
to fail 25% of the time with early ENOSPC. This is because my overcommit patch
was letting us go way over board, but it wasn't waiting long enough to let the
delalloc shrinker do it's job. The problem is we just start writeback and wait
a little bit hoping we flush enough, but we only free up delalloc space by
having the writes complete all the way. We do this by waiting for ordered
extents, which we do but only if we already free'd enough for the reservation,
which isn't right, we should flush ordered extents if we didn't reclaim enough
in case that will push us over the edge. With this patch I've not seen a
failure in this enospc test after running it in a loop for an hour. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Yeah yeah I know this is how we used to do it and then I changed it, but damnit
I'm changing it back. The fact is that writing out checksums will modify
metadata, which could cause us to dirty a block group we've already written out,
so we have to truncate it and all of it's checksums and re-write it which will
write new checksums which could dirty a blockg roup that has already been
written and you see where I'm going with this? This can cause unmount or really
anything that depends on a transaction to commit to take it's sweet damned time
to happen. So go back to the way it was, only this time we're specifically
setting NODATACOW because we can't go through the COW pathway anyway and we're
doing our own built-in cow'ing by truncating the free space cache. The other
new thing is once we truncate the old cache and preallocate the new space, we
don't need to do that song and dance at all for the rest of the transaction, we
can just overwrite the existing space with the new cache if the block group
changes for whatever reason, and the NODATACOW will let us do this fine. So
keep track of which transaction we last cleared our cache in and if we cleared
it in this transaction just say we're all setup and carry on. This survives
xfstests and stress.sh.
The inode cache will continue to use the normal csum infrastructure since it
only gets written once and there will be no more modifications to the fs tree in
a transaction commit.
Signed-off-by: Josef Bacik <josef@redhat.com>
My overcommit stuff can be a little racy when we're filling up the disk with
fs_mark and we overcommit into things that quickly get used up for data. So use
num_bytes to see if we have enough available space so we're less likely to
overcommit ourselves out of the ability to make reservations. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Some users have requested this and I've found I needed a way to disable cache
loading without actually clearing the cache, so introduce the no_space_cache
option. Before we check the super blocks cache generation field and if it was
populated we always turned space caching on. Now we check this and set the
space cache option on, and then parse the mount options so that if we want it
off it get's turned off. Then we check the mount option all the places we do
the caching work instead of checking the super's cache generation. This makes
things more consistent and lets us turn space caching off. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
One of the things that kills us is the fact that our ENOSPC reservations are
horribly over the top in most normal cases. There isn't too much that can be
done about this because when we are completely full we really need them to work
like this so we don't under reserve. However if there is plenty of unallocated
chunks on the disk we can use that to gauge how much we can overcommit. So this
patch adds chunk free space accounting so we always know how much unallocated
space we have. Then if we fail to make a reservation within our allocated
space, check to see if we can overcommit. In the normal flushing case (like
with delalloc metadata reservations) we'll take the free space and divide it by
2 if our metadata profile is setup for DUP or any of those, and then divide it
by 8 to make sure we don't overcommit too much. Then if we're in a non-flushing
case (we really need this reservation now!) we only limit ourselves to half of
the free space. This makes this fio test
[torrent]
filename=torrent-test
rw=randwrite
size=4g
ioengine=sync
directory=/mnt/btrfs-test
go from taking around 45 minutes to 10 seconds on my freshly formatted 3 TiB
file system. This doesn't seem to break my other enospc tests, but could really
use some more testing as this is a super scary change. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
There is a bug that may lead to early ENOSPC in our reservation code. We've
been checking against num_bytes which may be above and beyond what we want to
actually reserve, which could give us a false ENOSPC. Fix this by making sure
the unused space is above how much we want to reserve and not how much we're
trying to flush. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
I kept getting warnings from evict because we were calling
btrfs_start_transaction() with a transaction already started when doing a
balance. This is because we remove a block group which requires a transaction,
and the put the last reference on the cache inode. Instead of doing this we
need to delay the iput so it is done not within a transaction having started.
This gets rid of our warnings. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
The only thing that we need to have a trans handle for is in
reserve_metadata_bytes and thats to know how much flushing we can do. So
instead of passing it around, just check current->journal_info for a
trans_handle so we know if we can commit a transaction to try and free up space
or not. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Miao Xie
Josef Bacik
Chris Mason
David Sterba
Ilya Dryomov