Because btrfs cow's we can end up with extent buffers that are no longer
necessary just sitting around in memory.  So instead of evicting these pages, we
could end up evicting things we actually care about.  Thus we have
free_extent_buffer_stale for use when we are freeing tree blocks.  This will
make it so that the ref for the eb being in the radix tree is dropped as soon as
possible and then is freed when the refcount hits 0 instead of waiting to be
released by releasepage.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

We have been passing nothing but (u64)-1 to find_free_extent for search_end in
all of the callers, so it's completely useless, and we've always been passing 0
in as search_start, so just remove them as function arguments and move
search_start into find_free_extent.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

This is a relic from before we had the disk space cache and it was to make
bootup times when you had btrfs as root not be so damned slow.  Now that we have
the disk space cache this isn't a problem anymore and really having this code
casues uneeded fragmentation and complexity, so just remove it.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

The enospc tracing code added some interesting uses of
u64 pointer casts.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

When doing IO with large amounts of data fragmentation, the global block
reserve calulations are too low.  This increases them to avoid
ENOSPC crashes.
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

When overcommitting, we should check the sum of pinned space and
bytes for delayed item.
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>

A user reported a bug of btrfs's trim, that is we will trim 0 bytes
after a device delete.

The reproducer:

$ mkfs.btrfs disk1
$ mkfs.btrfs disk2
$ mount disk1 /mnt
$ fstrim -v /mnt
$ btrfs device add disk2 /mnt
$ btrfs device del disk1 /mnt
$ fstrim -v /mnt

This is because after we delete the device, the block group may start from
a non-zero place, which will confuse trim to discard nothing.
Reported-by: NLutz Euler <lutz.euler@freenet.de>
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>

When we did sysbench test for inline files, enospc error happened easily though
there was lots of free disk space which could be allocated for new chunks.

Reproduce steps:
 # mkfs.btrfs -b $((2 * 1024 * 1024 * 1024)) <test partition>
 # mount <test partition> /mnt
 # ulimit -n 102400
 # cd /mnt
 # sysbench --num-threads=1 --test=fileio --file-num=81920 \
 > --file-total-size=80M --file-block-size=1K --file-io-mode=sync \
 > --file-test-mode=seqwr prepare
 # sysbench --num-threads=1 --test=fileio --file-num=81920 \
 > --file-total-size=80M --file-block-size=1K --file-io-mode=sync \
 > --file-test-mode=seqwr run
 <soon later, BUG_ON() was triggered by enospc error>

The reason of this bug is:
Now, we can reserve space which is larger than the free space in the chunks if
we have enough free disk space which can be used for new chunks. By this way,
the space allocator should allocate a new chunk by force if there is no free
space in the free space cache. But there are two wrong checks which break this
operation.

One is
	if (ret == -ENOSPC && num_bytes > min_alloc_size)
in btrfs_reserve_extent(), it is wrong, we should try to allocate a new chunk
even we fail to allocate free space by minimum allocable size.

The other is
	if (space_info->force_alloc)
		force = space_info->force_alloc;
in do_chunk_alloc(). It makes the allocator ignore CHUNK_ALLOC_FORCE If someone
sets ->force_alloc to CHUNK_ALLOC_LIMITED, and makes the enospc error happen.

Fix these two wrong checks. Especially the second one, we fix it by changing
the value of CHUNK_ALLOC_LIMITED and CHUNK_ALLOC_FORCE, and make
CHUNK_ALLOC_FORCE greater than CHUNK_ALLOC_LIMITED since CHUNK_ALLOC_FORCE has
higher priority. And if the value which is passed in by the caller is greater
than ->force_alloc, use the passed value.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

system chunks by default are very small.  This makes them slightly
larger and also fixes the conditional checks to make sure we don't
allocate a billion of them at once.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

I was using i_mutex for this, but we're getting bogus lockdep warnings by doing
that and theres no real way to get rid of those, so just stop using i_mutex to
protect delalloc metadata reservations and use a delalloc mutex instead.  This
shouldn't be contended often at all, only if you are writing and mmap writing to
the file at the same time.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

This in addition to a script in my btrfs-tracing tree will help track down space
leaks when we're getting space left over in block groups on umount.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

I used these tracepoints when figuring out what the cluster stuff was doing, so
add them to mainline in case we need to profile this stuff again.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

Profile changing is done by launching a balance with
BTRFS_BALANCE_CONVERT bits set and target fields of respective
btrfs_balance_args structs initialized.  Profile reducing code in this
case will pick restriper's target profile if it's available instead of
doing a blind reduce.  If target profile is not yet available it goes
back to a plain reduce.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

Every caller of do_chunk_alloc() feeds it the reduced allocation
profile, so stop trying to reduce it one more time.  Instead check the
validity of the passed profile.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

Currently when new chunks are created respective avail_alloc_bits field
is updated to reflect profiles of all chunks present in the system.
However when chunks are removed profile bits are never cleared.

This patch clears profile bit of respective avail_alloc_bits field when
the last chunk with that profile is removed.  Restriper needs this to
properly operate when "downgrading".
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

Right now on-disk BTRFS_BLOCK_GROUP_* profile bits are used for
avail_{data,metadata,system}_alloc_bits fields, which gather info about
available allocation profiles in the FS.  When chunk is created or read
from disk, its profile is OR'ed with the corresponding avail_alloc_bits
field.  Since SINGLE is denoted by 0 in the on-disk format, currently
there is no way to tell when such chunks become avaialble.  Restriper
needs that information, so add a separate bit for SINGLE profile.

This bit is going to be in-memory only, it should never be written out
to disk, so it's not a disk format change.  However to avoid remappings
in future, reserve corresponding on-disk bit.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

Chunk's type and profile are encoded in u64 flags field.  Introduce
masks to easily access them.  Also fix the type of BTRFS_BLOCK_GROUP_*
constants, it should be ULL.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

{data,metadata,system}_alloc_profile fields have been unused for a long
time now.  Get rid of them.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

A bug was triggered while using seed device:

    # mkfs.btrfs /dev/loop1
    # btrfstune -S 1 /dev/loop1
    # mount -o /dev/loop1 /mnt
    # btrfs dev add /dev/loop2 /mnt

btrfs: block rsv returned -28
------------[ cut here ]------------
WARNING: at fs/btrfs/extent-tree.c:5969 btrfs_alloc_free_block+0x166/0x396 [btrfs]()
...
Call Trace:
...
[<f7b7c31c>] btrfs_cow_block+0x101/0x147 [btrfs]
[<f7b7eaa6>] btrfs_search_slot+0x1b8/0x55f [btrfs]
[<f7b7f844>] btrfs_insert_empty_items+0x42/0x7f [btrfs]
[<f7b7f8c1>] btrfs_insert_item+0x40/0x7e [btrfs]
[<f7b8ac02>] btrfs_make_block_group+0x243/0x2aa [btrfs]
[<f7bb3f53>] __btrfs_alloc_chunk+0x672/0x70e [btrfs]
[<f7bb41ff>] init_first_rw_device+0x77/0x13c [btrfs]
[<f7bb5a62>] btrfs_init_new_device+0x664/0x9fd [btrfs]
[<f7bbb65a>] btrfs_ioctl+0x694/0xdbe [btrfs]
[<c04f55f7>] do_vfs_ioctl+0x496/0x4cc
[<c04f5660>] sys_ioctl+0x33/0x4f
[<c07b9edf>] sysenter_do_call+0x12/0x38
---[ end trace 906adac595facc7d ]---

Since seed device is readonly, there's no usable space in the filesystem.
Afterwards we add a sprout device to it, and the kernel creates a METADATA
block group and a SYSTEM block group where comes free space we can reserve,
but we still get revervation failure because the global block_rsv hasn't
been updated accordingly.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>

Some functions never use the transaction handle passed to them.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>

We store the allocation start and length twice in ins, once right
after the other, but with intervening calls that may prevent the
duplicate from being optimized out by the compiler.  Remove one of the
assignments.
Signed-off-by: NAlexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Since the clustered allocation may be taking extents from a different
block group, there's no point in spin-locking and testing the current
block group free space before attempting to allocate space from a
cluster, even more so when we might refrain from even trying the
cluster in the current block group because, after the cluster was set
up, not enough free space remained.  Furthermore, cluster creation
attempts fail fast when the block group doesn't have enough free
space, so the test was completely superfluous.

I've move the free space test past the cluster allocation attempt,
where it is more useful, and arranged for a cluster in the current
block group to be released before trying an unclustered allocation,
when we reach the LOOP_NO_EMPTY_SIZE stage, so that the free space in
the cluster stands a chance of being combined with additional free
space in the block group so as to succeed in the allocation attempt.
Signed-off-by: NAlexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

The chunk allocation code has tried to keep a pretty tight lid on creating new
metadata chunks.  This is partially because in the past the reservation
code didn't give us an accurate idea of how much space was being used.

The new code is much more accurate, so we're able to get rid of some of these
checks.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Btrfs tries to batch extent allocation tree changes to improve performance
and reduce metadata trashing.  But it doesn't allocate new metadata chunks
while it is doing allocations for the extent allocation tree.

This commit changes the delayed refence code to do chunk allocations if we're
getting low on room.  It prevents crashes and improves performance.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Now that we may be holding back delayed refs for a limited period, we
might end up having no runnable delayed refs. Without this commit, we'd
do busy waiting in that thread until another (runnable) ref arives.
Instead, we're detecting this situation and use a waitqueue, such that
we only try to run more refs after
	a) another runnable ref was added  or
	b) delayed refs are no longer held back
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

When processing a delayed ref, first check if there are still old refs in
the process of being added. If so, put this ref back to the tree. To avoid
looping on this ref, choose a newer one in the next loop.
btrfs_find_ref_cluster has to take care of that.
Signed-off-by: NArne Jansen <sensille@gmx.net>
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

Add a for_cow parameter to add_delayed_*_ref and pass the appropriate value
from every call site. The for_cow parameter will later on be used to
determine if a ref will change anything with respect to qgroups.

Delayed refs coming from relocation are always counted as for_cow, as they
don't change subvol quota.

Also pass in the fs_info for later use.

btrfs_find_all_roots() will use this as an optimization, as changes that are
for_cow will not change anything with respect to which root points to a
certain leaf. Thus, we don't need to add the current sequence number to
those delayed refs.
Signed-off-by: NArne Jansen <sensille@gmx.net>
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>

A user reported a problem booting into a new kernel with the old format inodes.
He was panicing in cow_file_range while writing out the inode cache.  This is
because if the block group is not cached we'll just skip writing out the cache,
however if it gets dirtied again in the same transaction and it finished caching
we'd go ahead and write it out, but since we set cache_generation to the transid
we think we've already truncated it and will just carry on, running into
cow_file_range and blowing up.  We need to make sure we only set
cache_generation if we've done the truncate.  The user tested this patch and
verified that the panic no longer occured.  Thanks,
Reported-and-Tested-by: NKlaus Bitto <klaus.bitto@gmail.com>
Signed-off-by: NJosef Bacik <josef@redhat.com>

Running xfstests 269 with some tracing my scripts kept spitting out errors about
releasing bytes that we didn't actually have reserved.  This took me down a huge
rabbit hole and it turns out the way we deal with reserved_extents is wrong,
we need to only be setting it if the reservation succeeds, otherwise the free()
method will come in and unreserve space that isn't actually reserved yet, which
can lead to other warnings and such.  The math was all working out right in the
end, but it caused all sorts of other issues in addition to making my scripts
yell and scream and generally make it impossible for me to track down the
original issue I was looking for.  The other problem is with our error handling
in the reservation code.  There are two cases that we need to deal with

1) We raced with free.  In this case free won't free anything because csum_bytes
is modified before we dro the lock in our reservation path, so free rightly
doesn't release any space because the reservation code may be depending on that
reservation.  However if we fail, we need the reservation side to do the free at
that point since that space is no longer in use.  So as it stands the code was
doing this fine and it worked out, except in case #2

2) We don't race with free.  Nobody comes in and changes anything, and our
reservation fails.  In this case we didn't reserve anything anyway and we just
need to clean up csum_bytes but not free anything.  So we keep track of
csum_bytes before we drop the lock and if it hasn't changed we know we can just
decrement csum_bytes and carry on.

Because of the case where we can race with free()'s since we have to drop our
spin_lock to do the reservation, I'm going to serialize all reservations with
the i_mutex.  We already get this for free in the heavy use paths, truncate and
file write all hold the i_mutex, just needed to add it to page_mkwrite and
various ioctl/balance things.  With this patch my space leak scripts no longer
scream bloody murder.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

When we find an existing cluster, we switch to its block group as the
current block group, possibly skipping multiple blocks in the process.
Furthermore, under heavy contention, multiple threads may fail to
allocate from a cluster and then release just-created clusters just to
proceed to create new ones in a different block group.

This patch tries to allocate from an existing cluster regardless of its
block group, and doesn't switch to that group, instead proceeding to
try to allocate a cluster from the group it was iterating before the
attempt.
Signed-off-by: NAlexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

If we reach LOOP_NO_EMPTY_SIZE, we won't even try to use a cluster that
others might have set up.  Odds are that there won't be one, but if
someone else succeeded in setting it up, we might as well use it, even
if we don't try to set up a cluster again.
Signed-off-by: NAlexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

If we don't have a cluster, don't bother trying to allocate from it,
jumping right away to the attempt to allocate a new cluster.
Signed-off-by: NAlexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

We test whether a block group has enough free space to hold the
requested block, but when we're doing clustered allocation, we can
save some cycles by testing whether it has enough room for the cluster
upfront, otherwise we end up attempting to set up a cluster and
failing.  Only in the NO_EMPTY_SIZE loop do we attempt an unclustered
allocation, and by then we'll have zeroed the cluster size, so this
patch won't stop us from using the block group as a last resort.
Signed-off-by: NAlexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Instead of starting at zero (offset is always zero), request a cluster
starting at search_start, that denotes the beginning of the current
block group.
Signed-off-by: NAlexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

When I ran the xfstests, I found the test tasks was blocked on meta-data
reservation.

By debugging, I found the reason of this bug:
   start transaction
        |
	v
   reserve meta-data space
	|
	v
   flush delay allocation -> iput inode -> evict inode
	^					|
	|					v
   wait for delay allocation flush <- reserve meta-data space

And besides that, the flush on evicting inode will block the thread, which
is reclaiming the memory, and make oom happen easily.

Fix this bug by skipping the flush step when evicting inode.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>

We've been hitting panics when running xfstest 13 in a loop for long periods of
time.  And actually this problem has always existed so we've been hitting these
things randomly for a while.  Basically what happens is we get a thread coming
into the allocator and reading the space cache off of disk and adding the
entries to the free space cache as we go.  Then we get another thread that comes
in and tries to allocate from that block group.  Since block_group->cached !=
BTRFS_CACHE_NO it goes ahead and tries to do the allocation.  We do this because
if we're doing the old slow way of caching we don't want to hold people up and
wait for everything to finish.  The problem with this is we could end up
discarding the space cache at some arbitrary point in the future, which means we
could very well end up allocating space that is either bad, or when the real
caching happens it could end up thinking the space isn't in use when it really
is and cause all sorts of other problems.

The solution is to add a new flag to indicate we are loading the free space
cache from disk, and always try to cache the block group if cache->cached !=
BTRFS_CACHE_FINISHED.  That way if we are loading the space cache anybody else
who tries to allocate from the block group will have to wait until it's finished
to make sure it completes successfully.  Thanks,
Signed-off-by: NJosef Bacik <josef@redhat.com>

btrfs_block_rsv_add{, _noflush}() have similar code, so abstract that code.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NChris 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: NJosef Bacik <josef@redhat.com>
Signed-off-by: NChris 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: NJosef Bacik <josef@redhat.com>
Signed-off-by: NChris 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: NJosef Bacik <josef@redhat.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>