The crash[1] is found by xfstests/generic/208 with "-o compress",
it's not reproduced everytime, but it does panic.

The bug is quite interesting, it's actually introduced by a recent commit
(573aecaf,
Btrfs: actually limit the size of delalloc range).

Btrfs implements delay allocation, so during writeback, we
(1) get a page A and lock it
(2) search the state tree for delalloc bytes and lock all pages within the range
(3) process the delalloc range, including find disk space and create
    ordered extent and so on.
(4) submit the page A.

It runs well in normal cases, but if we're in a racy case, eg.
buffered compressed writes and aio-dio writes,
sometimes we may fail to lock all pages in the 'delalloc' range,
in which case, we need to fall back to search the state tree again with
a smaller range limit(max_bytes = PAGE_CACHE_SIZE - offset).

The mentioned commit has a side effect, that is, in the fallback case,
we can find delalloc bytes before the index of the page we already have locked,
so we're in the case of (delalloc_end <= *start) and return with (found > 0).

This ends with not locking delalloc pages but making ->writepage still
process them, and the crash happens.

This fixes it by just thinking that we find nothing and returning to caller
as the caller knows how to deal with it properly.

[1]:
------------[ cut here ]------------
kernel BUG at mm/page-writeback.c:2170!
[...]
CPU: 2 PID: 11755 Comm: btrfs-delalloc- Tainted: G           O 3.11.0+ #8
[...]
RIP: 0010:[<ffffffff810f5093>]  [<ffffffff810f5093>] clear_page_dirty_for_io+0x1e/0x83
[...]
[ 4934.248731] Stack:
[ 4934.248731]  ffff8801477e5dc8 ffffea00049b9f00 ffff8801869f9ce8 ffffffffa02b841a
[ 4934.248731]  0000000000000000 0000000000000000 0000000000000fff 0000000000000620
[ 4934.248731]  ffff88018db59c78 ffffea0005da8d40 ffffffffa02ff860 00000001810016c0
[ 4934.248731] Call Trace:
[ 4934.248731]  [<ffffffffa02b841a>] extent_range_clear_dirty_for_io+0xcf/0xf5 [btrfs]
[ 4934.248731]  [<ffffffffa02a8889>] compress_file_range+0x1dc/0x4cb [btrfs]
[ 4934.248731]  [<ffffffff8104f7af>] ? detach_if_pending+0x22/0x4b
[ 4934.248731]  [<ffffffffa02a8bad>] async_cow_start+0x35/0x53 [btrfs]
[ 4934.248731]  [<ffffffffa02c694b>] worker_loop+0x14b/0x48c [btrfs]
[ 4934.248731]  [<ffffffffa02c6800>] ? btrfs_queue_worker+0x25c/0x25c [btrfs]
[ 4934.248731]  [<ffffffff810608f5>] kthread+0x8d/0x95
[ 4934.248731]  [<ffffffff81060868>] ? kthread_freezable_should_stop+0x43/0x43
[ 4934.248731]  [<ffffffff814fe09c>] ret_from_fork+0x7c/0xb0
[ 4934.248731]  [<ffffffff81060868>] ? kthread_freezable_should_stop+0x43/0x43
[ 4934.248731] Code: ff 85 c0 0f 94 c0 0f b6 c0 59 5b 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 48 89 fb e8 2c de 00 00 49 89 c4 48 8b 03 a8 01 75 02 <0f> 0b 4d 85 e4 74 52 49 8b 84 24 80 00 00 00 f6 40 20 01 75 44
[ 4934.248731] RIP  [<ffffffff810f5093>] clear_page_dirty_for_io+0x1e/0x83
[ 4934.248731]  RSP <ffff8801869f9c48>
[ 4934.280307] ---[ end trace 36f06d3f8750236a ]---
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

So forever we have had this thing to limit the amount of delalloc pages we'll
setup to be written out to 128mb.  This is because we have to lock all the pages
in this range, so anything above this gets a bit unweildly, and also without a
limit we'll happily allocate gigantic chunks of disk space.  Turns out our check
for this wasn't quite right, we wouldn't actually limit the chunk we wanted to
write out, we'd just stop looking for more space after we went over the limit.
So if you do a giant 20gb dd on my box with lots of ram I could get 2gig
extents.  This is fine normally, except when you go to relocate these extents
and we can't find enough space to relocate these moster extents, since we have
to be able to allocate exactly the same sized extent to move it around.  So fix
this by actually enforcing the limit.  With this patch I'm no longer seeing
giant 1.5gb extents.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

PAGE_CACHE_SIZE == PAGE_SIZE is "unsigned long" everywhere, so there's no
need to cast it to "unsigned long".
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

u64 is "unsigned long long" on all architectures now, so there's no need to
cast it when formatting it using the "ll" length modifier.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Cc: Josef Bacik <jbacik@fusionio.com>
Cc: Chris Mason <chris.mason@fusionio.com>
Signed-off-by: NSergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

make C=2 fs/btrfs/ CF=-D__CHECK_ENDIAN__

I tried to filter out the warnings for which patches have already
been sent to the mailing list, pending for inclusion in btrfs-next.

All these changes should be obviously safe.
Signed-off-by: NStefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

We want this for btrfs_extent_same. Basically readpage and friends do their
own extent locking but for the purposes of dedupe, we want to have both
files locked down across a set of readpage operations (so that we can
compare data). Introduce this variant and a flag which can be set for
extent_read_full_page() to indicate that we are already locked.

Partial credit for this patch goes to Gabriel de Perthuis <g2p.code@gmail.com>
as I have included a fix from him to the original patch which avoids a
deadlock on compressed extents.
Signed-off-by: NMark Fasheh <mfasheh@suse.de>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

There is no reason we can't just set the path to blocking and then do normal
GFP_NOFS allocations for these extent buffers.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

We can get ENOMEM trying to allocate dummy bufs for the rewind operation of the
tree mod log.  Instead of BUG_ON()'ing in this case pass up ENOMEM.  I looked
back through the callers and I'm pretty sure I got everybody who did BUG_ON(ret)
in this path.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

This patch removes the io_tree argument for extent_clear_unlock_delalloc since
we always use &BTRFS_I(inode)->io_tree, and it separates out the extent tree
operations from the page operations.  This way we just pass in the extent bits
we want to clear and then pass in the operations we want done to the pages.
This is because I'm going to fix what extent bits we clear in some cases and
rather than add a bunch of new flags we'll just use the actual extent bits we
want to clear.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

When we read several pages at once, we needn't get the extent map object
every time we deal with a page, and we can cache the extent map object.
So, we can reduce the search time of the extent map, and besides that, we
also can reduce the lock contention of the extent map tree.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

In the past, we cached the checksum value in the extent state object, so we
had to split the extent state object by the block size, or we had no space
to keep this checksum value. But it increased the lock contention of the
extent state tree.

Now we removed this limit by caching the checksum into the bio object, so
it is unnecessary to do the extent state operations by the block size, we
can do it in batches, in this way, we can reduce the lock contention of
the extent state tree.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Before applying this patch, we set the uptodate flag and unlock the extent
by the page size, it is unnecessary, we can do it in batches, it can reduce
the lock contention of the extent state tree.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Before applying this patch, we cached the csum value into the extent state
tree when reading some data from the disk, this operation increased the lock
contention of the state tree.

Now, we just store the csum value into the bio structure or other unshared
structure, so we can reduce the lock contention.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

This patch add some branch prediction hints into the end IO function
of the read page, it reduced the percentage of the branch misses from
5.5% to 4.9%.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

xfstest btrfs/276 was freaking out on slower boxes partly because fiemap was
offsetting the physical based on the extent offset.  This is perfectly fine with
uncompressed extents, however the extent offset is into the uncompressed area,
not the compressed.  So we can return a physical value that isn't at all within
the area we have allocated on disk.  Fix this by returning the start of the
extent if it is compressed no matter what the offset.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

We always just try and reserve data space when we write, but if we are out of
space but have prealloc'ed extents we should still successfully write.  This
patch will try and see if we can write to prealloc'ed space and if we can go
ahead and allow the write to continue.  With this patch we now pass xfstests
generic/274.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

This has plagued us forever and I'm so over working around it.  When we truncate
down to a non-page aligned offset we will call btrfs_truncate_page to zero out
the end of the page and write it back to disk, this will keep us from exposing
stale data if we truncate back up from that point.  The problem with this is it
requires data space to do this, and people don't really expect to get ENOSPC
from truncate() for these sort of things.  This also tends to bite the orphan
cleanup stuff too which keeps people from mounting.  To get around this we can
just move this into btrfs_cont_expand() to make sure if we are truncating up
from a non-page size aligned i_size we will zero out the rest of this page so
that we don't expose stale data.  This will give ENOSPC if you try to truncate()
up or if you try to write past the end of isize, which is much more reasonable.
This fixes xfstests generic/083 failing to mount because of the orphan cleanup
failing.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

The 'end' value must exactly cover the end of the interval, which means
one byte less than the expected block alignment, or in case of a file
smaller than one block, one byte less than the inode size.
Signed-off-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Currently there is no way to truncate partial page where the end
truncate point is not at the end of the page. This is because it was not
needed and the functionality was enough for file system truncate
operation to work properly. However more file systems now support punch
hole feature and it can benefit from mm supporting truncating page just
up to the certain point.

Specifically, with this functionality truncate_inode_pages_range() can
be changed so it supports truncating partial page at the end of the
range (currently it will BUG_ON() if 'end' is not at the end of the
page).

This commit changes the invalidatepage() address space operation
prototype to accept range to be invalidated and update all the instances
for it.

We also change the block_invalidatepage() in the same way and actually
make a use of the new length argument implementing range invalidation.

Actual file system implementations will follow except the file systems
where the changes are really simple and should not change the behaviour
in any way .Implementation for truncate_page_range() which will be able
to accept page unaligned ranges will follow as well.
Signed-off-by: NLukas Czerner <lczerner@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>

Btrfs has been pointer tagging bi_private and using bi_bdev
to store the stripe index and mirror number of failed IOs.

As bios bubble back up through the call chain, we use these
to decide if and how to retry our IOs.  They are also used
to count IO failures on a per device basis.

Recently a bio tracepoint was added lead to crashes because
we were abusing bi_bdev.

This commit adds a btrfs bioset, and creates explicit fields
for the mirror number and stripe index.  The plan is to
extend this structure for all of the fields currently in
struct btrfs_bio, which will mean one less kmalloc in
our IO path.
Signed-off-by: NChris Mason <chris.mason@fusionio.com>
Reported-by: NTejun Heo <tj@kernel.org>

end_bio_extent_readpage computes whole_page based on bv_offset and
bv_len, without taking into account that blk_update_request may modify
them when some of the blocks to be read into a page produce a read
error.  This would cause the read to unlock only part of the file
range associated with the page, which would in turn leave the entire
page locked, which would not only keep the process blocked instead of
returning -EIO to it, but also prevent any further access to the file.

It turns out that btrfs always issues whole-page reads and writes.
The special handling of non-whole_page appears to be a mistake or a
left-over from a time when this wasn't the case.  Indeed,
end_bio_extent_writepage distinguished between whole_page and
non-whole_page writes but behaved identically in both cases!

I've replaced the whole_page computations with warnings, just to be
sure that we're not issuing partial page reads or writes.  The
warnings should probably just go away some time.
Signed-off-by: NAlexandre Oliva <oliva@gnu.org>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

lock_extent/unlock_extent expect an exclusive end.
Tested-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Signed-off-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

It's unused since 0b32f4bb.
Signed-off-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Big patch, but all it does is add statics to functions which
are in fact static, then remove the associated dead-code fallout.

removed functions:

btrfs_iref_to_path()
__btrfs_lookup_delayed_deletion_item()
__btrfs_search_delayed_insertion_item()
__btrfs_search_delayed_deletion_item()
find_eb_for_page()
btrfs_find_block_group()
range_straddles_pages()
extent_range_uptodate()
btrfs_file_extent_length()
btrfs_scrub_cancel_devid()
btrfs_start_transaction_lflush()

btrfs_print_tree() is left because it is used for debugging.
btrfs_start_transaction_lflush() and btrfs_reada_detach() are
left for symmetry.

ulist.c functions are left, another patch will take care of those.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Clean up the leak debugging in extent_io.c by moving
the debug code into functions.  This also removes the
list_heads used for debugging from the extent_buffer
and extent_state structures when debug is not enabled.

Since we need a global debug config to do that last
part, implement CONFIG_BTRFS_DEBUG to accommodate.

Thanks to Dave Sterba for the Kconfig bit.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

We can just look up the extent_buffers for the range and free stuff that way.
This makes the cleanup a bit cleaner and we can make sure to evict the
extent_buffers pretty quickly by marking them as stale.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

We need to tag metadata io with REQ_META to avoid priority inversion when using
io throttling cqroups.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

It is very likely that there are several blocks in bio, it is very
inefficient if we get their csums one by one. This patch improves
this problem by getting the csums in batch.

According to the result of the following test, the execute time of
__btrfs_lookup_bio_sums() is down by ~28%(300us -> 217us).

 # dd if=<mnt>/file of=/dev/null bs=1M count=1024
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

set_extent_bit()'s (u64 *failed_start) expects NULL not 0.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Btrfs uses page_mkwrite to ensure stable pages during
crc calculations and mmap workloads.  We call clear_page_dirty_for_io
before we do any crcs, and this forces any application with the file
mapped to wait for the crc to finish before it is allowed to change
the file.

With compression on, the clear_page_dirty_for_io step is happening after
we've compressed the pages.  This means the applications might be
changing the pages while we are compressing them, and some of those
modifications might not hit the disk.

This commit adds the clear_page_dirty_for_io before compression starts
and makes sure to redirty the page if we have to fallback to
uncompressed IO as well.
Signed-off-by: NChris Mason <chris.mason@fusionio.com>
Reported-by: NAlexandre Oliva <oliva@gnu.org>
cc: stable@vger.kernel.org

Just a little convenience macro - main reason to add it now is preparing
for immutable bio vecs, it'll reduce the size of the patch that puts
bi_sector/bi_size/bi_idx into a struct bvec_iter.
Signed-off-by: NKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Lars Ellenberg <drbd-dev@lists.linbit.com>
CC: Jiri Kosina <jkosina@suse.cz>
CC: Alasdair Kergon <agk@redhat.com>
CC: dm-devel@redhat.com
CC: Neil Brown <neilb@suse.de>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
CC: linux-s390@vger.kernel.org
CC: Chris Mason <chris.mason@fusionio.com>
CC: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: NSteven Whitehouse <swhiteho@redhat.com>

We want to avoid module.h where posible, since it in turn includes
nearly all of header space.  This means removing it where it is not
required, and using export.h where we are only exporting symbols via
EXPORT_SYMBOL and friends.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

The nodesize is capped at 64k and there are enough pages preallocated in
extent_buffer::inline_pages. The fallback to kmalloc never happened
because even on the smallest page size considered (4k) inline_pages
covered the needs.
Signed-off-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Though most of the btrfs codes are using ALIGN macro for page alignment,
there are still some codes using open-coded alignment like the
following:
------
        u64 mask = ((u64)root->stripesize - 1);
        u64 ret = (val + mask) & ~mask;
------
Or even hidden one:
------
        num_bytes = (end - start + blocksize) & ~(blocksize - 1);
------

Sometimes these open-coded alignment is not so easy to understand for
newbie like me.

This commit changes the open-coded alignment to the ALIGN macro for a
better readability.

Also there is a previous patch from David Sterba with similar changes,
but the patch is for 3.2 kernel and seems not merged.
http://www.spinics.net/lists/linux-btrfs/msg12747.html

Cc: David Sterba <dave@jikos.cz>
Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Nobody uses these io tree ops anymore so just remove them and clean up the code
a bit.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

->dirty_metadata_bytes is accessed very frequently, so use percpu
counter instead of the u64 variant to reduce the contention of
the lock.

This patch also fixed the problem that we access it without
lock protection in __btrfs_btree_balance_dirty(), which may
cause we skip the dirty pages flush.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Use wrapper page_offset to get byte-offset into filesystem object for page.
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>