The cleaner thread usually takes care of delayed iputs, with the
exception of the btrfs_end_transaction_throttle path.  Delaying iputs
means we are potentially delaying the eviction of an inode and it's
respective space.  The cleaner thread only gets woken up every 30
seconds, or when we require space.  If there are a lot of inodes that
need to be deleted we could induce a serious amount of latency while we
wait for these inodes to be evicted.  So instead wakeup the cleaner if
it's not already awake to process any new delayed iputs we add to the
list.  If we suddenly need space we will less likely be backed up
behind a bunch of inodes that are waiting to be deleted, and we could
possibly free space before we need to get into the flushing logic which
will save us some latency.
Reviewed-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This reverts commit e73e81b6.

This patch causes a few problems:

- adds latency to btrfs_finish_ordered_io
- as btrfs_finish_ordered_io is used for free space cache, generating
  more work from btrfs_btree_balance_dirty_nodelay could end up in the
  same workque, effectively deadlocking

12260 kworker/u96:16+btrfs-freespace-write D
[<0>] balance_dirty_pages+0x6e6/0x7ad
[<0>] balance_dirty_pages_ratelimited+0x6bb/0xa90
[<0>] btrfs_finish_ordered_io+0x3da/0x770
[<0>] normal_work_helper+0x1c5/0x5a0
[<0>] process_one_work+0x1ee/0x5a0
[<0>] worker_thread+0x46/0x3d0
[<0>] kthread+0xf5/0x130
[<0>] ret_from_fork+0x24/0x30
[<0>] 0xffffffffffffffff

Transaction commit will wait on the freespace cache:

838 btrfs-transacti D
[<0>] btrfs_start_ordered_extent+0x154/0x1e0
[<0>] btrfs_wait_ordered_range+0xbd/0x110
[<0>] __btrfs_wait_cache_io+0x49/0x1a0
[<0>] btrfs_write_dirty_block_groups+0x10b/0x3b0
[<0>] commit_cowonly_roots+0x215/0x2b0
[<0>] btrfs_commit_transaction+0x37e/0x910
[<0>] transaction_kthread+0x14d/0x180
[<0>] kthread+0xf5/0x130
[<0>] ret_from_fork+0x24/0x30
[<0>] 0xffffffffffffffff

And then writepages ends up waiting on transaction commit:

9520 kworker/u96:13+flush-btrfs-1 D
[<0>] wait_current_trans+0xac/0xe0
[<0>] start_transaction+0x21b/0x4b0
[<0>] cow_file_range_inline+0x10b/0x6b0
[<0>] cow_file_range.isra.69+0x329/0x4a0
[<0>] run_delalloc_range+0x105/0x3c0
[<0>] writepage_delalloc+0x119/0x180
[<0>] __extent_writepage+0x10c/0x390
[<0>] extent_write_cache_pages+0x26f/0x3d0
[<0>] extent_writepages+0x4f/0x80
[<0>] do_writepages+0x17/0x60
[<0>] __writeback_single_inode+0x59/0x690
[<0>] writeback_sb_inodes+0x291/0x4e0
[<0>] __writeback_inodes_wb+0x87/0xb0
[<0>] wb_writeback+0x3bb/0x500
[<0>] wb_workfn+0x40d/0x610
[<0>] process_one_work+0x1ee/0x5a0
[<0>] worker_thread+0x1e0/0x3d0
[<0>] kthread+0xf5/0x130
[<0>] ret_from_fork+0x24/0x30
[<0>] 0xffffffffffffffff

Eventually, we have every process in the system waiting on
balance_dirty_pages(), and nobody is able to make progress on page
writeback.

The original patch tried to fix an OOM condition, that happened on 4.4 but no
success reproducing that on later kernels (4.19 and 4.20). This is more likely
a problem in OOM itself.

Link: https://lore.kernel.org/linux-btrfs/20180528054821.9092-1-ethanlien@synology.com/Reported-by: NChris Mason <clm@fb.com>
CC: stable@vger.kernel.org # 4.18+
CC: ethanlien <ethanlien@synology.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The typos accumulate over time so once in a while time they get fixed in
a large patch.
Signed-off-by: NAndrea Gelmini <andrea.gelmini@gelma.net>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

In the error handling block, err holds the return value of either
btrfs_del_root_ref() or btrfs_del_inode_ref() but it hasn't been checked
since it's introduction with commit fe66a05a (Btrfs: improve error
handling for btrfs_insert_dir_item callers) in 2012.

If the error handling in the error handling fails, there's not much left
to do and the abort either happened earlier in the callees or is
necessary here.

So if one of btrfs_del_root_ref() or btrfs_del_inode_ref() failed, abort
the transaction, but still return the original code of the failure
stored in 'ret' as this will be reported to the user.
Signed-off-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We have a bunch of magic to make sure we're throttling delayed refs when
truncating a file.  Now that we have a delayed refs rsv and a mechanism
for refilling that reserve simply use that instead of all of this magic.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Now with the delayed_refs_rsv we can now know exactly how much pending
delayed refs space we need.  This means we can drastically simplify
btrfs_check_space_for_delayed_refs by simply checking how much space we
have reserved for the global rsv (which acts as a spill over buffer) and
the delayed refs rsv.  If our total size is beyond that amount then we
know it's time to commit the transaction and stop any more delayed refs
from being generated.

With the introduction of dealyed_refs_rsv infrastructure, namely
btrfs_update_delayed_refs_rsv we now know exactly how much pending
delayed refs space is required.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When using a 'var & (PAGE_SIZE - 1)' construct one is checking for a page
alignment and thus should use the PAGE_ALIGNED() macro instead of
open-coding it.

Convert all open-coded occurrences of PAGE_ALIGNED().
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Constructs like 'var & (PAGE_SIZE - 1)' or 'var & ~PAGE_MASK' can denote an
offset into a page.

So replace them by the offset_in_page() macro instead of open-coding it if
they're not used as an alignment check.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Running btrfs/124 in a loop hung up on me sporadically with the
following call trace:

	btrfs           D    0  5760   5324 0x00000000
	Call Trace:
	 ? __schedule+0x243/0x800
	 schedule+0x33/0x90
	 btrfs_start_ordered_extent+0x10c/0x1b0 [btrfs]
	 ? wait_woken+0xa0/0xa0
	 btrfs_wait_ordered_range+0xbb/0x100 [btrfs]
	 btrfs_relocate_block_group+0x1ff/0x230 [btrfs]
	 btrfs_relocate_chunk+0x49/0x100 [btrfs]
	 btrfs_balance+0xbeb/0x1740 [btrfs]
	 btrfs_ioctl_balance+0x2ee/0x380 [btrfs]
	 btrfs_ioctl+0x1691/0x3110 [btrfs]
	 ? lockdep_hardirqs_on+0xed/0x180
	 ? __handle_mm_fault+0x8e7/0xfb0
	 ? _raw_spin_unlock+0x24/0x30
	 ? __handle_mm_fault+0x8e7/0xfb0
	 ? do_vfs_ioctl+0xa5/0x6e0
	 ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
	 do_vfs_ioctl+0xa5/0x6e0
	 ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe
	 ksys_ioctl+0x3a/0x70
	 __x64_sys_ioctl+0x16/0x20
	 do_syscall_64+0x60/0x1b0
	 entry_SYSCALL_64_after_hwframe+0x49/0xbe

This happens because during page writeback it's valid for
writepage_delalloc to instantiate a delalloc range which doesn't belong
to the page currently being written back.

The reason this case is valid is due to find_lock_delalloc_range
returning any available range after the passed delalloc_start and
ignoring whether the page under writeback is within that range.

In turn ordered extents (OE) are always created for the returned range
from find_lock_delalloc_range. If, however, a failure occurs while OE
are being created then the clean up code in btrfs_cleanup_ordered_extents
will be called.

Unfortunately the code in btrfs_cleanup_ordered_extents doesn't consider
the case of such 'foreign' range being processed and instead it always
assumes that the range OE are created for belongs to the page. This
leads to the first page of such foregin range to not be cleaned up since
it's deliberately missed and skipped by the current cleaning up code.

Fix this by correctly checking whether the current page belongs to the
range being instantiated and if so adjsut the range parameters passed
for cleaning up. If it doesn't, then just clean the whole OE range
directly.

Fixes: 52427260 ("btrfs: Handle delalloc error correctly to avoid ordered extent hang")
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The test case btrfs/001 with inode_cache mount option will encounter the
following warning:

  WARNING: CPU: 1 PID: 23700 at fs/btrfs/inode.c:956 cow_file_range.isra.19+0x32b/0x430 [btrfs]
  CPU: 1 PID: 23700 Comm: btrfs Kdump: loaded Tainted: G        W  O      4.20.0-rc4-custom+ #30
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:cow_file_range.isra.19+0x32b/0x430 [btrfs]
  Call Trace:
   ? free_extent_buffer+0x46/0x90 [btrfs]
   run_delalloc_nocow+0x455/0x900 [btrfs]
   btrfs_run_delalloc_range+0x1a7/0x360 [btrfs]
   writepage_delalloc+0xf9/0x150 [btrfs]
   __extent_writepage+0x125/0x3e0 [btrfs]
   extent_write_cache_pages+0x1b6/0x3e0 [btrfs]
   ? __wake_up_common_lock+0x63/0xc0
   extent_writepages+0x50/0x80 [btrfs]
   do_writepages+0x41/0xd0
   ? __filemap_fdatawrite_range+0x9e/0xf0
   __filemap_fdatawrite_range+0xbe/0xf0
   btrfs_fdatawrite_range+0x1b/0x50 [btrfs]
   __btrfs_write_out_cache+0x42c/0x480 [btrfs]
   btrfs_write_out_ino_cache+0x84/0xd0 [btrfs]
   btrfs_save_ino_cache+0x551/0x660 [btrfs]
   commit_fs_roots+0xc5/0x190 [btrfs]
   btrfs_commit_transaction+0x2bf/0x8d0 [btrfs]
   btrfs_mksubvol+0x48d/0x4d0 [btrfs]
   btrfs_ioctl_snap_create_transid+0x170/0x180 [btrfs]
   btrfs_ioctl_snap_create_v2+0x124/0x180 [btrfs]
   btrfs_ioctl+0x123f/0x3030 [btrfs]

The file extent generation of the free space inode is equal to the last
snapshot of the file root, so the inode will be passed to cow_file_rage.
But the inode was created and its extents were preallocated in
btrfs_save_ino_cache, there are no cow copies on disk.

The preallocated extent is not yet in the extent tree, and
btrfs_cross_ref_exist will ignore the -ENOENT returned by
check_committed_ref, so we can directly write the inode to the disk.

Fixes: 78d4295b ("btrfs: lift some btrfs_cross_ref_exist checks in nocow path")
CC: stable@vger.kernel.org # 4.18+
Reviewed-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NLu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The log tree has a long standing problem that when a file is fsync'ed we
only check for new ancestors, created in the current transaction, by
following only the hard link for which the fsync was issued. We follow the
ancestors using the VFS' dget_parent() API. This means that if we create a
new link for a file in a directory that is new (or in an any other new
ancestor directory) and then fsync the file using an old hard link, we end
up not logging the new ancestor, and on log replay that new hard link and
ancestor do not exist. In some cases, involving renames, the file will not
exist at all.

Example:

  mkfs.btrfs -f /dev/sdb
  mount /dev/sdb /mnt

  mkdir /mnt/A
  touch /mnt/foo
  ln /mnt/foo /mnt/A/bar
  xfs_io -c fsync /mnt/foo

  <power failure>

In this example after log replay only the hard link named 'foo' exists
and directory A does not exist, which is unexpected. In other major linux
filesystems, such as ext4, xfs and f2fs for example, both hard links exist
and so does directory A after mounting again the filesystem.

Checking if any new ancestors are new and need to be logged was added in
2009 by commit 12fcfd22 ("Btrfs: tree logging unlink/rename fixes"),
however only for the ancestors of the hard link (dentry) for which the
fsync was issued, instead of checking for all ancestors for all of the
inode's hard links.

So fix this by tracking the id of the last transaction where a hard link
was created for an inode and then on fsync fallback to a full transaction
commit when an inode has more than one hard link and at least one new hard
link was created in the current transaction. This is the simplest solution
since this is not a common use case (adding frequently hard links for
which there's an ancestor created in the current transaction and then
fsync the file). In case it ever becomes a common use case, a solution
that consists of iterating the fs/subvol btree for each hard link and
check if any ancestor is new, could be implemented.

This solves many unexpected scenarios reported by Jayashree Mohan and
Vijay Chidambaram, and for which there is a new test case for fstests
under review.

Fixes: 12fcfd22 ("Btrfs: tree logging unlink/rename fixes")
CC: stable@vger.kernel.org # 4.4+
Reported-by: NVijay Chidambaram <vvijay03@gmail.com>
Reported-by: NJayashree Mohan <jayashree2912@gmail.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This function really checks whether adding more data to the bio will
straddle a stripe/chunk. So first let's give it a more appropraite name
- btrfs_bio_fits_in_stripe. Secondly, the offset parameter was never
used to just remove it. Thirdly, pages are submitted to either btree or
data inodes so it's guaranteed that tree->ops is set so replace the
check with an ASSERT. Finally, document the parameters of the function.
No functional changes.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

For data inodes this hook does nothing but to return -EAGAIN which is
used to signal to the endio routines that this bio belongs to a data
inode. If this is the case the actual retrying is handled by
bio_readpage_error. Alternatively, if this bio belongs to the btree
inode then btree_io_failed_hook just does some cleanup and doesn't retry
anything.

This patch simplifies the code flow by eliminating
readpage_io_failed_hook and instead open-coding btree_io_failed_hook in
end_bio_extent_readpage. Also eliminate some needless checks since IO is
always performed on either data inode or btree inode, both of which are
guaranteed to have their extent_io_tree::ops set.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The end_io callback implemented as btrfs_io_bio_endio_readpage only
calls kfree. Also the callback is set only in case the csum buffer is
allocated and not pointing to the inline buffer. We can use that
information to drop the indirection and call a helper that will free the
csums only in the right case.

This shrinks struct btrfs_io_bio by 8 bytes.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The async_cow::root is used to propagate fs_info to async_cow_submit.
We can't use inode to reach it because it could become NULL after
write without compression in async_cow_start.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

There's one caller and its code is simple, we can open code it in
run_one_async_done. The errors are passed through bio.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Up to commit 32955c54 ("btrfs: switch to discard_new_inode()") the
drop_on_err variable in btrfs_mkdir() was used to check whether the
inode had to be dropped via iput().

After commit 32955c54 ("btrfs: switch to discard_new_inode()")
discard_new_inode() is called when err is set and inode is non NULL.
Therefore drop_on_err is not used anymore and thus causes a warning when
building with -Wunused-but-set-variable.
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Snapshot is expected to be fast. But if there are writers steadily
creating dirty pages in our subvolume, the snapshot may take a very long
time to complete. To fix the problem, we use tagged writepage for
snapshot flusher as we do in the generic write_cache_pages(), so we can
omit pages dirtied after the snapshot command.

This does not change the semantics regarding which data get to the
snapshot, if there are pages being dirtied during the snapshotting
operation.  There's a sync called before snapshot is taken in old/new
case, any IO in flight just after that may be in the snapshot but this
depends on other system effects that might still sync the IO.

We do a simple snapshot speed test on a Intel D-1531 box:

fio --ioengine=libaio --iodepth=32 --bs=4k --rw=write --size=64G
--direct=0 --thread=1 --numjobs=1 --time_based --runtime=120
--filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5;
time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio

original: 1m58sec
patched:  6.54sec

This is the best case for this patch since for a sequential write case,
we omit nearly all pages dirtied after the snapshot command.

For a multi writers, random write test:

fio --ioengine=libaio --iodepth=32 --bs=4k --rw=randwrite --size=64G
--direct=0 --thread=1 --numjobs=4 --time_based --runtime=120
--filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5;
time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio

original: 15.83sec
patched:  10.35sec

The improvement is smaller compared to the sequential write case,
since we omit only half of the pages dirtied after snapshot command.
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NEthan Lien <ethanlien@synology.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This parameter was never used, yet was part of the interface of the
function ever since its introduction as extent_io_ops::writepage_end_io_hook
in e6dcd2dc ("Btrfs: New data=ordered implementation"). Now that
NULL is passed everywhere as a value for this parameter let's remove it
for good. No functional changes.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Btrfs has not allowed swap files since commit 35054394 ("Btrfs: stop
providing a bmap operation to avoid swapfile corruptions"). However, now
that the proper restrictions are in place, Btrfs can support swap files
through the swap file a_ops, similar to iomap in commit 67482129
("iomap: add a swapfile activation function").

For Btrfs, activation needs to make sure that the file can be used as a
swap file, which currently means that it must be fully allocated as
NOCOW with no compression on one device. It must also do the proper
tracking so that ioctls will not interfere with the swap file.
Deactivation clears this tracking.
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This is the counterpart to merge_extent_hook, similarly, it's used only
for data/freespace inodes so let's remove it, rename it and call it
directly where necessary. No functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This callback is used only for data and free space inodes. Such inodes
are guaranteed to have their extent_io_tree::private_data set to the
inode struct. Exploit this fact to directly call the function. Also give
it a more descriptive name. No functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This is the counterpart to ex-set_bit_hook (now btrfs_set_delalloc_extent),
similar to what was done before remove clear_bit_hook and rename the
function. No functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This callback is used to properly account delalloc extents for data
inodes (ordinary file inodes and freespace v1 inodes). Those can be
easily identified since they have their extent_io trees ->private_data
member point to the inode. Let's exploit this fact to remove the
needless indirection through extent_io_hooks and directly call the
function. Also give the function a name which reflects its purpose -
btrfs_set_delalloc_extent.

This patch also modified test_find_delalloc so that the extent_io_tree
used for testing doesn't have its ->private_data set which would have
caused a crash in btrfs_set_delalloc_extent due to the btrfs_inode->root
member not being initialised. The old version of the code also didn't
call set_bit_hook since the extent_io ops weren't set for the inode.  No
functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This callback was only used in debug builds by btrfs_leak_debug_check.
A better approach is to move its implementation in
btrfs_leak_debug_check and ensure the latter is only executed for extent
tree which have ->private_data set i.e. relate to a data node and not
the btree one. No functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This callback is ony ever called for data page writeout so there is no
need to actually abstract it via extent_io_ops. Lets just export it,
remove the definition of the callback and call it directly in the
functions that invoke the callback. Also rename the function to
btrfs_writepage_endio_finish_ordered since what it really does is
account finished io in the ordered extent data structures.  No
functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This hook is called only from __extent_writepage_io which is already
called only from the data page writeout path. So there is no need to
make an indirect call via extent_io_ops. This patch just removes the
callback definition, exports the callback function and calls it directly
at the only call site. Also give the function a more descriptive name.
No functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This callback is called only from writepage_delalloc which in turn is
guaranteed to be called from the data page writeout path. In the end
there is no reason to have the call to this function to be indrected via
the extent_io_ops structure. This patch removes the callback definition,
exports the function and calls it directly. No functional changes.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ rename to btrfs_run_delalloc_range ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When we are writing out a free space cache, during the transaction commit
phase, we can end up in a deadlock which results in a stack trace like the
following:

 schedule+0x28/0x80
 btrfs_tree_read_lock+0x8e/0x120 [btrfs]
 ? finish_wait+0x80/0x80
 btrfs_read_lock_root_node+0x2f/0x40 [btrfs]
 btrfs_search_slot+0xf6/0x9f0 [btrfs]
 ? evict_refill_and_join+0xd0/0xd0 [btrfs]
 ? inode_insert5+0x119/0x190
 btrfs_lookup_inode+0x3a/0xc0 [btrfs]
 ? kmem_cache_alloc+0x166/0x1d0
 btrfs_iget+0x113/0x690 [btrfs]
 __lookup_free_space_inode+0xd8/0x150 [btrfs]
 lookup_free_space_inode+0x5b/0xb0 [btrfs]
 load_free_space_cache+0x7c/0x170 [btrfs]
 ? cache_block_group+0x72/0x3b0 [btrfs]
 cache_block_group+0x1b3/0x3b0 [btrfs]
 ? finish_wait+0x80/0x80
 find_free_extent+0x799/0x1010 [btrfs]
 btrfs_reserve_extent+0x9b/0x180 [btrfs]
 btrfs_alloc_tree_block+0x1b3/0x4f0 [btrfs]
 __btrfs_cow_block+0x11d/0x500 [btrfs]
 btrfs_cow_block+0xdc/0x180 [btrfs]
 btrfs_search_slot+0x3bd/0x9f0 [btrfs]
 btrfs_lookup_inode+0x3a/0xc0 [btrfs]
 ? kmem_cache_alloc+0x166/0x1d0
 btrfs_update_inode_item+0x46/0x100 [btrfs]
 cache_save_setup+0xe4/0x3a0 [btrfs]
 btrfs_start_dirty_block_groups+0x1be/0x480 [btrfs]
 btrfs_commit_transaction+0xcb/0x8b0 [btrfs]

At cache_save_setup() we need to update the inode item of a block group's
cache which is located in the tree root (fs_info->tree_root), which means
that it may result in COWing a leaf from that tree. If that happens we
need to find a free metadata extent and while looking for one, if we find
a block group which was not cached yet we attempt to load its cache by
calling cache_block_group(). However this function will try to load the
inode of the free space cache, which requires finding the matching inode
item in the tree root - if that inode item is located in the same leaf as
the inode item of the space cache we are updating at cache_save_setup(),
we end up in a deadlock, since we try to obtain a read lock on the same
extent buffer that we previously write locked.

So fix this by using the tree root's commit root when searching for a
block group's free space cache inode item when we are attempting to load
a free space cache. This is safe since block groups once loaded stay in
memory forever, as well as their caches, so after they are first loaded
we will never need to read their inode items again. For new block groups,
once they are created they get their ->cached field set to
BTRFS_CACHE_FINISHED meaning we will not need to read their inode item.
Reported-by: NAndrew Nelson <andrew.s.nelson@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CAPTELenq9x5KOWuQ+fa7h1r3nsJG8vyiTH8+ifjURc_duHh2Wg@mail.gmail.com/
Fixes: 9d66e233 ("Btrfs: load free space cache if it exists")
Tested-by: NAndrew Nelson <andrew.s.nelson@gmail.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When the cow_file_range fails, the related resources are unlocked
according to the range [start..end), so the unlock cannot be repeated in
run_delalloc_nocow.

In some cases (e.g. cur_offset <= end && cow_start != -1), cur_offset is
not updated correctly, so move the cur_offset update before
cow_file_range.

  kernel BUG at mm/page-writeback.c:2663!
  Internal error: Oops - BUG: 0 [#1] SMP
  CPU: 3 PID: 31525 Comm: kworker/u8:7 Tainted: P O
  Hardware name: Realtek_RTD1296 (DT)
  Workqueue: writeback wb_workfn (flush-btrfs-1)
  task: ffffffc076db3380 ti: ffffffc02e9ac000 task.ti: ffffffc02e9ac000
  PC is at clear_page_dirty_for_io+0x1bc/0x1e8
  LR is at clear_page_dirty_for_io+0x14/0x1e8
  pc : [<ffffffc00033c91c>] lr : [<ffffffc00033c774>] pstate: 40000145
  sp : ffffffc02e9af4f0
  Process kworker/u8:7 (pid: 31525, stack limit = 0xffffffc02e9ac020)
  Call trace:
  [<ffffffc00033c91c>] clear_page_dirty_for_io+0x1bc/0x1e8
  [<ffffffbffc514674>] extent_clear_unlock_delalloc+0x1e4/0x210 [btrfs]
  [<ffffffbffc4fb168>] run_delalloc_nocow+0x3b8/0x948 [btrfs]
  [<ffffffbffc4fb948>] run_delalloc_range+0x250/0x3a8 [btrfs]
  [<ffffffbffc514c0c>] writepage_delalloc.isra.21+0xbc/0x1d8 [btrfs]
  [<ffffffbffc516048>] __extent_writepage+0xe8/0x248 [btrfs]
  [<ffffffbffc51630c>] extent_write_cache_pages.isra.17+0x164/0x378 [btrfs]
  [<ffffffbffc5185a8>] extent_writepages+0x48/0x68 [btrfs]
  [<ffffffbffc4f5828>] btrfs_writepages+0x20/0x30 [btrfs]
  [<ffffffc00033d758>] do_writepages+0x30/0x88
  [<ffffffc0003ba0f4>] __writeback_single_inode+0x34/0x198
  [<ffffffc0003ba6c4>] writeback_sb_inodes+0x184/0x3c0
  [<ffffffc0003ba96c>] __writeback_inodes_wb+0x6c/0xc0
  [<ffffffc0003bac20>] wb_writeback+0x1b8/0x1c0
  [<ffffffc0003bb0f0>] wb_workfn+0x150/0x250
  [<ffffffc0002b0014>] process_one_work+0x1dc/0x388
  [<ffffffc0002b02f0>] worker_thread+0x130/0x500
  [<ffffffc0002b6344>] kthread+0x10c/0x110
  [<ffffffc000284590>] ret_from_fork+0x10/0x40
  Code: d503201f a9025bb5 a90363b7 f90023b9 (d4210000)

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NRobbie Ko <robbieko@synology.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

At inode.c:evict_inode_truncate_pages(), when we iterate over the
inode's extent states, we access an extent state record's "state" field
after we unlocked the inode's io tree lock. This can lead to a
use-after-free issue because after we unlock the io tree that extent
state record might have been freed due to being merged into another
adjacent extent state record (a previous inflight bio for a read
operation finished in the meanwhile which unlocked a range in the io
tree and cause a merge of extent state records, as explained in the
comment before the while loop added in commit 6ca07097 ("Btrfs: fix
hang during inode eviction due to concurrent readahead")).

Fix this by keeping a copy of the extent state's flags in a local
variable and using it after unlocking the io tree.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201189
Fixes: b9d0b389 ("btrfs: Add handler for invalidate page")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When we insert the file extent once the ordered extent completes we free
the reserved extent reservation as it'll have been migrated to the
bytes_used counter.  However if we error out after this step we'll still
clear the reserved extent reservation, resulting in a negative
accounting of the reserved bytes for the block group and space info.
Fix this by only doing the free if we didn't successfully insert a file
extent for this extent.

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

At inode.c:compress_file_range(), under the "free_pages_out" label, we can
end up dereferencing the "pages" pointer when it has a NULL value. This
case happens when "start" has a value of 0 and we fail to allocate memory
for the "pages" pointer. When that happens we jump to the "cont" label and
then enter the "if (start == 0)" branch where we immediately call the
cow_file_range_inline() function. If that function returns 0 (success
creating an inline extent) or an error (like -ENOMEM for example) we jump
to the "free_pages_out" label and then access "pages[i]" leading to a NULL
pointer dereference, since "nr_pages" has a value greater than zero at
that point.

Fix this by setting "nr_pages" to 0 when we fail to allocate memory for
the "pages" pointer.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201119
Fixes: 771ed689 ("Btrfs: Optimize compressed writeback and reads")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The avg_delayed_ref_runtime can be referenced from the transaction
handle.
Signed-off-by: NLu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

It can be referenced from the transaction handle.
Signed-off-by: NLu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We don't need it, rsv->size is set once and never changes throughout
its lifetime, so just use that for the reserve size.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The only aops we define for symlinks are identical to the aops for
regular files. This has been the case since symlink support was added in
commit 2b8d99a7 ("Btrfs: symlinks and hard links"). As far as I can
tell, there wasn't a good reason to have separate aops then, and there
isn't now, so let's just do what most other filesystems do and reuse the
same structure.
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

rb_first_cached() trades an extra pointer "leftmost" for doing the
same job as rb_first() but in O(1).

As evict_inode_truncate_pages() removes all extent mapping by always
looking for the first rb entry, it's helpful to use rb_first_cached
instead.

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".
Tested-by: NHolger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

In btrfs_orphan_cleanup the final 'if (ret) goto out' cannot ever be
executed. This is due to the last assignment to 'ret' depending on the
return value of btrfs_iget. If an error other than -ENOENT is returned
then the loop is prematurely terminated by 'goto out'.  On the other
hand, if the error value is ENOENT then a subsequent if branch is
executed that always re-assigns 'ret' and in case it's an error just
terminates the loop. No functional changes.

Coverity-id: 1437392
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NLu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When we delete an inode,

btrfs_evict_inode() {
    truncate_inode_pages_final()
        truncate_inode_pages_range()
            lock_page()
            truncate_cleanup_page()
                 btrfs_invalidatepage()
                      wait_on_page_writeback
                           btrfs_lookup_ordered_range()
                 cancel_dirty_page()
           unlock_page()
     ...
     btrfs_wait_ordered_range()
     ...

As VFS has called ->invalidatepage() to get all ordered extents done (if
there are any) and truncated all page cache pages (no dirty pages to
writeback after this step), wait_ordered_range() is just a noop.
Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>