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Author SHA1 Message Date
Qu Wenruo
9a4ffa1bd6 btrfs: unify the error handling of btrfs_read_buffer() 
There is one oddball error handling of btrfs_read_buffer():

	ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
	if (!ret) {
		*eb_ret = tmp;
		return 0;
	}
	free_extent_buffer(tmp);
	btrfs_release_path(p);
	return -EIO;

While all other call sites check the error first.  Unify the behavior.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-03-14 13:13:53 +01:00
Qu Wenruo
4eb150d612 btrfs: unify the error handling pattern for read_tree_block() 
We had an error handling pattern for read_tree_block() like this:

	eb = read_tree_block();
	if (IS_ERR(eb)) {
		/*
		 * Handling error here
		 * Normally ended up with return or goto out.
		 */
	} else if (!extent_buffer_uptodate(eb)) {
		/*
		 * Different error handling here
		 * Normally also ended up with return or goto out;
		 */
	}

This is fine, but if we want to add extra check for each
read_tree_block(), the existing if-else-if is not that expandable and
will take reader some seconds to figure out there is no extra branch.

Here we change it to a more common way, without the extra else:

	eb = read_tree_block();
	if (IS_ERR(eb)) {
		/*
		 * Handling error here
		 */
		return eb or goto out;
	}
	if (!extent_buffer_uptodate(eb)) {
		/*
		 * Different error handling here
		 */
		return eb or goto out;
	}

This also removes some oddball call sites which uses some creative way
to check error.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-03-14 13:13:53 +01:00
Filipe Manana
0cae23b66a btrfs: avoid unnecessary computation when deleting items from a leaf 
When deleting items from a leaf, we always compute the sum of the data
sizes of the items that are going to be deleted. However we only use
that sum when the last item to delete is behind the last item in the
leaf. This unnecessarily wastes CPU time when we are deleting either
the whole leaf or from some slot > 0 up to the last item in the leaf,
and both of these cases are common (e.g. truncation operation, either
as a result of truncate(2) or when logging inodes, deleting checksums
after removing a large enough extent, etc).

So compute only the sum of the data sizes if the last item to be
deleted does not match the last item in the leaf.

This change if part of a patchset that is comprised of the following
patches:

  1/6 btrfs: remove unnecessary leaf free space checks when pushing items
  2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
  3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
  4/6 btrfs: remove constraint on number of visited leaves when replacing extents
  5/6 btrfs: remove useless path release in the fast fsync path
  6/6 btrfs: prepare extents to be logged before locking a log tree path

The last patch in the series has some performance test result in its
changelog.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-03-14 13:13:49 +01:00
Filipe Manana
7c4063d19e btrfs: avoid unnecessary COW of leaves when deleting items from a leaf 
When we delete items from a leaf, if we end up with more than two thirds
of unused leaf space, we try to delete the leaf by moving all its items
into its left and right neighbour leaves. Sometimes that is not possible
because there is not enough free space in the left and right leaves, and
in that case we end up not deleting our leaf.

The way we are doing this is not ideal and can be improved in the
following ways:

1) When we call push_leaf_left(), we pass a value of 1 byte to the data
   size parameter of push_leaf_left(). This is not realistic value because
   no item can have a size less than 25 bytes, which is the size of struct
   btrfs_item. This means that means that if the left leaf has not enough
   free space to push any item, we end up COWing it even if we end up not
   changing its content at all.

   COWing that leaf means allocating a new metadata extent, marking it
   dirty and doing more IO when committing a transaction or when syncing a
   log tree. For a log tree case, it's particularly more important to
   avoid the useless COW operation, as more IO can imply a higher latency
   for an fsync operation.

   So instead of passing 1 as the minimum data size for push_leaf_left(),
   pass the size of the first item in our leaf, as we don't want to COW
   the left leaf if we can't at least push the first item of our leaf;

2) When we call push_leaf_right(), we also pass a value of 1 byte as the
   data size parameter of push_leaf_right(). Like the previous case, it
   will also result in COWing the right leaf even if we are not able to
   move any items into it, since there can't be any item with a size
   smaller than 25 bytes (the size of struct btrfs_item).

   So instead of passing 1 as the minimum data size to push_leaf_right(),
   pass a size that corresponds to the sum of the size of all the
   remaining items in our leaf. We are not interested in moving less than
   that, because if we do, we are not able to delete our leaf and we have
   COWed the right leaf for nothing. Plus, moving only some of the items
   of our leaf, it means an even less balanced tree.

   Just like the previous case, we want to avoid the useless COW of the
   right leaf, this way we don't have to spend time allocating one new
   metadata extent, and doing more IO when committing a transaction or
   syncing a log tree. For the log tree case it's specially more important
   because more IO can result in a higher latency for a fsync operation.

So adjust the minimum data size passed to push_leaf_left() and
push_leaf_right() as mentioned above.

This change if part of a patchset that is comprised of the following
patches:

  1/6 btrfs: remove unnecessary leaf free space checks when pushing items
  2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
  3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
  4/6 btrfs: remove constraint on number of visited leaves when replacing extents
  5/6 btrfs: remove useless path release in the fast fsync path
  6/6 btrfs: prepare extents to be logged before locking a log tree path

Not being able to delete a leaf that became less than 1/3 full after
deleting items from it is actually common. For example, for the fio test
mentioned in the changelog of patch 6/6, we are only able to delete a
leaf at btrfs_del_items() about 5.3% of the time, due to its left and
right neighbour leaves not having enough free space to push all the
remaining items into them.

The last patch in the series has some performance test result in its
changelog.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-03-14 13:13:49 +01:00
Filipe Manana
b4e098a97f btrfs: remove unnecessary leaf free space checks when pushing items 
When trying to push items from a leaf into its left and right neighbours,
we lock the left or right leaf, check if it has the required minimum free
space, COW the leaf and then check again if it has the minimum required
free space. This second check is pointless:

1) Most and foremost because it's not needed. We have a write lock on the
   leaf and on its parent node, so no one can come in and change either
   the pre-COW or post-COW version of the leaf for the whole duration of
   the push_leaf_left() and push_leaf_right() calls;

2) The call to btrfs_leaf_free_space() is not trivial, it has a fair
   amount of arithmetic operations and access to fields in the leaf's
   header and items, so it's not very cheap.

So remove the duplicated free space checks.

This change if part of a patchset that is comprised of the following
patches:

  1/6 btrfs: remove unnecessary leaf free space checks when pushing items
  2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
  3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
  4/6 btrfs: remove constraint on number of visited leaves when replacing extents
  5/6 btrfs: remove useless path release in the fast fsync path
  6/6 btrfs: prepare extents to be logged before locking a log tree path

The last patch in the series has some performance test result in its
changelog.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-03-14 13:13:49 +01:00
Nikolay Borisov
c122799643 btrfs: refactor unlock_up 
The purpose of this function is to unlock all nodes in a btrfs path
which are above 'lowest_unlock' and whose slot used is different than 0.
As such it used slightly awkward structure of 'if' as well as somewhat
cryptic "no_skip" control variable which denotes whether we should
check the current level of skipability or no.

This patch does the following (cosmetic) refactorings:

* Renames 'no_skip' to 'check_skip' and makes it a boolean. This
  variable controls whether we are below the lowest_unlock/skip_level
  levels.

* Consolidates the 2 conditions which warrant checking whether the
  current level should be skipped under 1 common if (check_skip) branch,
  this increase indentation level but is not critical.

* Consolidates the 'skip_level < i && i >= lowest_unlock' and
  'i >= lowest_unlock && i > skip_level' condition into a common branch
  since those are identical.

* Eliminates the local extent_buffer variable as in this case it doesn't
  bring anything to function readability.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:26 +01:00
Filipe Manana
727e60604f btrfs: remove stale comment about locking at btrfs_search_slot() 
The comment refers to the old extent buffer locking code, where we used to
have custom locks that had blocking and spinning behaviour modes. That is
not the case anymore, since we have transitioned to rw semaphores, so the
comment does not offer any value anymore. Remove it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Filipe Manana
bb8e9a6080 btrfs: remove BUG_ON() after splitting leaf 
After calling split_leaf() we BUG_ON() if the returned value is greater
than zero. However split_leaf() only returns 0, in case of success, or a
negative value in case of an error.

The reason for the BUG_ON() is that if we ever get a positive return
value from split_leaf(), we can not simply propagate it to the callers
of btrfs_search_slot(), as that would be interpreted as "key not found"
and not as an error. That means it could result in callers ending up
causing some potential silent corruption.

So change the BUG_ON() to an ASSERT(), and in case assertions are
disabled, produce a warning and set the return value to an error, to make
it not possible to get into a silent corruption and having the error not
noticed.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Filipe Manana
109324cfda btrfs: move leaf search logic out of btrfs_search_slot() 
There's quite a significant amount of code for doing the key search for a
leaf at btrfs_search_slot(), with a couple labels and gotos in it, plus
btrfs_search_slot() is already big enough.

So move the logic that does the key search on a leaf into a new helper
function. This makes it better organized, removing the need for the labels
and the gotos, as well as reducing the indentation level and the size of
btrfs_search_slot().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Filipe Manana
e5e1c1741b btrfs: remove useless condition check before splitting leaf 
When inserting a key, we check if the write_lock_level is less than 1,
and if so we set it to 1, release the path and retry the tree traversal.

However that is unnecessary, because when ins_len is greater than 0, we
know that write_lock_level can never be less than 1.

The logic to retry is also buggy, because in case ins_len was decremented,
due to an exact key match and the search is not meant for item extension
(path->search_for_extension is 0), we retry without incrementing ins_len,
which would make the next retry decrement it again by the same amount.

So remove the check for write_lock_level being less than 1 and add an
assertion to assert it's always >= 1.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Filipe Manana
e2e58d0f8d btrfs: try to unlock parent nodes earlier when inserting a key 
When inserting a new key, we release the write lock on the leaf's parent
only after doing the binary search on the leaf. This is because if the
key ends up at slot 0, we will have to update the key at slot 0 of the
parent node. The same reasoning applies to any other upper level nodes
when their slot is 0. We also need to keep the parent locked in case the
leaf does not have enough free space to insert the new key/item, because
in that case we will split the leaf and we will need to add a new key to
the parent due to a new leaf resulting from the split operation.

However if the leaf has enough space for the new key and the key does not
end up at slot 0 of the leaf we could release our write lock on the parent
before doing the binary search on the leaf to figure out the destination
slot. That leads to reducing the amount of time other tasks are blocked
waiting to lock the parent, therefore increasing parallelism when there
are other tasks that are trying to access other leaves accessible through
the same parent. This also applies to other upper nodes besides the
immediate parent, when their slot is 0, since we keep locks on them until
we figure out if the leaf slot is slot 0 or not.

In fact, having the key ending at up slot 0 when is rare. Typically it
only happens when the key is less than or equals to the smallest, the
"left most", key of the entire btree, during a split attempt when we try
to push to the right sibling leaf or when the caller just wants to update
the item of an existing key. It's also very common that a leaf has enough
space to insert a new key, since after a split we move about half of the
keys from one into the new leaf.

So unlock the parent, and any other upper level nodes, when during a key
insertion we notice the key is greater then the first key in the leaf and
the leaf has enough free space. After unlocking the upper level nodes, do
the binary search using a low boundary of slot 1 and not slot 0, to figure
out the slot where the key will be inserted (or where the key already is
in case it exists and the caller wants to modify its item data).
This extra comparison, with the first key, is cheap and the key is very
likely already in a cache line because it immediately follows the header
of the extent buffer and we have recently read the level field of the
header (which in fact is the last field of the header).

The following fs_mark test was run on a non-debug kernel (debian's default
kernel config), with a 12 cores intel CPU, and using a NVMe device:

  $ cat run-fsmark.sh
  #!/bin/bash

  DEV=/dev/nvme0n1
  MNT=/mnt/nvme0n1
  MOUNT_OPTIONS="-o ssd"
  MKFS_OPTIONS="-O no-holes -R free-space-tree"
  FILES=100000
  THREADS=$(nproc --all)
  FILE_SIZE=0

  echo "performance" | \
	tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

  mkfs.btrfs -f $MKFS_OPTIONS $DEV
  mount $MOUNT_OPTIONS $DEV $MNT

  OPTS="-S 0 -L 10 -n $FILES -s $FILE_SIZE -t $THREADS -k"
  for ((i = 1; i <= $THREADS; i++)); do
      OPTS="$OPTS -d $MNT/d$i"
  done

  fs_mark $OPTS

  umount $MNT

Before this change:

FSUse%        Count         Size    Files/sec     App Overhead
     0      1200000            0     165273.6          5958381
     0      2400000            0     190938.3          6284477
     0      3600000            0     181429.1          6044059
     0      4800000            0     173979.2          6223418
     0      6000000            0     139288.0          6384560
     0      7200000            0     163000.4          6520083
     1      8400000            0      57799.2          5388544
     1      9600000            0      66461.6          5552969
     2     10800000            0      49593.5          5163675
     2     12000000            0      57672.1          4889398

After this change:

FSUse%        Count         Size    Files/sec            App Overhead
     0      1200000            0     167987.3 (+1.6%)         6272730
     0      2400000            0     198563.9 (+4.0%)         6048847
     0      3600000            0     197436.6 (+8.8%)         6163637
     0      4800000            0     202880.7 (+16.6%)        6371771
     1      6000000            0     167275.9 (+20.1%)        6556733
     1      7200000            0     204051.2 (+25.2%)        6817091
     1      8400000            0      69622.8 (+20.5%)        5525675
     1      9600000            0      69384.5 (+4.4%)         5700723
     1     10800000            0      61454.1 (+23.9%)        5363754
     3     12000000            0      61908.7 (+7.3%)         5370196

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Filipe Manana
fb81212c07 btrfs: allow generic_bin_search() to take low boundary as an argument 
Right now generic_bin_search() always uses a low boundary slot of 0, but
in the next patch we'll want to often skip slot 0 when searching for a
key. So make generic_bin_search() have the low boundary slot specified
as an argument, and move the check for the extent buffer level from
btrfs_bin_search() to generic_bin_search() to avoid adding another
wrapper around generic_bin_search().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Josef Bacik
120de408e4 btrfs: check the root node for uptodate before returning it 
Now that we clear the extent buffer uptodate if we fail to write it out
we need to check to see if our root node is uptodate before we search
down it.  Otherwise we could return stale data (or potentially corrupt
data that was caught by the write verification step) and think that the
path is OK to search down.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Filipe Manana
d96b34248c btrfs: make send work with concurrent block group relocation 
We don't allow send and balance/relocation to run in parallel in order
to prevent send failing or silently producing some bad stream. This is
because while send is using an extent (specially metadata) or about to
read a metadata extent and expecting it belongs to a specific parent
node, relocation can run, the transaction used for the relocation is
committed and the extent gets reallocated while send is still using the
extent, so it ends up with a different content than expected. This can
result in just failing to read a metadata extent due to failure of the
validation checks (parent transid, level, etc), failure to find a
backreference for a data extent, and other unexpected failures. Besides
reallocation, there's also a similar problem of an extent getting
discarded when it's unpinned after the transaction used for block group
relocation is committed.

The restriction between balance and send was added in commit 9e967495e0
("Btrfs: prevent send failures and crashes due to concurrent relocation"),
kernel 5.3, while the more general restriction between send and relocation
was added in commit 1cea5cf0e6 ("btrfs: ensure relocation never runs
while we have send operations running"), kernel 5.14.

Both send and relocation can be very long running operations. Relocation
because it has to do a lot of IO and expensive backreference lookups in
case there are many snapshots, and send due to read IO when operating on
very large trees. This makes it inconvenient for users and tools to deal
with scheduling both operations.

For zoned filesystem we also have automatic block group relocation, so
send can fail with -EAGAIN when users least expect it or send can end up
delaying the block group relocation for too long. In the future we might
also get the automatic block group relocation for non zoned filesystems.

This change makes it possible for send and relocation to run in parallel.
This is achieved the following way:

1) For all tree searches, send acquires a read lock on the commit root
   semaphore;

2) After each tree search, and before releasing the commit root semaphore,
   the leaf is cloned and placed in the search path (struct btrfs_path);

3) After releasing the commit root semaphore, the changed_cb() callback
   is invoked, which operates on the leaf and writes commands to the pipe
   (or file in case send/receive is not used with a pipe). It's important
   here to not hold a lock on the commit root semaphore, because if we did
   we could deadlock when sending and receiving to the same filesystem
   using a pipe - the send task blocks on the pipe because it's full, the
   receive task, which is the only consumer of the pipe, triggers a
   transaction commit when attempting to create a subvolume or reserve
   space for a write operation for example, but the transaction commit
   blocks trying to write lock the commit root semaphore, resulting in a
   deadlock;

4) Before moving to the next key, or advancing to the next change in case
   of an incremental send, check if a transaction used for relocation was
   committed (or is about to finish its commit). If so, release the search
   path(s) and restart the search, to where we were before, so that we
   don't operate on stale extent buffers. The search restarts are always
   possible because both the send and parent roots are RO, and no one can
   add, remove of update keys (change their offset) in RO trees - the
   only exception is deduplication, but that is still not allowed to run
   in parallel with send;

5) Periodically check if there is contention on the commit root semaphore,
   which means there is a transaction commit trying to write lock it, and
   release the semaphore and reschedule if there is contention, so as to
   avoid causing any significant delays to transaction commits.

This leaves some room for optimizations for send to have less path
releases and re searching the trees when there's relocation running, but
for now it's kept simple as it performs quite well (on very large trees
with resulting send streams in the order of a few hundred gigabytes).

Test case btrfs/187, from fstests, stresses relocation, send and
deduplication attempting to run in parallel, but without verifying if send
succeeds and if it produces correct streams. A new test case will be added
that exercises relocation happening in parallel with send and then checks
that send succeeds and the resulting streams are correct.

A final note is that for now this still leaves the mutual exclusion
between send operations and deduplication on files belonging to a root
used by send operations. A solution for that will be slightly more complex
but it will eventually be built on top of this change.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-07 14:18:23 +01:00
Josef Bacik
dc2e724e0f btrfs: rename btrfs_item_end_nr to btrfs_item_data_end 
The name btrfs_item_end_nr() is a bit of a misnomer, as it's actually
the offset of the end of the data the item points to.  In fact all of
the helpers that we use btrfs_item_end_nr() use data in their name, like
BTRFS_LEAF_DATA_SIZE() and leaf_data().  Rename to btrfs_item_data_end()
to make it clear what this helper is giving us.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-03 15:09:43 +01:00
Josef Bacik
3212fa14e7 btrfs: drop the _nr from the item helpers 
Now that all call sites are using the slot number to modify item values,
rename the SETGET helpers to raw_item_*(), and then rework the _nr()
helpers to be the btrfs_item_*() btrfs_set_item_*() helpers, and then
rename all of the callers to the new helpers.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-03 15:09:43 +01:00
Josef Bacik
7479420736 btrfs: introduce item_nr token variant helpers 
The last remaining place where we have the pattern of

	item = btrfs_item_nr(slot)
	<do something with the item>

are the token helpers.  Handle this by introducing token helpers that
will do the btrfs_item_nr() work inside of the helper itself, and then
convert all users of the btrfs_item token helpers to the new _nr()
variants.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-03 15:09:43 +01:00
Josef Bacik
c91666b1f6 btrfs: add btrfs_set_item_*_nr() helpers 
We have the pattern of

	item = btrfs_item_nr(slot);
	btrfs_set_item_*(leaf, item);

in a bunch of places in our code.  Fix this by adding
btrfs_set_item_*_nr() helpers which will do the appropriate work, and
replace those calls with

	btrfs_set_item_*_nr(leaf, slot);

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-03 15:09:42 +01:00
Josef Bacik
227f3cd0d5 btrfs: use btrfs_item_size_nr/btrfs_item_offset_nr everywhere 
We have this pattern in a lot of places

	item = btrfs_item_nr(slot);
	btrfs_item_size(leaf, item);

when we could simply use

	btrfs_item_size(leaf, slot);

Fix all callers of btrfs_item_size() and btrfs_item_offset() to use the
_nr variation of the helpers.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2022-01-03 15:09:42 +01:00
Linus Torvalds
9609134186 for-5.16-rc5-tag 
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Merge tag 'for-5.16-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "A few more fixes, almost all error handling one-liners and for stable.

   - regression fix in directory logging items

   - regression fix of extent buffer status bits handling after an error

   - fix memory leak in error handling path in tree-log

   - fix freeing invalid anon device number when handling errors during
     subvolume creation

   - fix warning when freeing leaf after subvolume creation failure

   - fix missing blkdev put in device scan error handling

   - fix invalid delayed ref after subvolume creation failure"

* tag 'for-5.16-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix missing blkdev_put() call in btrfs_scan_one_device()
  btrfs: fix warning when freeing leaf after subvolume creation failure
  btrfs: fix invalid delayed ref after subvolume creation failure
  btrfs: check WRITE_ERR when trying to read an extent buffer
  btrfs: fix missing last dir item offset update when logging directory
  btrfs: fix double free of anon_dev after failure to create subvolume
  btrfs: fix memory leak in __add_inode_ref()
 2021-12-17 13:50:58 -08:00
Filipe Manana
7a1636089a btrfs: fix invalid delayed ref after subvolume creation failure 
When creating a subvolume, at ioctl.c:create_subvol(), if we fail to
insert the new root's root item into the root tree, we are freeing the
metadata extent we reserved for the new root to prevent a metadata
extent leak, as we don't abort the transaction at that point (since
there is nothing at that point that is irreversible).

However we allocated the metadata extent for the new root which we are
creating for the new subvolume, so its delayed reference refers to the
ID of this new root. But when we free the metadata extent we pass the
root of the subvolume where the new subvolume is located to
btrfs_free_tree_block() - this is incorrect because this will generate
a delayed reference that refers to the ID of the parent subvolume's root,
and not to ID of the new root.

This results in a failure when running delayed references that leads to
a transaction abort and a trace like the following:

[3868.738042] RIP: 0010:__btrfs_free_extent+0x709/0x950 [btrfs]
[3868.739857] Code: 68 0f 85 e6 fb ff (...)
[3868.742963] RSP: 0018:ffffb0e9045cf910 EFLAGS: 00010246
[3868.743908] RAX: 00000000fffffffe RBX: 00000000fffffffe RCX: 0000000000000002
[3868.745312] RDX: 00000000fffffffe RSI: 0000000000000002 RDI: ffff90b0cd793b88
[3868.746643] RBP: 000000000e5d8000 R08: 0000000000000000 R09: ffff90b0cd793b88
[3868.747979] R10: 0000000000000002 R11: 00014ded97944d68 R12: 0000000000000000
[3868.749373] R13: ffff90b09afe4a28 R14: 0000000000000000 R15: ffff90b0cd793b88
[3868.750725] FS:  00007f281c4a8b80(0000) GS:ffff90b3ada00000(0000) knlGS:0000000000000000
[3868.752275] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[3868.753515] CR2: 00007f281c6a5000 CR3: 0000000108a42006 CR4: 0000000000370ee0
[3868.754869] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[3868.756228] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[3868.757803] Call Trace:
[3868.758281]  <TASK>
[3868.758655]  ? btrfs_merge_delayed_refs+0x178/0x1c0 [btrfs]
[3868.759827]  __btrfs_run_delayed_refs+0x2b1/0x1250 [btrfs]
[3868.761047]  btrfs_run_delayed_refs+0x86/0x210 [btrfs]
[3868.762069]  ? lock_acquired+0x19f/0x420
[3868.762829]  btrfs_commit_transaction+0x69/0xb20 [btrfs]
[3868.763860]  ? _raw_spin_unlock+0x29/0x40
[3868.764614]  ? btrfs_block_rsv_release+0x1c2/0x1e0 [btrfs]
[3868.765870]  create_subvol+0x1d8/0x9a0 [btrfs]
[3868.766766]  btrfs_mksubvol+0x447/0x4c0 [btrfs]
[3868.767669]  ? preempt_count_add+0x49/0xa0
[3868.768444]  __btrfs_ioctl_snap_create+0x123/0x190 [btrfs]
[3868.769639]  ? _copy_from_user+0x66/0xa0
[3868.770391]  btrfs_ioctl_snap_create_v2+0xbb/0x140 [btrfs]
[3868.771495]  btrfs_ioctl+0xd1e/0x35c0 [btrfs]
[3868.772364]  ? __slab_free+0x10a/0x360
[3868.773198]  ? rcu_read_lock_sched_held+0x12/0x60
[3868.774121]  ? lock_release+0x223/0x4a0
[3868.774863]  ? lock_acquired+0x19f/0x420
[3868.775634]  ? rcu_read_lock_sched_held+0x12/0x60
[3868.776530]  ? trace_hardirqs_on+0x1b/0xe0
[3868.777373]  ? _raw_spin_unlock_irqrestore+0x3e/0x60
[3868.778280]  ? kmem_cache_free+0x321/0x3c0
[3868.779011]  ? __x64_sys_ioctl+0x83/0xb0
[3868.779718]  __x64_sys_ioctl+0x83/0xb0
[3868.780387]  do_syscall_64+0x3b/0xc0
[3868.781059]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[3868.781953] RIP: 0033:0x7f281c59e957
[3868.782585] Code: 3c 1c 48 f7 d8 4c (...)
[3868.785867] RSP: 002b:00007ffe1f83e2b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
[3868.787198] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f281c59e957
[3868.788450] RDX: 00007ffe1f83e2c0 RSI: 0000000050009418 RDI: 0000000000000003
[3868.789748] RBP: 00007ffe1f83f300 R08: 0000000000000000 R09: 00007ffe1f83fe36
[3868.791214] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
[3868.792468] R13: 0000000000000003 R14: 00007ffe1f83e2c0 R15: 00000000000003cc
[3868.793765]  </TASK>
[3868.794037] irq event stamp: 0
[3868.794548] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
[3868.795670] hardirqs last disabled at (0): [<ffffffff98294214>] copy_process+0x934/0x2040
[3868.797086] softirqs last  enabled at (0): [<ffffffff98294214>] copy_process+0x934/0x2040
[3868.798309] softirqs last disabled at (0): [<0000000000000000>] 0x0
[3868.799284] ---[ end trace be24c7002fe27747 ]---
[3868.799928] BTRFS info (device dm-0): leaf 241188864 gen 1268 total ptrs 214 free space 469 owner 2
[3868.801133] BTRFS info (device dm-0): refs 2 lock_owner 225627 current 225627
[3868.802056]  item 0 key (237436928 169 0) itemoff 16250 itemsize 33
[3868.802863]          extent refs 1 gen 1265 flags 2
[3868.803447]          ref#0: tree block backref root 1610
(...)
[3869.064354]  item 114 key (241008640 169 0) itemoff 12488 itemsize 33
[3869.065421]          extent refs 1 gen 1268 flags 2
[3869.066115]          ref#0: tree block backref root 1689
(...)
[3869.403834] BTRFS error (device dm-0): unable to find ref byte nr 241008640 parent 0 root 1622  owner 0 offset 0
[3869.405641] BTRFS: error (device dm-0) in __btrfs_free_extent:3076: errno=-2 No such entry
[3869.407138] BTRFS: error (device dm-0) in btrfs_run_delayed_refs:2159: errno=-2 No such entry

Fix this by passing the new subvolume's root ID to btrfs_free_tree_block().
This requires changing the root argument of btrfs_free_tree_block() from
struct btrfs_root * to a u64, since at this point during the subvolume
creation we have not yet created the struct btrfs_root for the new
subvolume, and btrfs_free_tree_block() only needs a root ID and nothing
else from a struct btrfs_root.

This was triggered by test case generic/475 from fstests.

Fixes: 67addf2900 ("btrfs: fix metadata extent leak after failure to create subvolume")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-12-15 17:07:33 +01:00
Linus Torvalds
037c50bfbe for-5.16-tag 
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Merge tag 'for-5.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs updates from David Sterba:
 "The updates this time are more under the hood and enhancing existing
  features (subpage with compression and zoned namespaces).

  Performance related:

   - misc small inode logging improvements (+3% throughput, -11% latency
     on sample dbench workload)

   - more efficient directory logging: bulk item insertion, less tree
     searches and locking

   - speed up bulk insertion of items into a b-tree, which is used when
     logging directories, when running delayed items for directories
     (fsync and transaction commits) and when running the slow path
     (full sync) of an fsync (bulk creation run time -4%, deletion -12%)

  Core:

   - continued subpage support
      - make defragmentation work
      - make compression write work

   - zoned mode
      - support ZNS (zoned namespaces), zone capacity is number of
        usable blocks in each zone
      - add dedicated block group (zoned) for relocation, to prevent
        out of order writes in some cases
      - greedy block group reclaim, pick the ones with least usable
        space first

   - preparatory work for send protocol updates

   - error handling improvements

   - cleanups and refactoring

  Fixes:

   - lockdep warnings
      - in show_devname callback, on seeding device
      - device delete on loop device due to conversions to workqueues

   - fix deadlock between chunk allocation and chunk btree modifications

   - fix tracking of missing device count and status"

* tag 'for-5.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (140 commits)
  btrfs: remove root argument from check_item_in_log()
  btrfs: remove root argument from add_link()
  btrfs: remove root argument from btrfs_unlink_inode()
  btrfs: remove root argument from drop_one_dir_item()
  btrfs: clear MISSING device status bit in btrfs_close_one_device
  btrfs: call btrfs_check_rw_degradable only if there is a missing device
  btrfs: send: prepare for v2 protocol
  btrfs: fix comment about sector sizes supported in 64K systems
  btrfs: update device path inode time instead of bd_inode
  fs: export an inode_update_time helper
  btrfs: fix deadlock when defragging transparent huge pages
  btrfs: sysfs: convert scnprintf and snprintf to sysfs_emit
  btrfs: make btrfs_super_block size match BTRFS_SUPER_INFO_SIZE
  btrfs: update comments for chunk allocation -ENOSPC cases
  btrfs: fix deadlock between chunk allocation and chunk btree modifications
  btrfs: zoned: use greedy gc for auto reclaim
  btrfs: check-integrity: stop storing the block device name in btrfsic_dev_state
  btrfs: use btrfs_get_dev_args_from_path in dev removal ioctls
  btrfs: add a btrfs_get_dev_args_from_path helper
  btrfs: handle device lookup with btrfs_dev_lookup_args
  ...
 2021-11-01 12:48:25 -07:00
Filipe Manana
f064165661 btrfs: unexport setup_items_for_insert() 
Since setup_items_for_insert() is not used anymore outside of ctree.c,
make it static and remove its prototype from ctree.h. This also requires
to move the definition of setup_item_for_insert() from ctree.h to ctree.c
and move down btrfs_duplicate_item() so that it's defined after
setup_items_for_insert().

Further, since setup_item_for_insert() is used outside ctree.c, rename it
to btrfs_setup_item_for_insert().

This patch is part of a small patchset that is comprised of the following
patches:

  btrfs: loop only once over data sizes array when inserting an item batch
  btrfs: unexport setup_items_for_insert()
  btrfs: use single bulk copy operations when logging directories

This is patch 2/3 and performance results, and the specific tests, are
included in the changelog of patch 3/3.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-10-26 19:08:03 +02:00
Filipe Manana
b7ef5f3a6f btrfs: loop only once over data sizes array when inserting an item batch 
When inserting a batch of items into a btree, we end up looping over the
data sizes array 3 times:

1) Once in the caller of btrfs_insert_empty_items(), when it populates the
   array with the data sizes for each item;

2) Once at btrfs_insert_empty_items() to sum the elements of the data
   sizes array and compute the total data size;

3) And then once again at setup_items_for_insert(), where we do exactly
   the same as what we do at btrfs_insert_empty_items(), to compute the
   total data size.

That is not bad for small arrays, but when the arrays have hundreds of
elements, the time spent on looping is not negligible. For example when
doing batch inserts of delayed items for dir index items or when logging
a directory, it's common to have 200 to 260 dir index items in a single
batch when using a leaf size of 16K and using file names between 8 and 12
characters. For a 64K leaf size, multiply that by 4. Taking into account
that during directory logging or when flushing delayed dir index items we
can have many of those large batches, the time spent on the looping adds
up quickly.

It's also more important to avoid it at setup_items_for_insert(), since
we are holding a write lock on a leaf and, in some cases, on upper nodes
of the btree, which causes us to block other tasks that want to access
the leaf and nodes for longer than necessary.

So change the code so that setup_items_for_insert() and
btrfs_insert_empty_items() no longer compute the total data size, and
instead rely on the caller to supply it. This makes us loop over the
array only once, where we can both populate the data size array and
compute the total data size, taking advantage of spatial and temporal
locality. To make this more manageable, use a structure to contain
all the relevant details for a batch of items (keys array, data sizes
array, total data size, number of items), and use it as an argument
for btrfs_insert_empty_items() and setup_items_for_insert().

This patch is part of a small patchset that is comprised of the following
patches:

  btrfs: loop only once over data sizes array when inserting an item batch
  btrfs: unexport setup_items_for_insert()
  btrfs: use single bulk copy operations when logging directories

This is patch 1/3 and performance results, and the specific tests, are
included in the changelog of patch 3/3.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-10-26 19:08:03 +02:00
Filipe Manana
49d0c6424c btrfs: assert that extent buffers are write locked instead of only locked 
We currently use lockdep_assert_held() at btrfs_assert_tree_locked(), and
that checks that we hold a lock either in read mode or write mode.

However in all contexts we use btrfs_assert_tree_locked(), we actually
want to check if we are holding a write lock on the extent buffer's rw
semaphore - it would be a bug if in any of those contexts we were holding
a read lock instead.

So change btrfs_assert_tree_locked() to use lockdep_assert_held_write()
instead and, to make it more explicit, rename btrfs_assert_tree_locked()
to btrfs_assert_tree_write_locked(), so that it's clear we want to check
we are holding a write lock.

For now there are no contexts where we want to assert that we must have
a read lock, but in case that is needed in the future, we can add a new
helper function that just calls out lockdep_assert_held_read().

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-10-26 19:08:02 +02:00
Christoph Hellwig
e41d12f539 mm: don't include <linux/blk-cgroup.h> in <linux/backing-dev.h> 
There is no need to pull blk-cgroup.h and thus blkdev.h in here, so
break the include chain.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
 2021-10-18 06:17:01 -06:00
Marcos Paulo de Souza
0ff40a910f btrfs: introduce btrfs_search_backwards function 
It's a common practice to start a search using offset (u64)-1, which is
the u64 maximum value, meaning that we want the search_slot function to
be set in the last item with the same objectid and type.

Once we are in this position, it's a matter to start a search backwards
by calling btrfs_previous_item, which will check if we'll need to go to
a previous leaf and other necessary checks, only to be sure that we are
in last offset of the same object and type.

The new btrfs_search_backwards function does the all these steps when
necessary, and can be used to avoid code duplication.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-08-23 13:19:09 +02:00
David Sterba
809d6902b3 btrfs: make btrfs_next_leaf static inline 
btrfs_next_leaf is a simple wrapper for btrfs_next_old_leaf so move it
to header to avoid the function call overhead.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-08-23 13:19:02 +02:00
Filipe Manana
069a2e3778 btrfs: continue readahead of siblings even if target node is in memory 
At reada_for_search(), when attempting to readahead a node or leaf's
siblings, we skip the readahead of the siblings if the node/leaf is
already in memory. That is probably fine for the READA_FORWARD and
READA_BACK readahead types, as they are used on contexts where we
end up reading some consecutive leaves, but usually not the whole btree.

However for a READA_FORWARD_ALWAYS mode, currently only used for full
send operations, it does not make sense to skip the readahead if the
target node or leaf is already loaded in memory, since we know the caller
is visiting every node and leaf of the btree in ascending order.

So change the behaviour to not skip the readahead when the target node is
already in memory and the readahead mode is READA_FORWARD_ALWAYS.

The following test script was used to measure the improvement on a box
using an average, consumer grade, spinning disk, with 32GiB of RAM and
using a non-debug kernel config (Debian's default config).

  $ cat test.sh
  #!/bin/bash

  DEV=/dev/sdj
  MNT=/mnt/sdj
  MKFS_OPTIONS="--nodesize 16384"     # default, just to be explicit
  MOUNT_OPTIONS="-o max_inline=2048"  # default, just to be explicit

  mkfs.btrfs -f $MKFS_OPTIONS $DEV > /dev/null
  mount $MOUNT_OPTIONS $DEV $MNT

  # Create files with inline data to make it easier and faster to create
  # large btrees.
  add_files()
  {
      local total=$1
      local start_offset=$2
      local number_jobs=$3
      local total_per_job=$(($total / $number_jobs))

      echo "Creating $total new files using $number_jobs jobs"
      for ((n = 0; n < $number_jobs; n++)); do
          (
              local start_num=$(($start_offset + $n * $total_per_job))
              for ((i = 1; i <= $total_per_job; i++)); do
                  local file_num=$((start_num + $i))
                  local file_path="$MNT/file_${file_num}"
                  xfs_io -f -c "pwrite -S 0xab 0 2000" $file_path > /dev/null
                  if [ $? -ne 0 ]; then
                      echo "Failed creating file $file_path"
                      break
                  fi
              done
          ) &
          worker_pids[$n]=$!
      done

      wait ${worker_pids[@]}

      sync
      echo
      echo "btree node/leaf count: $(btrfs inspect-internal dump-tree -t 5 $DEV | egrep '^(node|leaf) ' | wc -l)"
  }

  file_count=2000000
  add_files $file_count 0 4

  echo
  echo "Creating snapshot..."
  btrfs subvolume snapshot -r $MNT $MNT/snap1

  umount $MNT

  echo 3 > /proc/sys/vm/drop_caches
  blockdev --flushbufs $DEV &> /dev/null
  hdparm -F $DEV &> /dev/null

  mount $MOUNT_OPTIONS $DEV $MNT

  echo
  echo "Testing full send..."
  start=$(date +%s)
  btrfs send $MNT/snap1 > /dev/null
  end=$(date +%s)
  echo
  echo "Full send took $((end - start)) seconds"

  umount $MNT

The duration of the full send operations, in seconds, were the following:

Before this change:  85 seconds
After this change:   76 seconds (-11.2%)

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-08-23 13:19:00 +02:00
Marcos Paulo de Souza
67d5e289a1 btrfs: remove max argument from generic_bin_search 
Both callers use btrfs_header_nritems to feed the max argument.  Remove
the argument and let generic_bin_search call it itself.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-08-23 13:18:59 +02:00
Filipe Manana
79bd37120b btrfs: rework chunk allocation to avoid exhaustion of the system chunk array 
Commit eafa4fd0ad ("btrfs: fix exhaustion of the system chunk array
due to concurrent allocations") fixed a problem that resulted in
exhausting the system chunk array in the superblock when there are many
tasks allocating chunks in parallel. Basically too many tasks enter the
first phase of chunk allocation without previous tasks having finished
their second phase of allocation, resulting in too many system chunks
being allocated. That was originally observed when running the fallocate
tests of stress-ng on a PowerPC machine, using a node size of 64K.

However that commit also introduced a deadlock where a task in phase 1 of
the chunk allocation waited for another task that had allocated a system
chunk to finish its phase 2, but that other task was waiting on an extent
buffer lock held by the first task, therefore resulting in both tasks not
making any progress. That change was later reverted by a patch with the
subject "btrfs: fix deadlock with concurrent chunk allocations involving
system chunks", since there is no simple and short solution to address it
and the deadlock is relatively easy to trigger on zoned filesystems, while
the system chunk array exhaustion is not so common.

This change reworks the chunk allocation to avoid the system chunk array
exhaustion. It accomplishes that by making the first phase of chunk
allocation do the updates of the device items in the chunk btree and the
insertion of the new chunk item in the chunk btree. This is done while
under the protection of the chunk mutex (fs_info->chunk_mutex), in the
same critical section that checks for available system space, allocates
a new system chunk if needed and reserves system chunk space. This way
we do not have chunk space reserved until the second phase completes.

The same logic is applied to chunk removal as well, since it keeps
reserved system space long after it is done updating the chunk btree.

For direct allocation of system chunks, the previous behaviour remains,
because otherwise we would deadlock on extent buffers of the chunk btree.
Changes to the chunk btree are by large done by chunk allocation and chunk
removal, which first reserve chunk system space and then later do changes
to the chunk btree. The other remaining cases are uncommon and correspond
to adding a device, removing a device and resizing a device. All these
other cases do not pre-reserve system space, they modify the chunk btree
right away, so they don't hold reserved space for a long period like chunk
allocation and chunk removal do.

The diff of this change is huge, but more than half of it is just addition
of comments describing both how things work regarding chunk allocation and
removal, including both the new behavior and the parts of the old behavior
that did not change.

CC: stable@vger.kernel.org # 5.12+
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Tested-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-07-07 17:42:41 +02:00
Josef Bacik
5963ffcaf3 btrfs: always abort the transaction if we abort a trans handle 
While stress testing our error handling I noticed that sometimes we
would still commit the transaction even though we had aborted the
transaction.

Currently we track if a trans handle has dirtied any metadata, and if it
hasn't we mark the filesystem as having an error (so no new transactions
can be started), but we will allow the current transaction to complete
as we do not mark the transaction itself as having been aborted.

This sounds good in theory, but we were not properly tracking IO errors
in btrfs_finish_ordered_io, and thus committing the transaction with
bogus free space data.  This isn't necessarily a problem per-se with the
free space cache, as the other guards in place would have kept us from
accepting the free space cache as valid, but highlights a real world
case where we had a bug and could have corrupted the filesystem because
of it.

This "skip abort on empty trans handle" is nice in theory, but assumes
we have perfect error handling everywhere, which we clearly do not.
Also we do not allow further transactions to be started, so all this
does is save the last transaction that was happening, which doesn't
necessarily gain us anything other than the potential for real
corruption.

Remove this particular bit of code, if we decide we need to abort the
transaction then abort the current one and keep us from doing real harm
to the file system, regardless of whether this specific trans handle
dirtied anything or not.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-06-21 15:19:06 +02:00
Filipe Manana
ace75066ce btrfs: improve btree readahead for full send operations 
Currently a full send operation uses the standard btree readahead when
iterating over the subvolume/snapshot btree, which despite bringing good
performance benefits, it could be improved in a few aspects for use cases
such as full send operations, which are guaranteed to visit every node
and leaf of a btree, in ascending and sequential order. The limitations
of that standard btree readahead implementation are the following:

1) It only triggers readahead for leaves that are physically close
   to the leaf being read, within a 64K range;

2) It only triggers readahead for the next or previous leaves if the
   leaf being read is not currently in memory;

3) It never triggers readahead for nodes.

So add a new readahead mode that addresses all these points and use it
for full send operations.

The following test script was used to measure the improvement on a box
using an average, consumer grade, spinning disk and with 16GiB of RAM:

  $ cat test.sh
  #!/bin/bash

  DEV=/dev/sdj
  MNT=/mnt/sdj
  MKFS_OPTIONS="--nodesize 16384"     # default, just to be explicit
  MOUNT_OPTIONS="-o max_inline=2048"  # default, just to be explicit

  mkfs.btrfs -f $MKFS_OPTIONS $DEV > /dev/null
  mount $MOUNT_OPTIONS $DEV $MNT

  # Create files with inline data to make it easier and faster to create
  # large btrees.
  add_files()
  {
      local total=$1
      local start_offset=$2
      local number_jobs=$3
      local total_per_job=$(($total / $number_jobs))

      echo "Creating $total new files using $number_jobs jobs"
      for ((n = 0; n < $number_jobs; n++)); do
          (
              local start_num=$(($start_offset + $n * $total_per_job))
              for ((i = 1; i <= $total_per_job; i++)); do
                  local file_num=$((start_num + $i))
                  local file_path="$MNT/file_${file_num}"
                  xfs_io -f -c "pwrite -S 0xab 0 2000" $file_path > /dev/null
                  if [ $? -ne 0 ]; then
                      echo "Failed creating file $file_path"
                      break
                  fi
              done
          ) &
          worker_pids[$n]=$!
      done

      wait ${worker_pids[@]}

      sync
      echo
      echo "btree node/leaf count: $(btrfs inspect-internal dump-tree -t 5 $DEV | egrep '^(node|leaf) ' | wc -l)"
  }

  initial_file_count=500000
  add_files $initial_file_count 0 4

  echo
  echo "Creating first snapshot..."
  btrfs subvolume snapshot -r $MNT $MNT/snap1

  echo
  echo "Adding more files..."
  add_files $((initial_file_count / 4)) $initial_file_count 4

  echo
  echo "Updating 1/50th of the initial files..."
  for ((i = 1; i < $initial_file_count; i += 50)); do
      xfs_io -c "pwrite -S 0xcd 0 20" $MNT/file_$i > /dev/null
  done

  echo
  echo "Creating second snapshot..."
  btrfs subvolume snapshot -r $MNT $MNT/snap2

  umount $MNT

  echo 3 > /proc/sys/vm/drop_caches
  blockdev --flushbufs $DEV &> /dev/null
  hdparm -F $DEV &> /dev/null

  mount $MOUNT_OPTIONS $DEV $MNT

  echo
  echo "Testing full send..."
  start=$(date +%s)
  btrfs send $MNT/snap1 > /dev/null
  end=$(date +%s)
  echo
  echo "Full send took $((end - start)) seconds"

  umount $MNT

The durations of the full send operation in seconds were the following:

Before this change:  217 seconds
After this change:   205 seconds (-5.7%)

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-04-19 17:25:17 +02:00
Filipe Manana
406808ab2f btrfs: use booleans where appropriate for the tree mod log functions 
Several functions of the tree modification log use integers as booleans,
so change them to use booleans instead, making their use more clear.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-04-19 17:25:16 +02:00
Filipe Manana
f3a84ccd28 btrfs: move the tree mod log code into its own file 
The tree modification log, which records modifications done to btrees, is
quite large and currently spread all over ctree.c, which is a huge file
already.

To make things better organized, move all that code into its own separate
source and header files. Functions and definitions that are used outside
of the module (mostly by ctree.c) are renamed so that they start with a
"btrfs_" prefix. Everything else remains unchanged.

This makes it easier to go over the tree modification log code every
time I need to go read it to fix a bug.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-04-19 17:25:16 +02:00
Filipe Manana
dbcc7d57bf btrfs: fix race when cloning extent buffer during rewind of an old root 
While resolving backreferences, as part of a logical ino ioctl call or
fiemap, we can end up hitting a BUG_ON() when replaying tree mod log
operations of a root, triggering a stack trace like the following:

  ------------[ cut here ]------------
  kernel BUG at fs/btrfs/ctree.c:1210!
  invalid opcode: 0000 [#1] SMP KASAN PTI
  CPU: 1 PID: 19054 Comm: crawl_335 Tainted: G        W         5.11.0-2d11c0084b02-misc-next+ #89
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
  RIP: 0010:__tree_mod_log_rewind+0x3b1/0x3c0
  Code: 05 48 8d 74 10 (...)
  RSP: 0018:ffffc90001eb70b8 EFLAGS: 00010297
  RAX: 0000000000000000 RBX: ffff88812344e400 RCX: ffffffffb28933b6
  RDX: 0000000000000007 RSI: dffffc0000000000 RDI: ffff88812344e42c
  RBP: ffffc90001eb7108 R08: 1ffff11020b60a20 R09: ffffed1020b60a20
  R10: ffff888105b050f9 R11: ffffed1020b60a1f R12: 00000000000000ee
  R13: ffff8880195520c0 R14: ffff8881bc958500 R15: ffff88812344e42c
  FS:  00007fd1955e8700(0000) GS:ffff8881f5600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007efdb7928718 CR3: 000000010103a006 CR4: 0000000000170ee0
  Call Trace:
   btrfs_search_old_slot+0x265/0x10d0
   ? lock_acquired+0xbb/0x600
   ? btrfs_search_slot+0x1090/0x1090
   ? free_extent_buffer.part.61+0xd7/0x140
   ? free_extent_buffer+0x13/0x20
   resolve_indirect_refs+0x3e9/0xfc0
   ? lock_downgrade+0x3d0/0x3d0
   ? __kasan_check_read+0x11/0x20
   ? add_prelim_ref.part.11+0x150/0x150
   ? lock_downgrade+0x3d0/0x3d0
   ? __kasan_check_read+0x11/0x20
   ? lock_acquired+0xbb/0x600
   ? __kasan_check_write+0x14/0x20
   ? do_raw_spin_unlock+0xa8/0x140
   ? rb_insert_color+0x30/0x360
   ? prelim_ref_insert+0x12d/0x430
   find_parent_nodes+0x5c3/0x1830
   ? resolve_indirect_refs+0xfc0/0xfc0
   ? lock_release+0xc8/0x620
   ? fs_reclaim_acquire+0x67/0xf0
   ? lock_acquire+0xc7/0x510
   ? lock_downgrade+0x3d0/0x3d0
   ? lockdep_hardirqs_on_prepare+0x160/0x210
   ? lock_release+0xc8/0x620
   ? fs_reclaim_acquire+0x67/0xf0
   ? lock_acquire+0xc7/0x510
   ? poison_range+0x38/0x40
   ? unpoison_range+0x14/0x40
   ? trace_hardirqs_on+0x55/0x120
   btrfs_find_all_roots_safe+0x142/0x1e0
   ? find_parent_nodes+0x1830/0x1830
   ? btrfs_inode_flags_to_xflags+0x50/0x50
   iterate_extent_inodes+0x20e/0x580
   ? tree_backref_for_extent+0x230/0x230
   ? lock_downgrade+0x3d0/0x3d0
   ? read_extent_buffer+0xdd/0x110
   ? lock_downgrade+0x3d0/0x3d0
   ? __kasan_check_read+0x11/0x20
   ? lock_acquired+0xbb/0x600
   ? __kasan_check_write+0x14/0x20
   ? _raw_spin_unlock+0x22/0x30
   ? __kasan_check_write+0x14/0x20
   iterate_inodes_from_logical+0x129/0x170
   ? iterate_inodes_from_logical+0x129/0x170
   ? btrfs_inode_flags_to_xflags+0x50/0x50
   ? iterate_extent_inodes+0x580/0x580
   ? __vmalloc_node+0x92/0xb0
   ? init_data_container+0x34/0xb0
   ? init_data_container+0x34/0xb0
   ? kvmalloc_node+0x60/0x80
   btrfs_ioctl_logical_to_ino+0x158/0x230
   btrfs_ioctl+0x205e/0x4040
   ? __might_sleep+0x71/0xe0
   ? btrfs_ioctl_get_supported_features+0x30/0x30
   ? getrusage+0x4b6/0x9c0
   ? __kasan_check_read+0x11/0x20
   ? lock_release+0xc8/0x620
   ? __might_fault+0x64/0xd0
   ? lock_acquire+0xc7/0x510
   ? lock_downgrade+0x3d0/0x3d0
   ? lockdep_hardirqs_on_prepare+0x210/0x210
   ? lockdep_hardirqs_on_prepare+0x210/0x210
   ? __kasan_check_read+0x11/0x20
   ? do_vfs_ioctl+0xfc/0x9d0
   ? ioctl_file_clone+0xe0/0xe0
   ? lock_downgrade+0x3d0/0x3d0
   ? lockdep_hardirqs_on_prepare+0x210/0x210
   ? __kasan_check_read+0x11/0x20
   ? lock_release+0xc8/0x620
   ? __task_pid_nr_ns+0xd3/0x250
   ? lock_acquire+0xc7/0x510
   ? __fget_files+0x160/0x230
   ? __fget_light+0xf2/0x110
   __x64_sys_ioctl+0xc3/0x100
   do_syscall_64+0x37/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7fd1976e2427
  Code: 00 00 90 48 8b 05 (...)
  RSP: 002b:00007fd1955e5cf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 00007fd1955e5f40 RCX: 00007fd1976e2427
  RDX: 00007fd1955e5f48 RSI: 00000000c038943b RDI: 0000000000000004
  RBP: 0000000001000000 R08: 0000000000000000 R09: 00007fd1955e6120
  R10: 0000557835366b00 R11: 0000000000000246 R12: 0000000000000004
  R13: 00007fd1955e5f48 R14: 00007fd1955e5f40 R15: 00007fd1955e5ef8
  Modules linked in:
  ---[ end trace ec8931a1c36e57be ]---

  (gdb) l *(__tree_mod_log_rewind+0x3b1)
  0xffffffff81893521 is in __tree_mod_log_rewind (fs/btrfs/ctree.c:1210).
  1205                     * the modification. as we're going backwards, we do the
  1206                     * opposite of each operation here.
  1207                     */
  1208                    switch (tm->op) {
  1209                    case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
  1210                            BUG_ON(tm->slot < n);
  1211                            fallthrough;
  1212                    case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
  1213                    case MOD_LOG_KEY_REMOVE:
  1214                            btrfs_set_node_key(eb, &tm->key, tm->slot);

Here's what happens to hit that BUG_ON():

1) We have one tree mod log user (through fiemap or the logical ino ioctl),
   with a sequence number of 1, so we have fs_info->tree_mod_seq == 1;

2) Another task is at ctree.c:balance_level() and we have eb X currently as
   the root of the tree, and we promote its single child, eb Y, as the new
   root.

   Then, at ctree.c:balance_level(), we call:

      tree_mod_log_insert_root(eb X, eb Y, 1);

3) At tree_mod_log_insert_root() we create tree mod log elements for each
   slot of eb X, of operation type MOD_LOG_KEY_REMOVE_WHILE_FREEING each
   with a ->logical pointing to ebX->start. These are placed in an array
   named tm_list.
   Lets assume there are N elements (N pointers in eb X);

4) Then, still at tree_mod_log_insert_root(), we create a tree mod log
   element of operation type MOD_LOG_ROOT_REPLACE, ->logical set to
   ebY->start, ->old_root.logical set to ebX->start, ->old_root.level set
   to the level of eb X and ->generation set to the generation of eb X;

5) Then tree_mod_log_insert_root() calls tree_mod_log_free_eb() with
   tm_list as argument. After that, tree_mod_log_free_eb() calls
   __tree_mod_log_insert() for each member of tm_list in reverse order,
   from highest slot in eb X, slot N - 1, to slot 0 of eb X;

6) __tree_mod_log_insert() sets the sequence number of each given tree mod
   log operation - it increments fs_info->tree_mod_seq and sets
   fs_info->tree_mod_seq as the sequence number of the given tree mod log
   operation.

   This means that for the tm_list created at tree_mod_log_insert_root(),
   the element corresponding to slot 0 of eb X has the highest sequence
   number (1 + N), and the element corresponding to the last slot has the
   lowest sequence number (2);

7) Then, after inserting tm_list's elements into the tree mod log rbtree,
   the MOD_LOG_ROOT_REPLACE element is inserted, which gets the highest
   sequence number, which is N + 2;

8) Back to ctree.c:balance_level(), we free eb X by calling
   btrfs_free_tree_block() on it. Because eb X was created in the current
   transaction, has no other references and writeback did not happen for
   it, we add it back to the free space cache/tree;

9) Later some other task T allocates the metadata extent from eb X, since
   it is marked as free space in the space cache/tree, and uses it as a
   node for some other btree;

10) The tree mod log user task calls btrfs_search_old_slot(), which calls
    get_old_root(), and finally that calls __tree_mod_log_oldest_root()
    with time_seq == 1 and eb_root == eb Y;

11) First iteration of the while loop finds the tree mod log element with
    sequence number N + 2, for the logical address of eb Y and of type
    MOD_LOG_ROOT_REPLACE;

12) Because the operation type is MOD_LOG_ROOT_REPLACE, we don't break out
    of the loop, and set root_logical to point to tm->old_root.logical
    which corresponds to the logical address of eb X;

13) On the next iteration of the while loop, the call to
    tree_mod_log_search_oldest() returns the smallest tree mod log element
    for the logical address of eb X, which has a sequence number of 2, an
    operation type of MOD_LOG_KEY_REMOVE_WHILE_FREEING and corresponds to
    the old slot N - 1 of eb X (eb X had N items in it before being freed);

14) We then break out of the while loop and return the tree mod log operation
    of type MOD_LOG_ROOT_REPLACE (eb Y), and not the one for slot N - 1 of
    eb X, to get_old_root();

15) At get_old_root(), we process the MOD_LOG_ROOT_REPLACE operation
    and set "logical" to the logical address of eb X, which was the old
    root. We then call tree_mod_log_search() passing it the logical
    address of eb X and time_seq == 1;

16) Then before calling tree_mod_log_search(), task T adds a key to eb X,
    which results in adding a tree mod log operation of type
    MOD_LOG_KEY_ADD to the tree mod log - this is done at
    ctree.c:insert_ptr() - but after adding the tree mod log operation
    and before updating the number of items in eb X from 0 to 1...

17) The task at get_old_root() calls tree_mod_log_search() and gets the
    tree mod log operation of type MOD_LOG_KEY_ADD just added by task T.
    Then it enters the following if branch:

    if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
       (...)
    } (...)

    Calls read_tree_block() for eb X, which gets a reference on eb X but
    does not lock it - task T has it locked.
    Then it clones eb X while it has nritems set to 0 in its header, before
    task T sets nritems to 1 in eb X's header. From hereupon we use the
    clone of eb X which no other task has access to;

18) Then we call __tree_mod_log_rewind(), passing it the MOD_LOG_KEY_ADD
    mod log operation we just got from tree_mod_log_search() in the
    previous step and the cloned version of eb X;

19) At __tree_mod_log_rewind(), we set the local variable "n" to the number
    of items set in eb X's clone, which is 0. Then we enter the while loop,
    and in its first iteration we process the MOD_LOG_KEY_ADD operation,
    which just decrements "n" from 0 to (u32)-1, since "n" is declared with
    a type of u32. At the end of this iteration we call rb_next() to find the
    next tree mod log operation for eb X, that gives us the mod log operation
    of type MOD_LOG_KEY_REMOVE_WHILE_FREEING, for slot 0, with a sequence
    number of N + 1 (steps 3 to 6);

20) Then we go back to the top of the while loop and trigger the following
    BUG_ON():

        (...)
        switch (tm->op) {
        case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
                 BUG_ON(tm->slot < n);
                 fallthrough;
        (...)

    Because "n" has a value of (u32)-1 (4294967295) and tm->slot is 0.

Fix this by taking a read lock on the extent buffer before cloning it at
ctree.c:get_old_root(). This should be done regardless of the extent
buffer having been freed and reused, as a concurrent task might be
modifying it (while holding a write lock on it).

Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Link: https://lore.kernel.org/linux-btrfs/20210227155037.GN28049@hungrycats.org/
Fixes: 834328a849 ("Btrfs: tree mod log's old roots could still be part of the tree")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-03-16 20:32:17 +01:00
Filipe Manana
72c9925f87 btrfs: fix extent buffer leak on failure to copy root 
At btrfs_copy_root(), if the call to btrfs_inc_ref() fails we end up
returning without unlocking and releasing our reference on the extent
buffer named "cow" we previously allocated with btrfs_alloc_tree_block().

So fix that by unlocking the extent buffer and dropping our reference on
it before returning.

Fixes: be20aa9dba ("Btrfs: Add mount option to turn off data cow")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-02-08 22:59:04 +01:00
Josef Bacik
867ed321f9 btrfs: abort the transaction if we fail to inc ref in btrfs_copy_root 
While testing my error handling patches, I added a error injection site
at btrfs_inc_extent_ref, to validate the error handling I added was
doing the correct thing.  However I hit a pretty ugly corruption while
doing this check, with the following error injection stack trace:

btrfs_inc_extent_ref
  btrfs_copy_root
    create_reloc_root
      btrfs_init_reloc_root
	btrfs_record_root_in_trans
	  btrfs_start_transaction
	    btrfs_update_inode
	      btrfs_update_time
		touch_atime
		  file_accessed
		    btrfs_file_mmap

This is because we do not catch the error from btrfs_inc_extent_ref,
which in practice would be ENOMEM, which means we lose the extent
references for a root that has already been allocated and inserted,
which is the problem.  Fix this by aborting the transaction if we fail
to do the reference modification.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-02-08 22:58:56 +01:00
Josef Bacik
f75e2b79b5 btrfs: allow error injection for btrfs_search_slot and btrfs_cow_block 
The following patches are going to address error handling in relocation,
in order to test those patches I need to be able to inject errors in
btrfs_search_slot and btrfs_cow_block, as we call both of these pretty
often in different cases during relocation.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2021-02-08 22:58:50 +01:00
ethanwu
9a66497156 btrfs: correctly calculate item size used when item key collision happens 
Item key collision is allowed for some item types, like dir item and
inode refs, but the overall item size is limited by the nodesize.

item size(ins_len) passed from btrfs_insert_empty_items to
btrfs_search_slot already contains size of btrfs_item.

When btrfs_search_slot reaches leaf, we'll see if we need to split leaf.
The check incorrectly reports that split leaf is required, because
it treats the space required by the newly inserted item as
btrfs_item + item data. But in item key collision case, only item data
is actually needed, the newly inserted item could merge into the existing
one. No new btrfs_item will be inserted.

And split_leaf return EOVERFLOW from following code:

  if (extend && data_size + btrfs_item_size_nr(l, slot) +
      sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
      return -EOVERFLOW;

In most cases, when callers receive EOVERFLOW, they either return
this error or handle in different ways. For example, in normal dir item
creation the userspace will get errno EOVERFLOW; in inode ref case
INODE_EXTREF is used instead.

However, this is not the case for rename. To avoid the unrecoverable
situation in rename, btrfs_check_dir_item_collision is called in
early phase of rename. In this function, when item key collision is
detected leaf space is checked:

  data_size = sizeof(*di) + name_len;
  if (data_size + btrfs_item_size_nr(leaf, slot) +
      sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info))

the sizeof(struct btrfs_item) + btrfs_item_size_nr(leaf, slot) here
refers to existing item size, the condition here correctly calculates
the needed size for collision case rather than the wrong case above.

The consequence of inconsistent condition check between
btrfs_check_dir_item_collision and btrfs_search_slot when item key
collision happens is that we might pass check here but fail
later at btrfs_search_slot. Rename fails and volume is forced readonly

  [436149.586170] ------------[ cut here ]------------
  [436149.586173] BTRFS: Transaction aborted (error -75)
  [436149.586196] WARNING: CPU: 0 PID: 16733 at fs/btrfs/inode.c:9870 btrfs_rename2+0x1938/0x1b70 [btrfs]
  [436149.586227] CPU: 0 PID: 16733 Comm: python Tainted: G      D           4.18.0-rc5+ #1
  [436149.586228] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016
  [436149.586238] RIP: 0010:btrfs_rename2+0x1938/0x1b70 [btrfs]
  [436149.586254] RSP: 0018:ffffa327043a7ce0 EFLAGS: 00010286
  [436149.586255] RAX: 0000000000000000 RBX: ffff8d8a17d13340 RCX: 0000000000000006
  [436149.586256] RDX: 0000000000000007 RSI: 0000000000000096 RDI: ffff8d8a7fc164b0
  [436149.586257] RBP: ffffa327043a7da0 R08: 0000000000000560 R09: 7265282064657472
  [436149.586258] R10: 0000000000000000 R11: 6361736e61725420 R12: ffff8d8a0d4c8b08
  [436149.586258] R13: ffff8d8a17d13340 R14: ffff8d8a33e0a540 R15: 00000000000001fe
  [436149.586260] FS:  00007fa313933740(0000) GS:ffff8d8a7fc00000(0000) knlGS:0000000000000000
  [436149.586261] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [436149.586262] CR2: 000055d8d9c9a720 CR3: 000000007aae0003 CR4: 00000000003606f0
  [436149.586295] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  [436149.586296] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  [436149.586296] Call Trace:
  [436149.586311]  vfs_rename+0x383/0x920
  [436149.586313]  ? vfs_rename+0x383/0x920
  [436149.586315]  do_renameat2+0x4ca/0x590
  [436149.586317]  __x64_sys_rename+0x20/0x30
  [436149.586324]  do_syscall_64+0x5a/0x120
  [436149.586330]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  [436149.586332] RIP: 0033:0x7fa3133b1d37
  [436149.586348] RSP: 002b:00007fffd3e43908 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
  [436149.586349] RAX: ffffffffffffffda RBX: 00007fa3133b1d30 RCX: 00007fa3133b1d37
  [436149.586350] RDX: 000055d8da06b5e0 RSI: 000055d8da225d60 RDI: 000055d8da2c4da0
  [436149.586351] RBP: 000055d8da2252f0 R08: 00007fa313782000 R09: 00000000000177e0
  [436149.586351] R10: 000055d8da010680 R11: 0000000000000246 R12: 00007fa313840b00

Thanks to Hans van Kranenburg for information about crc32 hash collision
tools, I was able to reproduce the dir item collision with following
python script.
https://github.com/wutzuchieh/misc_tools/blob/master/crc32_forge.py Run
it under a btrfs volume will trigger the abort transaction.  It simply
creates files and rename them to forged names that leads to
hash collision.

There are two ways to fix this. One is to simply revert the patch
878f2d2cb3 ("Btrfs: fix max dir item size calculation") to make the
condition consistent although that patch is correct about the size.

The other way is to handle the leaf space check correctly when
collision happens. I prefer the second one since it correct leaf
space check in collision case. This fix will not account
sizeof(struct btrfs_item) when the item already exists.
There are two places where ins_len doesn't contain
sizeof(struct btrfs_item), however.

  1. extent-tree.c: lookup_inline_extent_backref
  2. file-item.c: btrfs_csum_file_blocks

to make the logic of btrfs_search_slot more clear, we add a flag
search_for_extension in btrfs_path.

This flag indicates that ins_len passed to btrfs_search_slot doesn't
contain sizeof(struct btrfs_item). When key exists, btrfs_search_slot
will use the actual size needed to calculate the required leaf space.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: ethanwu <ethanwu@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-18 14:50:00 +01:00
Qu Wenruo
884b07d0f4 btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors 
To support sectorsize < PAGE_SIZE case, we need to take extra care of
extent buffer accessors.

Since sectorsize is smaller than PAGE_SIZE, one page can contain
multiple tree blocks, we must use eb->start to determine the real offset
to read/write for extent buffer accessors.

This patch introduces two helpers to do this:

- get_eb_page_index()
  This is to calculate the index to access extent_buffer::pages.
  It's just a simple wrapper around "start >> PAGE_SHIFT".

  For sectorsize == PAGE_SIZE case, nothing is changed.
  For sectorsize < PAGE_SIZE case, we always get index as 0, and
  the existing page shift also works.

- get_eb_offset_in_page()
  This is to calculate the offset to access extent_buffer::pages.
  This needs to take extent_buffer::start into consideration.

  For sectorsize == PAGE_SIZE case, extent_buffer::start is always
  aligned to PAGE_SIZE, thus adding extent_buffer::start to
  offset_in_page() won't change the result.
  For sectorsize < PAGE_SIZE case, adding extent_buffer::start gives
  us the correct offset to access.

This patch will touch the following parts to cover all extent buffer
accessors:

- BTRFS_SETGET_HEADER_FUNCS()
- read_extent_buffer()
- read_extent_buffer_to_user()
- memcmp_extent_buffer()
- write_extent_buffer_chunk_tree_uuid()
- write_extent_buffer_fsid()
- write_extent_buffer()
- memzero_extent_buffer()
- copy_extent_buffer_full()
- copy_extent_buffer()
- memcpy_extent_buffer()
- memmove_extent_buffer()
- btrfs_get_token_##bits()
- btrfs_get_##bits()
- btrfs_set_token_##bits()
- btrfs_set_##bits()
- generic_bin_search()

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-09 19:16:10 +01:00
Nikolay Borisov
95b982de37 btrfs: simplify return values in setup_nodes_for_search 
The function is needlessly convoluted. Fix that by:

* removing redundant sret variable definition in both if arms

* replace the again/done labels with direct return statements, the
  function is short enough and doesn't do anything special upon exit

* remove BUG_ON on split_node returning a positive number - it can't
  happen as split_node returns either 0 or a negative error code.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:13 +01:00
Nikolay Borisov
d5286a92ea btrfs: remove useless return value statement in split_node 
At the point when we set 'ret = 0' it's guaranteed that the function is
going to return 0 so directly return 0. No functional changes.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:12 +01:00
Josef Bacik
fe596ca3d3 btrfs: use btrfs_tree_read_lock in btrfs_search_slot 
We no longer use recursion, so
__btrfs_tree_read_lock(BTRFS_NESTING_NORMAL) == btrfs_tree_read_lock.
Replace this call with the simple helper.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:09 +01:00
Josef Bacik
1bb9659841 btrfs: merge back btrfs_read_lock_root_node helpers 
We no longer have recursive locking and there's no need for separate
helpers that allowed the transition to rwsem with minimal code changes.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:09 +01:00
Josef Bacik
2f5239dcb2 btrfs: remove btrfs_path::recurse 
With my async free space cache loading patches ("btrfs: load free space
cache asynchronously") we no longer have a user of path->recurse and can
remove it.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:09 +01:00
Josef Bacik
0e46318df8 btrfs: unlock to current level in btrfs_next_old_leaf 
Filipe reported the following lockdep splat

  ======================================================
  WARNING: possible circular locking dependency detected
  5.10.0-rc2-btrfs-next-71 #1 Not tainted
  ------------------------------------------------------
  find/324157 is trying to acquire lock:
  ffff8ebc48d293a0 (btrfs-tree-01#2/3){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]

  but task is already holding lock:
  ffff8eb9932c5088 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #1 (btrfs-tree-00){++++}-{3:3}:
	 lock_acquire+0xd8/0x490
	 down_write_nested+0x44/0x120
	 __btrfs_tree_lock+0x27/0x120 [btrfs]
	 btrfs_search_slot+0x2a3/0xc50 [btrfs]
	 btrfs_insert_empty_items+0x58/0xa0 [btrfs]
	 insert_with_overflow+0x44/0x110 [btrfs]
	 btrfs_insert_xattr_item+0xb8/0x1d0 [btrfs]
	 btrfs_setxattr+0xd6/0x4c0 [btrfs]
	 btrfs_setxattr_trans+0x68/0x100 [btrfs]
	 __vfs_setxattr+0x66/0x80
	 __vfs_setxattr_noperm+0x70/0x200
	 vfs_setxattr+0x6b/0x120
	 setxattr+0x125/0x240
	 path_setxattr+0xba/0xd0
	 __x64_sys_setxattr+0x27/0x30
	 do_syscall_64+0x33/0x80
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #0 (btrfs-tree-01#2/3){++++}-{3:3}:
	 check_prev_add+0x91/0xc60
	 __lock_acquire+0x1689/0x3130
	 lock_acquire+0xd8/0x490
	 down_read_nested+0x45/0x220
	 __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
	 btrfs_next_old_leaf+0x27d/0x580 [btrfs]
	 btrfs_real_readdir+0x1e3/0x4b0 [btrfs]
	 iterate_dir+0x170/0x1c0
	 __x64_sys_getdents64+0x83/0x140
	 do_syscall_64+0x33/0x80
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  other info that might help us debug this:

   Possible unsafe locking scenario:

	 CPU0                    CPU1
	 ----                    ----
    lock(btrfs-tree-00);
				 lock(btrfs-tree-01#2/3);
				 lock(btrfs-tree-00);
    lock(btrfs-tree-01#2/3);

   *** DEADLOCK ***

  5 locks held by find/324157:
   #0: ffff8ebc502c6e00 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x4d/0x60
   #1: ffff8eb97f689980 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: iterate_dir+0x52/0x1c0
   #2: ffff8ebaec00ca58 (btrfs-tree-02#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
   #3: ffff8eb98f986f78 (btrfs-tree-01#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
   #4: ffff8eb9932c5088 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]

  stack backtrace:
  CPU: 2 PID: 324157 Comm: find Not tainted 5.10.0-rc2-btrfs-next-71 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x8d/0xb5
   check_noncircular+0xff/0x110
   ? mark_lock.part.0+0x468/0xe90
   check_prev_add+0x91/0xc60
   __lock_acquire+0x1689/0x3130
   ? kvm_clock_read+0x14/0x30
   ? kvm_sched_clock_read+0x5/0x10
   lock_acquire+0xd8/0x490
   ? __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
   down_read_nested+0x45/0x220
   ? __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
   __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
   btrfs_next_old_leaf+0x27d/0x580 [btrfs]
   btrfs_real_readdir+0x1e3/0x4b0 [btrfs]
   iterate_dir+0x170/0x1c0
   __x64_sys_getdents64+0x83/0x140
   ? filldir+0x1d0/0x1d0
   do_syscall_64+0x33/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

This happens because btrfs_next_old_leaf searches down to our current
key, and then walks up the path until we can move to the next slot, and
then reads back down the path so we get the next leaf.

However it doesn't unlock any lower levels until it replaces them with
the new extent buffer.  This is technically fine, but of course causes
lockdep to complain, because we could be holding locks on lower levels
while locking upper levels.

Fix this by dropping all nodes below the level that we use as our new
starting point before we start reading back down the path.  This also
allows us to drop the nested/recursive locking magic, because we're no
longer locking two nodes at the same level anymore.

Reported-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:09 +01:00
Josef Bacik
ffeb03cfe2 btrfs: cleanup the locking in btrfs_next_old_leaf 
We are carrying around this next_rw_lock from when we would do spinning
vs blocking read locks.  Now that we have the rwsem locking we can
simply use the read lock flag unconditionally and the read lock helpers.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:09 +01:00
Josef Bacik
1b7ec85ef4 btrfs: pass root owner to read_tree_block 
In order to properly set the lockdep class of a newly allocated block we
need to know the owner of the block.  For non-refcounted trees this is
straightforward, we always know in advance what tree we're reading from.
For refcounted trees we don't necessarily know, however all refcounted
trees share the same lockdep class name, tree-<level>.

Fix all the callers of read_tree_block() to pass in the root objectid
we're using.  In places like relocation and backref we could probably
unconditionally use 0, but just in case use the root when we have it,
otherwise use 0 in the cases we don't have the root as it's going to be
a refcounted tree anyway.

This is a preparation patch for further changes.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:07 +01:00
Josef Bacik
206983b72a btrfs: use btrfs_read_node_slot in btrfs_realloc_node 
We have this open-coded nightmare in btrfs_realloc_node that does
the same thing that the normal read path does, which is to see if we
have the eb in memory already, and if not read it, and verify the eb is
uptodate.  Delete this open coding and simply use btrfs_read_node_slot.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 2020-12-08 15:54:06 +01:00