btrfs: add forward declarations and headers, part 1

Do a cleanup in the short headers:

- add forward declarations for types referenced by pointers
- add includes when types need them

This fixes potential compilation problems if the headers are reordered
or the missing includes are not provided indirectly.

Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: make module init/exit match their sequence

[BACKGROUND]
In theory init_btrfs_fs() and exit_btrfs_fs() should match their
sequence, thus normally they should look like this:

init_btrfs_fs() | exit_btrfs_fs()
----------------------+------------------------
init_A(); |
init_B(); |
init_C(); |
| exit_C();
| exit_B();
| exit_A();

So is for the error path of init_btrfs_fs().

But it's not the case, some exit functions don't match their init
functions sequence in init_btrfs_fs().

Furthermore in init_btrfs_fs(), we need to have a new error label for
each new init function we added. This is not really expandable,
especially recently we may add several new functions to init_btrfs_fs().

[ENHANCEMENT]
The patch will introduce the following things to enhance the situation:

- struct init_sequence
Just a wrapper of init and exit function pointers.

The init function must use int type as return value, thus some init
functions need to be updated to return 0.

The exit function can be NULL, as there are some init sequence just
outputting a message.

- struct mod_init_seq[] array
This is a const array, recording all the initialization we need to do
in init_btrfs_fs(), and the order follows the old init_btrfs_fs().

- bool mod_init_result[] array
This is a bool array, recording if we have initialized one entry in
mod_init_seq[].

The reason to split mod_init_seq[] and mod_init_result[] is to avoid
section mismatch in reference.

All init function are in .init.text, but if mod_init_seq[] records
the @initialized member it can no longer be const, thus will be put
into .data section, and cause modpost warning.

For init_btrfs_fs() we just call all init functions in their order in
mod_init_seq[] array, and after each call, setting corresponding
mod_init_result[] to true.

For exit_btrfs_fs() and error handling path of init_btrfs_fs(), we just
iterate mod_init_seq[] in reverse order, and skip all uninitialized
entry.

With this patch, init_btrfs_fs()/exit_btrfs_fs() will be much easier to
expand and will always follow the strict order.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: move common inode creation code into btrfs_create_new_inode()

All of our inode creation code paths duplicate the calls to
btrfs_init_inode_security() and btrfs_add_link(). Subvolume creation
additionally duplicates property inheritance and the call to
btrfs_set_inode_index(). Fix this by moving the common code into
btrfs_create_new_inode(). This accomplishes a few things at once:

1. It reduces code duplication.

2. It allows us to set up the inode completely before inserting the
inode item, removing calls to btrfs_update_inode().

3. It fixes a leak of an inode on disk in some error cases. For example,
in btrfs_create(), if btrfs_new_inode() succeeds, then we have
inserted an inode item and its inode ref. However, if something after
that fails (e.g., btrfs_init_inode_security()), then we end the
transaction and then decrement the link count on the inode. If the
transaction is committed and the system crashes before the failed
inode is deleted, then we leak that inode on disk. Instead, this
refactoring aborts the transaction when we can't recover more
gracefully.

4. It exposes various ways that subvolume creation diverges from mkdir
in terms of inheriting flags, properties, permissions, and POSIX
ACLs, a lot of which appears to be accidental. This patch explicitly
does _not_ change the existing non-standard behavior, but it makes
those differences more clear in the code and documents them so that
we can discuss whether they should be changed.

Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: skip compression property for anything other than files and dirs

The compression property only has effect on regular files and directories
(so that it's propagated to files and subdirectories created inside a
directory). For any other inode type (symlink, fifo, device, socket),
it's pointless to set the compression property because it does nothing
and ends up unnecessarily wasting leaf space due to the pointless xattr
(75 or 76 bytes, depending on the compression value). Symlinks in
particular are very common (for example, I have almost 10k symlinks under
/etc, /usr and /var alone) and therefore it's worth to avoid wasting
leaf space with the compression xattr.

For example, the compression property can end up on a symlink or character
device implicitly, through inheritance from a parent directory

$ mkdir /mnt/testdir
$ btrfs property set /mnt/testdir compression lzo

$ ln -s yadayada /mnt/testdir/lnk
$ mknod /mnt/testdir/dev c 0 0

Or explicitly like this:

$ ln -s yadayda /mnt/lnk
$ setfattr -h -n btrfs.compression -v lzo /mnt/lnk

So skip the compression property on inodes that are neither a regular
file nor a directory.

CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: do not allow compression on nodatacow files

Compression and nodatacow are mutually exclusive. A similar issue was
fixed by commit f37c563bab429 ("btrfs: add missing check for nocow and
compression inode flags"). Besides ioctl, there is another way to
enable/disable/reset compression directly via xattr. The following
steps will result in a invalid combination.

$ touch bar
$ chattr +C bar
$ lsattr bar
---------------C-- bar
$ setfattr -n btrfs.compression -v zstd bar
$ lsattr bar
--------c------C-- bar

To align with the logic in check_fsflags, nocompress will also be
unacceptable after this patch, to prevent mix any compression-related
options with nodatacow.

$ touch bar
$ chattr +C bar
$ lsattr bar
---------------C-- bar
$ setfattr -n btrfs.compression -v zstd bar
setfattr: bar: Invalid argument
$ setfattr -n btrfs.compression -v no bar
setfattr: bar: Invalid argument

When both compression and nodatacow are enabled, then
btrfs_run_delalloc_range prefers nodatacow and no compression happens.

Reported-by: Jayce Lin <jaycelin@synology.com>
CC: stable@vger.kernel.org # 5.10.x: e6f9d6964802: btrfs: export a helper for compression hard check
CC: stable@vger.kernel.org # 5.10.x
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chung-Chiang Cheng <cccheng@synology.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: delete unused function btrfs_set_prop_trans

The last consumer of btrfs_set_prop_trans() was taken away by the patch
("btrfs: start transaction in xattr_handler_set_prop") so now this
function can be deleted.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: export btrfs_set_prop

Make btrfs_set_prop() a non-static function, so that it can be called
from btrfs_ioctl_setflags(). We need btrfs_set_prop() instead of
btrfs_set_prop_trans() so that we can use the transaction which is
already started in the current thread.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: refactor btrfs_set_props to validate externally

In preparation to merge multiple transactions when setting the
compression flags, split btrfs_set_props() validation part outside of
it.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: refactor btrfs_set_prop and add btrfs_set_prop_trans

btrfs_set_prop() takes transaction pointer as the first argument,
however in ioctl.c for the purpose of setting the compression property,
we call btrfs_set_prop() with NULL transaction pointer. Down in
the call chain btrfs_setxattr() starts transaction to update the
attribute and also to update the inode.

So for clarity, create btrfs_set_prop_trans() with no transaction
pointer as argument, in preparation to start transaction here instead of
doing it down the call chain at btrfs_setxattr().

Also now the btrfs_set_prop() is a static function.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: merge _btrfs_set_prop helpers

btrfs_set_prop() is a redirect to __btrfs_set_prop() with the
transaction handle equal to NULL. __btrfs_set_prop() in turn passes
this to do_setxattr() which then transaction is actually created.

Instead merge __btrfs_set_prop() to btrfs_set_prop(), and update the
caller with NULL argument.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: replace GPL boilerplate by SPDX -- headers

Remove GPL boilerplate text (long, short, one-line) and keep the rest,
ie. personal, company or original source copyright statements. Add the
SPDX header.

Unify the include protection macros to match the file names.

Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: add support for inode properties

This change adds infrastructure to allow for generic properties for
inodes. Properties are name/value pairs that can be associated with
inodes for different purposes. They are stored as xattrs with the
prefix "btrfs."

Properties can be inherited - this means when a directory inode has
inheritable properties set, these are added to new inodes created
under that directory. Further, subvolumes can also have properties
associated with them, and they can be inherited from their parent
subvolume. Naturally, directory properties have priority over subvolume
properties (in practice a subvolume property is just a regular
property associated with the root inode, objectid 256, of the
subvolume's fs tree).

This change also adds one specific property implementation, named
"compression", whose values can be "lzo" or "zlib" and it's an
inheritable property.

The corresponding changes to btrfs-progs were also implemented.
A patch with xfstests for this feature will follow once there's
agreement on this change/feature.

Further, the script at the bottom of this commit message was used to
do some benchmarks to measure any performance penalties of this feature.

Basically the tests correspond to:

Test 1 - create a filesystem and mount it with compress-force=lzo,
then sequentially create N files of 64Kb each, measure how long it took
to create the files, unmount the filesystem, mount the filesystem and
perform an 'ls -lha' against the test directory holding the N files, and
report the time the command took.

Test 2 - create a filesystem and don't use any compression option when
mounting it - instead set the compression property of the subvolume's
root to 'lzo'. Then create N files of 64Kb, and report the time it took.
The unmount the filesystem, mount it again and perform an 'ls -lha' like
in the former test. This means every single file ends up with a property
(xattr) associated to it.

Test 3 - same as test 2, but uses 4 properties - 3 are duplicates of the
compression property, have no real effect other than adding more work
when inheriting properties and taking more btree leaf space.

Test 4 - same as test 3 but with 10 properties per file.

Results (in seconds, and averages of 5 runs each), for different N
numbers of files follow.

* Without properties (test 1)

file creation time ls -lha time
10 000 files 3.49 0.76
100 000 files 47.19 8.37
1 000 000 files 518.51 107.06

* With 1 property (compression property set to lzo - test 2)

file creation time ls -lha time
10 000 files 3.63 0.93
100 000 files 48.56 9.74
1 000 000 files 537.72 125.11

* With 4 properties (test 3)

file creation time ls -lha time
10 000 files 3.94 1.20
100 000 files 52.14 11.48
1 000 000 files 572.70 142.13

* With 10 properties (test 4)

file creation time ls -lha time
10 000 files 4.61 1.35
100 000 files 58.86 13.83
1 000 000 files 656.01 177.61

The increased latencies with properties are essencialy because of:

*) When creating an inode, we now synchronously write 1 more item
(an xattr item) for each property inherited from the parent dir
(or subvolume). This could be done in an asynchronous way such
as we do for dir intex items (delayed-inode.c), which could help
reduce the file creation latency;

*) With properties, we now have larger fs trees. For this particular
test each xattr item uses 75 bytes of leaf space in the fs tree.
This could be less by using a new item for xattr items, instead of
the current btrfs_dir_item, since we could cut the 'location' and
'type' fields (saving 18 bytes) and maybe 'transid' too (saving a
total of 26 bytes per xattr item) from the btrfs_dir_item type.

Also tried batching the xattr insertions (ignoring proper hash
collision handling, since it didn't exist) when creating files that
inherit properties from their parent inode/subvolume, but the end
results were (surprisingly) essentially the same.

Test script:

$ cat test.pl
#!/usr/bin/perl -w

use strict;
use Time::HiRes qw(time);
use constant NUM_FILES => 10_000;
use constant FILE_SIZES => (64 * 1024);
use constant DEV => '/dev/sdb4';
use constant MNT_POINT => '/home/fdmanana/btrfs-tests/dev';
use constant TEST_DIR => (MNT_POINT . '/testdir');

system("mkfs.btrfs", "-l", "16384", "-f", DEV) == 0 or die "mkfs.btrfs failed!";

# following line for testing without properties
#system("mount", "-o", "compress-force=lzo", DEV, MNT_POINT) == 0 or die "mount failed!";

# following 2 lines for testing with properties
system("mount", DEV, MNT_POINT) == 0 or die "mount failed!";
system("btrfs", "prop", "set", MNT_POINT, "compression", "lzo") == 0 or die "set prop failed!";

system("mkdir", TEST_DIR) == 0 or die "mkdir failed!";
my ($t1, $t2);

$t1 = time();
for (my $i = 1; $i <= NUM_FILES; $i++) {
my $p = TEST_DIR . '/file_' . $i;
open(my $f, '>', $p) or die "Error opening file!";
$f->autoflush(1);
for (my $j = 0; $j < FILE_SIZES; $j += 4096) {
print $f ('A' x 4096) or die "Error writing to file!";
}
close($f);
}
$t2 = time();
print "Time to create " . NUM_FILES . ": " . ($t2 - $t1) . " seconds.\n";
system("umount", DEV) == 0 or die "umount failed!";
system("mount", DEV, MNT_POINT) == 0 or die "mount failed!";

$t1 = time();
system("bash -c 'ls -lha " . TEST_DIR . " > /dev/null'") == 0 or die "ls failed!";
$t2 = time();
print "Time to ls -lha all files: " . ($t2 - $t1) . " seconds.\n";
system("umount", DEV) == 0 or die "umount failed!";

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>