Commit graph

415 commits

Author SHA1 Message Date
Qu Wenruo
c2ffb1ec1a btrfs: prepare compression folio alloc/free for bs > ps cases
This includes the following preparation for bs > ps cases:

- Always alloc/free the folio directly if bs > ps
  This adds a new @fs_info parameter for btrfs_alloc_compr_folio(), thus
  affecting all compression algorithms.

  For btrfs_free_compr_folio() it needs no parameter for now, as we can
  use the folio size to skip the caching part.

  For now the change is just to passing a @fs_info into the function,
  all the folio size assumption is still based on page size.

- Properly zero the last folio in compress_file_range()
  Since the compressed folios can be larger than a page, we need to
  properly zero the whole folio.

- Use correct folio size for btrfs_add_compressed_bio_folios()
  Instead of page size, use the correct folio size.

- Use correct folio size/shift for btrfs_compress_filemap_get_folio()
  As we are not only using simple page sized folios anymore.

- Use correct folio size for btrfs_decompress()
  There is an ASSERT() making sure the decompressed range is no larger
  than a page, which will be triggered for bs > ps cases.

- Skip readahead for compressed pages
  Similar to subpage cases.

- Make btrfs_alloc_folio_array() to accept a new @order parameter

- Add a helper to calculate the minimal folio size

All those changes should not affect the existing bs <= ps handling.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:24 +02:00
David Sterba
17dc82dc1e btrfs: fix typos in comments and strings
Annual typo fixing pass. Strangely codespell found only about 30% of
what is in this patch, the rest was done manually using text
spellchecker with a custom dictionary of acceptable terms.

Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:16 +02:00
Qu Wenruo
0d0b80929e btrfs: rename btrfs_compress_op to btrfs_compress_levels
Since all workspace managers are per-fs, there is no need nor no way to
store them inside btrfs_compress_op::wsm anymore.

With that said, we can do the following modifications:

- Remove zstd_workspace_mananger::ops
  Zstd always grab the global btrfs_compress_op[].
- Remove btrfs_compress_op::wsm member
- Rename btrfs_compress_op to btrfs_compress_levels

This should make it more clear that btrfs_compress_levels structures are
only to indicate the levels of each compress algorithm.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:16 +02:00
Qu Wenruo
9c8f4cf456 btrfs: cleanup the per-module compression workspace managers
Since all workspaces are handled by the per-fs workspace managers, we
can safely remove the old per-module managers.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:16 +02:00
Qu Wenruo
856d46c313 btrfs: migrate to use per-fs workspace manager
There are several interfaces involved for each algorithm:

- alloc workspace
  All algorithms allocate a workspace without the need for workspace
  manager.
  So no change needs to be done.

- get workspace
  This involves checking the workspace manager to find a free one, and
  if not, allocate a new one.

  For none and lzo, they share the same generic btrfs_get_workspace()
  helper, only needs to update that function to use the per-fs manager.

  For zlib it uses a wrapper around btrfs_get_workspace(), so no special
  work needed.

  For zstd, update zstd_find_workspace() and zstd_get_workspace() to
  utilize the per-fs manager.

- put workspace
  For none/zlib/lzo they share the same btrfs_put_workspace(), update
  that function to use the per-fs manager.

  For zstd, it's zstd_put_workspace(), the same update.

- zstd specific timer
  This is the timer to reclaim workspace, change it to grab the per-fs
  workspace manager instead.

Now all workspace are managed by the per-fs manager.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:15 +02:00
Qu Wenruo
6f9c3f48ac btrfs: add generic workspace manager initialization
This involves:

- Add (alloc|free)_workspace_manager helpers.
  These are the helper to alloc/free workspace_manager structure.

  The allocator will allocate a workspace_manager structure, initialize
  it, and pre-allocate one workspace for it.

  The freer will do the cleanup and set the manager pointer to NULL.

- Call alloc_workspace_manager() inside btrfs_alloc_compress_wsm()
- Call alloc_workspace_manager() inside btrfs_free_compress_wsm()
  For none, zlib and lzo compression algorithms.

For now the generic per-fs workspace managers won't really have any effect,
and all compression is still going through the global workspace manager.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:15 +02:00
Qu Wenruo
330f02b136 btrfs: add workspace manager initialization for zstd
This involves:

- Add zstd_alloc_workspace_manager() and zstd_free_workspace_manager()
  Those two functions will accept an fs_info pointer, and alloc/free
  fs_info->compr_wsm[BTRFS_COMPRESS_ZSTD] pointer.

- Add btrfs_alloc_compress_wsm() and btrfs_free_compress_wsm()
  Those are helpers allocating the workspace managers for all
  algorithms.
  For now only zstd is supported, and the timing is a little unusual,
  the btrfs_alloc_compress_wsm() should only be called after the
  sectorsize being initialized.

  Meanwhile btrfs_free_fs_info_compress() is called in
  btrfs_free_fs_info().

- Move the definition of btrfs_compression_type to "fs.h"
  The reason is that "compression.h" has already included "fs.h", thus
  we can not just include "compression.h" to get the definition of
  BTRFS_NR_COMPRESS_TYPES to define fs_info::compr_wsm[].

For now the per-fs zstd workspace manager won't really have any effect,
and all compression is still going through the global workspace manager.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:15 +02:00
Qu Wenruo
2c5cca03c1 btrfs: add an fs_info parameter for compression workspace manager
[BACKGROUND]
Currently btrfs shares workspaces and their managers for all filesystems,
this is mostly fine as all those workspaces are using page size based
buffers, and btrfs only support block size (bs) <= page size (ps).

This means even if bs < ps, we at most waste some buffer space in the
workspace, but everything will still work fine.

The problem here is that is limiting our support for bs > ps cases.

As now a workspace now may need larger buffer to handle bs > ps cases,
but since the pool has no way to distinguish different workspaces, a
regular workspace (which is still using buffer size based on ps) can be
passed to a btrfs whose bs > ps.

In that case the buffer is not large enough, and will cause various
problems.

[ENHANCEMENT]
To prepare for the per-fs workspace migration, add an fs_info parameter
to all workspace related functions.

For now this new fs_info parameter is not yet utilized.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-23 08:49:15 +02:00
Qu Wenruo
d71b419f27 btrfs: pass btrfs_inode pointer directly into btrfs_compress_folios()
For the 3 supported compression algorithms, two of them (zstd and zlib)
are already grabbing the btrfs inode for error messages.

It's more common to pass btrfs_inode and grab the address space from it.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-22 10:54:31 +02:00
Boris Burkov
f07b855c56 btrfs: try to search for data csums in commit root
If you run a workload with:

- a cgroup that does tons of parallel data reading, with a working set
  much larger than its memory limit
- a second cgroup that writes relatively fewer files, with overwrites,
  with no memory limit
(see full code listing at the bottom for a reproducer)

Then what quickly occurs is:

- we have a large number of threads trying to read the csum tree
- we have a decent number of threads deleting csums running delayed refs
- we have a large number of threads in direct reclaim and thus high
  memory pressure

The result of this is that we writeback the csum tree repeatedly mid
transaction, to get back the extent_buffer folios for reclaim. As a
result, we repeatedly COW the csum tree for the delayed refs that are
deleting csums. This means repeatedly write locking the higher levels of
the tree.

As a result of this, we achieve an unpleasant priority inversion. We
have:

- a high degree of contention on the csum root node (and other upper
  nodes) eb rwsem
- a memory starved cgroup doing tons of reclaim on CPU.
- many reader threads in the memory starved cgroup "holding" the sem
  as readers, but not scheduling promptly. i.e., task __state == 0, but
  not running on a cpu.
- btrfs_commit_transaction stuck trying to acquire the sem as a writer.
  (running delayed_refs, deleting csums for unreferenced data extents)

This results in arbitrarily long transactions. This then results in
seriously degraded performance for any cgroup using the filesystem (the
victim cgroup in the script).

It isn't an academic problem, as we see this exact problem in production
at Meta with one cgroup over its memory limit ruining btrfs performance
for the whole system, stalling critical system services that depend on
btrfs syncs.

The underlying scheduling "problem" with global rwsems is sort of thorny
and apparently well known and was discussed at LPC 2024, for example.

As a result, our main lever in the short term is just trying to reduce
contention on our various rwsems with an eye to reducing the frequency
of write locking, to avoid disabling the read lock fast acquisition path.

Luckily, it seems likely that many reads are for old extents written
many transactions ago, and that for those we *can* in fact search the
commit root. The commit_root_sem only gets taken write once, near the
end of transaction commit, no matter how much memory pressure there is,
so we have much less contention between readers and writers.

This change detects when we are trying to read an old extent (according
to extent map generation) and then wires that through bio_ctrl to the
btrfs_bio, which unfortunately isn't allocated yet when we have this
information. When we go to lookup the csums in lookup_bio_sums we can
check this condition on the btrfs_bio and do the commit root lookup
accordingly.

Note that a single bio_ctrl might collect a few extent_maps into a single
bio, so it is important to track a maximum generation across all the
extent_maps used for each bio to make an accurate decision on whether it
is valid to look in the commit root. If any extent_map is updated in the
current generation, we can't use the commit root.

To test and reproduce this issue, I used the following script and
accompanying C program (to avoid bottlenecks in constantly forking
thousands of dd processes):

====== big-read.c ======
  #include <fcntl.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <sys/mman.h>
  #include <sys/stat.h>
  #include <unistd.h>
  #include <errno.h>

  #define BUF_SZ (128 * (1 << 10UL))

  int read_once(int fd, size_t sz) {
  	char buf[BUF_SZ];
  	size_t rd = 0;
  	int ret = 0;

  	while (rd < sz) {
  		ret = read(fd, buf, BUF_SZ);
  		if (ret < 0) {
  			if (errno == EINTR)
  				continue;
  			fprintf(stderr, "read failed: %d\n", errno);
  			return -errno;
  		} else if (ret == 0) {
  			break;
  		} else {
  			rd += ret;
  		}
  	}
  	return rd;
  }

  int read_loop(char *fname) {
  	int fd;
  	struct stat st;
  	size_t sz = 0;
  	int ret;

  	while (1) {
  		fd = open(fname, O_RDONLY);
  		if (fd == -1) {
  			perror("open");
  			return 1;
  		}
  		if (!sz) {
  			if (!fstat(fd, &st)) {
  				sz = st.st_size;
  			} else {
  				perror("stat");
  				return 1;
  			}
  		}

                  ret = read_once(fd, sz);
  		close(fd);
  	}
  }

  int main(int argc, char *argv[]) {
  	int fd;
  	struct stat st;
  	off_t sz;
  	char *buf;
  	int ret;

  	if (argc != 2) {
  		fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
  		return 1;
  	}

  	return read_loop(argv[1]);
  }

====== repro.sh ======
  #!/usr/bin/env bash

  SCRIPT=$(readlink -f "$0")
  DIR=$(dirname "$SCRIPT")

  dev=$1
  mnt=$2
  shift
  shift

  CG_ROOT=/sys/fs/cgroup
  BAD_CG=$CG_ROOT/bad-nbr
  GOOD_CG=$CG_ROOT/good-nbr
  NR_BIGGOS=1
  NR_LITTLE=10
  NR_VICTIMS=32
  NR_VILLAINS=512

  START_SEC=$(date +%s)

  _elapsed() {
  	echo "elapsed: $(($(date +%s) - $START_SEC))"
  }

  _stats() {
  	local sysfs=/sys/fs/btrfs/$(findmnt -no UUID $dev)

  	echo "================"
  	date
  	_elapsed
  	cat $sysfs/commit_stats
  	cat $BAD_CG/memory.pressure
  }

  _setup_cgs() {
  	echo "+memory +cpuset" > $CG_ROOT/cgroup.subtree_control
  	mkdir -p $GOOD_CG
  	mkdir -p $BAD_CG
  	echo max > $BAD_CG/memory.max
  	# memory.high much less than the working set will cause heavy reclaim
  	echo $((1 << 30)) > $BAD_CG/memory.high

  	# victims get a subset of villain CPUs
  	echo 0 > $GOOD_CG/cpuset.cpus
  	echo 0,1,2,3 > $BAD_CG/cpuset.cpus
  }

  _kill_cg() {
  	local cg=$1
  	local attempts=0
  	echo "kill cgroup $cg"
  	[ -f $cg/cgroup.procs ] || return
  	while true; do
  		attempts=$((attempts + 1))
  		echo 1 > $cg/cgroup.kill
  		sleep 1
  		procs=$(wc -l $cg/cgroup.procs | cut -d' ' -f1)
  		[ $procs -eq 0 ] && break
  	done
  	rmdir $cg
  	echo "killed cgroup $cg in $attempts attempts"
  }

  _biggo_vol() {
  	echo $mnt/biggo_vol.$1
  }

  _biggo_file() {
  	echo $(_biggo_vol $1)/biggo
  }

  _subvoled_biggos() {
  	total_sz=$((10 << 30))
  	per_sz=$((total_sz / $NR_VILLAINS))
  	dd_count=$((per_sz >> 20))
  	echo "create $NR_VILLAINS subvols with a file of size $per_sz bytes for a total of $total_sz bytes."
  	for i in $(seq $NR_VILLAINS)
  	do
  		btrfs subvol create $(_biggo_vol $i) &>/dev/null
  		dd if=/dev/zero of=$(_biggo_file $i) bs=1M count=$dd_count &>/dev/null
  	done
  	echo "done creating subvols."
  }

  _setup() {
  	[ -f .done ] && rm .done
  	findmnt -n $dev && exit 1
        if [ -f .re-mkfs ]; then
		mkfs.btrfs -f -m single -d single $dev >/dev/null || exit 2
	else
		echo "touch .re-mkfs to populate the test fs"
	fi

  	mount -o noatime $dev $mnt || exit 3
  	[ -f .re-mkfs ] && _subvoled_biggos
  	_setup_cgs
  }

  _my_cleanup() {
  	echo "CLEANUP!"
  	_kill_cg $BAD_CG
  	_kill_cg $GOOD_CG
  	sleep 1
  	umount $mnt
  }

  _bad_exit() {
  	_err "Unexpected Exit! $?"
  	_stats
  	exit $?
  }

  trap _my_cleanup EXIT
  trap _bad_exit INT TERM

  _setup

  # Use a lot of page cache reading the big file
  _villain() {
  	local i=$1
  	echo $BASHPID > $BAD_CG/cgroup.procs
  	$DIR/big-read $(_biggo_file $i)
  }

  # Hit del_csum a lot by overwriting lots of small new files
  _victim() {
  	echo $BASHPID > $GOOD_CG/cgroup.procs
  	i=0;
  	while (true)
  	do
  		local tmp=$mnt/tmp.$i

  		dd if=/dev/zero of=$tmp bs=4k count=2 >/dev/null 2>&1
  		i=$((i+1))
  		[ $i -eq $NR_LITTLE ] && i=0
  	done
  }

  _one_sync() {
  	echo "sync..."
  	before=$(date +%s)
  	sync
  	after=$(date +%s)
  	echo "sync done in $((after - before))s"
  	_stats
  }

  # sync in a loop
  _sync() {
  	echo "start sync loop"
  	syncs=0
  	echo $BASHPID > $GOOD_CG/cgroup.procs
  	while true
  	do
  		[ -f .done ] && break
  		_one_sync
  		syncs=$((syncs + 1))
  		[ -f .done ] && break
  		sleep 10
  	done
  	if [ $syncs -eq 0 ]; then
  		echo "do at least one sync!"
  		_one_sync
  	fi
  	echo "sync loop done."
  }

  _sleep() {
  	local time=${1-60}
  	local now=$(date +%s)
  	local end=$((now + time))
  	while [ $now -lt $end ];
  	do
  		echo "SLEEP: $((end - now))s left. Sleep 10."
  		sleep 10
  		now=$(date +%s)
  	done
  }

  echo "start $NR_VILLAINS villains"
  for i in $(seq $NR_VILLAINS)
  do
  	_villain $i &
  	disown # get rid of annoying log on kill (done via cgroup anyway)
  done

  echo "start $NR_VICTIMS victims"
  for i in $(seq $NR_VICTIMS)
  do
  	_victim &
  	disown
  done

  _sync &
  SYNC_PID=$!

  _sleep $1
  _elapsed
  touch .done
  wait $SYNC_PID

  echo "OK"
  exit 0

Without this patch, that reproducer:

- Ran for 6+ minutes instead of 60s
- Hung hundreds of threads in D state on the csum reader lock
- Got a commit stuck for 3 minutes

sync done in 388s
================
Wed Jul  9 09:52:31 PM UTC 2025
elapsed: 420
commits 2
cur_commit_ms 0
last_commit_ms 159446
max_commit_ms 159446
total_commit_ms 160058
some avg10=99.03 avg60=98.97 avg300=75.43 total=418033386
full avg10=82.79 avg60=80.52 avg300=59.45 total=324995274

419 hits state R, D comms big-read
                 btrfs_tree_read_lock_nested
                 btrfs_read_lock_root_node
                 btrfs_search_slot
                 btrfs_lookup_csum
                 btrfs_lookup_bio_sums
                 btrfs_submit_bbio

1 hits state D comms btrfs-transacti
                 btrfs_tree_lock_nested
                 btrfs_lock_root_node
                 btrfs_search_slot
                 btrfs_del_csums
                 __btrfs_run_delayed_refs
                 btrfs_run_delayed_refs

With the patch, the reproducer exits naturally, in 65s, completing a
pretty decent 4 commits, despite heavy memory pressure. Occasionally you
can still trigger a rather long commit (couple seconds) but never one
that is minutes long.

sync done in 3s
================
elapsed: 65
commits 4
cur_commit_ms 0
last_commit_ms 485
max_commit_ms 689
total_commit_ms 2453
some avg10=98.28 avg60=64.54 avg300=19.39 total=64849893
full avg10=74.43 avg60=48.50 avg300=14.53 total=48665168

some random rwalker samples showed the most common stack in reclaim,
rather than the csum tree:
145 hits state R comms bash, sleep, dd, shuf
                 shrink_folio_list
                 shrink_lruvec
                 shrink_node
                 do_try_to_free_pages
                 try_to_free_mem_cgroup_pages
                 reclaim_high

Link: https://lpc.events/event/18/contributions/1883/
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-22 10:54:31 +02:00
Qu Wenruo
b98b208300 btrfs: reject invalid compression level
Inspired by recent changes to compression level parsing in
6db1df415d ("btrfs: accept and ignore compression level for lzo")
it turns out that we do not do any extra validation for compression
level input string, thus allowing things like "compress=lzo:invalid" to
be accepted without warnings.

Although we accept levels that are beyond the supported algorithm
ranges, accepting completely invalid level specification is not correct.

Fix the too loose checks for compression level, by doing proper error
handling of kstrtoint(), so that we will reject not only too large
values (beyond int range) but also completely wrong levels like
"lzo:invalid".

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-09-18 13:18:49 +02:00
David Sterba
ab5fcbb1ad btrfs: use pgoff_t for page index variables
Any conversion of offsets in the logical or the physical mapping space
of the pages is done by a shift and the target type should be pgoff_t
(type of struct page::index). Fix the locations where it's still
unsigned long.

Signed-off-by: David Sterba <dsterba@suse.com>
2025-07-21 23:58:05 +02:00
George Hu
afd1dacbd0 btrfs: replace nested usage of min & max with clamp in btrfs_compress_set_level()
Refactor the btrfs_compress_set_level() function by replacing the
nested usage of min() and max() macro with clamp() to simplify the
code and improve readability.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: George Hu <integral@archlinux.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-07-21 23:58:05 +02:00
David Sterba
44cac52341 btrfs: use our message helpers instead of pr_err/pr_warn/pr_info
Our message helpers accept NULL for the fs_info in the context that does
not provide and print the common header of the message. The use of pr_*
helpers is only for special reasons, like module loading, device
scanning or multi-line output (print-tree).

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-07-21 23:58:04 +02:00
David Sterba
d2080c7a00 btrfs: rename ret2 to ret in btrfs_submit_compressed_read()
We can now rename 'ret2' to 'ret' and use it for generic errors.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:49 +02:00
David Sterba
a83134b48a btrfs: rename ret to status in btrfs_submit_compressed_read()
We're using 'status' for the blk_status_t variables, rename 'ret' so we can
use it for generic errors.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:48 +02:00
David Sterba
79cbc151f9 btrfs: simplify reading bio status in end_compressed_writeback()
We don't need to have a separate variable to read the bio status, 'ret'
works for that just fine so remove 'error'.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:48 +02:00
Christoph Hellwig
8d243aa9a8 btrfs: use bvec_kmap_local() in btrfs_decompress_buf2page()
This removes the last direct poke into bvec internals in btrfs.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:47 +02:00
Filipe Manana
d846a6d3b0 btrfs: rename remaining exported extent map functions
Rename all the exported functions from extent_map.h that don't have a
'btrfs_' prefix in their names, so that they are consistent with all the
other functions, to make it clear they are btrfs specific functions and
to avoid potential name collisions in the future with functions defined
elsewhere in the kernel.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:45 +02:00
Filipe Manana
ae98ae2a50 btrfs: rename functions to allocate and free extent maps
These functions are exported and don't have a 'btrfs_' prefix in their
names, which goes against coding style conventions. Rename them to have
such prefix, making it clear they are from btrfs and avoiding potential
collisions in the future with functions defined elsewhere outside btrfs.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:45 +02:00
Filipe Manana
2e871330ce btrfs: rename extent map functions to get block start, end and check if in tree
These functions are exported and don't have a 'btrfs_' prefix in their
names, which goes against coding style conventions. Rename them to have
such prefix, making it clear they are from btrfs and avoiding potential
collisions in the future with functions defined elsewhere outside btrfs.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:45 +02:00
Filipe Manana
962162ffa6 btrfs: rename exported extent map compression functions
These functions are exported and don't have a 'btrfs_' prefix in their
names, which goes against coding style conventions. Rename them to have
such prefix, making it clear they are from btrfs and avoiding potential
collisions in the future with functions defined elsewhere outside btrfs.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:45 +02:00
Filipe Manana
242570e80b btrfs: add btrfs prefix to main lock, try lock and unlock extent functions
These functions are exported so they should have a 'btrfs_' prefix by
convention, to make it clear they are btrfs specific and to avoid
collisions with functions from elsewhere in the kernel. So add a prefix to
their name.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:43 +02:00
Qu Wenruo
2b14b74b99 btrfs: use folio_contains() for EOF detection
Currently we use the following pattern to detect if the folio contains
the end of a file:

	if (folio->index == end_index)
		folio_zero_range();

But that only works if the folio is page sized.

For the following case, it will not work and leave the range beyond EOF
uninitialized:

  The page size is 4K, and the fs block size is also 4K.

	16K        20K       24K
        |          |     |   |
	                 |
                         EOF at 22K

And we have a large folio sized 8K at file offset 16K.

In that case, the old "folio->index == end_index" will not work, thus
the range [22K, 24K) will not be zeroed out.

Fix the following call sites which use the above pattern:

- add_ra_bio_pages()

- extent_writepage()

Reviewed-by: Filipe Manana <fdmanana@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>
2025-05-15 14:30:43 +02:00
Qu Wenruo
af566bdaff btrfs: fix the file offset calculation inside btrfs_decompress_buf2page()
[BUG WITH EXPERIMENTAL LARGE FOLIOS]
When testing the experimental large data folio support with compression,
there are several ASSERT()s triggered from btrfs_decompress_buf2page()
when running fsstress with compress=zstd mount option:

- ASSERT(copy_len) from btrfs_decompress_buf2page()
- VM_BUG_ON(offset + len > PAGE_SIZE) from memcpy_to_page()

[CAUSE]
Inside btrfs_decompress_buf2page(), we need to grab the file offset from
the current bvec.bv_page, to check if we even need to copy data into the
bio.

And since we're using single page bvec, and no large folio, every page
inside the folio should have its index properly setup.

But when large folios are involved, only the first page (aka, the head
page) of a large folio has its index properly initialized.

The other pages inside the large folio will not have their indexes
properly initialized.

Thus the page_offset() call inside btrfs_decompress_buf2page() will
result garbage, and completely screw up the @copy_len calculation.

[FIX]
Instead of using page->index directly, go with page_pgoff(), which can
handle non-head pages correctly.

So introduce a helper, file_offset_from_bvec(), to get the file offset
from a single page bio_vec, so the copy_len calculation can be done
correctly.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:40 +02:00
Kees Cook
6f9a8ab796 btrfs: compression: adjust cb->compressed_folios allocation type
In preparation for making the kmalloc() family of allocators type aware,
we need to make sure that the returned type from the allocation matches
the type of the variable being assigned. (Before, the allocator would
always return "void *", which can be implicitly cast to any pointer type.)

The assigned type is "struct folio **" but the returned type will be
"struct page **". These are the same allocation size (pointer size), but
the types don't match. Adjust the allocation type to match the assignment.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Kees Cook <kees@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-02 13:19:52 +02:00
Daniel Vacek
fc5c0c5825 btrfs: defrag: extend ioctl to accept compression levels
The zstd and zlib compression types support setting compression levels.
Enhance the defrag interface to specify the levels as well. For zstd the
negative (realtime) levels are also accepted.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18 20:35:50 +01:00
Daniel Vacek
da798fa519 btrfs: zstd: enable negative compression levels mount option
Allow using the fast modes (negative compression levels) of zstd as a
mount option.

As per the results, the compression ratio is (expectedly) lower:

for level in {-15..-1} 1 2 3; \
do printf "level %3d\n" $level; \
  mount -o compress=zstd:$level /dev/sdb /mnt/test/; \
  grep sdb /proc/mounts; \
  cp -r /usr/bin       /mnt/test/; sync; compsize /mnt/test/bin; \
  cp -r /usr/share/doc /mnt/test/; sync; compsize /mnt/test/doc; \
  cp    enwik9         /mnt/test/; sync; compsize /mnt/test/enwik9; \
  cp    linux-6.13.tar /mnt/test/; sync; compsize /mnt/test/linux-6.13.tar; \
  rm -r /mnt/test/{bin,doc,enwik9,linux-6.13.tar}; \
  umount /mnt/test/; \
done |& tee results | \
awk '/^level/{print}/^TOTAL/{print$3"\t"$2"  |"}' | paste - - - - -

		266M	bin  |	45M	doc  |	953M	wiki |	1.4G	source
=============================+===============+===============+===============+
level -15	180M	67%  |	30M	68%  |	694M	72%  |	598M	40%  |
level -14	180M	67%  |	30M	67%  |	683M	71%  |	581M	39%  |
level -13	177M	66%  |	29M	66%  |	671M	70%  |	566M	38%  |
level -12	174M	65%  |	29M	65%  |	658M	69%  |	548M	37%  |
level -11	174M	65%  |	28M	64%  |	645M	67%  |	530M	35%  |
level -10	171M	64%  |	28M	62%  |	631M	66%  |	512M	34%  |
level  -9	165M	62%  |	27M	61%  |	615M	64%  |	493M	33%  |
level  -8	161M	60%  |	27M	59%  |	598M	62%  |	475M	32%  |
level  -7	155M	58%  |	26M	58%  |	582M	61%  |	457M	30%  |
level  -6	151M	56%  |	25M	56%  |	565M	59%  |	437M	29%  |
level  -5	145M	54%  |	24M	55%  |	545M	57%  |	417M	28%  |
level  -4	139M	52%  |	23M	52%  |	520M	54%  |	391M	26%  |
level  -3	135M	50%  |	22M	50%  |	495M	51%  |	369M	24%  |
level  -2	127M	47%  |	22M	48%  |	470M	49%  |	349M	23%  |
level  -1	120M	45%  |	21M	47%  |	452M	47%  |	332M	22%  |
level   1	110M	41%  |	17M	39%  |	362M	38%  |	290M	19%  |
level   2	106M	40%  |	17M	38%  |	349M	36%  |	288M	19%  |
level   3	104M	39%  |	16M	37%  |	340M	35%  |	276M	18%  |

The samples represent some data sets that can be commonly found and show
approximate compressibility. The fast levels trade off speed for ratio
and are best suitable for highly compressible data.

As can be seen above, comparing the results to the current default zstd
level 3, the negative levels are roughly 2x worse at -15 and the
ratio increases almost linearly with each level.

Signed-off-by: Daniel Vacek <neelx@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18 20:35:41 +01:00
Anand Jain
d07eaa9995 btrfs: use filemap_get_folio() helper
When fgp_flags and gfp_flags are zero, use filemap_get_folio(A, B)
instead of __filemap_get_folio(A, B, 0, 0)—no need for the extra
arguments 0, 0.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:19 +01:00
Qu Wenruo
0f71202665 btrfs: rename btrfs_folio_(set|start|end)_writer_lock()
Since there is no user of reader locks, rename the writer locks into a
more generic name, by removing the "_writer" part from the name.

And also rename btrfs_subpage::writer into btrfs_subpage::locked.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:18 +01:00
Qu Wenruo
336e69f302 btrfs: unify to use writer locks for subpage locking
Since commit d7172f52e9 ("btrfs: use per-buffer locking for
extent_buffer reading"), metadata read no longer relies on the subpage
reader locking.

This means we do not need to maintain a different metadata/data split
for locking, so we can convert the existing reader lock users by:

- add_ra_bio_pages()
  Convert to btrfs_folio_set_writer_lock()

- end_folio_read()
  Convert to btrfs_folio_end_writer_lock()

- begin_folio_read()
  Convert to btrfs_folio_set_writer_lock()

- folio_range_has_eb()
  Remove the subpage->readers checks, since it is always 0.

- Remove btrfs_subpage_start_reader() and btrfs_subpage_end_reader()

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:18 +01:00
David Sterba
a9c50c9756 btrfs: drop unused parameter level from alloc_heuristic_ws()
The compression heuristic pass does not need a level, so we can drop the
parameter.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:17 +01:00
David Sterba
3f4b1bc1c0 btrfs: lzo: drop unused paramter level from lzo_alloc_workspace()
The LZO compression has only one level, we don't need to pass the
parameter.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:16 +01:00
Qu Wenruo
dd5e276254 btrfs: compression: add an ASSERT() to ensure the read-in length is sane
There are already two bugs (one in zlib, one in zstd) that involved
compression path is not handling sector size < page size cases well.

So it makes more sense to make sure that btrfs_compress_folios() returns

Since we already have two bugs (one in zlib, one in zstd) in the
compression path resulting the @total_in be to larger than the
to-be-compressed range length, there is enough reason to add an ASSERT()
to make sure the total read-in length doesn't exceed the input length.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:12 +01:00
Li Zetao
aeb6d88148 btrfs: convert btrfs_decompress() to take a folio
The old page API is being gradually replaced and converted to use folio
to improve code readability and avoid repeated conversion between page
and folio. Based on the previous patch, the compression path can be
directly used in folio without converting to page.

Signed-off-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:21 +02:00
Li Zetao
b70f3a4546 btrfs: convert zstd_decompress() to take a folio
The old page API is being gradually replaced and converted to use folio
to improve code readability and avoid repeated conversion between page
and folio. And memcpy_to_page() can be replaced with memcpy_to_folio().
But there is no memzero_folio(), but it can be replaced equivalently by
folio_zero_range().

Signed-off-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:21 +02:00
Li Zetao
9f9a4e43a8 btrfs: convert lzo_decompress() to take a folio
The old page API is being gradually replaced and converted to use folio
to improve code readability and avoid repeated conversion between page
and folio. And memcpy_to_page() can be replaced with memcpy_to_folio().
But there is no memzero_folio(), but it can be replaced equivalently by
folio_zero_range().

Signed-off-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:21 +02:00
Li Zetao
54c78d497b btrfs: convert zlib_decompress() to take a folio
The old page API is being gradually replaced and converted to use folio
to improve code readability and avoid repeated conversion between page
and folio. And memcpy_to_page() can be replaced with memcpy_to_folio().
But there is no memzero_folio(), but it can be replaced equivalently by
folio_zero_range().

Signed-off-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:21 +02:00
Josef Bacik
ac325fc2aa btrfs: do not hold the extent lock for entire read
Historically we've held the extent lock throughout the entire read.
There's been a few reasons for this, but it's mostly just caused us
problems.  For example, this prevents us from allowing page faults
during direct io reads, because we could deadlock.  This has forced us
to only allow 4k reads at a time for io_uring NOWAIT requests because we
have no idea if we'll be forced to page fault and thus have to do a
whole lot of work.

On the buffered side we are protected by the page lock, as long as we're
reading things like buffered writes, punch hole, and even direct IO to a
certain degree will get hung up on the page lock while the page is in
flight.

On the direct side we have the dio extent lock, which acts much like the
way the extent lock worked previously to this patch, however just for
direct reads.  This protects direct reads from concurrent direct writes,
while we're protected from buffered writes via the inode lock.

Now that we're protected in all cases, narrow the extent lock to the
part where we're getting the extent map to submit the reads, no longer
holding the extent lock for the entire read operation.  Push the extent
lock down into do_readpage() so that we're only grabbing it when looking
up the extent map.  This portion was contributed by Goldwyn.

Co-developed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:20 +02:00
David Sterba
792e86ef31 btrfs: rename btrfs_submit_bio() to btrfs_submit_bbio()
The function name is a bit misleading as it submits the btrfs_bio
(bbio), rename it so we can use btrfs_submit_bio() when an actual bio is
submitted.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:19 +02:00
Josef Bacik
c808c1dcb1 btrfs: convert add_ra_bio_pages() to use only folios
Willy is going to get rid of page->index, and add_ra_bio_pages uses
page->index.  Make his life easier by converting add_ra_bio_pages to use
folios so that we are no longer using page->index.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:13 +02:00
Filipe Manana
8e7860543a btrfs: fix extent map use-after-free when adding pages to compressed bio
At add_ra_bio_pages() we are accessing the extent map to calculate
'add_size' after we dropped our reference on the extent map, resulting
in a use-after-free. Fix this by computing 'add_size' before dropping our
extent map reference.

Reported-by: syzbot+853d80cba98ce1157ae6@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/000000000000038144061c6d18f2@google.com/
Fixes: 6a40491020 ("btrfs: subpage: make add_ra_bio_pages() compatible")
CC: stable@vger.kernel.org # 6.1+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 16:32:22 +02:00
Qu Wenruo
fea91134c2 btrfs: remove the extra_gfp parameter from btrfs_alloc_folio_array()
The function btrfs_alloc_folio_array() is only utilized in
btrfs_submit_compressed_read() and no other location, and the only
caller is not utilizing the @extra_gfp parameter.

Reviewed-by: Filipe Manana <fdmanana@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>
2024-07-11 15:33:30 +02:00
David Sterba
e2877c2a03 btrfs: pass a btrfs_inode to btrfs_compress_heuristic()
Pass a struct btrfs_inode to btrfs_compress_heuristic() as it's an
internal interface, allowing to remove some use of BTRFS_I.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:28 +02:00
David Sterba
a1f4e3d7bd btrfs: switch btrfs_ordered_extent::inode to struct btrfs_inode
The structure is internal so we should use struct btrfs_inode for that,
allowing to remove some use of BTRFS_I.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:28 +02:00
Qu Wenruo
c77a8c6100 btrfs: remove extent_map::block_start member
The member extent_map::block_start can be calculated from
extent_map::disk_bytenr + extent_map::offset for regular extents.
And otherwise just extent_map::disk_bytenr.

And this is already validated by the validate_extent_map().  Now we can
remove the member.

However there is a special case in btrfs_create_dio_extent() where we
for NOCOW/PREALLOC ordered extents cannot directly use the resulting
btrfs_file_extent, as btrfs_split_ordered_extent() cannot handle them
yet.

So for that call site, we pass file_extent->disk_bytenr +
file_extent->num_bytes as disk_bytenr for the ordered extent, and 0 for
offset.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
2024-07-11 15:33:21 +02:00
Qu Wenruo
e28b851ed9 btrfs: remove extent_map::block_len member
The extent_map::block_len is either extent_map::len (non-compressed
extent) or extent_map::disk_num_bytes (compressed extent).

Since we already have sanity checks to do the cross-checks between the
new and old members, we can drop the old extent_map::block_len now.

For most call sites, they can manually select extent_map::len or
extent_map::disk_num_bytes, since most if not all of them have checked
if the extent is compressed.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
2024-07-11 15:33:20 +02:00
Qu Wenruo
4aa7b5d178 btrfs: remove extent_map::orig_start member
Since we have extent_map::offset, the old extent_map::orig_start is just
extent_map::start - extent_map::offset for non-hole/inline extents.

And since the new extent_map::offset is already verified by
validate_extent_map() while the old orig_start is not, let's just remove
the old member from all call sites.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
2024-07-11 15:33:20 +02:00
Filipe Manana
416d6ab49d btrfs: fix misspelled end IO compression callbacks
Fix typo in the end IO compression callbacks, from "comprssed" to
"compressed".

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:16 +02:00
Josef Bacik
e094f48040 btrfs: change root->root_key.objectid to btrfs_root_id()
A comment from Filipe on one of my previous cleanups brought my
attention to a new helper we have for getting the root id of a root,
which makes it easier to read in the code.

The changes where made with the following Coccinelle semantic patch:

// <smpl>
@@
expression E,E1;
@@
(
 E->root_key.objectid = E1
|
- E->root_key.objectid
+ btrfs_root_id(E)
)
// </smpl>

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor style fixups ]
Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07 21:31:06 +02:00