e8513c012d
Add ref_tracker infrastructure for struct btrfs_delayed_node.
It is a response to the largest btrfs related crash in our fleet. We're
seeing soft lockups in btrfs_kill_all_delayed_nodes() that seem to be a
result of delayed_nodes not being released properly.
A ref_tracker object is allocated on reference count increases and freed
on reference count decreases. The ref_tracker object stores a stack
trace of where it is allocated. The ref_tracker_dir object is embedded
in btrfs_delayed_node and keeps track of all current and some old/freed
ref_tracker objects. When a leak is detected we can print the stack
traces for all ref_trackers that have not yet been freed.
Here is a common example of taking a reference to a delayed_node and
freeing it with ref_tracker.
struct btrfs_ref_tracker tracker;
struct btrfs_delayed_node *node;
node = btrfs_get_delayed_node(inode, &tracker);
// use delayed_node...
btrfs_release_delayed_node(node, &tracker);
There are two special cases where the delayed_node reference is "long
lived", meaning that the thread that takes the reference and the thread
that releases the reference are different. The 'inode_cache_tracker'
tracks the delayed_node stored in btrfs_inode. The 'node_list_tracker'
tracks the delayed_node stored in the btrfs_delayed_root
node_list/prepare_list. These trackers are embedded in the
btrfs_delayed_node.
btrfs_ref_tracker and btrfs_ref_tracker_dir are wrappers that either
compile to the corresponding ref_tracker structs or empty structs
depending on CONFIG_BTRFS_DEBUG. There are also btrfs wrappers for
the ref_tracker API.
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
3.7 KiB
SPDX-License-Identifier: GPL-2.0
config BTRFS_FS tristate "Btrfs filesystem support" select BLK_CGROUP_PUNT_BIO select CRC32 select CRYPTO select CRYPTO_CRC32C select CRYPTO_XXHASH select CRYPTO_SHA256 select CRYPTO_BLAKE2B select ZLIB_INFLATE select ZLIB_DEFLATE select LZO_COMPRESS select LZO_DECOMPRESS select ZSTD_COMPRESS select ZSTD_DECOMPRESS select FS_IOMAP select RAID6_PQ select XOR_BLOCKS depends on PAGE_SIZE_LESS_THAN_256KB
help
Btrfs is a general purpose copy-on-write filesystem with extents,
writable snapshotting, support for multiple devices and many more
features focused on fault tolerance, repair and easy administration.
The filesystem disk format is no longer unstable, and it's not
expected to change unless there are strong reasons to do so. If there
is a format change, file systems with a unchanged format will
continue to be mountable and usable by newer kernels.
For more information, please see the web pages at
https://btrfs.readthedocs.io
To compile this file system support as a module, choose M here. The
module will be called btrfs.
If unsure, say N.
config BTRFS_FS_POSIX_ACL bool "Btrfs POSIX Access Control Lists" depends on BTRFS_FS select FS_POSIX_ACL help POSIX Access Control Lists (ACLs) support permissions for users and groups beyond the owner/group/world scheme.
If you don't know what Access Control Lists are, say N
config BTRFS_FS_RUN_SANITY_TESTS bool "Btrfs will run sanity tests upon loading" depends on BTRFS_FS help This will run sanity tests for core functionality like free space, extent maps, extent io, extent buffers, inodes, qgroups and others, at module load time. These are mostly regression tests and are only interesting to developers.
If unsure, say N.
config BTRFS_DEBUG bool "Btrfs debugging support" depends on BTRFS_FS select REF_TRACKER if STACKTRACE_SUPPORT help Enable run-time debugging support for the btrfs filesystem.
Additional potentially expensive checks, debugging functionality or
sysfs exported information is enabled, like leak checks of internal
objects, optional forced space fragmentation and /sys/fs/btrfs/debug .
This has negative impact on performance.
If unsure, say N.
config BTRFS_ASSERT bool "Btrfs assert support" depends on BTRFS_FS help Enable run-time assertion checking. Additional safety checks are done, simple enough not to affect performance but verify invariants and assumptions of code to run properly. This may result in panics, and is meant for developers but can be enabled in general.
If unsure, say N.
config BTRFS_EXPERIMENTAL bool "Btrfs experimental features" depends on BTRFS_FS default n help Enable experimental features. These features may not be stable enough for end users. This is meant for btrfs developers or users who wish to test the functionality and report problems.
Current list:
- COW fixup worker warning - last warning before removing the
functionality catching out-of-band page
dirtying, not necessary since 5.8
- RAID mirror read policy - additional read policies for balancing
reading from redundant block group
profiles (currently: pid, round-robin,
fixed devid)
- send stream protocol v3 - fs-verity support
- checksum offload mode - sysfs knob to affect when checksums are
calculated (at IO time, or in a thread)
- raid-stripe-tree - additional mapping of extents to devices to
support RAID1* profiles on zoned devices,
RAID56 not yet supported
- extent tree v2 - complex rework of extent tracking
- large folio support
If unsure, say N.