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fe11ac191c
Make btrfs use the library APIs instead of crypto_shash, for all checksum computations. This has many benefits: - Allows future checksum types, e.g. XXH3 or CRC64, to be more easily supported. Only a library API will be needed, not crypto_shash too. - Eliminates the overhead of the generic crypto layer, including an indirect call for every function call and other API overhead. A microbenchmark of btrfs_check_read_bio() with crc32c checksums shows a speedup from 658 cycles to 608 cycles per 4096-byte block. - Decreases the stack usage of btrfs by reducing the size of checksum contexts from 384 bytes to 240 bytes, and by eliminating the need for some functions to declare a checksum context at all. - Increases reliability. The library functions always succeed and return void. In contrast, crypto_shash can fail and return errors. Also, the library functions are guaranteed to be available when btrfs is loaded; there's no longer any need to use module softdeps to try to work around the crypto modules sometimes not being loaded. - Fixes a bug where blake2b checksums didn't work on kernels booted with fips=1. Since btrfs checksums are for integrity only, it's fine for them to use non-FIPS-approved algorithms. Note that with having to handle 4 algorithms instead of just 1-2, this commit does result in a slightly positive diffstat. That being said, this wouldn't have been the case if btrfs had actually checked for errors from crypto_shash, which technically it should have been doing. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Neal Gompa <neal@gompa.dev> Signed-off-by: Eric Biggers <ebiggers@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
122 lines
3.8 KiB
Text
122 lines
3.8 KiB
Text
# SPDX-License-Identifier: GPL-2.0
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config BTRFS_FS
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tristate "Btrfs filesystem support"
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select BLK_CGROUP_PUNT_BIO
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select CRC32
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select CRYPTO_LIB_BLAKE2B
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select CRYPTO_LIB_SHA256
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select ZLIB_INFLATE
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select ZLIB_DEFLATE
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select LZO_COMPRESS
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select LZO_DECOMPRESS
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select ZSTD_COMPRESS
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select ZSTD_DECOMPRESS
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select FS_IOMAP
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select RAID6_PQ
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select XOR_BLOCKS
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select XXHASH
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depends on PAGE_SIZE_LESS_THAN_256KB
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help
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Btrfs is a general purpose copy-on-write filesystem with extents,
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writable snapshotting, support for multiple devices and many more
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features focused on fault tolerance, repair and easy administration.
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The filesystem disk format is no longer unstable, and it's not
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expected to change unless there are strong reasons to do so. If there
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is a format change, file systems with a unchanged format will
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continue to be mountable and usable by newer kernels.
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For more information, please see the web pages at
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https://btrfs.readthedocs.io
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To compile this file system support as a module, choose M here. The
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module will be called btrfs.
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If unsure, say N.
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config BTRFS_FS_POSIX_ACL
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bool "Btrfs POSIX Access Control Lists"
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depends on BTRFS_FS
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select FS_POSIX_ACL
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help
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POSIX Access Control Lists (ACLs) support permissions for users and
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groups beyond the owner/group/world scheme.
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If you don't know what Access Control Lists are, say N
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config BTRFS_FS_RUN_SANITY_TESTS
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bool "Btrfs will run sanity tests upon loading"
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depends on BTRFS_FS
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help
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This will run sanity tests for core functionality like free space,
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extent maps, extent io, extent buffers, inodes, qgroups and others,
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at module load time. These are mostly regression tests and are only
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interesting to developers.
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If unsure, say N.
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config BTRFS_DEBUG
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bool "Btrfs debugging support"
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depends on BTRFS_FS
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select REF_TRACKER if STACKTRACE_SUPPORT
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help
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Enable run-time debugging support for the btrfs filesystem.
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Additional potentially expensive checks, debugging functionality or
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sysfs exported information is enabled, like leak checks of internal
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objects, optional forced space fragmentation and /sys/fs/btrfs/debug .
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This has negative impact on performance.
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If unsure, say N.
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config BTRFS_ASSERT
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bool "Btrfs assert support"
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depends on BTRFS_FS
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help
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Enable run-time assertion checking. Additional safety checks are
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done, simple enough not to affect performance but verify invariants
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and assumptions of code to run properly. This may result in panics,
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and is meant for developers but can be enabled in general.
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If unsure, say N.
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config BTRFS_EXPERIMENTAL
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bool "Btrfs experimental features"
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depends on BTRFS_FS
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default n
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help
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Enable experimental features. These features may not be stable enough
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for end users. This is meant for btrfs developers or users who wish
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to test the functionality and report problems.
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Current list:
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- COW fixup worker warning - last warning before removing the
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functionality catching out-of-band page
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dirtying, not necessary since 5.8
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- RAID mirror read policy - additional read policies for balancing
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reading from redundant block group
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profiles (currently: pid, round-robin,
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fixed devid)
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- send stream protocol v3 - fs-verity support
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- checksum offload mode - sysfs knob to affect when checksums are
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calculated (at IO time, or in a thread)
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- raid-stripe-tree - additional mapping of extents to devices to
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support RAID1* profiles on zoned devices,
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RAID56 not yet supported
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- extent tree v2 - complex rework of extent tracking
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- large folio and block size (> page size) support
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- shutdown ioctl and auto-degradation support
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- asynchronous checksum generation for data writes
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If unsure, say N.
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