Commit Graph

2176 Commits

Author SHA1 Message Date
David Howells
ddca5b0eba netfs: Adjust docs after foliation
Adjust the netfslib docs in light of the foliation changes.

Also un-kdoc-mark netfs_skip_folio_read() since it's internal and isn't
part of the API.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-cachefs@redhat.com
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/163706992597.3179783.18360472879717076435.stgit@warthog.procyon.org.uk/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-29 10:10:26 -08:00
Salvatore Bonaccorso
2d239f0f6a docs: filesystem: cifs: ksmbd: Fix small layout issues
In some senteces there were missing spaces between words.

Fix wording in item to show which prints are enabled and add a space
beween the cat command and its argument.

Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steve French <sfrench@samba.org>
CC: Hyunchul Lee <hyc.lee@gmail.com>
Cc: linux-cifs@vger.kernel.org
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
2021-11-25 00:09:26 -06:00
Wasin Thonkaew
53b606fa29 docs: filesystems: Fix grammatical error "with" to "which"
Signed-off-by: Wasin Thonkaew <wasin@wasin.io>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-11-15 02:54:37 -07:00
Linus Torvalds
5664896ba2 Merge tag 'f2fs-for-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim:
 "In this cycle, we've applied relatively small number of patches which
  fix subtle corner cases mainly, while introducing a new mount option
  to be able to fragment the disk intentionally for performance tests.

  Enhancements:

   - add a mount option to fragmente on-disk layout to understand the
     performance

   - support direct IO for multi-partitions

   - add a fault injection of dquot_initialize

  Bug fixes:

   - address some lockdep complaints

   - fix a deadlock issue with quota

   - fix a memory tuning condition

   - fix compression condition to improve the ratio

   - fix disabling compression on the non-empty compressed file

   - invalidate cached pages before IPU/DIO writes

  And, we've added some minor clean-ups as usual"

* tag 'f2fs-for-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
  f2fs: fix UAF in f2fs_available_free_memory
  f2fs: invalidate META_MAPPING before IPU/DIO write
  f2fs: support fault injection for dquot_initialize()
  f2fs: fix incorrect return value in f2fs_sanity_check_ckpt()
  f2fs: compress: disallow disabling compress on non-empty compressed file
  f2fs: compress: fix overwrite may reduce compress ratio unproperly
  f2fs: multidevice: support direct IO
  f2fs: introduce fragment allocation mode mount option
  f2fs: replace snprintf in show functions with sysfs_emit
  f2fs: include non-compressed blocks in compr_written_block
  f2fs: fix wrong condition to trigger background checkpoint correctly
  f2fs: fix to use WHINT_MODE
  f2fs: fix up f2fs_lookup tracepoints
  f2fs: set SBI_NEED_FSCK flag when inconsistent node block found
  f2fs: introduce excess_dirty_threshold()
  f2fs: avoid attaching SB_ACTIVE flag during mount
  f2fs: quota: fix potential deadlock
  f2fs: should use GFP_NOFS for directory inodes
2021-11-13 11:20:22 -08:00
Linus Torvalds
38764c7340 Merge tag 'nfsd-5.16' of git://linux-nfs.org/~bfields/linux
Pull nfsd updates from Bruce Fields:
 "A slow cycle for nfsd: mainly cleanup, including Neil's patch dropping
  support for a filehandle format deprecated 20 years ago, and further
  xdr-related cleanup from Chuck"

* tag 'nfsd-5.16' of git://linux-nfs.org/~bfields/linux: (26 commits)
  nfsd4: remove obselete comment
  nfsd: document server-to-server-copy parameters
  NFSD:fix boolreturn.cocci warning
  nfsd: update create verifier comment
  SUNRPC: Change return value type of .pc_encode
  SUNRPC: Replace the "__be32 *p" parameter to .pc_encode
  NFSD: Save location of NFSv4 COMPOUND status
  SUNRPC: Change return value type of .pc_decode
  SUNRPC: Replace the "__be32 *p" parameter to .pc_decode
  SUNRPC: De-duplicate .pc_release() call sites
  SUNRPC: Simplify the SVC dispatch code path
  SUNRPC: Capture value of xdr_buf::page_base
  SUNRPC: Add trace event when alloc_pages_bulk() makes no progress
  svcrdma: Split svcrmda_wc_{read,write} tracepoints
  svcrdma: Split the svcrdma_wc_send() tracepoint
  svcrdma: Split the svcrdma_wc_receive() tracepoint
  NFSD: Have legacy NFSD WRITE decoders use xdr_stream_subsegment()
  SUNRPC: xdr_stream_subsegment() must handle non-zero page_bases
  NFSD: Initialize pointer ni with NULL and not plain integer 0
  NFSD: simplify struct nfsfh
  ...
2021-11-10 16:45:54 -08:00
Linus Torvalds
624ad333d4 Merge tag 'docs-5.16' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
 "This is a relatively unexciting cycle for documentation.

   - Some small scripts/kerneldoc fixes

   - More Chinese translation work, but at a much reduced rate.

   - The tip-tree maintainer's handbook

  ...plus the usual array of build fixes, typo fixes, etc"

* tag 'docs-5.16' of git://git.lwn.net/linux: (53 commits)
  kernel-doc: support DECLARE_PHY_INTERFACE_MASK()
  docs/zh_CN: add core-api xarray translation
  docs/zh_CN: add core-api assoc_array translation
  speakup: Fix typo in documentation "boo" -> "boot"
  docs: submitting-patches: make section about the Link: tag more explicit
  docs: deprecated.rst: Clarify open-coded arithmetic with literals
  scripts: documentation-file-ref-check: fix bpf selftests path
  scripts: documentation-file-ref-check: ignore hidden files
  coding-style.rst: trivial: fix location of driver model macros
  docs: f2fs: fix text alignment
  docs/zh_CN add PCI pci.rst translation
  docs/zh_CN add PCI index.rst translation
  docs: translations: zh_CN: memory-hotplug.rst: fix a typo
  docs: translations: zn_CN: irq-affinity.rst: add a missing extension
  block: add documentation for inflight
  scripts: kernel-doc: Ignore __alloc_size() attribute
  docs: pdfdocs: Adjust \headheight for fancyhdr
  docs: UML: user_mode_linux_howto_v2 edits
  docs: use the lore redirector everywhere
  docs: proc.rst: mountinfo: align columns
  ...
2021-11-02 22:11:39 -07:00
Linus Torvalds
67a135b80e Merge tag 'erofs-for-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs
Pull erofs updates from Gao Xiang:
 "There are some new features available for this cycle. Firstly, EROFS
  LZMA algorithm support, specifically called MicroLZMA, is available as
  an option for embedded devices, LiveCDs and/or as the secondary
  auxiliary compression algorithm besides the primary algorithm in one
  file.

  In order to better support the LZMA fixed-sized output compression,
  especially for 4KiB pcluster size (which has lowest memory pressure
  thus useful for memory-sensitive scenarios), Lasse introduced a new
  LZMA header/container format called MicroLZMA to minimize the original
  LZMA1 header (for example, we don't need to waste 4-byte dictionary
  size and another 8-byte uncompressed size, which can be calculated by
  fs directly, for each pcluster) and enable EROFS fixed-sized output
  compression.

  Note that MicroLZMA can also be later used by other things in addition
  to EROFS too where wasting minimal amount of space for headers is
  important and it can be only compiled by enabling XZ_DEC_MICROLZMA.
  MicroLZMA has been supported by the latest upstream XZ embedded [1] &
  XZ utils [2], apply the latest related XZ embedded upstream patches by
  the XZ author Lasse here.

  Secondly, multiple device is also supported in this cycle, which is
  designed for multi-layer container images. By working together with
  inter-layer data deduplication and compression, we can achieve the
  next high-performance container image solution. Our team will announce
  the new Nydus container image service [3] implementation with new RAFS
  v6 (EROFS-compatible) format in Open Source Summit 2021 China [4]
  soon.

  Besides, the secondary compression head support and readmore
  decompression strategy are also included in this cycle. There are also
  some minor bugfixes and cleanups, as always.

  Summary:

   - support multiple devices for multi-layer container images;

   - support the secondary compression head;

   - support readmore decompression strategy;

   - support new LZMA algorithm (specifically called MicroLZMA);

   - some bugfixes & cleanups"

* tag 'erofs-for-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: don't trigger WARN() when decompression fails
  erofs: get rid of ->lru usage
  erofs: lzma compression support
  erofs: rename some generic methods in decompressor
  lib/xz, lib/decompress_unxz.c: Fix spelling in comments
  lib/xz: Add MicroLZMA decoder
  lib/xz: Move s->lzma.len = 0 initialization to lzma_reset()
  lib/xz: Validate the value before assigning it to an enum variable
  lib/xz: Avoid overlapping memcpy() with invalid input with in-place decompression
  erofs: introduce readmore decompression strategy
  erofs: introduce the secondary compression head
  erofs: get compression algorithms directly on mapping
  erofs: add multiple device support
  erofs: decouple basic mount options from fs_context
  erofs: remove the fast path of per-CPU buffer decompression
2021-11-01 11:39:22 -07:00
Linus Torvalds
cd3e8ea847 Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt
Pull fscrypt updates from Eric Biggers:
 "Some cleanups for fs/crypto/:

   - Allow 256-bit master keys with AES-256-XTS

   - Improve documentation and comments

   - Remove unneeded field fscrypt_operations::max_namelen"

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
  fscrypt: improve a few comments
  fscrypt: allow 256-bit master keys with AES-256-XTS
  fscrypt: improve documentation for inline encryption
  fscrypt: clean up comments in bio.c
  fscrypt: remove fscrypt_operations::max_namelen
2021-11-01 11:36:35 -07:00
Linus Torvalds
9ac211426f Merge tag 'locks-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull file locking updates from Jeff Layton:
 "Most of this is just follow-on cleanup work of documentation and
  comments from the mandatory locking removal in v5.15.

  The only real functional change is that LOCK_MAND flock() support is
  also being removed, as it has basically been non-functional since the
  v2.5 days"

* tag 'locks-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  fs: remove leftover comments from mandatory locking removal
  locks: remove changelog comments
  docs: fs: locks.rst: update comment about mandatory file locking
  Documentation: remove reference to now removed mandatory-locking doc
  locks: remove LOCK_MAND flock lock support
2021-11-01 09:06:53 -07:00
Linus Torvalds
49f8275c7d Merge tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecache
Pull memory folios from Matthew Wilcox:
 "Add memory folios, a new type to represent either order-0 pages or the
  head page of a compound page. This should be enough infrastructure to
  support filesystems converting from pages to folios.

  The point of all this churn is to allow filesystems and the page cache
  to manage memory in larger chunks than PAGE_SIZE. The original plan
  was to use compound pages like THP does, but I ran into problems with
  some functions expecting only a head page while others expect the
  precise page containing a particular byte.

  The folio type allows a function to declare that it's expecting only a
  head page. Almost incidentally, this allows us to remove various calls
  to VM_BUG_ON(PageTail(page)) and compound_head().

  This converts just parts of the core MM and the page cache. For 5.17,
  we intend to convert various filesystems (XFS and AFS are ready; other
  filesystems may make it) and also convert more of the MM and page
  cache to folios. For 5.18, multi-page folios should be ready.

  The multi-page folios offer some improvement to some workloads. The
  80% win is real, but appears to be an artificial benchmark (postgres
  startup, which isn't a serious workload). Real workloads (eg building
  the kernel, running postgres in a steady state, etc) seem to benefit
  between 0-10%. I haven't heard of any performance losses as a result
  of this series. Nobody has done any serious performance tuning; I
  imagine that tweaking the readahead algorithm could provide some more
  interesting wins. There are also other places where we could choose to
  create large folios and currently do not, such as writes that are
  larger than PAGE_SIZE.

  I'd like to thank all my reviewers who've offered review/ack tags:
  Christoph Hellwig, David Howells, Jan Kara, Jeff Layton, Johannes
  Weiner, Kirill A. Shutemov, Michal Hocko, Mike Rapoport, Vlastimil
  Babka, William Kucharski, Yu Zhao and Zi Yan.

  I'd also like to thank those who gave feedback I incorporated but
  haven't offered up review tags for this part of the series: Nick
  Piggin, Mel Gorman, Ming Lei, Darrick Wong, Ted Ts'o, John Hubbard,
  Hugh Dickins, and probably a few others who I forget"

* tag 'folio-5.16' of git://git.infradead.org/users/willy/pagecache: (90 commits)
  mm/writeback: Add folio_write_one
  mm/filemap: Add FGP_STABLE
  mm/filemap: Add filemap_get_folio
  mm/filemap: Convert mapping_get_entry to return a folio
  mm/filemap: Add filemap_add_folio()
  mm/filemap: Add filemap_alloc_folio
  mm/page_alloc: Add folio allocation functions
  mm/lru: Add folio_add_lru()
  mm/lru: Convert __pagevec_lru_add_fn to take a folio
  mm: Add folio_evictable()
  mm/workingset: Convert workingset_refault() to take a folio
  mm/filemap: Add readahead_folio()
  mm/filemap: Add folio_mkwrite_check_truncate()
  mm/filemap: Add i_blocks_per_folio()
  mm/writeback: Add folio_redirty_for_writepage()
  mm/writeback: Add folio_account_redirty()
  mm/writeback: Add folio_clear_dirty_for_io()
  mm/writeback: Add folio_cancel_dirty()
  mm/writeback: Add folio_account_cleaned()
  mm/writeback: Add filemap_dirty_folio()
  ...
2021-11-01 08:47:59 -07:00
Chao Yu
10a2687856 f2fs: support fault injection for dquot_initialize()
This patch adds a new function f2fs_dquot_initialize() to wrap
dquot_initialize(), and it supports to inject fault into
f2fs_dquot_initialize() to simulate inner failure occurs in
dquot_initialize().

Usage:
a) echo 65536 > /sys/fs/f2fs/<dev>/inject_type or
b) mount -o fault_type=65536 <dev> <mountpoint>

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2021-10-29 10:38:53 -07:00
Daeho Jeong
6691d940b0 f2fs: introduce fragment allocation mode mount option
Added two options into "mode=" mount option to make it possible for
developers to simulate filesystem fragmentation/after-GC situation
itself. The developers use these modes to understand filesystem
fragmentation/after-GC condition well, and eventually get some
insights to handle them better.

"fragment:segment": f2fs allocates a new segment in ramdom position.
		With this, we can simulate the after-GC condition.
"fragment:block" : We can scatter block allocation with
		"max_fragment_chunk" and "max_fragment_hole" sysfs
		nodes. f2fs will allocate 1..<max_fragment_chunk>
		blocks in a chunk and make a hole in the length of
		1..<max_fragment_hole> by turns	in a newly allocated
		free segment. Plus, this mode implicitly enables
		"fragment:segment" option for more randomness.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2021-10-26 14:04:30 -07:00
Fengnan Chang
8c3b018874 docs: f2fs: fix text alignment
The docs build was generating this warning:

  Documentation/filesystems/f2fs.rst:306: WARNING: Block quote ends without a blank line; unexpected unindent.

Remove the extra white space that was confusing sphinx.

Fixes: 151b1982be (f2fs: compress: add nocompress extensions support)
Signed-off-by: Fengnan Chang <changfengnan@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20211023025833.216030-1-changfengnan@vivo.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-10-26 09:33:22 -06:00
Mauro Carvalho Chehab
f7c9ee0c72 docs: fs: locks.rst: update comment about mandatory file locking
The mandatory file locking got removed due to its problems, but
the fs locks documentation still points to it.

Update the text there, informing that it was removed on Kernel
5.14.

Fixes: f7e33bdbd6 ("fs: remove mandatory file locking support")
Reported-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2021-10-19 06:48:21 -04:00
Gao Xiang
dfeab2e95a erofs: add multiple device support
In order to support multi-layer container images, add multiple
device feature to EROFS. Two ways are available to use for now:

 - Devices can be mapped into 32-bit global block address space;
 - Device ID can be specified with the chunk indexes format.

Note that it assumes no extent would cross device boundary and mkfs
should take care of it seriously.

In the future, a dedicated device manager could be introduced then
thus extra devices can be automatically scanned by UUID as well.

Link: https://lore.kernel.org/r/20211014081010.43485-1-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2021-10-18 00:13:30 +08:00
Linus Torvalds
86a44e9067 Merge tag 'ntfs3_for_5.15' of git://github.com/Paragon-Software-Group/linux-ntfs3
Pull ntfs3 fixes from Konstantin Komarov:
 "Use the new api for mounting as requested by Christoph.

  Also fixed:

   - some memory leaks and panic

   - xfstests (tested on x86_64) generic/016 generic/021 generic/022
     generic/041 generic/274 generic/423

   - some typos, wrong returned error codes, dead code, etc"

* tag 'ntfs3_for_5.15' of git://github.com/Paragon-Software-Group/linux-ntfs3: (70 commits)
  fs/ntfs3: Check for NULL pointers in ni_try_remove_attr_list
  fs/ntfs3: Refactor ntfs_read_mft
  fs/ntfs3: Refactor ni_parse_reparse
  fs/ntfs3: Refactor ntfs_create_inode
  fs/ntfs3: Refactor ntfs_readlink_hlp
  fs/ntfs3: Rework ntfs_utf16_to_nls
  fs/ntfs3: Fix memory leak if fill_super failed
  fs/ntfs3: Keep prealloc for all types of files
  fs/ntfs3: Remove unnecessary functions
  fs/ntfs3: Forbid FALLOC_FL_PUNCH_HOLE for normal files
  fs/ntfs3: Refactoring of ntfs_set_ea
  fs/ntfs3: Remove locked argument in ntfs_set_ea
  fs/ntfs3: Use available posix_acl_release instead of ntfs_posix_acl_release
  fs/ntfs3: Check for NULL if ATTR_EA_INFO is incorrect
  fs/ntfs3: Refactoring of ntfs_init_from_boot
  fs/ntfs3: Reject mount if boot's cluster size < media sector size
  fs/ntfs3: Refactoring lock in ntfs_init_acl
  fs/ntfs3: Change posix_acl_equiv_mode to posix_acl_update_mode
  fs/ntfs3: Pass flags to ntfs_set_ea in ntfs_set_acl_ex
  fs/ntfs3: Refactor ntfs_get_acl_ex for better readability
  ...
2021-10-15 09:58:11 -04:00
Christoph Anton Mitterer
b0b719cea8 docs: proc.rst: mountinfo: align columns
Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
Link: https://lore.kernel.org/r/20211007040001.103413-3-mail@christoph.anton.mitterer.name
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-10-12 13:52:22 -06:00
Christoph Anton Mitterer
ff9c3d4360 docs: proc.rst: mountinfo: improved field numbering
Without reading thoroughly, one could easily oversee that there may be several
fields after #6.
Made it more clearly by changing the field numbering.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
Link: https://lore.kernel.org/r/20211007040001.103413-2-mail@christoph.anton.mitterer.name
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-10-12 13:52:22 -06:00
Jonathan Corbet
7275423c17 ext4: docs: Take out unneeded escaping
The new file Documentation/orphan/ext4.rst escapes underscores ("\_")
throughout.  However, RST doesn't actually require that, so the escaping
only succeeds in making the document less readable.  Remove the unneeded
escapes.

Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210902220854.198850-3-corbet@lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-10-07 08:46:02 -06:00
Jonathan Corbet
91c76340b4 ext4: docs: switch away from list-table
Commit 3a6541e97c (Add documentation about the orphan file feature) added
a new document on orphan files, which is great.  But the use of
"list-table" results in documents that are absolutely unreadable in their
plain-text form.  Switch this file to the regular RST table format instead;
the rendered (HTML) output is identical.

Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210902220854.198850-2-corbet@lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-10-07 08:46:02 -06:00
Jeff Layton
ec60f38a91 Documentation: remove reference to now removed mandatory-locking doc
When I removed the document on mandatory locking from the tree, I missed
removing the reference to it from the index file.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2021-10-05 06:02:53 -04:00
Matthew Wilcox (Oracle)
6abbaa5b01 fs/netfs: Add folio fscache functions
Match the page writeback functions by adding
folio_start_fscache(), folio_end_fscache(), folio_wait_fscache() and
folio_wait_fscache_killable().  Remove set_page_private_2().  Also rewrite
the kernel-doc to describe when to use the function rather than what the
function does, and include the kernel-doc in the appropriate rst file.
Saves 31 bytes of text in netfs_rreq_unlock() due to set_page_fscache()
calling page_folio() once instead of three times.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
2021-09-27 09:27:31 -04:00
Eric Biggers
7f595d6a6c fscrypt: allow 256-bit master keys with AES-256-XTS
fscrypt currently requires a 512-bit master key when AES-256-XTS is
used, since AES-256-XTS keys are 512-bit and fscrypt requires that the
master key be at least as long any key that will be derived from it.

However, this is overly strict because AES-256-XTS doesn't actually have
a 512-bit security strength, but rather 256-bit.  The fact that XTS
takes twice the expected key size is a quirk of the XTS mode.  It is
sufficient to use 256 bits of entropy for AES-256-XTS, provided that it
is first properly expanded into a 512-bit key, which HKDF-SHA512 does.

Therefore, relax the check of the master key size to use the security
strength of the derived key rather than the size of the derived key
(except for v1 encryption policies, which don't use HKDF).

Besides making things more flexible for userspace, this is needed in
order for the use of a KDF which only takes a 256-bit key to be
introduced into the fscrypt key hierarchy.  This will happen with
hardware-wrapped keys support, as all known hardware which supports that
feature uses an SP800-108 KDF using AES-256-CMAC, so the wrapped keys
are wrapped 256-bit AES keys.  Moreover, there is interest in fscrypt
supporting the same type of AES-256-CMAC based KDF in software as an
alternative to HKDF-SHA512.  There is no security problem with such
features, so fix the key length check to work properly with them.

Reviewed-by: Paul Crowley <paulcrowley@google.com>
Link: https://lore.kernel.org/r/20210921030303.5598-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-09-22 11:29:38 -07:00
J. Bruce Fields
dc451bbc6f nfs: reexport documentation
We've supported reexport for a while but documentation is limited.  This
is mainly a simplified version of the text I wrote for the linux-nfs
wiki at https://wiki.linux-nfs.org/wiki/index.php/NFS_re-export.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2021-09-21 17:51:47 -04:00
Eric Biggers
abb861fac0 fscrypt: improve documentation for inline encryption
Currently the fscrypt inline encryption support is documented in the
"Implementation details" section, and it doesn't go into much detail.
It's really more than just an "implementation detail" though, as there
is a user-facing mount option.  Also, hardware-wrapped key support (an
upcoming feature) will depend on inline encryption and will affect the
on-disk format; by definition that's not just an implementation detail.

Therefore, move this documentation into its own section and expand it.

Link: https://lore.kernel.org/r/20210916174928.65529-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-09-20 19:32:34 -07:00