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fscrypt: document that CephFS supports fscrypt now
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The help text for CONFIG_FS_ENCRYPTION and the fscrypt.rst documentation
file both list the filesystems that support fscrypt.  CephFS added
support for fscrypt in v6.6, so add CephFS to the list.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Eric Biggers <[email protected]>
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ebiggers committed Dec 27, 2023
1 parent 0fc24a6 commit c1f1f5b
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18 changes: 9 additions & 9 deletions Documentation/filesystems/fscrypt.rst
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Expand Up @@ -31,15 +31,15 @@ However, except for filenames, fscrypt does not encrypt filesystem
metadata.

Unlike eCryptfs, which is a stacked filesystem, fscrypt is integrated
directly into supported filesystems --- currently ext4, F2FS, and
UBIFS. This allows encrypted files to be read and written without
caching both the decrypted and encrypted pages in the pagecache,
thereby nearly halving the memory used and bringing it in line with
unencrypted files. Similarly, half as many dentries and inodes are
needed. eCryptfs also limits encrypted filenames to 143 bytes,
causing application compatibility issues; fscrypt allows the full 255
bytes (NAME_MAX). Finally, unlike eCryptfs, the fscrypt API can be
used by unprivileged users, with no need to mount anything.
directly into supported filesystems --- currently ext4, F2FS, UBIFS,
and CephFS. This allows encrypted files to be read and written
without caching both the decrypted and encrypted pages in the
pagecache, thereby nearly halving the memory used and bringing it in
line with unencrypted files. Similarly, half as many dentries and
inodes are needed. eCryptfs also limits encrypted filenames to 143
bytes, causing application compatibility issues; fscrypt allows the
full 255 bytes (NAME_MAX). Finally, unlike eCryptfs, the fscrypt API
can be used by unprivileged users, with no need to mount anything.

fscrypt does not support encrypting files in-place. Instead, it
supports marking an empty directory as encrypted. Then, after
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2 changes: 1 addition & 1 deletion fs/crypto/Kconfig
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Expand Up @@ -11,7 +11,7 @@ config FS_ENCRYPTION
feature is similar to ecryptfs, but it is more memory
efficient since it avoids caching the encrypted and
decrypted pages in the page cache. Currently Ext4,
F2FS and UBIFS make use of this feature.
F2FS, UBIFS, and CephFS make use of this feature.

# Filesystems supporting encryption must select this if FS_ENCRYPTION. This
# allows the algorithms to be built as modules when all the filesystems are,
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