Eric Biggers <ebiggers@xxxxxxxxxx> writes: > On Thu, Mar 09, 2023 at 12:19:09PM +0000, Luís Henriques wrote: >> This patch introduces a new helper function which prepares an atomic_open. >> Because atomic open can act as a lookup if handed a dentry that is negative, >> we need to set DCACHE_NOKEY_NAME if the key for the parent isn't available. >> >> The reason for getting the encryption info before checking if the directory >> has the encryption key is because we may have the key available but the >> encryption info isn't yet set (maybe due to a drop_caches). The regular >> open path will use fscrypt_file_open for that but in the atomic open a >> different approach is required. >> >> Signed-off-by: Luís Henriques <lhenriques@xxxxxxx> >> --- >> fs/crypto/hooks.c | 14 ++++++++++++++ >> include/linux/fscrypt.h | 6 ++++++ >> 2 files changed, 20 insertions(+) >> >> diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c >> index 7b8c5a1104b5..cbb828ecc5eb 100644 >> --- a/fs/crypto/hooks.c >> +++ b/fs/crypto/hooks.c >> @@ -117,6 +117,20 @@ int __fscrypt_prepare_readdir(struct inode *dir) >> } >> EXPORT_SYMBOL_GPL(__fscrypt_prepare_readdir); >> >> +int __fscrypt_prepare_atomic_open(struct inode *dir, struct dentry *dentry) > > Anything exported to filesystems should have a kerneldoc comment. That would be > a good place to put some of the explanation that you currently have only in the > commit message. > > Also, double-underscored functions are not for use by filesystems directly. > Normally the pattern would be to make fscrypt_prepare_atomic_open() an inline > function that checks IS_ENCRYPTED() and calls an out-of-line function > __fscrypt_prepare_atomic_open(). But if it happens to be simpler to make the > caller handle the IS_ENCRYPTED() check in this case, then there should simply be > one function: fscrypt_prepare_atomic_open() (no leading underscores). Thank you, Eric. I'll make sure that next rev will take these comments into account. It definitely makes sense to move (or duplicate) the details as a kerneldoc comment. >> +{ >> + int err = fscrypt_get_encryption_info(dir, true); >> + >> + if (err || (!err && !fscrypt_has_encryption_key(dir))) { >> + spin_lock(&dentry->d_lock); >> + dentry->d_flags |= DCACHE_NOKEY_NAME; >> + spin_unlock(&dentry->d_lock); >> + } > > Why does DCACHE_NOKEY_NAME need to be set on error? > > Also note that the '!err &&' part has no effect. To be honest, I wasn't really sure that if the d_flags should be set on error either. I'll drop that, and then the 'if' statement will make more sense without the '||'. Cheers -- Luís
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