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). > +{ > + 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. - Eric
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