Re: [f2fs-dev] [PATCH 3/4] f2fs: rework filename handling

[Chao Yu <yuchao0@huawei.com>]

On 2020/5/7 15:59, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Rework f2fs's handling of filenames to use a new 'struct f2fs_filename'.
> Similar to 'struct ext4_filename', this stores the usr_fname, disk_name,
> dirhash, crypto_buf, and casefolded name.  Some of these names can be
> NULL in some cases.  'struct f2fs_filename' differs from
> 'struct fscrypt_name' mainly in that the casefolded name is included.
> 
> For user-initiated directory operations like lookup() and create(),
> initialize the f2fs_filename by translating the corresponding
> fscrypt_name, then computing the dirhash and casefolded name if needed.
> 
> This makes the dirhash and casefolded name be cached for each syscall,
> so we don't have to recompute them repeatedly.  (Previously, f2fs
> computed the dirhash once per directory level, and the casefolded name
> once per directory block.)  This improves performance.
> 
> This rework also makes it much easier to correctly handle all
> combinations of normal, encrypted, casefolded, and encrypted+casefolded
> directories.  (The fourth isn't supported yet but is being worked on.)
> 
> The only other cases where an f2fs_filename gets initialized are for two
> filesystem-internal operations: (1) when converting an inline directory
> to a regular one, we grab the needed disk_name and hash from an existing
> f2fs_dir_entry; and (2) when roll-forward recovering a new dentry, we
> grab the needed disk_name from f2fs_inode::i_name and compute the hash.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,


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