Re: [PATCH v10 3/4] f2fs: Use generic casefolding support

Eric Biggers
2020-07-08T01:41:22Z

On Tue, Jul 07, 2020 at 04:31:22AM -0700, Daniel Rosenberg wrote:
> This switches f2fs over to the generic support provided in
> the previous patch.
>
> Since casefolded dentries behave the same in ext4 and f2fs, we decrease
> the maintenance burden by unifying them, and any optimizations will
> immediately apply to both.
>
> Signed-off-by: Daniel Rosenberg <drosen@google.com>
> ---
> fs/f2fs/dir.c | 83 +++++------------------------------------
> fs/f2fs/f2fs.h | 4 --
> fs/f2fs/super.c | 10 ++---
> fs/f2fs/sysfs.c | 10 +++--
> include/linux/f2fs_fs.h | 3 --
> 5 files changed, 20 insertions(+), 90 deletions(-)

Looks good, you can add:

Reviewed-by: Eric Biggers <ebiggers@google.com>

One nit below:

> #ifdef CONFIG_UNICODE
> -static int f2fs_d_compare(const struct dentry *dentry, unsigned int len,
> - const char *str, const struct qstr *name)
> -{
> - const struct dentry *parent = READ_ONCE(dentry->d_parent);
> - const struct inode *dir = READ_ONCE(parent->d_inode);
> - const struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
> - struct qstr entry = QSTR_INIT(str, len);
> - char strbuf[DNAME_INLINE_LEN];
> - int res;
> -
> - if (!dir || !IS_CASEFOLDED(dir))
> - goto fallback;
> -
> - /*
> - * If the dentry name is stored in-line, then it may be concurrently
> - * modified by a rename. If this happens, the VFS will eventually retry
> - * the lookup, so it doesn't matter what ->d_compare() returns.
> - * However, it's unsafe to call utf8_strncasecmp() with an unstable
> - * string. Therefore, we have to copy the name into a temporary buffer.
> - */
> - if (len <= DNAME_INLINE_LEN - 1) {
> - memcpy(strbuf, str, len);
> - strbuf[len] = 0;
> - entry.name = strbuf;
> - /* prevent compiler from optimizing out the temporary buffer */
> - barrier();
> - }
> -
> - res = utf8_strncasecmp(sbi->s_encoding, name, &entry);
> - if (res >= 0)
> - return res;
> -
> - if (f2fs_has_strict_mode(sbi))
> - return -EINVAL;
> -fallback:
> - if (len != name->len)
> - return 1;
> - return !!memcmp(str, name->name, len);
> -}
> -
> -static int f2fs_d_hash(const struct dentry *dentry, struct qstr *str)
> -{
> - struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
> - const struct unicode_map *um = sbi->s_encoding;
> - const struct inode *inode = READ_ONCE(dentry->d_inode);
> - unsigned char *norm;
> - int len, ret = 0;
> -
> - if (!inode || !IS_CASEFOLDED(inode))
> - return 0;
> -
> - norm = f2fs_kmalloc(sbi, PATH_MAX, GFP_ATOMIC);
> - if (!norm)
> - return -ENOMEM;
> -
> - len = utf8_casefold(um, str, norm, PATH_MAX);
> - if (len < 0) {
> - if (f2fs_has_strict_mode(sbi))
> - ret = -EINVAL;
> - goto out;
> - }
> - str->hash = full_name_hash(dentry, norm, len);
> -out:
> - kvfree(norm);
> - return ret;
> -}
>
> const struct dentry_operations f2fs_dentry_ops = {
> - .d_hash = f2fs_d_hash,
> - .d_compare = f2fs_d_compare,
> + .d_hash = generic_ci_d_hash,
> + .d_compare = generic_ci_d_compare,
> };
> #endif

This leaves an extra blank line just above f2fs_dentry_ops.

- Eric