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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZYJCqndz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZYJCqndz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F6E9C4CED0; Thu, 19 Dec 2024 13:29:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734614947; bh=7WUNTbFDqFvgrpqNjFRokUfM8y1E12dGmPZWJmDuTeE=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=ZYJCqndzMxbdDAqchZWAhhO2UPJM/ZyZVz68iqXniQH9ZSdDxkm4rp/VtAlzlaNDE mjqaEndjXmh4nJgq730anDadzmfjCoU9/9rHdLUMLkNgfPWjN1DN0eWMqtnjMs6WZ8 Tgcsim88mFfunqiswQDFYs2mYFzW2+lsu3socllzmLTICqIyzScOSRgH7CFJdvOL8R VCLSYFI4LVh647YkT53SI92jXlcf0wQbB6s8qBbLiaWHUTftyLQwpnf+HQD1D0uz5G I8608aQg9F/QvauYA+YgyiyG9qQ6GZN8g4uYABRHTU+D8BbOBi+qJWS7zGgCqL0gH9 xkIkH5e2bvicA== Message-ID: <31e9c60b-0fd1-4d98-baf9-cf02e44c367d@kernel.org> Date: Thu, 19 Dec 2024 21:29:11 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: Chao Yu , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] f2fs: Introduce linear search for dentries To: Daniel Lee , Jaegeuk Kim References: <20241217075552.1167994-1-chullee@google.com> Content-Language: en-US From: Chao Yu Autocrypt: addr=chao@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Daniel, On 2024/12/17 15:55, Daniel Lee wrote: > This patch addresses an issue where some files in case-insensitive > directories become inaccessible due to changes in how the kernel function, > utf8_casefold(), generates case-folded strings from the commit 5c26d2f1d3f5 > ("unicode: Don't special case ignorable code points"). > > F2FS uses these case-folded names to calculate hash values for locating > dentries and stores them on disk. Since utf8_casefold() can produce > different output across kernel versions, stored hash values and newly > calculated hash values may differ. This results in affected files no > longer being found via the hash-based lookup. > > To resolve this, the patch introduces a linear search fallback. > If the initial hash-based search fails, F2FS will sequentially scan the > directory entries. > Need a fixes line? > Link: https://bugzilla.kernel.org/show_bug.cgi?id=219586 > Signed-off-by: Daniel Lee > --- > fs/f2fs/dir.c | 38 ++++++++++++++++++++++++++++---------- > fs/f2fs/f2fs.h | 6 ++++-- > fs/f2fs/inline.c | 5 +++-- > 3 files changed, 35 insertions(+), 14 deletions(-) > > diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c > index 47a5c806cf16..a85d19b4e178 100644 > --- a/fs/f2fs/dir.c > +++ b/fs/f2fs/dir.c > @@ -175,7 +175,8 @@ static unsigned long dir_block_index(unsigned int level, > static struct f2fs_dir_entry *find_in_block(struct inode *dir, > struct page *dentry_page, > const struct f2fs_filename *fname, > - int *max_slots) > + int *max_slots, > + bool use_hash) > { > struct f2fs_dentry_block *dentry_blk; > struct f2fs_dentry_ptr d; > @@ -183,7 +184,7 @@ static struct f2fs_dir_entry *find_in_block(struct inode *dir, > dentry_blk = (struct f2fs_dentry_block *)page_address(dentry_page); > > make_dentry_ptr_block(dir, &d, dentry_blk); > - return f2fs_find_target_dentry(&d, fname, max_slots); > + return f2fs_find_target_dentry(&d, fname, max_slots, use_hash); > } > > static inline int f2fs_match_name(const struct inode *dir, > @@ -208,7 +209,8 @@ static inline int f2fs_match_name(const struct inode *dir, > } > > struct f2fs_dir_entry *f2fs_find_target_dentry(const struct f2fs_dentry_ptr *d, > - const struct f2fs_filename *fname, int *max_slots) > + const struct f2fs_filename *fname, int *max_slots, > + bool use_hash) > { > struct f2fs_dir_entry *de; > unsigned long bit_pos = 0; > @@ -231,7 +233,7 @@ struct f2fs_dir_entry *f2fs_find_target_dentry(const struct f2fs_dentry_ptr *d, > continue; > } > > - if (de->hash_code == fname->hash) { > + if (!use_hash || de->hash_code == fname->hash) { > res = f2fs_match_name(d->inode, fname, > d->filename[bit_pos], > le16_to_cpu(de->name_len)); > @@ -258,11 +260,12 @@ struct f2fs_dir_entry *f2fs_find_target_dentry(const struct f2fs_dentry_ptr *d, > static struct f2fs_dir_entry *find_in_level(struct inode *dir, > unsigned int level, > const struct f2fs_filename *fname, > - struct page **res_page) > + struct page **res_page, > + bool use_hash) > { > int s = GET_DENTRY_SLOTS(fname->disk_name.len); > unsigned int nbucket, nblock; > - unsigned int bidx, end_block; > + unsigned int bidx, end_block, bucket_no; > struct page *dentry_page; > struct f2fs_dir_entry *de = NULL; > pgoff_t next_pgofs; > @@ -272,8 +275,11 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir, > nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level); > nblock = bucket_blocks(level); > > + bucket_no = use_hash ? le32_to_cpu(fname->hash) % nbucket : 0; > + > +start_find_bucket: > bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level, > - le32_to_cpu(fname->hash) % nbucket); > + bucket_no); > end_block = bidx + nblock; > > while (bidx < end_block) { > @@ -290,7 +296,7 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir, > } > } > > - de = find_in_block(dir, dentry_page, fname, &max_slots); > + de = find_in_block(dir, dentry_page, fname, &max_slots, use_hash); > if (IS_ERR(de)) { > *res_page = ERR_CAST(de); > de = NULL; > @@ -307,6 +313,9 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir, > bidx++; > } > > + if (!use_hash && !de && ++bucket_no < nbucket) > + goto start_find_bucket; > + > if (!de && room && F2FS_I(dir)->chash != fname->hash) { Do we need to avoid accessing or assigning hash if use_hash is false? Thanks, > F2FS_I(dir)->chash = fname->hash; > F2FS_I(dir)->clevel = level; > @@ -323,11 +332,13 @@ struct f2fs_dir_entry *__f2fs_find_entry(struct inode *dir, > struct f2fs_dir_entry *de = NULL; > unsigned int max_depth; > unsigned int level; > + bool use_hash = true; > > *res_page = NULL; > > +start_find_entry: > if (f2fs_has_inline_dentry(dir)) { > - de = f2fs_find_in_inline_dir(dir, fname, res_page); > + de = f2fs_find_in_inline_dir(dir, fname, res_page, use_hash); > goto out; > } > > @@ -343,11 +354,18 @@ struct f2fs_dir_entry *__f2fs_find_entry(struct inode *dir, > } > > for (level = 0; level < max_depth; level++) { > - de = find_in_level(dir, level, fname, res_page); > + de = find_in_level(dir, level, fname, res_page, use_hash); > if (de || IS_ERR(*res_page)) > break; > } > + > out: > +#if IS_ENABLED(CONFIG_UNICODE) > + if (IS_CASEFOLDED(dir) && !de && use_hash) { > + use_hash = false; > + goto start_find_entry; > + } > +#endif > /* This is to increase the speed of f2fs_create */ > if (!de) > F2FS_I(dir)->task = current; > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index f523dd302bf6..1afebb9c4061 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -3588,7 +3588,8 @@ int f2fs_prepare_lookup(struct inode *dir, struct dentry *dentry, > struct f2fs_filename *fname); > void f2fs_free_filename(struct f2fs_filename *fname); > struct f2fs_dir_entry *f2fs_find_target_dentry(const struct f2fs_dentry_ptr *d, > - const struct f2fs_filename *fname, int *max_slots); > + const struct f2fs_filename *fname, int *max_slots, > + bool use_hash); > int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d, > unsigned int start_pos, struct fscrypt_str *fstr); > void f2fs_do_make_empty_dir(struct inode *inode, struct inode *parent, > @@ -4224,7 +4225,8 @@ int f2fs_write_inline_data(struct inode *inode, struct folio *folio); > int f2fs_recover_inline_data(struct inode *inode, struct page *npage); > struct f2fs_dir_entry *f2fs_find_in_inline_dir(struct inode *dir, > const struct f2fs_filename *fname, > - struct page **res_page); > + struct page **res_page, > + bool use_hash); > int f2fs_make_empty_inline_dir(struct inode *inode, struct inode *parent, > struct page *ipage); > int f2fs_add_inline_entry(struct inode *dir, const struct f2fs_filename *fname, > diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c > index cbd2a0d34804..3e3c35d4c98b 100644 > --- a/fs/f2fs/inline.c > +++ b/fs/f2fs/inline.c > @@ -352,7 +352,8 @@ int f2fs_recover_inline_data(struct inode *inode, struct page *npage) > > struct f2fs_dir_entry *f2fs_find_in_inline_dir(struct inode *dir, > const struct f2fs_filename *fname, > - struct page **res_page) > + struct page **res_page, > + bool use_hash) > { > struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb); > struct f2fs_dir_entry *de; > @@ -369,7 +370,7 @@ struct f2fs_dir_entry *f2fs_find_in_inline_dir(struct inode *dir, > inline_dentry = inline_data_addr(dir, ipage); > > make_dentry_ptr_inline(dir, &d, inline_dentry); > - de = f2fs_find_target_dentry(&d, fname, NULL); > + de = f2fs_find_target_dentry(&d, fname, NULL, use_hash); > unlock_page(ipage); > if (IS_ERR(de)) { > *res_page = ERR_CAST(de);