Re: [PATCH v3] f2fs: Introduce linear search for dentries
From: Chao Yu
Date: Sun Dec 22 2024 - 08:35:37 EST
On 2024/12/21 7:41, 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.
Fixes: 5c26d2f1d3f5 ("unicode: Don't special case ignorable code points")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219586
Signed-off-by: Daniel Lee <chullee@xxxxxxxxxx>
---
v3:
- Fix the unused label warning
v2:
- Only update chash if use_hash is true
fs/f2fs/dir.c | 42 +++++++++++++++++++++++++++++++-----------
fs/f2fs/f2fs.h | 6 ++++--
fs/f2fs/inline.c | 5 +++--
3 files changed, 38 insertions(+), 15 deletions(-)
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 47a5c806cf16..058b8be9a373 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;
@@ -307,7 +313,10 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir,
bidx++;
}
- if (!de && room && F2FS_I(dir)->chash != fname->hash) {
+ if (!use_hash && !de && ++bucket_no < nbucket)
+ goto start_find_bucket;
+
+ if (use_hash && !de && room && F2FS_I(dir)->chash != fname->hash) {
F2FS_I(dir)->chash = fname->hash;
F2FS_I(dir)->clevel = level;
What about cleaning up w/
if (de)
return de;
if (use_hash) {
if (room && F2FS_I(dir)->chash != fname->hash) {
...
}
} else if (++bucket_no < nbucket)
goto start_find_bucket;
}
return NULL;
Otherwise, it looks good to me, anyway,
Reviewed-by: Chao Yu <chao@xxxxxxxxxx>
Thanks,
}
@@ -323,11 +332,15 @@ 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;
+#if IS_ENABLED(CONFIG_UNICODE)
+start_find_entry:
+#endif
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 +356,18 @@ 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);