[PATCH 4/5] f2fs: describe dentry block layout dynamically
From: Xinping Zhang
Date: Wed Aug 26 2026 - 17:40:58 EST
An on-disk dentry block contains a bitmap, reserved padding, a
variable-length dir-entry array, and matching filename slots. A fixed C
structure ties their offsets to the compile-time block size and requires
error-prone reserved-size definitions.
Remove the whole-block structure and its compile-time layout macros.
Compute the offsets from the block size and expose the regions through the
existing zero-copy dentry pointer. Pass the owning directory inode at every
block-view initialization to keep the helper contract consistent.
No functional change is intended; this commit continues to use the fixed
F2FS block size.
Signed-off-by: Kelvin Zhang <zhangxp1998@xxxxxxxxx>
---
fs/f2fs/dir.c | 51 +++++++++++++++++++++--------------------
fs/f2fs/f2fs.h | 31 ++++++++++++++++---------
fs/f2fs/inline.c | 2 +-
fs/f2fs/super.c | 6 +++++
include/linux/f2fs_fs.h | 31 ++++++++++++-------------
5 files changed, 68 insertions(+), 53 deletions(-)
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index fd0e2cd31a81..75ff36a13f60 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -195,7 +195,7 @@ static struct f2fs_dir_entry *find_in_block(struct
inode *dir,
int *max_slots,
bool use_hash)
{
- struct f2fs_dentry_block *dentry_blk;
+ void *dentry_blk;
struct f2fs_dentry_ptr d;
dentry_blk = folio_address(dentry_folio);
@@ -518,7 +518,7 @@ static int make_empty_dir(struct inode *inode,
struct inode *parent, struct folio *folio)
{
struct folio *dentry_folio;
- struct f2fs_dentry_block *dentry_blk;
+ void *dentry_blk;
struct f2fs_dentry_ptr d;
if (f2fs_has_inline_dentry(inode))
@@ -530,7 +530,7 @@ static int make_empty_dir(struct inode *inode,
dentry_blk = folio_address(dentry_folio);
- make_dentry_ptr_block(NULL, &d, dentry_blk);
+ make_dentry_ptr_block(inode, &d, dentry_blk);
f2fs_do_make_empty_dir(inode, parent, &d);
folio_mark_dirty(dentry_folio);
@@ -690,7 +690,7 @@ int f2fs_add_regular_entry(struct inode *dir,
const struct f2fs_filename *fname,
unsigned long bidx, block;
unsigned int nbucket, nblock;
struct folio *dentry_folio = NULL;
- struct f2fs_dentry_block *dentry_blk = NULL;
+ void *dentry_blk = NULL;
struct f2fs_dentry_ptr d;
struct folio *folio = NULL;
int slots, err = 0;
@@ -727,9 +727,9 @@ int f2fs_add_regular_entry(struct inode *dir,
const struct f2fs_filename *fname,
return PTR_ERR(dentry_folio);
dentry_blk = folio_address(dentry_folio);
- bit_pos = f2fs_room_for_filename(&dentry_blk->dentry_bitmap,
- slots, NR_DENTRY_IN_BLOCK);
- if (bit_pos < NR_DENTRY_IN_BLOCK)
+ make_dentry_ptr_block(dir, &d, dentry_blk);
+ bit_pos = f2fs_room_for_filename(d.bitmap, slots, d.max);
+ if (bit_pos < d.max)
goto add_dentry;
f2fs_folio_put(dentry_folio, true);
@@ -750,7 +750,6 @@ int f2fs_add_regular_entry(struct inode *dir,
const struct f2fs_filename *fname,
}
}
- make_dentry_ptr_block(NULL, &d, dentry_blk);
f2fs_update_dentry(ino, mode, &d, &fname->disk_name, fname->hash,
bit_pos);
@@ -887,7 +886,8 @@ void f2fs_drop_nlink(struct inode *dir, struct inode *inode)
void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct folio *folio,
struct inode *dir, struct inode *inode)
{
- struct f2fs_dentry_block *dentry_blk;
+ void *dentry_blk;
+ struct f2fs_dentry_ptr d;
unsigned int bit_pos;
int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
pgoff_t index = folio->index;
@@ -905,18 +905,17 @@ void f2fs_delete_entry(struct f2fs_dir_entry
*dentry, struct folio *folio,
f2fs_folio_wait_writeback(folio, DATA, true, true);
dentry_blk = folio_address(folio);
- bit_pos = dentry - dentry_blk->dentry;
+ make_dentry_ptr_block(dir, &d, dentry_blk);
+ bit_pos = dentry - d.dentry;
for (i = 0; i < slots; i++)
- __clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
+ __clear_bit_le(bit_pos + i, d.bitmap);
/* Let's check and deallocate this dentry page */
- bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
- NR_DENTRY_IN_BLOCK,
- 0);
+ bit_pos = find_next_bit_le(d.bitmap, d.max, 0);
folio_mark_dirty(folio);
- if (bit_pos == NR_DENTRY_IN_BLOCK &&
- !f2fs_truncate_hole(dir, index, index + 1)) {
+ if (bit_pos == d.max &&
+ !f2fs_truncate_hole(dir, index, index + 1)) {
f2fs_clear_page_cache_dirty_tag(folio);
folio_clear_dirty_for_io(folio);
folio_clear_uptodate(folio);
@@ -938,7 +937,8 @@ bool f2fs_empty_dir(struct inode *dir)
{
unsigned long bidx = 0;
unsigned int bit_pos;
- struct f2fs_dentry_block *dentry_blk;
+ void *dentry_blk;
+ struct f2fs_dentry_ptr d;
unsigned long nblock = dir_blocks(dir);
if (f2fs_has_inline_dentry(dir))
@@ -959,17 +959,16 @@ bool f2fs_empty_dir(struct inode *dir)
}
dentry_blk = folio_address(dentry_folio);
+ make_dentry_ptr_block(dir, &d, dentry_blk);
if (bidx == 0)
bit_pos = 2;
else
bit_pos = 0;
- bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
- NR_DENTRY_IN_BLOCK,
- bit_pos);
+ bit_pos = find_next_bit_le(d.bitmap, d.max, bit_pos);
f2fs_folio_put(dentry_folio, false);
- if (bit_pos < NR_DENTRY_IN_BLOCK)
+ if (bit_pos < d.max)
return false;
bidx++;
@@ -1066,10 +1065,12 @@ static int f2fs_readdir(struct file *file,
struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
unsigned long npages = dir_blocks(inode);
- struct f2fs_dentry_block *dentry_blk = NULL;
+ void *dentry_blk = NULL;
struct file_ra_state *ra = &file->f_ra;
loff_t start_pos = ctx->pos;
- unsigned int n = ((unsigned long)ctx->pos / NR_DENTRY_IN_BLOCK);
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ unsigned int entries = sbi->dentries_per_block;
+ unsigned int n = (unsigned long)ctx->pos / entries;
struct f2fs_dentry_ptr d;
struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
int err = 0;
@@ -1089,7 +1090,7 @@ static int f2fs_readdir(struct file *file,
struct dir_context *ctx)
goto out_free;
}
- for (; n < npages; ctx->pos = n * NR_DENTRY_IN_BLOCK) {
+ for (; n < npages; ctx->pos = n * entries) {
struct folio *dentry_folio;
pgoff_t next_pgofs;
@@ -1122,7 +1123,7 @@ static int f2fs_readdir(struct file *file,
struct dir_context *ctx)
make_dentry_ptr_block(inode, &d, dentry_blk);
err = f2fs_fill_dentries(ctx, &d,
- n * NR_DENTRY_IN_BLOCK, &fstr);
+ n * entries, &fstr);
f2fs_folio_put(dentry_folio, false);
if (err)
break;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d1235ba80331..026419aed2e9 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -668,17 +668,6 @@ struct f2fs_dentry_ptr {
int nr_bitmap;
};
-static inline void make_dentry_ptr_block(struct inode *inode,
- struct f2fs_dentry_ptr *d, struct f2fs_dentry_block *t)
-{
- d->inode = inode;
- d->max = NR_DENTRY_IN_BLOCK;
- d->nr_bitmap = SIZE_OF_DENTRY_BITMAP;
- d->bitmap = t->dentry_bitmap;
- d->dentry = t->dentry;
- d->filename = t->filename;
-}
-
static inline void make_dentry_ptr_inline(struct inode *inode,
struct f2fs_dentry_ptr *d, void *t)
{
@@ -1864,6 +1853,9 @@ struct f2fs_sb_info {
unsigned int blocksize; /* block size */
unsigned int sit_entries_per_block; /* SIT entries in a block */
unsigned int orphans_per_block; /* orphan inodes in a block */
+ unsigned int dentries_per_block; /* dentries in a block */
+ unsigned int dentry_bitmap_size; /* dentry bitmap size in bytes */
+ unsigned int dentry_reserved_size; /* dentry reserved bytes */
unsigned int root_ino_num; /* root inode number*/
unsigned int node_ino_num; /* node inode number*/
unsigned int meta_ino_num; /* meta inode number*/
@@ -2264,6 +2256,23 @@ f2fs_orphan_footer(void *orphan_block, struct
f2fs_sb_info *sbi)
sizeof(struct f2fs_orphan_footer));
}
+static inline void make_dentry_ptr_block(struct inode *inode,
+ struct f2fs_dentry_ptr *d, void *t)
+{
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ unsigned int entries = sbi->dentries_per_block;
+ unsigned int bitmap_size = sbi->dentry_bitmap_size;
+ unsigned int reserved_size = sbi->dentry_reserved_size;
+
+ d->inode = inode;
+ d->max = entries;
+ d->nr_bitmap = bitmap_size;
+ d->bitmap = t;
+ d->dentry = t + bitmap_size + reserved_size;
+ d->filename = t + bitmap_size + reserved_size +
+ SIZE_OF_DIR_ENTRY * entries;
+}
+
static inline struct f2fs_super_block *F2FS_RAW_SUPER(struct f2fs_sb_info *sbi)
{
return (struct f2fs_super_block *)(sbi->raw_super);
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index aec06fb4fd76..718dd785865a 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -415,7 +415,7 @@ static int f2fs_move_inline_dirents(struct inode
*dir, struct folio *ifolio,
{
struct folio *folio;
struct dnode_of_data dn;
- struct f2fs_dentry_block *dentry_blk;
+ void *dentry_blk;
struct f2fs_dentry_ptr src, dst;
int err;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f324e9cf4264..133c279b9931 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -4352,6 +4352,12 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
sizeof(struct f2fs_sit_entry);
sbi->orphans_per_block = (sbi->blocksize -
sizeof(struct f2fs_orphan_footer)) / sizeof(__le32);
+ sbi->dentries_per_block = (BITS_PER_BYTE * sbi->blocksize) /
+ ((SIZE_OF_DIR_ENTRY + F2FS_SLOT_LEN) * BITS_PER_BYTE + 1);
+ sbi->dentry_bitmap_size = DIV_ROUND_UP(sbi->dentries_per_block,
+ BITS_PER_BYTE);
+ sbi->dentry_reserved_size = sbi->blocksize - sbi->dentry_bitmap_size -
+ (SIZE_OF_DIR_ENTRY + F2FS_SLOT_LEN) * sbi->dentries_per_block;
sbi->log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
sbi->blocks_per_seg = BIT(sbi->log_blocks_per_seg);
sbi->segs_per_sec = le32_to_cpu(raw_super->segs_per_sec);
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index a5111556d923..b4bb4e2f99b3 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -602,15 +602,7 @@ typedef __le32 f2fs_hash_t;
* dentry, when converting inline dentry we should handle this carefully.
*/
-/* the number of dentry in a block */
-#define NR_DENTRY_IN_BLOCK ((BITS_PER_BYTE * F2FS_BLKSIZE) / \
- ((SIZE_OF_DIR_ENTRY + F2FS_SLOT_LEN) * BITS_PER_BYTE + 1))
#define SIZE_OF_DIR_ENTRY 11 /* by byte */
-#define SIZE_OF_DENTRY_BITMAP ((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
- BITS_PER_BYTE)
-#define SIZE_OF_RESERVED (F2FS_BLKSIZE - ((SIZE_OF_DIR_ENTRY + \
- F2FS_SLOT_LEN) * \
- NR_DENTRY_IN_BLOCK + SIZE_OF_DENTRY_BITMAP))
#define MIN_INLINE_DENTRY_SIZE 40 /* just include '.' and '..' entries */
/* One directory entry slot representing F2FS_SLOT_LEN-sized file name */
@@ -621,14 +613,21 @@ struct f2fs_dir_entry {
__u8 file_type; /* file type */
} __packed;
-/* Block-sized directory entry block */
-struct f2fs_dentry_block {
- /* validity bitmap for directory entries in each block */
- __u8 dentry_bitmap[SIZE_OF_DENTRY_BITMAP];
- __u8 reserved[SIZE_OF_RESERVED];
- struct f2fs_dir_entry dentry[NR_DENTRY_IN_BLOCK];
- __u8 filename[NR_DENTRY_IN_BLOCK][F2FS_SLOT_LEN];
-} __packed;
+/*
+ * A dentry block is laid out as follows, where the number of entries and all
+ * offsets are determined by the filesystem block size at runtime:
+ *
+ * 0 blocksize
+ * +--------+----------+-------------------+-----------------------+
+ * | bitmap | reserved | dir_entry[entries]| filename[entries][8] |
+ * +--------+----------+-------------------+-----------------------+
+ *
+ * entries = (BITS_PER_BYTE * blocksize) /
+ * ((SIZE_OF_DIR_ENTRY + F2FS_SLOT_LEN) * BITS_PER_BYTE + 1)
+ * bitmap_size = DIV_ROUND_UP(entries, BITS_PER_BYTE)
+ * reserved_size = blocksize - bitmap_size -
+ * (SIZE_OF_DIR_ENTRY + F2FS_SLOT_LEN) * entries
+ */
#define F2FS_DEF_PROJID 0 /* default project ID */
--
2.53.0