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linux-stable/fs/exfat/dir.c
Yuezhang Mo 8a3f5711ad exfat: reduce FAT chain traversal 
Before this commit, ->dir and ->entry of exfat_inode_info record the
first cluster of the parent directory and the directory entry index
starting from this cluster.

The directory entry set will be gotten during write-back-inode/rmdir/
unlink/rename. If the clusters of the parent directory are not
continuous, the FAT chain will be traversed from the first cluster of
the parent directory to find the cluster where ->entry is located.

After this commit, ->dir records the cluster where the first directory
entry in the directory entry set is located, and ->entry records the
directory entry index in the cluster, so that there is almost no need
to access the FAT when getting the directory entry set.

Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Aoyama Wataru <wataru.aoyama@sony.com>
Reviewed-by: Daniel Palmer <daniel.palmer@sony.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
2024-11-25 17:08:27 +09:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
*/
#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/bio.h>
#include <linux/buffer_head.h>
#include "exfat_raw.h"
#include "exfat_fs.h"
static int exfat_extract_uni_name(struct exfat_dentry *ep,
unsigned short *uniname)
{
int i, len = 0;
for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
*uniname = le16_to_cpu(ep->dentry.name.unicode_0_14[i]);
if (*uniname == 0x0)
return len;
uniname++;
len++;
}
*uniname = 0x0;
return len;
}
static int exfat_get_uniname_from_ext_entry(struct super_block *sb,
struct exfat_chain *p_dir, int entry, unsigned short *uniname)
{
int i, err;
struct exfat_entry_set_cache es;
unsigned int uni_len = 0, len;
err = exfat_get_dentry_set(&es, sb, p_dir, entry, ES_ALL_ENTRIES);
if (err)
return err;
/*
* First entry : file entry
* Second entry : stream-extension entry
* Third entry : first file-name entry
* So, the index of first file-name dentry should start from 2.
*/
for (i = ES_IDX_FIRST_FILENAME; i < es.num_entries; i++) {
struct exfat_dentry *ep = exfat_get_dentry_cached(&es, i);
/* end of name entry */
if (exfat_get_entry_type(ep) != TYPE_EXTEND)
break;
len = exfat_extract_uni_name(ep, uniname);
uni_len += len;
if (len != EXFAT_FILE_NAME_LEN || uni_len >= MAX_NAME_LENGTH)
break;
uniname += EXFAT_FILE_NAME_LEN;
}
exfat_put_dentry_set(&es, false);
return 0;
}
/* read a directory entry from the opened directory */
static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_entry *dir_entry)
{
int i, dentries_per_clu, num_ext, err;
unsigned int type, clu_offset, max_dentries;
struct exfat_chain dir, clu;
struct exfat_uni_name uni_name;
struct exfat_dentry *ep;
struct super_block *sb = inode->i_sb;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct exfat_inode_info *ei = EXFAT_I(inode);
unsigned int dentry = EXFAT_B_TO_DEN(*cpos) & 0xFFFFFFFF;
struct buffer_head *bh;
/* check if the given file ID is opened */
if (ei->type != TYPE_DIR)
return -EPERM;
exfat_chain_set(&dir, ei->start_clu,
EXFAT_B_TO_CLU(i_size_read(inode), sbi), ei->flags);
dentries_per_clu = sbi->dentries_per_clu;
max_dentries = (unsigned int)min_t(u64, MAX_EXFAT_DENTRIES,
(u64)EXFAT_CLU_TO_DEN(sbi->num_clusters, sbi));
clu_offset = EXFAT_DEN_TO_CLU(dentry, sbi);
exfat_chain_dup(&clu, &dir);
if (clu.flags == ALLOC_NO_FAT_CHAIN) {
clu.dir += clu_offset;
clu.size -= clu_offset;
} else {
/* hint_information */
if (clu_offset > 0 && ei->hint_bmap.off != EXFAT_EOF_CLUSTER &&
ei->hint_bmap.off > 0 && clu_offset >= ei->hint_bmap.off) {
clu_offset -= ei->hint_bmap.off;
clu.dir = ei->hint_bmap.clu;
}
while (clu_offset > 0 && clu.dir != EXFAT_EOF_CLUSTER) {
if (exfat_get_next_cluster(sb, &(clu.dir)))
return -EIO;
clu_offset--;
}
}
while (clu.dir != EXFAT_EOF_CLUSTER && dentry < max_dentries) {
i = dentry & (dentries_per_clu - 1);
for ( ; i < dentries_per_clu; i++, dentry++) {
ep = exfat_get_dentry(sb, &clu, i, &bh);
if (!ep)
return -EIO;
type = exfat_get_entry_type(ep);
if (type == TYPE_UNUSED) {
brelse(bh);
break;
}
if (type != TYPE_FILE && type != TYPE_DIR) {
brelse(bh);
continue;
}
num_ext = ep->dentry.file.num_ext;
dir_entry->attr = le16_to_cpu(ep->dentry.file.attr);
*uni_name.name = 0x0;
err = exfat_get_uniname_from_ext_entry(sb, &clu, i,
uni_name.name);
if (err) {
brelse(bh);
continue;
}
exfat_utf16_to_nls(sb, &uni_name,
dir_entry->namebuf.lfn,
dir_entry->namebuf.lfnbuf_len);
brelse(bh);
ep = exfat_get_dentry(sb, &clu, i + 1, &bh);
if (!ep)
return -EIO;
dir_entry->entry = i;
dir_entry->dir = clu;
brelse(bh);
ei->hint_bmap.off = EXFAT_DEN_TO_CLU(dentry, sbi);
ei->hint_bmap.clu = clu.dir;
*cpos = EXFAT_DEN_TO_B(dentry + 1 + num_ext);
return 0;
}
if (clu.flags == ALLOC_NO_FAT_CHAIN) {
if (--clu.size > 0)
clu.dir++;
else
clu.dir = EXFAT_EOF_CLUSTER;
} else {
if (exfat_get_next_cluster(sb, &(clu.dir)))
return -EIO;
}
}
dir_entry->namebuf.lfn[0] = '\0';
*cpos = EXFAT_DEN_TO_B(dentry);
return 0;
}
static void exfat_init_namebuf(struct exfat_dentry_namebuf *nb)
{
nb->lfn = NULL;
nb->lfnbuf_len = 0;
}
static int exfat_alloc_namebuf(struct exfat_dentry_namebuf *nb)
{
nb->lfn = __getname();
if (!nb->lfn)
return -ENOMEM;
nb->lfnbuf_len = MAX_VFSNAME_BUF_SIZE;
return 0;
}
static void exfat_free_namebuf(struct exfat_dentry_namebuf *nb)
{
if (!nb->lfn)
return;
__putname(nb->lfn);
exfat_init_namebuf(nb);
}
/*
* Before calling dir_emit*(), sbi->s_lock should be released
* because page fault can occur in dir_emit*().
*/
#define ITER_POS_FILLED_DOTS (2)
static int exfat_iterate(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
struct inode *tmp;
struct exfat_dir_entry de;
struct exfat_dentry_namebuf *nb = &(de.namebuf);
struct exfat_inode_info *ei = EXFAT_I(inode);
unsigned long inum;
loff_t cpos, i_pos;
int err = 0, fake_offset = 0;
exfat_init_namebuf(nb);
cpos = ctx->pos;
if (!dir_emit_dots(file, ctx))
goto out;
if (ctx->pos == ITER_POS_FILLED_DOTS) {
cpos = 0;
fake_offset = 1;
}
cpos = round_up(cpos, DENTRY_SIZE);
/* name buffer should be allocated before use */
err = exfat_alloc_namebuf(nb);
if (err)
goto out;
get_new:
mutex_lock(&EXFAT_SB(sb)->s_lock);
if (ei->flags == ALLOC_NO_FAT_CHAIN && cpos >= i_size_read(inode))
goto end_of_dir;
err = exfat_readdir(inode, &cpos, &de);
if (err) {
/*
* At least we tried to read a sector.
* Move cpos to next sector position (should be aligned).
*/
if (err == -EIO) {
cpos += 1 << (sb->s_blocksize_bits);
cpos &= ~(sb->s_blocksize - 1);
}
err = -EIO;
goto end_of_dir;
}
if (!nb->lfn[0])
goto end_of_dir;
i_pos = ((loff_t)de.dir.dir << 32) | (de.entry & 0xffffffff);
tmp = exfat_iget(sb, i_pos);
if (tmp) {
inum = tmp->i_ino;
iput(tmp);
} else {
inum = iunique(sb, EXFAT_ROOT_INO);
}
mutex_unlock(&EXFAT_SB(sb)->s_lock);
if (!dir_emit(ctx, nb->lfn, strlen(nb->lfn), inum,
(de.attr & EXFAT_ATTR_SUBDIR) ? DT_DIR : DT_REG))
goto out;
ctx->pos = cpos;
goto get_new;
end_of_dir:
if (!cpos && fake_offset)
cpos = ITER_POS_FILLED_DOTS;
ctx->pos = cpos;
mutex_unlock(&EXFAT_SB(sb)->s_lock);
out:
/*
* To improve performance, free namebuf after unlock sb_lock.
* If namebuf is not allocated, this function do nothing
*/
exfat_free_namebuf(nb);
return err;
}
WRAP_DIR_ITER(exfat_iterate) // FIXME!
const struct file_operations exfat_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = shared_exfat_iterate,
.unlocked_ioctl = exfat_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = exfat_compat_ioctl,
#endif
.fsync = exfat_file_fsync,
};
int exfat_alloc_new_dir(struct inode *inode, struct exfat_chain *clu)
{
int ret;
exfat_chain_set(clu, EXFAT_EOF_CLUSTER, 0, ALLOC_NO_FAT_CHAIN);
ret = exfat_alloc_cluster(inode, 1, clu, IS_DIRSYNC(inode));
if (ret)
return ret;
return exfat_zeroed_cluster(inode, clu->dir);
}
int exfat_calc_num_entries(struct exfat_uni_name *p_uniname)
{
int len;
len = p_uniname->name_len;
if (len == 0)
return -EINVAL;
/* 1 file entry + 1 stream entry + name entries */
return ES_ENTRY_NUM(len);
}
unsigned int exfat_get_entry_type(struct exfat_dentry *ep)
{
if (ep->type == EXFAT_UNUSED)
return TYPE_UNUSED;
if (IS_EXFAT_DELETED(ep->type))
return TYPE_DELETED;
if (ep->type == EXFAT_INVAL)
return TYPE_INVALID;
if (IS_EXFAT_CRITICAL_PRI(ep->type)) {
if (ep->type == EXFAT_BITMAP)
return TYPE_BITMAP;
if (ep->type == EXFAT_UPCASE)
return TYPE_UPCASE;
if (ep->type == EXFAT_VOLUME)
return TYPE_VOLUME;
if (ep->type == EXFAT_FILE) {
if (le16_to_cpu(ep->dentry.file.attr) & EXFAT_ATTR_SUBDIR)
return TYPE_DIR;
return TYPE_FILE;
}
return TYPE_CRITICAL_PRI;
}
if (IS_EXFAT_BENIGN_PRI(ep->type)) {
if (ep->type == EXFAT_GUID)
return TYPE_GUID;
if (ep->type == EXFAT_PADDING)
return TYPE_PADDING;
if (ep->type == EXFAT_ACLTAB)
return TYPE_ACLTAB;
return TYPE_BENIGN_PRI;
}
if (IS_EXFAT_CRITICAL_SEC(ep->type)) {
if (ep->type == EXFAT_STREAM)
return TYPE_STREAM;
if (ep->type == EXFAT_NAME)
return TYPE_EXTEND;
if (ep->type == EXFAT_ACL)
return TYPE_ACL;
return TYPE_CRITICAL_SEC;
}
if (ep->type == EXFAT_VENDOR_EXT)
return TYPE_VENDOR_EXT;
if (ep->type == EXFAT_VENDOR_ALLOC)
return TYPE_VENDOR_ALLOC;
return TYPE_BENIGN_SEC;
}
static void exfat_set_entry_type(struct exfat_dentry *ep, unsigned int type)
{
if (type == TYPE_UNUSED) {
ep->type = EXFAT_UNUSED;
} else if (type == TYPE_DELETED) {
ep->type &= EXFAT_DELETE;
} else if (type == TYPE_STREAM) {
ep->type = EXFAT_STREAM;
} else if (type == TYPE_EXTEND) {
ep->type = EXFAT_NAME;
} else if (type == TYPE_BITMAP) {
ep->type = EXFAT_BITMAP;
} else if (type == TYPE_UPCASE) {
ep->type = EXFAT_UPCASE;
} else if (type == TYPE_VOLUME) {
ep->type = EXFAT_VOLUME;
} else if (type == TYPE_DIR) {
ep->type = EXFAT_FILE;
ep->dentry.file.attr = cpu_to_le16(EXFAT_ATTR_SUBDIR);
} else if (type == TYPE_FILE) {
ep->type = EXFAT_FILE;
ep->dentry.file.attr = cpu_to_le16(EXFAT_ATTR_ARCHIVE);
}
}
static void exfat_init_stream_entry(struct exfat_dentry *ep,
unsigned int start_clu, unsigned long long size)
{
memset(ep, 0, sizeof(*ep));
exfat_set_entry_type(ep, TYPE_STREAM);
if (size == 0)
ep->dentry.stream.flags = ALLOC_FAT_CHAIN;
else
ep->dentry.stream.flags = ALLOC_NO_FAT_CHAIN;
ep->dentry.stream.start_clu = cpu_to_le32(start_clu);
ep->dentry.stream.valid_size = cpu_to_le64(size);
ep->dentry.stream.size = cpu_to_le64(size);
}
static void exfat_init_name_entry(struct exfat_dentry *ep,
unsigned short *uniname)
{
int i;
exfat_set_entry_type(ep, TYPE_EXTEND);
ep->dentry.name.flags = 0x0;
for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
if (*uniname != 0x0) {
ep->dentry.name.unicode_0_14[i] = cpu_to_le16(*uniname);
uniname++;
} else {
ep->dentry.name.unicode_0_14[i] = 0x0;
}
}
}
void exfat_init_dir_entry(struct exfat_entry_set_cache *es,
unsigned int type, unsigned int start_clu,
unsigned long long size, struct timespec64 *ts)
{
struct super_block *sb = es->sb;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct exfat_dentry *ep;
ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
memset(ep, 0, sizeof(*ep));
exfat_set_entry_type(ep, type);
exfat_set_entry_time(sbi, ts,
&ep->dentry.file.create_tz,
&ep->dentry.file.create_time,
&ep->dentry.file.create_date,
&ep->dentry.file.create_time_cs);
exfat_set_entry_time(sbi, ts,
&ep->dentry.file.modify_tz,
&ep->dentry.file.modify_time,
&ep->dentry.file.modify_date,
&ep->dentry.file.modify_time_cs);
exfat_set_entry_time(sbi, ts,
&ep->dentry.file.access_tz,
&ep->dentry.file.access_time,
&ep->dentry.file.access_date,
NULL);
ep = exfat_get_dentry_cached(es, ES_IDX_STREAM);
exfat_init_stream_entry(ep, start_clu, size);
}
static void exfat_free_benign_secondary_clusters(struct inode *inode,
struct exfat_dentry *ep)
{
struct super_block *sb = inode->i_sb;
struct exfat_chain dir;
unsigned int start_clu =
le32_to_cpu(ep->dentry.generic_secondary.start_clu);
u64 size = le64_to_cpu(ep->dentry.generic_secondary.size);
unsigned char flags = ep->dentry.generic_secondary.flags;
if (!(flags & ALLOC_POSSIBLE) || !start_clu || !size)
return;
exfat_chain_set(&dir, start_clu,
EXFAT_B_TO_CLU_ROUND_UP(size, EXFAT_SB(sb)),
flags);
exfat_free_cluster(inode, &dir);
}
void exfat_init_ext_entry(struct exfat_entry_set_cache *es, int num_entries,
struct exfat_uni_name *p_uniname)
{
int i;
unsigned short *uniname = p_uniname->name;
struct exfat_dentry *ep;
ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
ep->dentry.file.num_ext = (unsigned char)(num_entries - 1);
ep = exfat_get_dentry_cached(es, ES_IDX_STREAM);
ep->dentry.stream.name_len = p_uniname->name_len;
ep->dentry.stream.name_hash = cpu_to_le16(p_uniname->name_hash);
for (i = ES_IDX_FIRST_FILENAME; i < num_entries; i++) {
ep = exfat_get_dentry_cached(es, i);
exfat_init_name_entry(ep, uniname);
uniname += EXFAT_FILE_NAME_LEN;
}
exfat_update_dir_chksum(es);
}
void exfat_remove_entries(struct inode *inode, struct exfat_entry_set_cache *es,
int order)
{
int i;
struct exfat_dentry *ep;
for (i = order; i < es->num_entries; i++) {
ep = exfat_get_dentry_cached(es, i);
if (exfat_get_entry_type(ep) & TYPE_BENIGN_SEC)
exfat_free_benign_secondary_clusters(inode, ep);
exfat_set_entry_type(ep, TYPE_DELETED);
}
if (order < es->num_entries)
es->modified = true;
}
void exfat_update_dir_chksum(struct exfat_entry_set_cache *es)
{
int chksum_type = CS_DIR_ENTRY, i;
unsigned short chksum = 0;
struct exfat_dentry *ep;
for (i = ES_IDX_FILE; i < es->num_entries; i++) {
ep = exfat_get_dentry_cached(es, i);
chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
chksum_type);
chksum_type = CS_DEFAULT;
}
ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
ep->dentry.file.checksum = cpu_to_le16(chksum);
es->modified = true;
}
int exfat_put_dentry_set(struct exfat_entry_set_cache *es, int sync)
{
int i, err = 0;
if (es->modified)
err = exfat_update_bhs(es->bh, es->num_bh, sync);
for (i = 0; i < es->num_bh; i++)
if (err)
bforget(es->bh[i]);
else
brelse(es->bh[i]);
if (IS_DYNAMIC_ES(es))
kfree(es->bh);
return err;
}
static int exfat_walk_fat_chain(struct super_block *sb,
struct exfat_chain *p_dir, unsigned int byte_offset,
unsigned int *clu)
{
struct exfat_sb_info *sbi = EXFAT_SB(sb);
unsigned int clu_offset;
unsigned int cur_clu;
clu_offset = EXFAT_B_TO_CLU(byte_offset, sbi);
cur_clu = p_dir->dir;
if (p_dir->flags == ALLOC_NO_FAT_CHAIN) {
cur_clu += clu_offset;
} else {
while (clu_offset > 0) {
if (exfat_get_next_cluster(sb, &cur_clu))
return -EIO;
if (cur_clu == EXFAT_EOF_CLUSTER) {
exfat_fs_error(sb,
"invalid dentry access beyond EOF (clu : %u, eidx : %d)",
p_dir->dir,
EXFAT_B_TO_DEN(byte_offset));
return -EIO;
}
clu_offset--;
}
}
*clu = cur_clu;
return 0;
}
static int exfat_find_location(struct super_block *sb, struct exfat_chain *p_dir,
int entry, sector_t *sector, int *offset)
{
int ret;
unsigned int off, clu = 0;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
off = EXFAT_DEN_TO_B(entry);
ret = exfat_walk_fat_chain(sb, p_dir, off, &clu);
if (ret)
return ret;
/* byte offset in cluster */
off = EXFAT_CLU_OFFSET(off, sbi);
/* byte offset in sector */
*offset = EXFAT_BLK_OFFSET(off, sb);
/* sector offset in cluster */
*sector = EXFAT_B_TO_BLK(off, sb);
*sector += exfat_cluster_to_sector(sbi, clu);
return 0;
}
#define EXFAT_MAX_RA_SIZE (128*1024)
static int exfat_dir_readahead(struct super_block *sb, sector_t sec)
{
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct buffer_head *bh;
unsigned int max_ra_count = EXFAT_MAX_RA_SIZE >> sb->s_blocksize_bits;
unsigned int page_ra_count = PAGE_SIZE >> sb->s_blocksize_bits;
unsigned int adj_ra_count = max(sbi->sect_per_clus, page_ra_count);
unsigned int ra_count = min(adj_ra_count, max_ra_count);
/* Read-ahead is not required */
if (sbi->sect_per_clus == 1)
return 0;
if (sec < sbi->data_start_sector) {
exfat_err(sb, "requested sector is invalid(sect:%llu, root:%llu)",
(unsigned long long)sec, sbi->data_start_sector);
return -EIO;
}
/* Not sector aligned with ra_count, resize ra_count to page size */
if ((sec - sbi->data_start_sector) & (ra_count - 1))
ra_count = page_ra_count;
bh = sb_find_get_block(sb, sec);
if (!bh || !buffer_uptodate(bh)) {
unsigned int i;
for (i = 0; i < ra_count; i++)
sb_breadahead(sb, (sector_t)(sec + i));
}
brelse(bh);
return 0;
}
struct exfat_dentry *exfat_get_dentry(struct super_block *sb,
struct exfat_chain *p_dir, int entry, struct buffer_head **bh)
{
unsigned int dentries_per_page = EXFAT_B_TO_DEN(PAGE_SIZE);
int off;
sector_t sec;
if (p_dir->dir == DIR_DELETED) {
exfat_err(sb, "abnormal access to deleted dentry");
return NULL;
}
if (exfat_find_location(sb, p_dir, entry, &sec, &off))
return NULL;
if (p_dir->dir != EXFAT_FREE_CLUSTER &&
!(entry & (dentries_per_page - 1)))
exfat_dir_readahead(sb, sec);
*bh = sb_bread(sb, sec);
if (!*bh)
return NULL;
return (struct exfat_dentry *)((*bh)->b_data + off);
}
enum exfat_validate_dentry_mode {
ES_MODE_GET_FILE_ENTRY,
ES_MODE_GET_STRM_ENTRY,
ES_MODE_GET_NAME_ENTRY,
ES_MODE_GET_CRITICAL_SEC_ENTRY,
ES_MODE_GET_BENIGN_SEC_ENTRY,
};
static bool exfat_validate_entry(unsigned int type,
enum exfat_validate_dentry_mode *mode)
{
if (type == TYPE_UNUSED || type == TYPE_DELETED)
return false;
switch (*mode) {
case ES_MODE_GET_FILE_ENTRY:
if (type != TYPE_STREAM)
return false;
*mode = ES_MODE_GET_STRM_ENTRY;
break;
case ES_MODE_GET_STRM_ENTRY:
if (type != TYPE_EXTEND)
return false;
*mode = ES_MODE_GET_NAME_ENTRY;
break;
case ES_MODE_GET_NAME_ENTRY:
if (type & TYPE_BENIGN_SEC)
*mode = ES_MODE_GET_BENIGN_SEC_ENTRY;
else if (type != TYPE_EXTEND)
return false;
break;
case ES_MODE_GET_BENIGN_SEC_ENTRY:
/* Assume unreconized benign secondary entry */
if (!(type & TYPE_BENIGN_SEC))
return false;
break;
default:
return false;
}
return true;
}
struct exfat_dentry *exfat_get_dentry_cached(
struct exfat_entry_set_cache *es, int num)
{
int off = es->start_off + num * DENTRY_SIZE;
struct buffer_head *bh = es->bh[EXFAT_B_TO_BLK(off, es->sb)];
char *p = bh->b_data + EXFAT_BLK_OFFSET(off, es->sb);
return (struct exfat_dentry *)p;
}
/*
* Returns a set of dentries.
*
* Note It provides a direct pointer to bh->data via exfat_get_dentry_cached().
* User should call exfat_get_dentry_set() after setting 'modified' to apply
* changes made in this entry set to the real device.
*
* in:
* sb+p_dir+entry: indicates a file/dir
* num_entries: specifies how many dentries should be included.
* It will be set to es->num_entries if it is not 0.
* If num_entries is 0, es->num_entries will be obtained
* from the first dentry.
* out:
* es: pointer of entry set on success.
* return:
* 0 on success
* -error code on failure
*/
static int __exfat_get_dentry_set(struct exfat_entry_set_cache *es,
struct super_block *sb, struct exfat_chain *p_dir, int entry,
unsigned int num_entries)
{
int ret, i, num_bh;
unsigned int off;
sector_t sec;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct buffer_head *bh;
if (p_dir->dir == DIR_DELETED) {
exfat_err(sb, "access to deleted dentry");
return -EIO;
}
ret = exfat_find_location(sb, p_dir, entry, &sec, &off);
if (ret)
return ret;
memset(es, 0, sizeof(*es));
es->sb = sb;
es->modified = false;
es->start_off = off;
es->bh = es->__bh;
bh = sb_bread(sb, sec);
if (!bh)
return -EIO;
es->bh[es->num_bh++] = bh;
if (num_entries == ES_ALL_ENTRIES) {
struct exfat_dentry *ep;
ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
if (ep->type != EXFAT_FILE) {
brelse(bh);
return -EIO;
}
num_entries = ep->dentry.file.num_ext + 1;
}
es->num_entries = num_entries;
num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
if (num_bh > ARRAY_SIZE(es->__bh)) {
es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_NOFS);
if (!es->bh) {
brelse(bh);
return -ENOMEM;
}
es->bh[0] = bh;
}
for (i = 1; i < num_bh; i++) {
/* get the next sector */
if (exfat_is_last_sector_in_cluster(sbi, sec)) {
unsigned int clu = exfat_sector_to_cluster(sbi, sec);
if (p_dir->flags == ALLOC_NO_FAT_CHAIN)
clu++;
else if (exfat_get_next_cluster(sb, &clu))
goto put_es;
sec = exfat_cluster_to_sector(sbi, clu);
} else {
sec++;
}
bh = sb_bread(sb, sec);
if (!bh)
goto put_es;
es->bh[es->num_bh++] = bh;
}
return 0;
put_es:
exfat_put_dentry_set(es, false);
return -EIO;
}
int exfat_get_dentry_set(struct exfat_entry_set_cache *es,
struct super_block *sb, struct exfat_chain *p_dir,
int entry, unsigned int num_entries)
{
int ret, i;
struct exfat_dentry *ep;
enum exfat_validate_dentry_mode mode = ES_MODE_GET_FILE_ENTRY;
ret = __exfat_get_dentry_set(es, sb, p_dir, entry, num_entries);
if (ret < 0)
return ret;
/* validate cached dentries */
for (i = ES_IDX_STREAM; i < es->num_entries; i++) {
ep = exfat_get_dentry_cached(es, i);
if (!exfat_validate_entry(exfat_get_entry_type(ep), &mode))
goto put_es;
}
return 0;
put_es:
exfat_put_dentry_set(es, false);
return -EIO;
}
static int exfat_validate_empty_dentry_set(struct exfat_entry_set_cache *es)
{
struct exfat_dentry *ep;
struct buffer_head *bh;
int i, off;
bool unused_hit = false;
/*
* ONLY UNUSED OR DELETED DENTRIES ARE ALLOWED:
* Although it violates the specification for a deleted entry to
* follow an unused entry, some exFAT implementations could work
* like this. Therefore, to improve compatibility, let's allow it.
*/
for (i = 0; i < es->num_entries; i++) {
ep = exfat_get_dentry_cached(es, i);
if (ep->type == EXFAT_UNUSED) {
unused_hit = true;
} else if (!IS_EXFAT_DELETED(ep->type)) {
if (unused_hit)
goto err_used_follow_unused;
i++;
goto count_skip_entries;
}
}
return 0;
err_used_follow_unused:
off = es->start_off + (i << DENTRY_SIZE_BITS);
bh = es->bh[EXFAT_B_TO_BLK(off, es->sb)];
exfat_fs_error(es->sb,
"in sector %lld, dentry %d should be unused, but 0x%x",
bh->b_blocknr, off >> DENTRY_SIZE_BITS, ep->type);
return -EIO;
count_skip_entries:
es->num_entries = EXFAT_B_TO_DEN(EXFAT_BLK_TO_B(es->num_bh, es->sb) - es->start_off);
for (; i < es->num_entries; i++) {
ep = exfat_get_dentry_cached(es, i);
if (IS_EXFAT_DELETED(ep->type))
break;
}
return i;
}
/*
* Get an empty dentry set.
*
* in:
* sb+p_dir+entry: indicates the empty dentry location
* num_entries: specifies how many empty dentries should be included.
* out:
* es: pointer of empty dentry set on success.
* return:
* 0 : on success
* >0 : the dentries are not empty, the return value is the number of
* dentries to be skipped for the next lookup.
* <0 : on failure
*/
int exfat_get_empty_dentry_set(struct exfat_entry_set_cache *es,
struct super_block *sb, struct exfat_chain *p_dir,
int entry, unsigned int num_entries)
{
int ret;
ret = __exfat_get_dentry_set(es, sb, p_dir, entry, num_entries);
if (ret < 0)
return ret;
ret = exfat_validate_empty_dentry_set(es);
if (ret)
exfat_put_dentry_set(es, false);
return ret;
}
static inline void exfat_reset_empty_hint(struct exfat_hint_femp *hint_femp)
{
hint_femp->eidx = EXFAT_HINT_NONE;
hint_femp->count = 0;
}
static inline void exfat_set_empty_hint(struct exfat_inode_info *ei,
struct exfat_hint_femp *candi_empty, struct exfat_chain *clu,
int dentry, int num_entries, int entry_type)
{
if (ei->hint_femp.eidx == EXFAT_HINT_NONE ||
ei->hint_femp.eidx > dentry) {
int total_entries = EXFAT_B_TO_DEN(i_size_read(&ei->vfs_inode));
if (candi_empty->count == 0) {
candi_empty->cur = *clu;
candi_empty->eidx = dentry;
}
if (entry_type == TYPE_UNUSED)
candi_empty->count += total_entries - dentry;
else
candi_empty->count++;
if (candi_empty->count == num_entries ||
candi_empty->count + candi_empty->eidx == total_entries)
ei->hint_femp = *candi_empty;
}
}
enum {
DIRENT_STEP_FILE,
DIRENT_STEP_STRM,
DIRENT_STEP_NAME,
DIRENT_STEP_SECD,
};
/*
* @ei: inode info of parent directory
* @p_dir: directory structure of parent directory
* @num_entries:entry size of p_uniname
* @hint_opt: If p_uniname is found, filled with optimized dir/entry
* for traversing cluster chain.
* @return:
* >= 0: file directory entry position where the name exists
* -ENOENT: entry with the name does not exist
* -EIO: I/O error
*/
int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
struct exfat_chain *p_dir, struct exfat_uni_name *p_uniname,
struct exfat_hint *hint_opt)
{
int i, rewind = 0, dentry = 0, end_eidx = 0, num_ext = 0, len;
int order, step, name_len = 0;
int dentries_per_clu;
unsigned int entry_type;
unsigned short *uniname = NULL;
struct exfat_chain clu;
struct exfat_hint *hint_stat = &ei->hint_stat;
struct exfat_hint_femp candi_empty;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
int num_entries = exfat_calc_num_entries(p_uniname);
if (num_entries < 0)
return num_entries;
dentries_per_clu = sbi->dentries_per_clu;
exfat_chain_dup(&clu, p_dir);
if (hint_stat->eidx) {
clu.dir = hint_stat->clu;
dentry = hint_stat->eidx;
end_eidx = dentry;
}
exfat_reset_empty_hint(&ei->hint_femp);
rewind:
order = 0;
step = DIRENT_STEP_FILE;
exfat_reset_empty_hint(&candi_empty);
while (clu.dir != EXFAT_EOF_CLUSTER) {
i = dentry & (dentries_per_clu - 1);
for (; i < dentries_per_clu; i++, dentry++) {
struct exfat_dentry *ep;
struct buffer_head *bh;
if (rewind && dentry == end_eidx)
goto not_found;
ep = exfat_get_dentry(sb, &clu, i, &bh);
if (!ep)
return -EIO;
entry_type = exfat_get_entry_type(ep);
if (entry_type == TYPE_UNUSED ||
entry_type == TYPE_DELETED) {
step = DIRENT_STEP_FILE;
exfat_set_empty_hint(ei, &candi_empty, &clu,
dentry, num_entries,
entry_type);
brelse(bh);
if (entry_type == TYPE_UNUSED)
goto not_found;
continue;
}
exfat_reset_empty_hint(&candi_empty);
if (entry_type == TYPE_FILE || entry_type == TYPE_DIR) {
step = DIRENT_STEP_FILE;
hint_opt->clu = clu.dir;
hint_opt->eidx = i;
num_ext = ep->dentry.file.num_ext;
step = DIRENT_STEP_STRM;
brelse(bh);
continue;
}
if (entry_type == TYPE_STREAM) {
u16 name_hash;
if (step != DIRENT_STEP_STRM) {
step = DIRENT_STEP_FILE;
brelse(bh);
continue;
}
step = DIRENT_STEP_FILE;
name_hash = le16_to_cpu(
ep->dentry.stream.name_hash);
if (p_uniname->name_hash == name_hash &&
p_uniname->name_len ==
ep->dentry.stream.name_len) {
step = DIRENT_STEP_NAME;
order = 1;
name_len = 0;
}
brelse(bh);
continue;
}
brelse(bh);
if (entry_type == TYPE_EXTEND) {
unsigned short entry_uniname[16], unichar;
if (step != DIRENT_STEP_NAME ||
name_len >= MAX_NAME_LENGTH) {
step = DIRENT_STEP_FILE;
continue;
}
if (++order == 2)
uniname = p_uniname->name;
else
uniname += EXFAT_FILE_NAME_LEN;
len = exfat_extract_uni_name(ep, entry_uniname);
name_len += len;
unichar = *(uniname+len);
*(uniname+len) = 0x0;
if (exfat_uniname_ncmp(sb, uniname,
entry_uniname, len)) {
step = DIRENT_STEP_FILE;
} else if (p_uniname->name_len == name_len) {
if (order == num_ext)
goto found;
step = DIRENT_STEP_SECD;
}
*(uniname+len) = unichar;
continue;
}
if (entry_type &
(TYPE_CRITICAL_SEC | TYPE_BENIGN_SEC)) {
if (step == DIRENT_STEP_SECD) {
if (++order == num_ext)
goto found;
continue;
}
}
step = DIRENT_STEP_FILE;
}
if (clu.flags == ALLOC_NO_FAT_CHAIN) {
if (--clu.size > 0)
clu.dir++;
else
clu.dir = EXFAT_EOF_CLUSTER;
} else {
if (exfat_get_next_cluster(sb, &clu.dir))
return -EIO;
}
}
not_found:
/*
* We started at not 0 index,so we should try to find target
* from 0 index to the index we started at.
*/
if (!rewind && end_eidx) {
rewind = 1;
dentry = 0;
clu.dir = p_dir->dir;
goto rewind;
}
/*
* set the EXFAT_EOF_CLUSTER flag to avoid search
* from the beginning again when allocated a new cluster
*/
if (ei->hint_femp.eidx == EXFAT_HINT_NONE) {
ei->hint_femp.cur.dir = EXFAT_EOF_CLUSTER;
ei->hint_femp.eidx = p_dir->size * dentries_per_clu;
ei->hint_femp.count = 0;
}
/* initialized hint_stat */
hint_stat->clu = p_dir->dir;
hint_stat->eidx = 0;
return -ENOENT;
found:
/* next dentry we'll find is out of this cluster */
if (!((dentry + 1) & (dentries_per_clu - 1))) {
int ret = 0;
if (clu.flags == ALLOC_NO_FAT_CHAIN) {
if (--clu.size > 0)
clu.dir++;
else
clu.dir = EXFAT_EOF_CLUSTER;
} else {
ret = exfat_get_next_cluster(sb, &clu.dir);
}
if (ret || clu.dir == EXFAT_EOF_CLUSTER) {
/* just initialized hint_stat */
hint_stat->clu = p_dir->dir;
hint_stat->eidx = 0;
return (dentry - num_ext);
}
}
hint_stat->clu = clu.dir;
hint_stat->eidx = dentry + 1;
return dentry - num_ext;
}
int exfat_count_dir_entries(struct super_block *sb, struct exfat_chain *p_dir)
{
int i, count = 0;
int dentries_per_clu;
unsigned int entry_type;
struct exfat_chain clu;
struct exfat_dentry *ep;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct buffer_head *bh;
dentries_per_clu = sbi->dentries_per_clu;
exfat_chain_dup(&clu, p_dir);
while (clu.dir != EXFAT_EOF_CLUSTER) {
for (i = 0; i < dentries_per_clu; i++) {
ep = exfat_get_dentry(sb, &clu, i, &bh);
if (!ep)
return -EIO;
entry_type = exfat_get_entry_type(ep);
brelse(bh);
if (entry_type == TYPE_UNUSED)
return count;
if (entry_type != TYPE_DIR)
continue;
count++;
}
if (clu.flags == ALLOC_NO_FAT_CHAIN) {
if (--clu.size > 0)
clu.dir++;
else
clu.dir = EXFAT_EOF_CLUSTER;
} else {
if (exfat_get_next_cluster(sb, &(clu.dir)))
return -EIO;
}
}
return count;
}
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