From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/fs/fat/inode.c | 72 ++++++++++++++++++++++--------------
1 files changed, 44 insertions(+), 28 deletions(-)
diff --git a/kernel/fs/fat/inode.c b/kernel/fs/fat/inode.c
index 607e1d1..577c73a 100644
--- a/kernel/fs/fat/inode.c
+++ b/kernel/fs/fat/inode.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/fs/fat/inode.c
*
@@ -20,6 +21,7 @@
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <asm/unaligned.h>
+#include <linux/random.h>
#include <linux/iversion.h>
#include "fat.h"
@@ -29,6 +31,11 @@
#endif
#define KB_IN_SECTORS 2
+
+/* DOS dates from 1980/1/1 through 2107/12/31 */
+#define FAT_DATE_MIN (0<<9 | 1<<5 | 1)
+#define FAT_DATE_MAX (127<<9 | 12<<5 | 31)
+#define FAT_TIME_MAX (23<<11 | 59<<5 | 29)
/*
* A deserialized copy of the on-disk structure laid out in struct
@@ -203,10 +210,9 @@
return mpage_readpage(page, fat_get_block);
}
-static int fat_readpages(struct file *file, struct address_space *mapping,
- struct list_head *pages, unsigned nr_pages)
+static void fat_readahead(struct readahead_control *rac)
{
- return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
+ mpage_readahead(rac, fat_get_block);
}
static void fat_write_failed(struct address_space *mapping, loff_t to)
@@ -244,7 +250,7 @@
if (err < len)
fat_write_failed(mapping, pos + len);
if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
- inode->i_mtime = inode->i_ctime = current_time(inode);
+ fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
mark_inode_dirty(inode);
}
@@ -337,7 +343,7 @@
static const struct address_space_operations fat_aops = {
.readpage = fat_readpage,
- .readpages = fat_readpages,
+ .readahead = fat_readahead,
.writepage = fat_writepage,
.writepages = fat_writepages,
.write_begin = fat_write_begin,
@@ -515,7 +521,7 @@
inode->i_uid = sbi->options.fs_uid;
inode->i_gid = sbi->options.fs_gid;
inode_inc_iversion(inode);
- inode->i_generation = get_seconds();
+ inode->i_generation = prandom_u32();
if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
inode->i_generation &= ~1;
@@ -564,7 +570,7 @@
de->cdate, de->ctime_cs);
fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
} else
- inode->i_ctime = inode->i_atime = inode->i_mtime;
+ fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
return 0;
}
@@ -686,7 +692,7 @@
b = (struct fat_boot_sector *) bh->b_data;
- if (sbi->fat_bits == 32) {
+ if (is_fat32(sbi)) {
if (set)
b->fat32.state |= FAT_STATE_DIRTY;
else
@@ -753,15 +759,9 @@
return &ei->vfs_inode;
}
-static void fat_i_callback(struct rcu_head *head)
+static void fat_free_inode(struct inode *inode)
{
- struct inode *inode = container_of(head, struct inode, i_rcu);
kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
-}
-
-static void fat_destroy_inode(struct inode *inode)
-{
- call_rcu(&inode->i_rcu, fat_i_callback);
}
static void init_once(void *foo)
@@ -836,8 +836,7 @@
buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
buf->f_bfree = sbi->free_clusters;
buf->f_bavail = sbi->free_clusters;
- buf->f_fsid.val[0] = (u32)id;
- buf->f_fsid.val[1] = (u32)(id >> 32);
+ buf->f_fsid = u64_to_fsid(id);
buf->f_namelen =
(sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
@@ -927,7 +926,7 @@
static int fat_show_options(struct seq_file *m, struct dentry *root);
static const struct super_operations fat_sops = {
.alloc_inode = fat_alloc_inode,
- .destroy_inode = fat_destroy_inode,
+ .free_inode = fat_free_inode,
.write_inode = fat_write_inode,
.evict_inode = fat_evict_inode,
.put_super = fat_put_super,
@@ -1393,7 +1392,7 @@
inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
inode->i_op = sbi->dir_ops;
inode->i_fop = &fat_dir_operations;
- if (sbi->fat_bits == 32) {
+ if (is_fat32(sbi)) {
MSDOS_I(inode)->i_start = sbi->root_cluster;
error = fat_calc_dir_size(inode);
if (error < 0)
@@ -1420,7 +1419,7 @@
struct msdos_sb_info *sbi = MSDOS_SB(sb);
/* Divide first to avoid overflow */
- if (sbi->fat_bits != 12) {
+ if (!is_fat12(sbi)) {
unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
return ent_per_sec * sbi->fat_length;
}
@@ -1613,6 +1612,7 @@
int debug;
long error;
char buf[50];
+ struct timespec64 ts;
/*
* GFP_KERNEL is ok here, because while we do hold the
@@ -1629,6 +1629,11 @@
sb->s_magic = MSDOS_SUPER_MAGIC;
sb->s_op = &fat_sops;
sb->s_export_op = &fat_export_ops;
+ /*
+ * fat timestamps are complex and truncated by fat itself, so
+ * we set 1 here to be fast
+ */
+ sb->s_time_gran = 1;
mutex_init(&sbi->nfs_build_inode_lock);
ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
@@ -1701,6 +1706,12 @@
sbi->free_clus_valid = 0;
sbi->prev_free = FAT_START_ENT;
sb->s_maxbytes = 0xffffffff;
+ fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
+ sb->s_time_min = ts.tv_sec;
+
+ fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
+ cpu_to_le16(FAT_DATE_MAX), 0);
+ sb->s_time_max = ts.tv_sec;
if (!sbi->fat_length && bpb.fat32_length) {
struct fat_boot_fsinfo *fsinfo;
@@ -1741,7 +1752,7 @@
}
/* interpret volume ID as a little endian 32 bit integer */
- if (sbi->fat_bits == 32)
+ if (is_fat32(sbi))
sbi->vol_id = bpb.fat32_vol_id;
else /* fat 16 or 12 */
sbi->vol_id = bpb.fat16_vol_id;
@@ -1767,11 +1778,11 @@
total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
- if (sbi->fat_bits != 32)
+ if (!is_fat32(sbi))
sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
- if (sbi->fat_bits == 32)
+ if (is_fat32(sbi))
sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
else /* fat 16 or 12 */
sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
@@ -1779,7 +1790,7 @@
/* check that FAT table does not overflow */
fat_clusters = calc_fat_clusters(sb);
total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
- if (total_clusters > MAX_FAT(sb)) {
+ if (total_clusters > max_fat(sb)) {
if (!silent)
fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
total_clusters);
@@ -1801,11 +1812,15 @@
fat_ent_access_init(sb);
/*
- * The low byte of FAT's first entry must have same value with
- * media-field. But in real world, too many devices is
- * writing wrong value. So, removed that validity check.
+ * The low byte of the first FAT entry must have the same value as
+ * the media field of the boot sector. But in real world, too many
+ * devices are writing wrong values. So, removed that validity check.
*
- * if (FAT_FIRST_ENT(sb, media) != first)
+ * The removed check compared the first FAT entry to a value dependent
+ * on the media field like this:
+ * == (0x0F00 | media), for FAT12
+ * == (0XFF00 | media), for FAT16
+ * == (0x0FFFFF | media), for FAT32
*/
error = -EINVAL;
@@ -1964,3 +1979,4 @@
module_exit(exit_fat_fs)
MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);
--
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