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2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771 
 kernel/fs/fat/inode.c
....@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  *  linux/fs/fat/inode.c
34  *
....@@ -20,6 +21,7 @@
2021 #include <linux/blkdev.h>
2122 #include <linux/backing-dev.h>
2223 #include <asm/unaligned.h>
24
+#include <linux/random.h>
2325 #include <linux/iversion.h>
2426 #include "fat.h"
2527 
....@@ -29,6 +31,11 @@
2931 #endif
3032 
3133 #define KB_IN_SECTORS 2
34
+
35
+/* DOS dates from 1980/1/1 through 2107/12/31 */
36
+#define FAT_DATE_MIN (0<<9 | 1<<5 | 1)
37
+#define FAT_DATE_MAX (127<<9 | 12<<5 | 31)
38
+#define FAT_TIME_MAX (23<<11 | 59<<5 | 29)
3239 
3340 /*
3441  * A deserialized copy of the on-disk structure laid out in struct
....@@ -203,10 +210,9 @@
203210 	return mpage_readpage(page, fat_get_block);
204211 }
205212 
206
-static int fat_readpages(struct file *file, struct address_space *mapping,
207
-			 struct list_head *pages, unsigned nr_pages)
213
+static void fat_readahead(struct readahead_control *rac)
208214 {
209
-	return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
215
+	mpage_readahead(rac, fat_get_block);
210216 }
211217 
212218 static void fat_write_failed(struct address_space *mapping, loff_t to)
....@@ -244,7 +250,7 @@
244250 	if (err < len)
245251 		fat_write_failed(mapping, pos + len);
246252 	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
247
-		inode->i_mtime = inode->i_ctime = current_time(inode);
253
+		fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
248254 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
249255 		mark_inode_dirty(inode);
250256 	}
....@@ -337,7 +343,7 @@
337343 
338344 static const struct address_space_operations fat_aops = {
339345 	.readpage	= fat_readpage,
340
-	.readpages	= fat_readpages,
346
+	.readahead	= fat_readahead,
341347 	.writepage	= fat_writepage,
342348 	.writepages	= fat_writepages,
343349 	.write_begin	= fat_write_begin,
....@@ -515,7 +521,7 @@
515521 	inode->i_uid = sbi->options.fs_uid;
516522 	inode->i_gid = sbi->options.fs_gid;
517523 	inode_inc_iversion(inode);
518
-	inode->i_generation = get_seconds();
524
+	inode->i_generation = prandom_u32();
519525 
520526 	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
521527 		inode->i_generation &= ~1;
....@@ -564,7 +570,7 @@
564570 				  de->cdate, de->ctime_cs);
565571 		fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
566572 	} else
567
-		inode->i_ctime = inode->i_atime = inode->i_mtime;
573
+		fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
568574 
569575 	return 0;
570576 }
....@@ -686,7 +692,7 @@
686692 
687693 	b = (struct fat_boot_sector *) bh->b_data;
688694 
689
-	if (sbi->fat_bits == 32) {
695
+	if (is_fat32(sbi)) {
690696 		if (set)
691697 			b->fat32.state |= FAT_STATE_DIRTY;
692698 		else
....@@ -753,15 +759,9 @@
753759 	return &ei->vfs_inode;
754760 }
755761 
756
-static void fat_i_callback(struct rcu_head *head)
762
+static void fat_free_inode(struct inode *inode)
757763 {
758
-	struct inode *inode = container_of(head, struct inode, i_rcu);
759764 	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
760
-}
761
-
762
-static void fat_destroy_inode(struct inode *inode)
763
-{
764
-	call_rcu(&inode->i_rcu, fat_i_callback);
765765 }
766766 
767767 static void init_once(void *foo)
....@@ -836,8 +836,7 @@
836836 	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
837837 	buf->f_bfree = sbi->free_clusters;
838838 	buf->f_bavail = sbi->free_clusters;
839
-	buf->f_fsid.val[0] = (u32)id;
840
-	buf->f_fsid.val[1] = (u32)(id >> 32);
839
+	buf->f_fsid = u64_to_fsid(id);
841840 	buf->f_namelen =
842841 		(sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
843842 
....@@ -927,7 +926,7 @@
927926 static int fat_show_options(struct seq_file *m, struct dentry *root);
928927 static const struct super_operations fat_sops = {
929928 	.alloc_inode	= fat_alloc_inode,
930
-	.destroy_inode	= fat_destroy_inode,
929
+	.free_inode	= fat_free_inode,
931930 	.write_inode	= fat_write_inode,
932931 	.evict_inode	= fat_evict_inode,
933932 	.put_super	= fat_put_super,
....@@ -1393,7 +1392,7 @@
13931392 	inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
13941393 	inode->i_op = sbi->dir_ops;
13951394 	inode->i_fop = &fat_dir_operations;
1396
-	if (sbi->fat_bits == 32) {
1395
+	if (is_fat32(sbi)) {
13971396 		MSDOS_I(inode)->i_start = sbi->root_cluster;
13981397 		error = fat_calc_dir_size(inode);
13991398 		if (error < 0)
....@@ -1420,7 +1419,7 @@
14201419 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
14211420 
14221421 	/* Divide first to avoid overflow */
1423
-	if (sbi->fat_bits != 12) {
1422
+	if (!is_fat12(sbi)) {
14241423 		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
14251424 		return ent_per_sec * sbi->fat_length;
14261425 	}
....@@ -1613,6 +1612,7 @@
16131612 	int debug;
16141613 	long error;
16151614 	char buf[50];
1615
+	struct timespec64 ts;
16161616 
16171617 	/*
16181618 	 * GFP_KERNEL is ok here, because while we do hold the
....@@ -1629,6 +1629,11 @@
16291629 	sb->s_magic = MSDOS_SUPER_MAGIC;
16301630 	sb->s_op = &fat_sops;
16311631 	sb->s_export_op = &fat_export_ops;
1632
+	/*
1633
+	 * fat timestamps are complex and truncated by fat itself, so
1634
+	 * we set 1 here to be fast
1635
+	 */
1636
+	sb->s_time_gran = 1;
16321637 	mutex_init(&sbi->nfs_build_inode_lock);
16331638 	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
16341639 			     DEFAULT_RATELIMIT_BURST);
....@@ -1701,6 +1706,12 @@
17011706 	sbi->free_clus_valid = 0;
17021707 	sbi->prev_free = FAT_START_ENT;
17031708 	sb->s_maxbytes = 0xffffffff;
1709
+	fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
1710
+	sb->s_time_min = ts.tv_sec;
1711
+
1712
+	fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
1713
+			  cpu_to_le16(FAT_DATE_MAX), 0);
1714
+	sb->s_time_max = ts.tv_sec;
17041715 
17051716 	if (!sbi->fat_length && bpb.fat32_length) {
17061717 		struct fat_boot_fsinfo *fsinfo;
....@@ -1741,7 +1752,7 @@
17411752 	}
17421753 
17431754 	/* interpret volume ID as a little endian 32 bit integer */
1744
-	if (sbi->fat_bits == 32)
1755
+	if (is_fat32(sbi))
17451756 		sbi->vol_id = bpb.fat32_vol_id;
17461757 	else /* fat 16 or 12 */
17471758 		sbi->vol_id = bpb.fat16_vol_id;
....@@ -1767,11 +1778,11 @@
17671778 
17681779 	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
17691780 
1770
-	if (sbi->fat_bits != 32)
1781
+	if (!is_fat32(sbi))
17711782 		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
17721783 
17731784 	/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1774
-	if (sbi->fat_bits == 32)
1785
+	if (is_fat32(sbi))
17751786 		sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
17761787 	else /* fat 16 or 12 */
17771788 		sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
....@@ -1779,7 +1790,7 @@
17791790 	/* check that FAT table does not overflow */
17801791 	fat_clusters = calc_fat_clusters(sb);
17811792 	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1782
-	if (total_clusters > MAX_FAT(sb)) {
1793
+	if (total_clusters > max_fat(sb)) {
17831794 		if (!silent)
17841795 			fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
17851796 			       total_clusters);
....@@ -1801,11 +1812,15 @@
18011812 	fat_ent_access_init(sb);
18021813 
18031814 	/*
1804
-	 * The low byte of FAT's first entry must have same value with
1805
-	 * media-field.  But in real world, too many devices is
1806
-	 * writing wrong value.  So, removed that validity check.
1815
+	 * The low byte of the first FAT entry must have the same value as
1816
+	 * the media field of the boot sector. But in real world, too many
1817
+	 * devices are writing wrong values. So, removed that validity check.
18071818 	 *
1808
-	 * if (FAT_FIRST_ENT(sb, media) != first)
1819
+	 * The removed check compared the first FAT entry to a value dependent
1820
+	 * on the media field like this:
1821
+	 * == (0x0F00 | media), for FAT12
1822
+	 * == (0XFF00 | media), for FAT16
1823
+	 * == (0x0FFFFF | media), for FAT32
18091824 	 */
18101825 
18111826 	error = -EINVAL;
....@@ -1964,3 +1979,4 @@
19641979 module_exit(exit_fat_fs)
19651980 
19661981 MODULE_LICENSE("GPL");
1982
+MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);