xref: /openbmc/linux/fs/fat/misc.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  *  linux/fs/fat/misc.c
3  *
4  *  Written 1992,1993 by Werner Almesberger
5  *  22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
6  *		 and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
7  */
8 
9 #include <linux/module.h>
10 #include <linux/fs.h>
11 #include <linux/msdos_fs.h>
12 #include <linux/buffer_head.h>
13 
14 /*
15  * fat_fs_panic reports a severe file system problem and sets the file system
16  * read-only. The file system can be made writable again by remounting it.
17  */
18 void fat_fs_panic(struct super_block *s, const char *fmt, ...)
19 {
20 	va_list args;
21 
22 	printk(KERN_ERR "FAT: Filesystem panic (dev %s)\n", s->s_id);
23 
24 	printk(KERN_ERR "    ");
25 	va_start(args, fmt);
26 	vprintk(fmt, args);
27 	va_end(args);
28 	printk("\n");
29 
30 	if (!(s->s_flags & MS_RDONLY)) {
31 		s->s_flags |= MS_RDONLY;
32 		printk(KERN_ERR "    File system has been set read-only\n");
33 	}
34 }
35 
36 EXPORT_SYMBOL_GPL(fat_fs_panic);
37 
38 /* Flushes the number of free clusters on FAT32 */
39 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
40 void fat_clusters_flush(struct super_block *sb)
41 {
42 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
43 	struct buffer_head *bh;
44 	struct fat_boot_fsinfo *fsinfo;
45 
46 	if (sbi->fat_bits != 32)
47 		return;
48 
49 	bh = sb_bread(sb, sbi->fsinfo_sector);
50 	if (bh == NULL) {
51 		printk(KERN_ERR "FAT: bread failed in fat_clusters_flush\n");
52 		return;
53 	}
54 
55 	fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
56 	/* Sanity check */
57 	if (!IS_FSINFO(fsinfo)) {
58 		printk(KERN_ERR "FAT: Did not find valid FSINFO signature.\n"
59 		       "     Found signature1 0x%08x signature2 0x%08x"
60 		       " (sector = %lu)\n",
61 		       le32_to_cpu(fsinfo->signature1),
62 		       le32_to_cpu(fsinfo->signature2),
63 		       sbi->fsinfo_sector);
64 	} else {
65 		if (sbi->free_clusters != -1)
66 			fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
67 		if (sbi->prev_free != -1)
68 			fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
69 		mark_buffer_dirty(bh);
70 	}
71 	brelse(bh);
72 }
73 
74 /*
75  * fat_chain_add() adds a new cluster to the chain of clusters represented
76  * by inode.
77  */
78 int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
79 {
80 	struct super_block *sb = inode->i_sb;
81 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
82 	int ret, new_fclus, last;
83 
84 	/*
85 	 * We must locate the last cluster of the file to add this new
86 	 * one (new_dclus) to the end of the link list (the FAT).
87 	 */
88 	last = new_fclus = 0;
89 	if (MSDOS_I(inode)->i_start) {
90 		int fclus, dclus;
91 
92 		ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
93 		if (ret < 0)
94 			return ret;
95 		new_fclus = fclus + 1;
96 		last = dclus;
97 	}
98 
99 	/* add new one to the last of the cluster chain */
100 	if (last) {
101 		struct fat_entry fatent;
102 
103 		fatent_init(&fatent);
104 		ret = fat_ent_read(inode, &fatent, last);
105 		if (ret >= 0) {
106 			int wait = inode_needs_sync(inode);
107 			ret = fat_ent_write(inode, &fatent, new_dclus, wait);
108 			fatent_brelse(&fatent);
109 		}
110 		if (ret < 0)
111 			return ret;
112 //		fat_cache_add(inode, new_fclus, new_dclus);
113 	} else {
114 		MSDOS_I(inode)->i_start = new_dclus;
115 		MSDOS_I(inode)->i_logstart = new_dclus;
116 		/*
117 		 * Since generic_osync_inode() synchronize later if
118 		 * this is not directory, we don't here.
119 		 */
120 		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
121 			ret = fat_sync_inode(inode);
122 			if (ret)
123 				return ret;
124 		} else
125 			mark_inode_dirty(inode);
126 	}
127 	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
128 		fat_fs_panic(sb, "clusters badly computed (%d != %lu)",
129 			new_fclus, inode->i_blocks >> (sbi->cluster_bits - 9));
130 		fat_cache_inval_inode(inode);
131 	}
132 	inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
133 
134 	return 0;
135 }
136 
137 extern struct timezone sys_tz;
138 
139 /* Linear day numbers of the respective 1sts in non-leap years. */
140 static int day_n[] = {
141    /* Jan  Feb  Mar  Apr   May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
142 	0,  31,  59,  90,  120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0, 0
143 };
144 
145 /* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
146 int date_dos2unix(unsigned short time, unsigned short date)
147 {
148 	int month, year, secs;
149 
150 	/*
151 	 * first subtract and mask after that... Otherwise, if
152 	 * date == 0, bad things happen
153 	 */
154 	month = ((date >> 5) - 1) & 15;
155 	year = date >> 9;
156 	secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
157 	    ((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
158 	    month < 2 ? 1 : 0)+3653);
159 			/* days since 1.1.70 plus 80's leap day */
160 	secs += sys_tz.tz_minuteswest*60;
161 	return secs;
162 }
163 
164 /* Convert linear UNIX date to a MS-DOS time/date pair. */
165 void fat_date_unix2dos(int unix_date, __le16 *time, __le16 *date)
166 {
167 	int day, year, nl_day, month;
168 
169 	unix_date -= sys_tz.tz_minuteswest*60;
170 
171 	/* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
172 	if (unix_date < 315532800)
173 		unix_date = 315532800;
174 
175 	*time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
176 	    (((unix_date/3600) % 24) << 11));
177 	day = unix_date/86400-3652;
178 	year = day/365;
179 	if ((year+3)/4+365*year > day)
180 		year--;
181 	day -= (year+3)/4+365*year;
182 	if (day == 59 && !(year & 3)) {
183 		nl_day = day;
184 		month = 2;
185 	} else {
186 		nl_day = (year & 3) || day <= 59 ? day : day-1;
187 		for (month = 0; month < 12; month++) {
188 			if (day_n[month] > nl_day)
189 				break;
190 		}
191 	}
192 	*date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9));
193 }
194 
195 EXPORT_SYMBOL_GPL(fat_date_unix2dos);
196 
197 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
198 {
199 	int i, err = 0;
200 
201 	ll_rw_block(SWRITE, nr_bhs, bhs);
202 	for (i = 0; i < nr_bhs; i++) {
203 		wait_on_buffer(bhs[i]);
204 		if (buffer_eopnotsupp(bhs[i])) {
205 			clear_buffer_eopnotsupp(bhs[i]);
206 			err = -EOPNOTSUPP;
207 		} else if (!err && !buffer_uptodate(bhs[i]))
208 			err = -EIO;
209 	}
210 	return err;
211 }
212 
213