fs/hfsplus/wrapper.c

   1 /*
   2  *  linux/fs/hfsplus/wrapper.c
   3  *
   4  * Copyright (C) 2001
   5  * Brad Boyer (flar@allandria.com)
   6  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   7  *
   8  * Handling of HFS wrappers around HFS+ volumes
   9  */
  10
  11 #include <linux/fs.h>
  12 #include <linux/blkdev.h>
  13 #include <linux/cdrom.h>
  14 #include <linux/genhd.h>
  15 #include <asm/unaligned.h>
  16
  17 #include "hfsplus_fs.h"
  18 #include "hfsplus_raw.h"
  19
  20 struct hfsplus_wd {
  21         u32 ablk_size;
  22         u16 ablk_start;
  23         u16 embed_start;
  24         u16 embed_count;
  25 };
  26
  27 /**
  28  * hfsplus_submit_bio - Perform block I/O
  29  * @sb: super block of volume for I/O
  30  * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
  31  * @buf: buffer for I/O
  32  * @data: output pointer for location of requested data
  33  * @op: direction of I/O
  34  * @op_flags: request op flags
  35  *
  36  * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
  37  * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
  38  * @data will return a pointer to the start of the requested sector,
  39  * which may not be the same location as @buf.
  40  *
  41  * If @sector is not aligned to the bdev logical block size it will
  42  * be rounded down. For writes this means that @buf should contain data
  43  * that starts at the rounded-down address. As long as the data was
  44  * read using hfsplus_submit_bio() and the same buffer is used things
  45  * will work correctly.
  46  */
  47 int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
  48                        void *buf, void **data, int op, int op_flags)
  49 {
  50         struct bio *bio;
  51         int ret = 0;
  52         u64 io_size;
  53         loff_t start;
  54         int offset;
  55
  56         /*
  57          * Align sector to hardware sector size and find offset. We
  58          * assume that io_size is a power of two, which _should_
  59          * be true.
  60          */
  61         io_size = hfsplus_min_io_size(sb);
  62         start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
  63         offset = start & (io_size - 1);
  64         sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
  65
  66         bio = bio_alloc(GFP_NOIO, 1);
  67         bio->bi_iter.bi_sector = sector;
  68         bio->bi_bdev = sb->s_bdev;
  69         bio_set_op_attrs(bio, op, op_flags);
  70
  71         if (op != WRITE && data)
  72                 *data = (u8 *)buf + offset;
  73
  74         while (io_size > 0) {
  75                 unsigned int page_offset = offset_in_page(buf);
  76                 unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
  77                                          io_size);
  78
  79                 ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
  80                 if (ret != len) {
  81                         ret = -EIO;
  82                         goto out;
  83                 }
  84                 io_size -= len;
  85                 buf = (u8 *)buf + len;
  86         }
  87
  88         ret = submit_bio_wait(bio);
  89 out:
  90         bio_put(bio);
  91         return ret < 0 ? ret : 0;
  92 }
  93
  94 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
  95 {
  96         u32 extent;
  97         u16 attrib;
  98         __be16 sig;
  99
 100         sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
 101         if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
 102             sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
 103                 return 0;
 104
 105         attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
 106         if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
 107            !(attrib & HFSP_WRAP_ATTRIB_SPARED))
 108                 return 0;
 109
 110         wd->ablk_size =
 111                 be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
 112         if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
 113                 return 0;
 114         if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
 115                 return 0;
 116         wd->ablk_start =
 117                 be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
 118
 119         extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
 120         wd->embed_start = (extent >> 16) & 0xFFFF;
 121         wd->embed_count = extent & 0xFFFF;
 122
 123         return 1;
 124 }
 125
 126 static int hfsplus_get_last_session(struct super_block *sb,
 127                                     sector_t *start, sector_t *size)
 128 {
 129         struct cdrom_multisession ms_info;
 130         struct cdrom_tocentry te;
 131         int res;
 132
 133         /* default values */
 134         *start = 0;
 135         *size = i_size_read(sb->s_bdev->bd_inode) >> 9;
 136
 137         if (HFSPLUS_SB(sb)->session >= 0) {
 138                 te.cdte_track = HFSPLUS_SB(sb)->session;
 139                 te.cdte_format = CDROM_LBA;
 140                 res = ioctl_by_bdev(sb->s_bdev,
 141                         CDROMREADTOCENTRY, (unsigned long)&te);
 142                 if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
 143                         *start = (sector_t)te.cdte_addr.lba << 2;
 144                         return 0;
 145                 }
 146                 pr_err("invalid session number or type of track\n");
 147                 return -EINVAL;
 148         }
 149         ms_info.addr_format = CDROM_LBA;
 150         res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION,
 151                 (unsigned long)&ms_info);
 152         if (!res && ms_info.xa_flag)
 153                 *start = (sector_t)ms_info.addr.lba << 2;
 154         return 0;
 155 }
 156
 157 /* Find the volume header and fill in some minimum bits in superblock */
 158 /* Takes in super block, returns true if good data read */
 159 int hfsplus_read_wrapper(struct super_block *sb)
 160 {
 161         struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
 162         struct hfsplus_wd wd;
 163         sector_t part_start, part_size;
 164         u32 blocksize;
 165         int error = 0;
 166
 167         error = -EINVAL;
 168         blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
 169         if (!blocksize)
 170                 goto out;
 171
 172         if (hfsplus_get_last_session(sb, &part_start, &part_size))
 173                 goto out;
 174
 175         error = -ENOMEM;
 176         sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 177         if (!sbi->s_vhdr_buf)
 178                 goto out;
 179         sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 180         if (!sbi->s_backup_vhdr_buf)
 181                 goto out_free_vhdr;
 182
 183 reread:
 184         error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
 185                                    sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
 186                                    REQ_OP_READ, 0);
 187         if (error)
 188                 goto out_free_backup_vhdr;
 189
 190         error = -EINVAL;
 191         switch (sbi->s_vhdr->signature) {
 192         case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
 193                 set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
 194                 /*FALLTHRU*/
 195         case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
 196                 break;
 197         case cpu_to_be16(HFSP_WRAP_MAGIC):
 198                 if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
 199                         goto out_free_backup_vhdr;
 200                 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
 201                 part_start += (sector_t)wd.ablk_start +
 202                                (sector_t)wd.embed_start * wd.ablk_size;
 203                 part_size = (sector_t)wd.embed_count * wd.ablk_size;
 204                 goto reread;
 205         default:
 206                 /*
 207                  * Check for a partition block.
 208                  *
 209                  * (should do this only for cdrom/loop though)
 210                  */
 211                 if (hfs_part_find(sb, &part_start, &part_size))
 212                         goto out_free_backup_vhdr;
 213                 goto reread;
 214         }
 215
 216         error = hfsplus_submit_bio(sb, part_start + part_size - 2,
 217                                    sbi->s_backup_vhdr_buf,
 218                                    (void **)&sbi->s_backup_vhdr, REQ_OP_READ,
 219                                    0);
 220         if (error)
 221                 goto out_free_backup_vhdr;
 222
 223         error = -EINVAL;
 224         if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
 225                 pr_warn("invalid secondary volume header\n");
 226                 goto out_free_backup_vhdr;
 227         }
 228
 229         blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
 230
 231         /*
 232          * Block size must be at least as large as a sector and a multiple of 2.
 233          */
 234         if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
 235                 goto out_free_backup_vhdr;
 236         sbi->alloc_blksz = blocksize;
 237         sbi->alloc_blksz_shift = ilog2(blocksize);
 238         blocksize = min_t(u32, sbi->alloc_blksz, PAGE_SIZE);
 239
 240         /*
 241          * Align block size to block offset.
 242          */
 243         while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
 244                 blocksize >>= 1;
 245
 246         if (sb_set_blocksize(sb, blocksize) != blocksize) {
 247                 pr_err("unable to set blocksize to %u!\n", blocksize);
 248                 goto out_free_backup_vhdr;
 249         }
 250
 251         sbi->blockoffset =
 252                 part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
 253         sbi->part_start = part_start;
 254         sbi->sect_count = part_size;
 255         sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
 256         return 0;
 257
 258 out_free_backup_vhdr:
 259         kfree(sbi->s_backup_vhdr_buf);
 260 out_free_vhdr:
 261         kfree(sbi->s_vhdr_buf);
 262 out:
 263         return error;
 264 }