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Linux/fs/hfsplus/wrapper.c

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

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