Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6
[linux-2.6] / fs / jffs2 / read.c
1 /*
2  * JFFS2 -- Journalling Flash File System, Version 2.
3  *
4  * Copyright © 2001-2007 Red Hat, Inc.
5  *
6  * Created by David Woodhouse <dwmw2@infradead.org>
7  *
8  * For licensing information, see the file 'LICENCE' in this directory.
9  *
10  */
11
12 #include <linux/kernel.h>
13 #include <linux/slab.h>
14 #include <linux/crc32.h>
15 #include <linux/pagemap.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/compiler.h>
18 #include "nodelist.h"
19 #include "compr.h"
20
21 int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
22                      struct jffs2_full_dnode *fd, unsigned char *buf,
23                      int ofs, int len)
24 {
25         struct jffs2_raw_inode *ri;
26         size_t readlen;
27         uint32_t crc;
28         unsigned char *decomprbuf = NULL;
29         unsigned char *readbuf = NULL;
30         int ret = 0;
31
32         ri = jffs2_alloc_raw_inode();
33         if (!ri)
34                 return -ENOMEM;
35
36         ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);
37         if (ret) {
38                 jffs2_free_raw_inode(ri);
39                 printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret);
40                 return ret;
41         }
42         if (readlen != sizeof(*ri)) {
43                 jffs2_free_raw_inode(ri);
44                 printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
45                        ref_offset(fd->raw), sizeof(*ri), readlen);
46                 return -EIO;
47         }
48         crc = crc32(0, ri, sizeof(*ri)-8);
49
50         D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
51                   ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
52                   crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
53                   je32_to_cpu(ri->offset), buf));
54         if (crc != je32_to_cpu(ri->node_crc)) {
55                 printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
56                        je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
57                 ret = -EIO;
58                 goto out_ri;
59         }
60         /* There was a bug where we wrote hole nodes out with csize/dsize
61            swapped. Deal with it */
62         if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
63             je32_to_cpu(ri->csize)) {
64                 ri->dsize = ri->csize;
65                 ri->csize = cpu_to_je32(0);
66         }
67
68         D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
69                 printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
70                        len, ofs, je32_to_cpu(ri->dsize));
71                 ret = -EINVAL;
72                 goto out_ri;
73         });
74
75
76         if (ri->compr == JFFS2_COMPR_ZERO) {
77                 memset(buf, 0, len);
78                 goto out_ri;
79         }
80
81         /* Cases:
82            Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
83            Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
84            Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
85            Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
86         */
87         if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
88                 readbuf = buf;
89         } else {
90                 readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
91                 if (!readbuf) {
92                         ret = -ENOMEM;
93                         goto out_ri;
94                 }
95         }
96         if (ri->compr != JFFS2_COMPR_NONE) {
97                 if (len < je32_to_cpu(ri->dsize)) {
98                         decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
99                         if (!decomprbuf) {
100                                 ret = -ENOMEM;
101                                 goto out_readbuf;
102                         }
103                 } else {
104                         decomprbuf = buf;
105                 }
106         } else {
107                 decomprbuf = readbuf;
108         }
109
110         D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
111                   readbuf));
112         ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
113                                je32_to_cpu(ri->csize), &readlen, readbuf);
114
115         if (!ret && readlen != je32_to_cpu(ri->csize))
116                 ret = -EIO;
117         if (ret)
118                 goto out_decomprbuf;
119
120         crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
121         if (crc != je32_to_cpu(ri->data_crc)) {
122                 printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
123                        je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
124                 ret = -EIO;
125                 goto out_decomprbuf;
126         }
127         D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
128         if (ri->compr != JFFS2_COMPR_NONE) {
129                 D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
130                           je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
131                 ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
132                 if (ret) {
133                         printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
134                         goto out_decomprbuf;
135                 }
136         }
137
138         if (len < je32_to_cpu(ri->dsize)) {
139                 memcpy(buf, decomprbuf+ofs, len);
140         }
141  out_decomprbuf:
142         if(decomprbuf != buf && decomprbuf != readbuf)
143                 kfree(decomprbuf);
144  out_readbuf:
145         if(readbuf != buf)
146                 kfree(readbuf);
147  out_ri:
148         jffs2_free_raw_inode(ri);
149
150         return ret;
151 }
152
153 int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
154                            unsigned char *buf, uint32_t offset, uint32_t len)
155 {
156         uint32_t end = offset + len;
157         struct jffs2_node_frag *frag;
158         int ret;
159
160         D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
161                   f->inocache->ino, offset, offset+len));
162
163         frag = jffs2_lookup_node_frag(&f->fragtree, offset);
164
165         /* XXX FIXME: Where a single physical node actually shows up in two
166            frags, we read it twice. Don't do that. */
167         /* Now we're pointing at the first frag which overlaps our page */
168         while(offset < end) {
169                 D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
170                 if (unlikely(!frag || frag->ofs > offset)) {
171                         uint32_t holesize = end - offset;
172                         if (frag) {
173                                 D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
174                                 holesize = min(holesize, frag->ofs - offset);
175                         }
176                         D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset, offset+holesize));
177                         memset(buf, 0, holesize);
178                         buf += holesize;
179                         offset += holesize;
180                         continue;
181                 } else if (unlikely(!frag->node)) {
182                         uint32_t holeend = min(end, frag->ofs + frag->size);
183                         D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));
184                         memset(buf, 0, holeend - offset);
185                         buf += holeend - offset;
186                         offset = holeend;
187                         frag = frag_next(frag);
188                         continue;
189                 } else {
190                         uint32_t readlen;
191                         uint32_t fragofs; /* offset within the frag to start reading */
192
193                         fragofs = offset - frag->ofs;
194                         readlen = min(frag->size - fragofs, end - offset);
195                         D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",
196                                   frag->ofs+fragofs, frag->ofs+fragofs+readlen,
197                                   ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
198                         ret = jffs2_read_dnode(c, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
199                         D2(printk(KERN_DEBUG "node read done\n"));
200                         if (ret) {
201                                 D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));
202                                 memset(buf, 0, readlen);
203                                 return ret;
204                         }
205                         buf += readlen;
206                         offset += readlen;
207                         frag = frag_next(frag);
208                         D2(printk(KERN_DEBUG "node read was OK. Looping\n"));
209                 }
210         }
211         return 0;
212 }
213