fs/jffs2/file.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright © 2001-2007 Red Hat, Inc.
   5  * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
   6  *
   7  * Created by David Woodhouse <dwmw2@infradead.org>
   8  *
   9  * For licensing information, see the file 'LICENCE' in this directory.
  10  *
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/kernel.h>
  16 #include <linux/fs.h>
  17 #include <linux/time.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/highmem.h>
  20 #include <linux/crc32.h>
  21 #include <linux/jffs2.h>
  22 #include "nodelist.h"
  23
  24 static int jffs2_write_end(struct file *filp, struct address_space *mapping,
  25                         loff_t pos, unsigned len, unsigned copied,
  26                         struct page *pg, void *fsdata);
  27 static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
  28                         loff_t pos, unsigned len, unsigned flags,
  29                         struct page **pagep, void **fsdata);
  30 static int jffs2_readpage (struct file *filp, struct page *pg);
  31
  32 int jffs2_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
  33 {
  34         struct inode *inode = filp->f_mapping->host;
  35         struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
  36         int ret;
  37
  38         ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
  39         if (ret)
  40                 return ret;
  41
  42         inode_lock(inode);
  43         /* Trigger GC to flush any pending writes for this inode */
  44         jffs2_flush_wbuf_gc(c, inode->i_ino);
  45         inode_unlock(inode);
  46
  47         return 0;
  48 }
  49
  50 const struct file_operations jffs2_file_operations =
  51 {
  52         .llseek =       generic_file_llseek,
  53         .open =         generic_file_open,
  54         .read_iter =    generic_file_read_iter,
  55         .write_iter =   generic_file_write_iter,
  56         .unlocked_ioctl=jffs2_ioctl,
  57         .mmap =         generic_file_readonly_mmap,
  58         .fsync =        jffs2_fsync,
  59         .splice_read =  generic_file_splice_read,
  60 };
  61
  62 /* jffs2_file_inode_operations */
  63
  64 const struct inode_operations jffs2_file_inode_operations =
  65 {
  66         .get_acl =      jffs2_get_acl,
  67         .set_acl =      jffs2_set_acl,
  68         .setattr =      jffs2_setattr,
  69         .listxattr =    jffs2_listxattr,
  70 };
  71
  72 const struct address_space_operations jffs2_file_address_operations =
  73 {
  74         .readpage =     jffs2_readpage,
  75         .write_begin =  jffs2_write_begin,
  76         .write_end =    jffs2_write_end,
  77 };
  78
  79 static int jffs2_do_readpage_nolock (struct inode *inode, struct page *pg)
  80 {
  81         struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
  82         struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
  83         unsigned char *pg_buf;
  84         int ret;
  85
  86         jffs2_dbg(2, "%s(): ino #%lu, page at offset 0x%lx\n",
  87                   __func__, inode->i_ino, pg->index << PAGE_SHIFT);
  88
  89         BUG_ON(!PageLocked(pg));
  90
  91         pg_buf = kmap(pg);
  92         /* FIXME: Can kmap fail? */
  93
  94         ret = jffs2_read_inode_range(c, f, pg_buf, pg->index << PAGE_SHIFT,
  95                                      PAGE_SIZE);
  96
  97         if (ret) {
  98                 ClearPageUptodate(pg);
  99                 SetPageError(pg);
 100         } else {
 101                 SetPageUptodate(pg);
 102                 ClearPageError(pg);
 103         }
 104
 105         flush_dcache_page(pg);
 106         kunmap(pg);
 107
 108         jffs2_dbg(2, "readpage finished\n");
 109         return ret;
 110 }
 111
 112 int jffs2_do_readpage_unlock(struct inode *inode, struct page *pg)
 113 {
 114         int ret = jffs2_do_readpage_nolock(inode, pg);
 115         unlock_page(pg);
 116         return ret;
 117 }
 118
 119
 120 static int jffs2_readpage (struct file *filp, struct page *pg)
 121 {
 122         struct jffs2_inode_info *f = JFFS2_INODE_INFO(pg->mapping->host);
 123         int ret;
 124
 125         mutex_lock(&f->sem);
 126         ret = jffs2_do_readpage_unlock(pg->mapping->host, pg);
 127         mutex_unlock(&f->sem);
 128         return ret;
 129 }
 130
 131 static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
 132                         loff_t pos, unsigned len, unsigned flags,
 133                         struct page **pagep, void **fsdata)
 134 {
 135         struct page *pg;
 136         struct inode *inode = mapping->host;
 137         struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
 138         struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
 139         pgoff_t index = pos >> PAGE_SHIFT;
 140         uint32_t pageofs = index << PAGE_SHIFT;
 141         int ret = 0;
 142
 143         jffs2_dbg(1, "%s()\n", __func__);
 144
 145         if (pageofs > inode->i_size) {
 146                 /* Make new hole frag from old EOF to new page */
 147                 struct jffs2_raw_inode ri;
 148                 struct jffs2_full_dnode *fn;
 149                 uint32_t alloc_len;
 150
 151                 jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
 152                           (unsigned int)inode->i_size, pageofs);
 153
 154                 ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
 155                                           ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
 156                 if (ret)
 157                         goto out_err;
 158
 159                 mutex_lock(&f->sem);
 160                 memset(&ri, 0, sizeof(ri));
 161
 162                 ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
 163                 ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
 164                 ri.totlen = cpu_to_je32(sizeof(ri));
 165                 ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));
 166
 167                 ri.ino = cpu_to_je32(f->inocache->ino);
 168                 ri.version = cpu_to_je32(++f->highest_version);
 169                 ri.mode = cpu_to_jemode(inode->i_mode);
 170                 ri.uid = cpu_to_je16(i_uid_read(inode));
 171                 ri.gid = cpu_to_je16(i_gid_read(inode));
 172                 ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
 173                 ri.atime = ri.ctime = ri.mtime = cpu_to_je32(get_seconds());
 174                 ri.offset = cpu_to_je32(inode->i_size);
 175                 ri.dsize = cpu_to_je32(pageofs - inode->i_size);
 176                 ri.csize = cpu_to_je32(0);
 177                 ri.compr = JFFS2_COMPR_ZERO;
 178                 ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
 179                 ri.data_crc = cpu_to_je32(0);
 180
 181                 fn = jffs2_write_dnode(c, f, &ri, NULL, 0, ALLOC_NORMAL);
 182
 183                 if (IS_ERR(fn)) {
 184                         ret = PTR_ERR(fn);
 185                         jffs2_complete_reservation(c);
 186                         mutex_unlock(&f->sem);
 187                         goto out_err;
 188                 }
 189                 ret = jffs2_add_full_dnode_to_inode(c, f, fn);
 190                 if (f->metadata) {
 191                         jffs2_mark_node_obsolete(c, f->metadata->raw);
 192                         jffs2_free_full_dnode(f->metadata);
 193                         f->metadata = NULL;
 194                 }
 195                 if (ret) {
 196                         jffs2_dbg(1, "Eep. add_full_dnode_to_inode() failed in write_begin, returned %d\n",
 197                                   ret);
 198                         jffs2_mark_node_obsolete(c, fn->raw);
 199                         jffs2_free_full_dnode(fn);
 200                         jffs2_complete_reservation(c);
 201                         mutex_unlock(&f->sem);
 202                         goto out_err;
 203                 }
 204                 jffs2_complete_reservation(c);
 205                 inode->i_size = pageofs;
 206                 mutex_unlock(&f->sem);
 207         }
 208
 209         /*
 210          * While getting a page and reading data in, lock c->alloc_sem until
 211          * the page is Uptodate. Otherwise GC task may attempt to read the same
 212          * page in read_cache_page(), which causes a deadlock.
 213          */
 214         mutex_lock(&c->alloc_sem);
 215         pg = grab_cache_page_write_begin(mapping, index, flags);
 216         if (!pg) {
 217                 ret = -ENOMEM;
 218                 goto release_sem;
 219         }
 220         *pagep = pg;
 221
 222         /*
 223          * Read in the page if it wasn't already present. Cannot optimize away
 224          * the whole page write case until jffs2_write_end can handle the
 225          * case of a short-copy.
 226          */
 227         if (!PageUptodate(pg)) {
 228                 mutex_lock(&f->sem);
 229                 ret = jffs2_do_readpage_nolock(inode, pg);
 230                 mutex_unlock(&f->sem);
 231                 if (ret) {
 232                         unlock_page(pg);
 233                         put_page(pg);
 234                         goto release_sem;
 235                 }
 236         }
 237         jffs2_dbg(1, "end write_begin(). pg->flags %lx\n", pg->flags);
 238
 239 release_sem:
 240         mutex_unlock(&c->alloc_sem);
 241 out_err:
 242         return ret;
 243 }
 244
 245 static int jffs2_write_end(struct file *filp, struct address_space *mapping,
 246                         loff_t pos, unsigned len, unsigned copied,
 247                         struct page *pg, void *fsdata)
 248 {
 249         /* Actually commit the write from the page cache page we're looking at.
 250          * For now, we write the full page out each time. It sucks, but it's simple
 251          */
 252         struct inode *inode = mapping->host;
 253         struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
 254         struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
 255         struct jffs2_raw_inode *ri;
 256         unsigned start = pos & (PAGE_SIZE - 1);
 257         unsigned end = start + copied;
 258         unsigned aligned_start = start & ~3;
 259         int ret = 0;
 260         uint32_t writtenlen = 0;
 261
 262         jffs2_dbg(1, "%s(): ino #%lu, page at 0x%lx, range %d-%d, flags %lx\n",
 263                   __func__, inode->i_ino, pg->index << PAGE_SHIFT,
 264                   start, end, pg->flags);
 265
 266         /* We need to avoid deadlock with page_cache_read() in
 267            jffs2_garbage_collect_pass(). So the page must be
 268            up to date to prevent page_cache_read() from trying
 269            to re-lock it. */
 270         BUG_ON(!PageUptodate(pg));
 271
 272         if (end == PAGE_SIZE) {
 273                 /* When writing out the end of a page, write out the
 274                    _whole_ page. This helps to reduce the number of
 275                    nodes in files which have many short writes, like
 276                    syslog files. */
 277                 aligned_start = 0;
 278         }
 279
 280         ri = jffs2_alloc_raw_inode();
 281
 282         if (!ri) {
 283                 jffs2_dbg(1, "%s(): Allocation of raw inode failed\n",
 284                           __func__);
 285                 unlock_page(pg);
 286                 put_page(pg);
 287                 return -ENOMEM;
 288         }
 289
 290         /* Set the fields that the generic jffs2_write_inode_range() code can't find */
 291         ri->ino = cpu_to_je32(inode->i_ino);
 292         ri->mode = cpu_to_jemode(inode->i_mode);
 293         ri->uid = cpu_to_je16(i_uid_read(inode));
 294         ri->gid = cpu_to_je16(i_gid_read(inode));
 295         ri->isize = cpu_to_je32((uint32_t)inode->i_size);
 296         ri->atime = ri->ctime = ri->mtime = cpu_to_je32(get_seconds());
 297
 298         /* In 2.4, it was already kmapped by generic_file_write(). Doesn't
 299            hurt to do it again. The alternative is ifdefs, which are ugly. */
 300         kmap(pg);
 301
 302         ret = jffs2_write_inode_range(c, f, ri, page_address(pg) + aligned_start,
 303                                       (pg->index << PAGE_SHIFT) + aligned_start,
 304                                       end - aligned_start, &writtenlen);
 305
 306         kunmap(pg);
 307
 308         if (ret) {
 309                 /* There was an error writing. */
 310                 SetPageError(pg);
 311         }
 312
 313         /* Adjust writtenlen for the padding we did, so we don't confuse our caller */
 314         writtenlen -= min(writtenlen, (start - aligned_start));
 315
 316         if (writtenlen) {
 317                 if (inode->i_size < pos + writtenlen) {
 318                         inode->i_size = pos + writtenlen;
 319                         inode->i_blocks = (inode->i_size + 511) >> 9;
 320
 321                         inode->i_ctime = inode->i_mtime = ITIME(je32_to_cpu(ri->ctime));
 322                 }
 323         }
 324
 325         jffs2_free_raw_inode(ri);
 326
 327         if (start+writtenlen < end) {
 328                 /* generic_file_write has written more to the page cache than we've
 329                    actually written to the medium. Mark the page !Uptodate so that
 330                    it gets reread */
 331                 jffs2_dbg(1, "%s(): Not all bytes written. Marking page !uptodate\n",
 332                         __func__);
 333                 SetPageError(pg);
 334                 ClearPageUptodate(pg);
 335         }
 336
 337         jffs2_dbg(1, "%s() returning %d\n",
 338                   __func__, writtenlen > 0 ? writtenlen : ret);
 339         unlock_page(pg);
 340         put_page(pg);
 341         return writtenlen > 0 ? writtenlen : ret;
 342 }