linux/fs/sync.c
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   1/*
   2 * High-level sync()-related operations
   3 */
   4
   5#include <linux/kernel.h>
   6#include <linux/file.h>
   7#include <linux/fs.h>
   8#include <linux/module.h>
   9#include <linux/sched.h>
  10#include <linux/writeback.h>
  11#include <linux/syscalls.h>
  12#include <linux/linkage.h>
  13#include <linux/pagemap.h>
  14#include <linux/quotaops.h>
  15#include <linux/buffer_head.h>
  16
  17#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
  18                        SYNC_FILE_RANGE_WAIT_AFTER)
  19
  20/*
  21 * sync everything.  Start out by waking pdflush, because that writes back
  22 * all queues in parallel.
  23 */
  24static void do_sync(unsigned long wait)
  25{
  26        wakeup_pdflush(0);
  27        sync_inodes(0);         /* All mappings, inodes and their blockdevs */
  28        DQUOT_SYNC(NULL);
  29        sync_supers();          /* Write the superblocks */
  30        sync_filesystems(0);    /* Start syncing the filesystems */
  31        sync_filesystems(wait); /* Waitingly sync the filesystems */
  32        sync_inodes(wait);      /* Mappings, inodes and blockdevs, again. */
  33        if (!wait)
  34                printk("Emergency Sync complete\n");
  35        if (unlikely(laptop_mode))
  36                laptop_sync_completion();
  37}
  38
  39SYSCALL_DEFINE0(sync)
  40{
  41        do_sync(1);
  42        return 0;
  43}
  44
  45void emergency_sync(void)
  46{
  47        pdflush_operation(do_sync, 0);
  48}
  49
  50/*
  51 * Generic function to fsync a file.
  52 *
  53 * filp may be NULL if called via the msync of a vma.
  54 */
  55int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
  56{
  57        struct inode * inode = dentry->d_inode;
  58        struct super_block * sb;
  59        int ret, err;
  60
  61        /* sync the inode to buffers */
  62        ret = write_inode_now(inode, 0);
  63
  64        /* sync the superblock to buffers */
  65        sb = inode->i_sb;
  66        lock_super(sb);
  67        if (sb->s_dirt && sb->s_op->write_super)
  68                sb->s_op->write_super(sb);
  69        unlock_super(sb);
  70
  71        /* .. finally sync the buffers to disk */
  72        err = sync_blockdev(sb->s_bdev);
  73        if (!ret)
  74                ret = err;
  75        return ret;
  76}
  77
  78long do_fsync(struct file *file, int datasync)
  79{
  80        int ret;
  81        int err;
  82        struct address_space *mapping = file->f_mapping;
  83
  84        if (!file->f_op || !file->f_op->fsync) {
  85                /* Why?  We can still call filemap_fdatawrite */
  86                ret = -EINVAL;
  87                goto out;
  88        }
  89
  90        ret = filemap_fdatawrite(mapping);
  91
  92        /*
  93         * We need to protect against concurrent writers, which could cause
  94         * livelocks in fsync_buffers_list().
  95         */
  96        mutex_lock(&mapping->host->i_mutex);
  97        err = file->f_op->fsync(file, file->f_path.dentry, datasync);
  98        if (!ret)
  99                ret = err;
 100        mutex_unlock(&mapping->host->i_mutex);
 101        err = filemap_fdatawait(mapping);
 102        if (!ret)
 103                ret = err;
 104out:
 105        return ret;
 106}
 107
 108static long __do_fsync(unsigned int fd, int datasync)
 109{
 110        struct file *file;
 111        int ret = -EBADF;
 112
 113        file = fget(fd);
 114        if (file) {
 115                ret = do_fsync(file, datasync);
 116                fput(file);
 117        }
 118        return ret;
 119}
 120
 121SYSCALL_DEFINE1(fsync, unsigned int, fd)
 122{
 123        return __do_fsync(fd, 0);
 124}
 125
 126SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
 127{
 128        return __do_fsync(fd, 1);
 129}
 130
 131/*
 132 * sys_sync_file_range() permits finely controlled syncing over a segment of
 133 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
 134 * zero then sys_sync_file_range() will operate from offset out to EOF.
 135 *
 136 * The flag bits are:
 137 *
 138 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
 139 * before performing the write.
 140 *
 141 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
 142 * range which are not presently under writeback. Note that this may block for
 143 * significant periods due to exhaustion of disk request structures.
 144 *
 145 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
 146 * after performing the write.
 147 *
 148 * Useful combinations of the flag bits are:
 149 *
 150 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
 151 * in the range which were dirty on entry to sys_sync_file_range() are placed
 152 * under writeout.  This is a start-write-for-data-integrity operation.
 153 *
 154 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
 155 * are not presently under writeout.  This is an asynchronous flush-to-disk
 156 * operation.  Not suitable for data integrity operations.
 157 *
 158 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
 159 * completion of writeout of all pages in the range.  This will be used after an
 160 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
 161 * for that operation to complete and to return the result.
 162 *
 163 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
 164 * a traditional sync() operation.  This is a write-for-data-integrity operation
 165 * which will ensure that all pages in the range which were dirty on entry to
 166 * sys_sync_file_range() are committed to disk.
 167 *
 168 *
 169 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
 170 * I/O errors or ENOSPC conditions and will return those to the caller, after
 171 * clearing the EIO and ENOSPC flags in the address_space.
 172 *
 173 * It should be noted that none of these operations write out the file's
 174 * metadata.  So unless the application is strictly performing overwrites of
 175 * already-instantiated disk blocks, there are no guarantees here that the data
 176 * will be available after a crash.
 177 */
 178SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
 179                                unsigned int flags)
 180{
 181        int ret;
 182        struct file *file;
 183        loff_t endbyte;                 /* inclusive */
 184        int fput_needed;
 185        umode_t i_mode;
 186
 187        ret = -EINVAL;
 188        if (flags & ~VALID_FLAGS)
 189                goto out;
 190
 191        endbyte = offset + nbytes;
 192
 193        if ((s64)offset < 0)
 194                goto out;
 195        if ((s64)endbyte < 0)
 196                goto out;
 197        if (endbyte < offset)
 198                goto out;
 199
 200        if (sizeof(pgoff_t) == 4) {
 201                if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
 202                        /*
 203                         * The range starts outside a 32 bit machine's
 204                         * pagecache addressing capabilities.  Let it "succeed"
 205                         */
 206                        ret = 0;
 207                        goto out;
 208                }
 209                if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
 210                        /*
 211                         * Out to EOF
 212                         */
 213                        nbytes = 0;
 214                }
 215        }
 216
 217        if (nbytes == 0)
 218                endbyte = LLONG_MAX;
 219        else
 220                endbyte--;              /* inclusive */
 221
 222        ret = -EBADF;
 223        file = fget_light(fd, &fput_needed);
 224        if (!file)
 225                goto out;
 226
 227        i_mode = file->f_path.dentry->d_inode->i_mode;
 228        ret = -ESPIPE;
 229        if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
 230                        !S_ISLNK(i_mode))
 231                goto out_put;
 232
 233        ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
 234out_put:
 235        fput_light(file, fput_needed);
 236out:
 237        return ret;
 238}
 239#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 240asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
 241                                    long flags)
 242{
 243        return SYSC_sync_file_range((int) fd, offset, nbytes,
 244                                    (unsigned int) flags);
 245}
 246SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
 247#endif
 248
 249/* It would be nice if people remember that not all the world's an i386
 250   when they introduce new system calls */
 251SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
 252                                 loff_t offset, loff_t nbytes)
 253{
 254        return sys_sync_file_range(fd, offset, nbytes, flags);
 255}
 256#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 257asmlinkage long SyS_sync_file_range2(long fd, long flags,
 258                                     loff_t offset, loff_t nbytes)
 259{
 260        return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
 261                                     offset, nbytes);
 262}
 263SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
 264#endif
 265
 266/*
 267 * `endbyte' is inclusive
 268 */
 269int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
 270                          loff_t endbyte, unsigned int flags)
 271{
 272        int ret;
 273
 274        if (!mapping) {
 275                ret = -EINVAL;
 276                goto out;
 277        }
 278
 279        ret = 0;
 280        if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
 281                ret = wait_on_page_writeback_range(mapping,
 282                                        offset >> PAGE_CACHE_SHIFT,
 283                                        endbyte >> PAGE_CACHE_SHIFT);
 284                if (ret < 0)
 285                        goto out;
 286        }
 287
 288        if (flags & SYNC_FILE_RANGE_WRITE) {
 289                ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
 290                                                WB_SYNC_NONE);
 291                if (ret < 0)
 292                        goto out;
 293        }
 294
 295        if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
 296                ret = wait_on_page_writeback_range(mapping,
 297                                        offset >> PAGE_CACHE_SHIFT,
 298                                        endbyte >> PAGE_CACHE_SHIFT);
 299        }
 300out:
 301        return ret;
 302}
 303EXPORT_SYMBOL_GPL(do_sync_mapping_range);
 304