/*
 * High-level sync()-related operations
 */

#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/writeback.h>
#include <linux/syscalls.h>
#include <linux/linkage.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.h>

#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
                        SYNC_FILE_RANGE_WAIT_AFTER)

/*
 * sync everything.  Start out by waking pdflush, because that writes back
 * all queues in parallel.
 */
static void do_sync(unsigned long wait)
{
        wakeup_pdflush(0);
        sync_inodes(0);         /* All mappings, inodes and their blockdevs */
        DQUOT_SYNC(NULL);
        sync_supers();          /* Write the superblocks */
        sync_filesystems(0);    /* Start syncing the filesystems */
        sync_filesystems(wait); /* Waitingly sync the filesystems */
        sync_inodes(wait);      /* Mappings, inodes and blockdevs, again. */
        if (!wait)
                printk("Emergency Sync complete\n");
        if (unlikely(laptop_mode))
                laptop_sync_completion();
}

asmlinkage long sys_sync(void)
{
        do_sync(1);
        return 0;
}

void emergency_sync(void)
{
        pdflush_operation(do_sync, 0);
}

/*
 * Generic function to fsync a file.
 *
 * filp may be NULL if called via the msync of a vma.
 */
int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
{
        struct inode * inode = dentry->d_inode;
        struct super_block * sb;
        int ret, err;

        /* sync the inode to buffers */
        ret = write_inode_now(inode, 0);

        /* sync the superblock to buffers */
        sb = inode->i_sb;
        lock_super(sb);
        if (sb->s_dirt && sb->s_op->write_super)
                sb->s_op->write_super(sb);
        unlock_super(sb);

        /* .. finally sync the buffers to disk */
        err = sync_blockdev(sb->s_bdev);
        if (!ret)
                ret = err;
        return ret;
}

long do_fsync(struct file *file, int datasync)
{
        int ret;
        int err;
        struct address_space *mapping = file->f_mapping;

        if (!file->f_op || !file->f_op->fsync) {
                /* Why?  We can still call filemap_fdatawrite */
                ret = -EINVAL;
                goto out;
        }

        ret = filemap_fdatawrite(mapping);

        /*
         * We need to protect against concurrent writers, which could cause
         * livelocks in fsync_buffers_list().
         */
        mutex_lock(&mapping->host->i_mutex);
        err = file->f_op->fsync(file, file->f_path.dentry, datasync);
        if (!ret)
                ret = err;
        mutex_unlock(&mapping->host->i_mutex);
        err = filemap_fdatawait(mapping);
        if (!ret)
                ret = err;
out:
        return ret;
}

static long __do_fsync(unsigned int fd, int datasync)
{
        struct file *file;
        int ret = -EBADF;

        file = fget(fd);
        if (file) {
                ret = do_fsync(file, datasync);
                fput(file);
        }
        return ret;
}

asmlinkage long sys_fsync(unsigned int fd)
{
        return __do_fsync(fd, 0);
}

asmlinkage long sys_fdatasync(unsigned int fd)
{
        return __do_fsync(fd, 1);
}

/*
 * sys_sync_file_range() permits finely controlled syncing over a segment of
 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
 * zero then sys_sync_file_range() will operate from offset out to EOF.
 *
 * The flag bits are:
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
 * before performing the write.
 *
 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
 * range which are not presently under writeback. Note that this may block for
 * significant periods due to exhaustion of disk request structures.
 *
 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
 * after performing the write.
 *
 * Useful combinations of the flag bits are:
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
 * in the range which were dirty on entry to sys_sync_file_range() are placed
 * under writeout.  This is a start-write-for-data-integrity operation.
 *
 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
 * are not presently under writeout.  This is an asynchronous flush-to-disk
 * operation.  Not suitable for data integrity operations.
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
 * completion of writeout of all pages in the range.  This will be used after an
 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
 * for that operation to complete and to return the result.
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
 * a traditional sync() operation.  This is a write-for-data-integrity operation
 * which will ensure that all pages in the range which were dirty on entry to
 * sys_sync_file_range() are committed to disk.
 *
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
 * I/O errors or ENOSPC conditions and will return those to the caller, after
 * clearing the EIO and ENOSPC flags in the address_space.
 *
 * It should be noted that none of these operations write out the file's
 * metadata.  So unless the application is strictly performing overwrites of
 * already-instantiated disk blocks, there are no guarantees here that the data
 * will be available after a crash.
 */
asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
                                        unsigned int flags)
{
        int ret;
        struct file *file;
        loff_t endbyte;                 /* inclusive */
        int fput_needed;
        umode_t i_mode;

        ret = -EINVAL;
        if (flags & ~VALID_FLAGS)
                goto out;

        endbyte = offset + nbytes;

        if ((s64)offset < 0)
                goto out;
        if ((s64)endbyte < 0)
                goto out;
        if (endbyte < offset)
                goto out;

        if (sizeof(pgoff_t) == 4) {
                if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
                        /*
                         * The range starts outside a 32 bit machine's
                         * pagecache addressing capabilities.  Let it "succeed"
                         */
                        ret = 0;
                        goto out;
                }
                if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
                        /*
                         * Out to EOF
                         */
                        nbytes = 0;
                }
        }

        if (nbytes == 0)
                endbyte = LLONG_MAX;
        else
                endbyte--;              /* inclusive */

        ret = -EBADF;
        file = fget_light(fd, &fput_needed);
        if (!file)
                goto out;

        i_mode = file->f_path.dentry->d_inode->i_mode;
        ret = -ESPIPE;
        if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
                        !S_ISLNK(i_mode))
                goto out_put;

        ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
out_put:
        fput_light(file, fput_needed);
out:
        return ret;
}

/* It would be nice if people remember that not all the world's an i386
   when they introduce new system calls */
asmlinkage long sys_sync_file_range2(int fd, unsigned int flags,
                                     loff_t offset, loff_t nbytes)
{
        return sys_sync_file_range(fd, offset, nbytes, flags);
}

/*
 * `endbyte' is inclusive
 */
int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
                          loff_t endbyte, unsigned int flags)
{
        int ret;

        if (!mapping) {
                ret = -EINVAL;
                goto out;
        }

        ret = 0;
        if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
                ret = wait_on_page_writeback_range(mapping,
                                        offset >> PAGE_CACHE_SHIFT,
                                        endbyte >> PAGE_CACHE_SHIFT);
                if (ret < 0)
                        goto out;
        }

        if (flags & SYNC_FILE_RANGE_WRITE) {
                ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
                                                WB_SYNC_NONE);
                if (ret < 0)
                        goto out;
        }

        if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
                ret = wait_on_page_writeback_range(mapping,
                                        offset >> PAGE_CACHE_SHIFT,
                                        endbyte >> PAGE_CACHE_SHIFT);
        }
out:
        return ret;
}
EXPORT_SYMBOL_GPL(do_sync_mapping_range);