1 files changed, 366 insertions, 0 deletions
diff --git a/fs/sync.c b/fs/sync.c
new file mode 100644
index 000000000..fbc98ee62
--- /dev/null
+++ b/fs/sync.c
@@ -0,0 +1,366 @@
+/*
+ * High-level sync()-related operations
+ */
+
+#include <linux/kernel.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/namei.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/backing-dev.h>
+#include "internal.h"
+
+#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
+			SYNC_FILE_RANGE_WAIT_AFTER)
+
+/*
+ * Do the filesystem syncing work. For simple filesystems
+ * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
+ * submit IO for these buffers via __sync_blockdev(). This also speeds up the
+ * wait == 1 case since in that case write_inode() functions do
+ * sync_dirty_buffer() and thus effectively write one block at a time.
+ */
+static int __sync_filesystem(struct super_block *sb, int wait)
+{
+	if (wait)
+		sync_inodes_sb(sb);
+	else
+		writeback_inodes_sb(sb, WB_REASON_SYNC);
+
+	if (sb->s_op->sync_fs)
+		sb->s_op->sync_fs(sb, wait);
+	return __sync_blockdev(sb->s_bdev, wait);
+}
+
+/*
+ * Write out and wait upon all dirty data associated with this
+ * superblock.  Filesystem data as well as the underlying block
+ * device.  Takes the superblock lock.
+ */
+int sync_filesystem(struct super_block *sb)
+{
+	int ret;
+
+	/*
+	 * We need to be protected against the filesystem going from
+	 * r/o to r/w or vice versa.
+	 */
+	WARN_ON(!rwsem_is_locked(&sb->s_umount));
+
+	/*
+	 * No point in syncing out anything if the filesystem is read-only.
+	 */
+	if (sb->s_flags & MS_RDONLY)
+		return 0;
+
+	ret = __sync_filesystem(sb, 0);
+	if (ret < 0)
+		return ret;
+	return __sync_filesystem(sb, 1);
+}
+EXPORT_SYMBOL(sync_filesystem);
+
+static void sync_inodes_one_sb(struct super_block *sb, void *arg)
+{
+	if (!(sb->s_flags & MS_RDONLY))
+		sync_inodes_sb(sb);
+}
+
+static void sync_fs_one_sb(struct super_block *sb, void *arg)
+{
+	if (!(sb->s_flags & MS_RDONLY) && sb->s_op->sync_fs)
+		sb->s_op->sync_fs(sb, *(int *)arg);
+}
+
+static void fdatawrite_one_bdev(struct block_device *bdev, void *arg)
+{
+	filemap_fdatawrite(bdev->bd_inode->i_mapping);
+}
+
+static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
+{
+	filemap_fdatawait(bdev->bd_inode->i_mapping);
+}
+
+/*
+ * Sync everything. We start by waking flusher threads so that most of
+ * writeback runs on all devices in parallel. Then we sync all inodes reliably
+ * which effectively also waits for all flusher threads to finish doing
+ * writeback. At this point all data is on disk so metadata should be stable
+ * and we tell filesystems to sync their metadata via ->sync_fs() calls.
+ * Finally, we writeout all block devices because some filesystems (e.g. ext2)
+ * just write metadata (such as inodes or bitmaps) to block device page cache
+ * and do not sync it on their own in ->sync_fs().
+ */
+SYSCALL_DEFINE0(sync)
+{
+	int nowait = 0, wait = 1;
+
+	wakeup_flusher_threads(0, WB_REASON_SYNC);
+	iterate_supers(sync_inodes_one_sb, NULL);
+	iterate_supers(sync_fs_one_sb, &nowait);
+	iterate_supers(sync_fs_one_sb, &wait);
+	iterate_bdevs(fdatawrite_one_bdev, NULL);
+	iterate_bdevs(fdatawait_one_bdev, NULL);
+	if (unlikely(laptop_mode))
+		laptop_sync_completion();
+	return 0;
+}
+
+static void do_sync_work(struct work_struct *work)
+{
+	int nowait = 0;
+
+	/*
+	 * Sync twice to reduce the possibility we skipped some inodes / pages
+	 * because they were temporarily locked
+	 */
+	iterate_supers(sync_inodes_one_sb, &nowait);
+	iterate_supers(sync_fs_one_sb, &nowait);
+	iterate_bdevs(fdatawrite_one_bdev, NULL);
+	iterate_supers(sync_inodes_one_sb, &nowait);
+	iterate_supers(sync_fs_one_sb, &nowait);
+	iterate_bdevs(fdatawrite_one_bdev, NULL);
+	printk("Emergency Sync complete\n");
+	kfree(work);
+}
+
+void emergency_sync(void)
+{
+	struct work_struct *work;
+
+	work = kmalloc(sizeof(*work), GFP_ATOMIC);
+	if (work) {
+		INIT_WORK(work, do_sync_work);
+		schedule_work(work);
+	}
+}
+
+/*
+ * sync a single super
+ */
+SYSCALL_DEFINE1(syncfs, int, fd)
+{
+	struct fd f = fdget(fd);
+	struct super_block *sb;
+	int ret;
+
+	if (!f.file)
+		return -EBADF;
+	sb = f.file->f_path.dentry->d_sb;
+
+	down_read(&sb->s_umount);
+	ret = sync_filesystem(sb);
+	up_read(&sb->s_umount);
+
+	fdput(f);
+	return ret;
+}
+
+/**
+ * vfs_fsync_range - helper to sync a range of data & metadata to disk
+ * @file:		file to sync
+ * @start:		offset in bytes of the beginning of data range to sync
+ * @end:		offset in bytes of the end of data range (inclusive)
+ * @datasync:		perform only datasync
+ *
+ * Write back data in range @start..@end and metadata for @file to disk.  If
+ * @datasync is set only metadata needed to access modified file data is
+ * written.
+ */
+int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct inode *inode = file->f_mapping->host;
+
+	if (!file->f_op->fsync)
+		return -EINVAL;
+	if (!datasync && (inode->i_state & I_DIRTY_TIME)) {
+		spin_lock(&inode->i_lock);
+		inode->i_state &= ~I_DIRTY_TIME;
+		spin_unlock(&inode->i_lock);
+		mark_inode_dirty_sync(inode);
+	}
+	return file->f_op->fsync(file, start, end, datasync);
+}
+EXPORT_SYMBOL(vfs_fsync_range);
+
+/**
+ * vfs_fsync - perform a fsync or fdatasync on a file
+ * @file:		file to sync
+ * @datasync:		only perform a fdatasync operation
+ *
+ * Write back data and metadata for @file to disk.  If @datasync is
+ * set only metadata needed to access modified file data is written.
+ */
+int vfs_fsync(struct file *file, int datasync)
+{
+	return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
+}
+EXPORT_SYMBOL(vfs_fsync);
+
+static int do_fsync(unsigned int fd, int datasync)
+{
+	struct fd f = fdget(fd);
+	int ret = -EBADF;
+
+	if (f.file) {
+		ret = vfs_fsync(f.file, datasync);
+		fdput(f);
+	}
+	return ret;
+}
+
+SYSCALL_DEFINE1(fsync, unsigned int, fd)
+{
+	return do_fsync(fd, 0);
+}
+
+SYSCALL_DEFINE1(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.
+ */
+SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
+				unsigned int, flags)
+{
+	int ret;
+	struct fd f;
+	struct address_space *mapping;
+	loff_t endbyte;			/* inclusive */
+	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;
+	f = fdget(fd);
+	if (!f.file)
+		goto out;
+
+	i_mode = file_inode(f.file)->i_mode;
+	ret = -ESPIPE;
+	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
+			!S_ISLNK(i_mode))
+		goto out_put;
+
+	mapping = f.file->f_mapping;
+	if (!mapping) {
+		ret = -EINVAL;
+		goto out_put;
+	}
+
+	ret = 0;
+	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
+		ret = filemap_fdatawait_range(mapping, offset, endbyte);
+		if (ret < 0)
+			goto out_put;
+	}
+
+	if (flags & SYNC_FILE_RANGE_WRITE) {
+		ret = filemap_fdatawrite_range(mapping, offset, endbyte);
+		if (ret < 0)
+			goto out_put;
+	}
+
+	if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
+		ret = filemap_fdatawait_range(mapping, offset, endbyte);
+
+out_put:
+	fdput(f);
+out:
+	return ret;
+}
+
+/* It would be nice if people remember that not all the world's an i386
+   when they introduce new system calls */
+SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
+				 loff_t, offset, loff_t, nbytes)
+{
+	return sys_sync_file_range(fd, offset, nbytes, flags);
+}