initial_commit

1 files changed, 402 insertions, 0 deletions

diff --git a/fs/sync.c b/fs/sync.c
new file mode 100644
index 00000000..c38ec163
--- /dev/null
+++ b/fs/sync.c
@@ -0,0 +1,402 @@
+/*
+ * High-level sync()-related operations
+ */
+
+#include <linux/kernel.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/module.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/buffer_head.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)
+{
+	/*
+	 * This should be safe, as we require bdi backing to actually
+	 * write out data in the first place
+	 */
+	if (sb->s_bdi == &noop_backing_dev_info)
+		return 0;
+
+	if (sb->s_qcop && sb->s_qcop->quota_sync)
+		sb->s_qcop->quota_sync(sb, -1, wait);
+
+	if (wait)
+		sync_inodes_sb(sb);
+	else
+		writeback_inodes_sb(sb);
+
+	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_GPL(sync_filesystem);
+
+static void sync_one_sb(struct super_block *sb, void *arg)
+{
+	if (!(sb->s_flags & MS_RDONLY))
+		__sync_filesystem(sb, *(int *)arg);
+}
+/*
+ * Sync all the data for all the filesystems (called by sys_sync() and
+ * emergency sync)
+ */
+static void sync_filesystems(int wait)
+{
+	iterate_supers(sync_one_sb, &wait);
+}
+
+/*
+ * sync everything.  Start out by waking pdflush, because that writes back
+ * all queues in parallel.
+ */
+SYSCALL_DEFINE0(sync)
+{
+	wakeup_flusher_threads(0);
+	sync_filesystems(0);
+	sync_filesystems(1);
+	if (unlikely(laptop_mode))
+		laptop_sync_completion();
+	return 0;
+}
+
+static void do_sync_work(struct work_struct *work)
+{
+	/*
+	 * Sync twice to reduce the possibility we skipped some inodes / pages
+	 * because they were temporarily locked
+	 */
+	sync_filesystems(0);
+	sync_filesystems(0);
+	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 file *file;
+	struct super_block *sb;
+	int ret;
+	int fput_needed;
+
+	file = fget_light(fd, &fput_needed);
+	if (!file)
+		return -EBADF;
+	sb = file->f_dentry->d_sb;
+
+	down_read(&sb->s_umount);
+	ret = sync_filesystem(sb);
+	up_read(&sb->s_umount);
+
+	fput_light(file, fput_needed);
+	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 address_space *mapping = file->f_mapping;
+	int err, ret;
+
+	if (!file->f_op || !file->f_op->fsync) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = filemap_write_and_wait_range(mapping, start, end);
+
+	/*
+	 * 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, datasync);
+	if (!ret)
+		ret = err;
+	mutex_unlock(&mapping->host->i_mutex);
+
+out:
+	return ret;
+}
+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 file *file;
+	int ret = -EBADF;
+
+	file = fget(fd);
+	if (file) {
+		ret = vfs_fsync(file, datasync);
+		fput(file);
+	}
+	return ret;
+}
+
+SYSCALL_DEFINE1(fsync, unsigned int, fd)
+{
+	return do_fsync(fd, 0);
+}
+
+SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
+{
+	return do_fsync(fd, 1);
+}
+
+/**
+ * generic_write_sync - perform syncing after a write if file / inode is sync
+ * @file:	file to which the write happened
+ * @pos:	offset where the write started
+ * @count:	length of the write
+ *
+ * This is just a simple wrapper about our general syncing function.
+ */
+int generic_write_sync(struct file *file, loff_t pos, loff_t count)
+{
+	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
+		return 0;
+	return vfs_fsync_range(file, pos, pos + count - 1,
+			       (file->f_flags & __O_SYNC) ? 0 : 1);
+}
+EXPORT_SYMBOL(generic_write_sync);
+
+/*
+ * 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_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
+				unsigned int flags)
+{
+	int ret;
+	struct file *file;
+	struct address_space *mapping;
+	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;
+
+	mapping = 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:
+	fput_light(file, fput_needed);
+out:
+	return ret;
+}
+#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
+asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
+				    long flags)
+{
+	return SYSC_sync_file_range((int) fd, offset, nbytes,
+				    (unsigned int) flags);
+}
+SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
+#endif
+
+/* It would be nice if people remember that not all the world's an i386
+   when they introduce new system calls */
+SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
+				 loff_t offset, loff_t nbytes)
+{
+	return sys_sync_file_range(fd, offset, nbytes, flags);
+}
+#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
+asmlinkage long SyS_sync_file_range2(long fd, long flags,
+				     loff_t offset, loff_t nbytes)
+{
+	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
+				     offset, nbytes);
+}
+SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
+#endif