/* *  linux/fs/ext3/fsync.c * *  Copyright (C) 1993  Stephen Tweedie (sct@redhat.com) *  from *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr) *                      Laboratoire MASI - Institut Blaise Pascal *                      Universite Pierre et Marie Curie (Paris VI) *  from *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds * *  ext3fs fsync primitive * *  Big-endian to little-endian byte-swapping/bitmaps by *        David S. Miller (davem@caip.rutgers.edu), 1995 * *  Removed unnecessary code duplication for little endian machines *  and excessive __inline__s. *        Andi Kleen, 1997 * * Major simplications and cleanup - we only need to do the metadata, because * we can depend on generic_block_fdatasync() to sync the data blocks. */ #include <linux/blkdev.h>#include <linux/writeback.h>#include "ext3.h" /* * akpm: A new design for ext3_sync_file(). * * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). * There cannot be a transaction open by this task. * Another task could have dirtied this inode.  Its data can be in any * state in the journalling system. * * What we do is just kick off a commit and wait on it.  This will snapshot the * inode to disk. */ int ext3_sync_file(struct file *file, loff_t start, loff_t end, int datasync){	struct inode *inode = file->f_mapping->host;	struct ext3_inode_info *ei = EXT3_I(inode);	journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;	int ret, needs_barrier = 0;	tid_t commit_tid; 	trace_ext3_sync_file_enter(file, datasync); 	if (inode->i_sb->s_flags & MS_RDONLY) {		/* Make sure that we read updated state */		smp_rmb();		if (EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS)			return -EROFS;		return 0;	}	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);	if (ret)		goto out; 	J_ASSERT(ext3_journal_current_handle() == NULL); 	/*	 * data=writeback,ordered:	 *  The caller's filemap_fdatawrite()/wait will sync the data.	 *  Metadata is in the journal, we wait for a proper transaction	 *  to commit here.	 *	 * data=journal:	 *  filemap_fdatawrite won't do anything (the buffers are clean).	 *  ext3_force_commit will write the file data into the journal and	 *  will wait on that.	 *  filemap_fdatawait() will encounter a ton of newly-dirtied pages	 *  (they were dirtied by commit).  But that's OK - the blocks are	 *  safe in-journal, which is all fsync() needs to ensure.	 */	if (ext3_should_journal_data(inode)) {		ret = ext3_force_commit(inode->i_sb);		goto out;	} 	if (datasync)		commit_tid = atomic_read(&ei->i_datasync_tid);	else		commit_tid = atomic_read(&ei->i_sync_tid); 	if (test_opt(inode->i_sb, BARRIER) &&	    !journal_trans_will_send_data_barrier(journal, commit_tid))		needs_barrier = 1;	log_start_commit(journal, commit_tid);	ret = log_wait_commit(journal, commit_tid); 	/*	 * In case we didn't commit a transaction, we have to flush	 * disk caches manually so that data really is on persistent	 * storage	 */	if (needs_barrier) {		int err; 		err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);		if (!ret)			ret = err;	}out:	trace_ext3_sync_file_exit(inode, ret);	return ret;}