1/*
  2 *  linux/fs/ext3/fsync.c
  3 *
  4 *  Copyright (C) 1993  Stephen Tweedie (sct@redhat.com)
  5 *  from
  6 *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
  7 *                      Laboratoire MASI - Institut Blaise Pascal
  8 *                      Universite Pierre et Marie Curie (Paris VI)
  9 *  from
 10 *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds
 11 *
 12 *  ext3fs fsync primitive
 13 *
 14 *  Big-endian to little-endian byte-swapping/bitmaps by
 15 *        David S. Miller (davem@caip.rutgers.edu), 1995
 16 *
 17 *  Removed unnecessary code duplication for little endian machines
 18 *  and excessive __inline__s.
 19 *        Andi Kleen, 1997
 20 *
 21 * Major simplications and cleanup - we only need to do the metadata, because
 22 * we can depend on generic_block_fdatasync() to sync the data blocks.
 23 */
 24
 25#include <linux/blkdev.h>
 26#include <linux/writeback.h>
 27#include "ext3.h"
 28
 29/*
 30 * akpm: A new design for ext3_sync_file().
 31 *
 32 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
 33 * There cannot be a transaction open by this task.
 34 * Another task could have dirtied this inode.  Its data can be in any
 35 * state in the journalling system.
 36 *
 37 * What we do is just kick off a commit and wait on it.  This will snapshot the
 38 * inode to disk.
 39 */
 40
 41int ext3_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 42{
 43	struct inode *inode = file->f_mapping->host;
 44	struct ext3_inode_info *ei = EXT3_I(inode);
 45	journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
 46	int ret, needs_barrier = 0;
 47	tid_t commit_tid;
 48
 49	trace_ext3_sync_file_enter(file, datasync);
 50
 51	if (inode->i_sb->s_flags & MS_RDONLY)
 52		return 0;
 53
 54	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
 55	if (ret)
 56		goto out;
 57
 58	J_ASSERT(ext3_journal_current_handle() == NULL);
 59
 60	/*
 61	 * data=writeback,ordered:
 62	 *  The caller's filemap_fdatawrite()/wait will sync the data.
 63	 *  Metadata is in the journal, we wait for a proper transaction
 64	 *  to commit here.
 65	 *
 66	 * data=journal:
 67	 *  filemap_fdatawrite won't do anything (the buffers are clean).
 68	 *  ext3_force_commit will write the file data into the journal and
 69	 *  will wait on that.
 70	 *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
 71	 *  (they were dirtied by commit).  But that's OK - the blocks are
 72	 *  safe in-journal, which is all fsync() needs to ensure.
 73	 */
 74	if (ext3_should_journal_data(inode)) {
 75		ret = ext3_force_commit(inode->i_sb);
 76		goto out;
 77	}
 78
 79	if (datasync)
 80		commit_tid = atomic_read(&ei->i_datasync_tid);
 81	else
 82		commit_tid = atomic_read(&ei->i_sync_tid);
 83
 84	if (test_opt(inode->i_sb, BARRIER) &&
 85	    !journal_trans_will_send_data_barrier(journal, commit_tid))
 86		needs_barrier = 1;
 87	log_start_commit(journal, commit_tid);
 88	ret = log_wait_commit(journal, commit_tid);
 89
 90	/*
 91	 * In case we didn't commit a transaction, we have to flush
 92	 * disk caches manually so that data really is on persistent
 93	 * storage
 94	 */
 95	if (needs_barrier)
 96		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
 97out:
 98	trace_ext3_sync_file_exit(inode, ret);
 99	return ret;
100}