fs/ext3/fsync.c

   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/time.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/fs.h>
  28 #include <linux/sched.h>
  29 #include <linux/writeback.h>
  30 #include <linux/jbd.h>
  31 #include <linux/ext3_fs.h>
  32 #include <linux/ext3_jbd.h>
  33 #include <trace/events/ext3.h>
  34
  35 /*
  36  * akpm: A new design for ext3_sync_file().
  37  *
  38  * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
  39  * There cannot be a transaction open by this task.
  40  * Another task could have dirtied this inode.  Its data can be in any
  41  * state in the journalling system.
  42  *
  43  * What we do is just kick off a commit and wait on it.  This will snapshot the
  44  * inode to disk.
  45  */
  46
  47 int ext3_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
  48 {
  49         struct inode *inode = file->f_mapping->host;
  50         struct ext3_inode_info *ei = EXT3_I(inode);
  51         journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
  52         int ret, needs_barrier = 0;
  53         tid_t commit_tid;
  54
  55         trace_ext3_sync_file_enter(file, datasync);
  56
  57         if (inode->i_sb->s_flags & MS_RDONLY)
  58                 return 0;
  59
  60         ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
  61         if (ret)
  62                 goto out;
  63
  64         /*
  65          * Taking the mutex here just to keep consistent with how fsync was
  66          * called previously, however it looks like we don't need to take
  67          * i_mutex at all.
  68          */
  69         mutex_lock(&inode->i_mutex);
  70
  71         J_ASSERT(ext3_journal_current_handle() == NULL);
  72
  73         /*
  74          * data=writeback,ordered:
  75          *  The caller's filemap_fdatawrite()/wait will sync the data.
  76          *  Metadata is in the journal, we wait for a proper transaction
  77          *  to commit here.
  78          *
  79          * data=journal:
  80          *  filemap_fdatawrite won't do anything (the buffers are clean).
  81          *  ext3_force_commit will write the file data into the journal and
  82          *  will wait on that.
  83          *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
  84          *  (they were dirtied by commit).  But that's OK - the blocks are
  85          *  safe in-journal, which is all fsync() needs to ensure.
  86          */
  87         if (ext3_should_journal_data(inode)) {
  88                 mutex_unlock(&inode->i_mutex);
  89                 ret = ext3_force_commit(inode->i_sb);
  90                 goto out;
  91         }
  92
  93         if (datasync)
  94                 commit_tid = atomic_read(&ei->i_datasync_tid);
  95         else
  96                 commit_tid = atomic_read(&ei->i_sync_tid);
  97
  98         if (test_opt(inode->i_sb, BARRIER) &&
  99             !journal_trans_will_send_data_barrier(journal, commit_tid))
 100                 needs_barrier = 1;
 101         log_start_commit(journal, commit_tid);
 102         ret = log_wait_commit(journal, commit_tid);
 103
 104         /*
 105          * In case we didn't commit a transaction, we have to flush
 106          * disk caches manually so that data really is on persistent
 107          * storage
 108          */
 109         if (needs_barrier)
 110                 blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
 111
 112         mutex_unlock(&inode->i_mutex);
 113 out:
 114         trace_ext3_sync_file_exit(inode, ret);
 115         return ret;
 116 }