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