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, 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         J_ASSERT(ext3_journal_current_handle() == NULL);
  58
  59         /*
  60          * data=writeback,ordered:
  61          *  The caller's filemap_fdatawrite()/wait will sync the data.
  62          *  Metadata is in the journal, we wait for a proper transaction
  63          *  to commit here.
  64          *
  65          * data=journal:
  66          *  filemap_fdatawrite won't do anything (the buffers are clean).
  67          *  ext3_force_commit will write the file data into the journal and
  68          *  will wait on that.
  69          *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
  70          *  (they were dirtied by commit).  But that's OK - the blocks are
  71          *  safe in-journal, which is all fsync() needs to ensure.
  72          */
  73         if (ext3_should_journal_data(inode))
  74                 return ext3_force_commit(inode->i_sb);
  75
  76         if (datasync)
  77                 commit_tid = atomic_read(&ei->i_datasync_tid);
  78         else
  79                 commit_tid = atomic_read(&ei->i_sync_tid);
  80
  81         if (test_opt(inode->i_sb, BARRIER) &&
  82             !journal_trans_will_send_data_barrier(journal, commit_tid))
  83                 needs_barrier = 1;
  84         log_start_commit(journal, commit_tid);
  85         ret = log_wait_commit(journal, commit_tid);
  86
  87         /*
  88          * In case we didn't commit a transaction, we have to flush
  89          * disk caches manually so that data really is on persistent
  90          * storage
  91          */
  92         if (needs_barrier)
  93                 blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
  94         return ret;
  95 }