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/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
  41 int 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                 int err;
  97
  98                 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
  99                 if (!ret)
 100                         ret = err;
 101         }
 102 out:
 103         trace_ext3_sync_file_exit(inode, ret);
 104         return ret;
 105 }