This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / fs / ext4 / fsync.c

diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
new file mode 100644 (file)
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--- /dev/null
+++ b/fs/ext4/fsync.c
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+/*
+ *  linux/fs/ext4/fsync.c
+ *
+ *  Copyright (C) 1993  Stephen Tweedie (sct@redhat.com)
+ *  from
+ *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
+ *                      Laboratoire MASI - Institut Blaise Pascal
+ *                      Universite Pierre et Marie Curie (Paris VI)
+ *  from
+ *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  ext4fs fsync primitive
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ *
+ *  Removed unnecessary code duplication for little endian machines
+ *  and excessive __inline__s.
+ *        Andi Kleen, 1997
+ *
+ * Major simplications and cleanup - we only need to do the metadata, because
+ * we can depend on generic_block_fdatasync() to sync the data blocks.
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/writeback.h>
+#include <linux/jbd2.h>
+#include <linux/ext4_fs.h>
+#include <linux/ext4_jbd2.h>
+
+/*
+ * akpm: A new design for ext4_sync_file().
+ *
+ * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
+ * There cannot be a transaction open by this task.
+ * Another task could have dirtied this inode.  Its data can be in any
+ * state in the journalling system.
+ *
+ * What we do is just kick off a commit and wait on it.  This will snapshot the
+ * inode to disk.
+ */
+
+int ext4_sync_file(struct file * file, struct dentry *dentry, int datasync)
+{
+       struct inode *inode = dentry->d_inode;
+       int ret = 0;
+
+       J_ASSERT(ext4_journal_current_handle() == 0);
+
+       /*
+        * data=writeback:
+        *  The caller's filemap_fdatawrite()/wait will sync the data.
+        *  sync_inode() will sync the metadata
+        *
+        * data=ordered:
+        *  The caller's filemap_fdatawrite() will write the data and
+        *  sync_inode() will write the inode if it is dirty.  Then the caller's
+        *  filemap_fdatawait() will wait on the pages.
+        *
+        * data=journal:
+        *  filemap_fdatawrite won't do anything (the buffers are clean).
+        *  ext4_force_commit will write the file data into the journal and
+        *  will wait on that.
+        *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
+        *  (they were dirtied by commit).  But that's OK - the blocks are
+        *  safe in-journal, which is all fsync() needs to ensure.
+        */
+       if (ext4_should_journal_data(inode)) {
+               ret = ext4_force_commit(inode->i_sb);
+               goto out;
+       }
+
+       /*
+        * The VFS has written the file data.  If the inode is unaltered
+        * then we need not start a commit.
+        */
+       if (inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) {
+               struct writeback_control wbc = {
+                       .sync_mode = WB_SYNC_ALL,
+                       .nr_to_write = 0, /* sys_fsync did this */
+               };
+               ret = sync_inode(inode, &wbc);
+       }
+out:
+       return ret;
+}