/* * 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() == NULL); /* * 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; }