/* * 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/blkdev.h> #include "ext4.h" #include "ext4_jbd2.h" #include <trace/events/ext4.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. * * i_mutex lock is held when entering and exiting this function */ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync) { struct inode *inode = dentry->d_inode; struct ext4_inode_info *ei = EXT4_I(inode); journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; int ret; tid_t commit_tid; J_ASSERT(ext4_journal_current_handle() == NULL); trace_ext4_sync_file(file, dentry, datasync); if (inode->i_sb->s_flags & MS_RDONLY) return 0; ret = flush_completed_IO(inode); if (ret < 0) return ret; if (!journal) return simple_fsync(file, dentry, datasync); /* * data=writeback,ordered: * The caller's filemap_fdatawrite()/wait will sync the data. * Metadata is in the journal, we wait for proper transaction to * commit here. * * 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)) return ext4_force_commit(inode->i_sb); commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; if (jbd2_log_start_commit(journal, commit_tid)) { /* * When the journal is on a different device than the * fs data disk, we need to issue the barrier in * writeback mode. (In ordered mode, the jbd2 layer * will take care of issuing the barrier. In * data=journal, all of the data blocks are written to * the journal device.) */ if (ext4_should_writeback_data(inode) && (journal->j_fs_dev != journal->j_dev) && (journal->j_flags & JBD2_BARRIER)) blkdev_issue_flush(inode->i_sb->s_bdev, NULL); jbd2_log_wait_commit(journal, commit_tid); } else if (journal->j_flags & JBD2_BARRIER) blkdev_issue_flush(inode->i_sb->s_bdev, NULL); return ret; }