1 /* 2 * linux/fs/ext4/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 * ext4fs 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/fs.h> 27 #include <linux/sched.h> 28 #include <linux/writeback.h> 29 #include <linux/jbd2.h> 30 #include <linux/blkdev.h> 31 #include "ext4.h" 32 #include "ext4_jbd2.h" 33 34 /* 35 * akpm: A new design for ext4_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 ext4_sync_file(struct file * file, struct dentry *dentry, int datasync) 47 { 48 struct inode *inode = dentry->d_inode; 49 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 50 int ret = 0; 51 52 J_ASSERT(ext4_journal_current_handle() == NULL); 53 54 /* 55 * data=writeback: 56 * The caller's filemap_fdatawrite()/wait will sync the data. 57 * sync_inode() will sync the metadata 58 * 59 * data=ordered: 60 * The caller's filemap_fdatawrite() will write the data and 61 * sync_inode() will write the inode if it is dirty. Then the caller's 62 * filemap_fdatawait() will wait on the pages. 63 * 64 * data=journal: 65 * filemap_fdatawrite won't do anything (the buffers are clean). 66 * ext4_force_commit will write the file data into the journal and 67 * will wait on that. 68 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 69 * (they were dirtied by commit). But that's OK - the blocks are 70 * safe in-journal, which is all fsync() needs to ensure. 71 */ 72 if (ext4_should_journal_data(inode)) { 73 ret = ext4_force_commit(inode->i_sb); 74 goto out; 75 } 76 77 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 78 goto out; 79 80 /* 81 * The VFS has written the file data. If the inode is unaltered 82 * then we need not start a commit. 83 */ 84 if (inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) { 85 struct writeback_control wbc = { 86 .sync_mode = WB_SYNC_ALL, 87 .nr_to_write = 0, /* sys_fsync did this */ 88 }; 89 ret = sync_inode(inode, &wbc); 90 if (journal && (journal->j_flags & JBD2_BARRIER)) 91 blkdev_issue_flush(inode->i_sb->s_bdev, NULL); 92 } 93 out: 94 return ret; 95 } 96