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 32 #include "ext4.h" 33 #include "ext4_jbd2.h" 34 35 #include <trace/events/ext4.h> 36 37 /* 38 * akpm: A new design for ext4_sync_file(). 39 * 40 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 41 * There cannot be a transaction open by this task. 42 * Another task could have dirtied this inode. Its data can be in any 43 * state in the journalling system. 44 * 45 * What we do is just kick off a commit and wait on it. This will snapshot the 46 * inode to disk. 47 */ 48 49 int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync) 50 { 51 struct inode *inode = dentry->d_inode; 52 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 53 int ret = 0; 54 55 J_ASSERT(ext4_journal_current_handle() == NULL); 56 57 trace_ext4_sync_file(file, dentry, datasync); 58 59 /* 60 * data=writeback: 61 * The caller's filemap_fdatawrite()/wait will sync the data. 62 * sync_inode() will sync the metadata 63 * 64 * data=ordered: 65 * The caller's filemap_fdatawrite() will write the data and 66 * sync_inode() will write the inode if it is dirty. Then the caller's 67 * filemap_fdatawait() will wait on the pages. 68 * 69 * data=journal: 70 * filemap_fdatawrite won't do anything (the buffers are clean). 71 * ext4_force_commit will write the file data into the journal and 72 * will wait on that. 73 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 74 * (they were dirtied by commit). But that's OK - the blocks are 75 * safe in-journal, which is all fsync() needs to ensure. 76 */ 77 if (ext4_should_journal_data(inode)) { 78 ret = ext4_force_commit(inode->i_sb); 79 goto out; 80 } 81 82 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 83 goto out; 84 85 /* 86 * The VFS has written the file data. If the inode is unaltered 87 * then we need not start a commit. 88 */ 89 if (inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) { 90 struct writeback_control wbc = { 91 .sync_mode = WB_SYNC_ALL, 92 .nr_to_write = 0, /* sys_fsync did this */ 93 }; 94 ret = sync_inode(inode, &wbc); 95 if (journal && (journal->j_flags & JBD2_BARRIER)) 96 blkdev_issue_flush(inode->i_sb->s_bdev, NULL); 97 } 98 out: 99 return ret; 100 } 101