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 * i_mutex lock is held when entering and exiting this function 49 */ 50 51 int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync) 52 { 53 struct inode *inode = dentry->d_inode; 54 struct ext4_inode_info *ei = EXT4_I(inode); 55 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 56 int ret; 57 tid_t commit_tid; 58 59 J_ASSERT(ext4_journal_current_handle() == NULL); 60 61 trace_ext4_sync_file(file, dentry, datasync); 62 63 if (inode->i_sb->s_flags & MS_RDONLY) 64 return 0; 65 66 ret = flush_completed_IO(inode); 67 if (ret < 0) 68 return ret; 69 70 if (!journal) 71 return simple_fsync(file, dentry, datasync); 72 73 /* 74 * data=writeback,ordered: 75 * The caller's filemap_fdatawrite()/wait will sync the data. 76 * Metadata is in the journal, we wait for proper transaction to 77 * commit here. 78 * 79 * data=journal: 80 * filemap_fdatawrite won't do anything (the buffers are clean). 81 * ext4_force_commit will write the file data into the journal and 82 * will wait on that. 83 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 84 * (they were dirtied by commit). But that's OK - the blocks are 85 * safe in-journal, which is all fsync() needs to ensure. 86 */ 87 if (ext4_should_journal_data(inode)) 88 return ext4_force_commit(inode->i_sb); 89 90 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 91 if (jbd2_log_start_commit(journal, commit_tid)) { 92 /* 93 * When the journal is on a different device than the 94 * fs data disk, we need to issue the barrier in 95 * writeback mode. (In ordered mode, the jbd2 layer 96 * will take care of issuing the barrier. In 97 * data=journal, all of the data blocks are written to 98 * the journal device.) 99 */ 100 if (ext4_should_writeback_data(inode) && 101 (journal->j_fs_dev != journal->j_dev) && 102 (journal->j_flags & JBD2_BARRIER)) 103 blkdev_issue_flush(inode->i_sb->s_bdev, NULL); 104 jbd2_log_wait_commit(journal, commit_tid); 105 } else if (journal->j_flags & JBD2_BARRIER) 106 blkdev_issue_flush(inode->i_sb->s_bdev, NULL); 107 return ret; 108 } 109