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 * If we're not journaling and this is a just-created file, we have to 39 * sync our parent directory (if it was freshly created) since 40 * otherwise it will only be written by writeback, leaving a huge 41 * window during which a crash may lose the file. This may apply for 42 * the parent directory's parent as well, and so on recursively, if 43 * they are also freshly created. 44 */ 45 static int ext4_sync_parent(struct inode *inode) 46 { 47 struct dentry *dentry = NULL; 48 struct inode *next; 49 int ret = 0; 50 51 if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) 52 return 0; 53 inode = igrab(inode); 54 while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 55 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 56 dentry = d_find_any_alias(inode); 57 if (!dentry) 58 break; 59 next = igrab(dentry->d_parent->d_inode); 60 dput(dentry); 61 if (!next) 62 break; 63 iput(inode); 64 inode = next; 65 ret = sync_mapping_buffers(inode->i_mapping); 66 if (ret) 67 break; 68 ret = sync_inode_metadata(inode, 1); 69 if (ret) 70 break; 71 } 72 iput(inode); 73 return ret; 74 } 75 76 /* 77 * akpm: A new design for ext4_sync_file(). 78 * 79 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 80 * There cannot be a transaction open by this task. 81 * Another task could have dirtied this inode. Its data can be in any 82 * state in the journalling system. 83 * 84 * What we do is just kick off a commit and wait on it. This will snapshot the 85 * inode to disk. 86 */ 87 88 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 89 { 90 struct inode *inode = file->f_mapping->host; 91 struct ext4_inode_info *ei = EXT4_I(inode); 92 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 93 int ret = 0, err; 94 tid_t commit_tid; 95 bool needs_barrier = false; 96 97 J_ASSERT(ext4_journal_current_handle() == NULL); 98 99 trace_ext4_sync_file_enter(file, datasync); 100 101 if (inode->i_sb->s_flags & MS_RDONLY) { 102 /* Make sure that we read updated s_mount_flags value */ 103 smp_rmb(); 104 if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED) 105 ret = -EROFS; 106 goto out; 107 } 108 109 if (!journal) { 110 ret = generic_file_fsync(file, start, end, datasync); 111 if (!ret && !hlist_empty(&inode->i_dentry)) 112 ret = ext4_sync_parent(inode); 113 goto out; 114 } 115 116 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 117 if (ret) 118 return ret; 119 /* 120 * data=writeback,ordered: 121 * The caller's filemap_fdatawrite()/wait will sync the data. 122 * Metadata is in the journal, we wait for proper transaction to 123 * commit here. 124 * 125 * data=journal: 126 * filemap_fdatawrite won't do anything (the buffers are clean). 127 * ext4_force_commit will write the file data into the journal and 128 * will wait on that. 129 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 130 * (they were dirtied by commit). But that's OK - the blocks are 131 * safe in-journal, which is all fsync() needs to ensure. 132 */ 133 if (ext4_should_journal_data(inode)) { 134 ret = ext4_force_commit(inode->i_sb); 135 goto out; 136 } 137 138 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 139 if (journal->j_flags & JBD2_BARRIER && 140 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 141 needs_barrier = true; 142 ret = jbd2_complete_transaction(journal, commit_tid); 143 if (needs_barrier) { 144 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 145 if (!ret) 146 ret = err; 147 } 148 out: 149 trace_ext4_sync_file_exit(inode, ret); 150 return ret; 151 } 152