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 * __sync_file - generic_file_fsync without the locking and filemap_write 78 * @inode: inode to sync 79 * @datasync: only sync essential metadata if true 80 * 81 * This is just generic_file_fsync without the locking. This is needed for 82 * nojournal mode to make sure this inodes data/metadata makes it to disk 83 * properly. The i_mutex should be held already. 84 */ 85 static int __sync_inode(struct inode *inode, int datasync) 86 { 87 int err; 88 int ret; 89 90 ret = sync_mapping_buffers(inode->i_mapping); 91 if (!(inode->i_state & I_DIRTY)) 92 return ret; 93 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 94 return ret; 95 96 err = sync_inode_metadata(inode, 1); 97 if (ret == 0) 98 ret = err; 99 return ret; 100 } 101 102 /* 103 * akpm: A new design for ext4_sync_file(). 104 * 105 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 106 * There cannot be a transaction open by this task. 107 * Another task could have dirtied this inode. Its data can be in any 108 * state in the journalling system. 109 * 110 * What we do is just kick off a commit and wait on it. This will snapshot the 111 * inode to disk. 112 */ 113 114 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 115 { 116 struct inode *inode = file->f_mapping->host; 117 struct ext4_inode_info *ei = EXT4_I(inode); 118 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 119 int ret, err; 120 tid_t commit_tid; 121 bool needs_barrier = false; 122 123 J_ASSERT(ext4_journal_current_handle() == NULL); 124 125 trace_ext4_sync_file_enter(file, datasync); 126 127 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 128 if (ret) 129 return ret; 130 mutex_lock(&inode->i_mutex); 131 132 if (inode->i_sb->s_flags & MS_RDONLY) 133 goto out; 134 135 ret = ext4_flush_unwritten_io(inode); 136 if (ret < 0) 137 goto out; 138 139 if (!journal) { 140 ret = __sync_inode(inode, datasync); 141 if (!ret && !hlist_empty(&inode->i_dentry)) 142 ret = ext4_sync_parent(inode); 143 goto out; 144 } 145 146 /* 147 * data=writeback,ordered: 148 * The caller's filemap_fdatawrite()/wait will sync the data. 149 * Metadata is in the journal, we wait for proper transaction to 150 * commit here. 151 * 152 * data=journal: 153 * filemap_fdatawrite won't do anything (the buffers are clean). 154 * ext4_force_commit will write the file data into the journal and 155 * will wait on that. 156 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 157 * (they were dirtied by commit). But that's OK - the blocks are 158 * safe in-journal, which is all fsync() needs to ensure. 159 */ 160 if (ext4_should_journal_data(inode)) { 161 ret = ext4_force_commit(inode->i_sb); 162 goto out; 163 } 164 165 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 166 if (journal->j_flags & JBD2_BARRIER && 167 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 168 needs_barrier = true; 169 ret = jbd2_complete_transaction(journal, commit_tid); 170 if (needs_barrier) { 171 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 172 if (!ret) 173 ret = err; 174 } 175 out: 176 mutex_unlock(&inode->i_mutex); 177 trace_ext4_sync_file_exit(inode, ret); 178 return ret; 179 } 180