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 writeback_control wbc; 48 struct dentry *dentry = NULL; 49 struct inode *next; 50 int ret = 0; 51 52 if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) 53 return 0; 54 inode = igrab(inode); 55 while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 56 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 57 dentry = d_find_any_alias(inode); 58 if (!dentry) 59 break; 60 next = igrab(dentry->d_parent->d_inode); 61 dput(dentry); 62 if (!next) 63 break; 64 iput(inode); 65 inode = next; 66 ret = sync_mapping_buffers(inode->i_mapping); 67 if (ret) 68 break; 69 memset(&wbc, 0, sizeof(wbc)); 70 wbc.sync_mode = WB_SYNC_ALL; 71 wbc.nr_to_write = 0; /* only write out the inode */ 72 ret = sync_inode(inode, &wbc); 73 if (ret) 74 break; 75 } 76 iput(inode); 77 return ret; 78 } 79 80 /** 81 * __sync_file - generic_file_fsync without the locking and filemap_write 82 * @inode: inode to sync 83 * @datasync: only sync essential metadata if true 84 * 85 * This is just generic_file_fsync without the locking. This is needed for 86 * nojournal mode to make sure this inodes data/metadata makes it to disk 87 * properly. The i_mutex should be held already. 88 */ 89 static int __sync_inode(struct inode *inode, int datasync) 90 { 91 int err; 92 int ret; 93 94 ret = sync_mapping_buffers(inode->i_mapping); 95 if (!(inode->i_state & I_DIRTY)) 96 return ret; 97 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 98 return ret; 99 100 err = sync_inode_metadata(inode, 1); 101 if (ret == 0) 102 ret = err; 103 return ret; 104 } 105 106 /* 107 * akpm: A new design for ext4_sync_file(). 108 * 109 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 110 * There cannot be a transaction open by this task. 111 * Another task could have dirtied this inode. Its data can be in any 112 * state in the journalling system. 113 * 114 * What we do is just kick off a commit and wait on it. This will snapshot the 115 * inode to disk. 116 * 117 * i_mutex lock is held when entering and exiting this function 118 */ 119 120 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 121 { 122 struct inode *inode = file->f_mapping->host; 123 struct ext4_inode_info *ei = EXT4_I(inode); 124 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 125 int ret, err; 126 tid_t commit_tid; 127 bool needs_barrier = false; 128 129 J_ASSERT(ext4_journal_current_handle() == NULL); 130 131 trace_ext4_sync_file_enter(file, datasync); 132 133 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 134 if (ret) 135 return ret; 136 mutex_lock(&inode->i_mutex); 137 138 if (inode->i_sb->s_flags & MS_RDONLY) 139 goto out; 140 141 ret = ext4_flush_unwritten_io(inode); 142 if (ret < 0) 143 goto out; 144 145 if (!journal) { 146 ret = __sync_inode(inode, datasync); 147 if (!ret && !hlist_empty(&inode->i_dentry)) 148 ret = ext4_sync_parent(inode); 149 goto out; 150 } 151 152 /* 153 * data=writeback,ordered: 154 * The caller's filemap_fdatawrite()/wait will sync the data. 155 * Metadata is in the journal, we wait for proper transaction to 156 * commit here. 157 * 158 * data=journal: 159 * filemap_fdatawrite won't do anything (the buffers are clean). 160 * ext4_force_commit will write the file data into the journal and 161 * will wait on that. 162 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 163 * (they were dirtied by commit). But that's OK - the blocks are 164 * safe in-journal, which is all fsync() needs to ensure. 165 */ 166 if (ext4_should_journal_data(inode)) { 167 ret = ext4_force_commit(inode->i_sb); 168 goto out; 169 } 170 171 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 172 if (journal->j_flags & JBD2_BARRIER && 173 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 174 needs_barrier = true; 175 jbd2_log_start_commit(journal, commit_tid); 176 ret = jbd2_log_wait_commit(journal, commit_tid); 177 if (needs_barrier) { 178 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 179 if (!ret) 180 ret = err; 181 } 182 out: 183 mutex_unlock(&inode->i_mutex); 184 trace_ext4_sync_file_exit(inode, ret); 185 return ret; 186 } 187