1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext4/fsync.c 4 * 5 * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com) 6 * from 7 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr) 8 * Laboratoire MASI - Institut Blaise Pascal 9 * Universite Pierre et Marie Curie (Paris VI) 10 * from 11 * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds 12 * 13 * ext4fs fsync primitive 14 * 15 * Big-endian to little-endian byte-swapping/bitmaps by 16 * David S. Miller (davem@caip.rutgers.edu), 1995 17 * 18 * Removed unnecessary code duplication for little endian machines 19 * and excessive __inline__s. 20 * Andi Kleen, 1997 21 * 22 * Major simplications and cleanup - we only need to do the metadata, because 23 * we can depend on generic_block_fdatasync() to sync the data blocks. 24 */ 25 26 #include <linux/time.h> 27 #include <linux/fs.h> 28 #include <linux/sched.h> 29 #include <linux/writeback.h> 30 #include <linux/blkdev.h> 31 #include <linux/buffer_head.h> 32 33 #include "ext4.h" 34 #include "ext4_jbd2.h" 35 36 #include <trace/events/ext4.h> 37 38 /* 39 * If we're not journaling and this is a just-created file, we have to 40 * sync our parent directory (if it was freshly created) since 41 * otherwise it will only be written by writeback, leaving a huge 42 * window during which a crash may lose the file. This may apply for 43 * the parent directory's parent as well, and so on recursively, if 44 * they are also freshly created. 45 */ 46 static int ext4_sync_parent(struct inode *inode) 47 { 48 struct dentry *dentry, *next; 49 int ret = 0; 50 51 if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) 52 return 0; 53 dentry = d_find_any_alias(inode); 54 if (!dentry) 55 return 0; 56 while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 57 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 58 59 next = dget_parent(dentry); 60 dput(dentry); 61 dentry = next; 62 inode = dentry->d_inode; 63 64 /* 65 * The directory inode may have gone through rmdir by now. But 66 * the inode itself and its blocks are still allocated (we hold 67 * a reference to the inode via its dentry), so it didn't go 68 * through ext4_evict_inode()) and so we are safe to flush 69 * metadata blocks and the inode. 70 */ 71 ret = sync_mapping_buffers(inode->i_mapping); 72 if (ret) 73 break; 74 ret = sync_inode_metadata(inode, 1); 75 if (ret) 76 break; 77 } 78 dput(dentry); 79 return ret; 80 } 81 82 static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end, 83 int datasync, bool *needs_barrier) 84 { 85 struct inode *inode = file->f_inode; 86 struct writeback_control wbc = { 87 .sync_mode = WB_SYNC_ALL, 88 .nr_to_write = 0, 89 }; 90 int ret; 91 92 ret = generic_buffers_fsync_noflush(file, start, end, datasync); 93 if (ret) 94 return ret; 95 96 /* Force writeout of inode table buffer to disk */ 97 ret = ext4_write_inode(inode, &wbc); 98 if (ret) 99 return ret; 100 101 ret = ext4_sync_parent(inode); 102 103 if (test_opt(inode->i_sb, BARRIER)) 104 *needs_barrier = true; 105 106 return ret; 107 } 108 109 static int ext4_fsync_journal(struct inode *inode, bool datasync, 110 bool *needs_barrier) 111 { 112 struct ext4_inode_info *ei = EXT4_I(inode); 113 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 114 tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 115 116 /* 117 * Fastcommit does not really support fsync on directories or other 118 * special files. Force a full commit. 119 */ 120 if (!S_ISREG(inode->i_mode)) 121 return ext4_force_commit(inode->i_sb); 122 123 if (journal->j_flags & JBD2_BARRIER && 124 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 125 *needs_barrier = true; 126 127 return ext4_fc_commit(journal, commit_tid); 128 } 129 130 /* 131 * akpm: A new design for ext4_sync_file(). 132 * 133 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 134 * There cannot be a transaction open by this task. 135 * Another task could have dirtied this inode. Its data can be in any 136 * state in the journalling system. 137 * 138 * What we do is just kick off a commit and wait on it. This will snapshot the 139 * inode to disk. 140 */ 141 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 142 { 143 int ret = 0, err; 144 bool needs_barrier = false; 145 struct inode *inode = file->f_mapping->host; 146 147 ret = ext4_emergency_state(inode->i_sb); 148 if (unlikely(ret)) 149 return ret; 150 151 ASSERT(ext4_journal_current_handle() == NULL); 152 153 trace_ext4_sync_file_enter(file, datasync); 154 155 if (sb_rdonly(inode->i_sb)) 156 goto out; 157 158 if (!EXT4_SB(inode->i_sb)->s_journal) { 159 ret = ext4_fsync_nojournal(file, start, end, datasync, 160 &needs_barrier); 161 if (needs_barrier) 162 goto issue_flush; 163 goto out; 164 } 165 166 ret = file_write_and_wait_range(file, start, end); 167 if (ret) 168 goto out; 169 170 /* 171 * The caller's filemap_fdatawrite()/wait will sync the data. 172 * Metadata is in the journal, we wait for proper transaction to 173 * commit here. 174 */ 175 ret = ext4_fsync_journal(inode, datasync, &needs_barrier); 176 177 issue_flush: 178 if (needs_barrier) { 179 err = blkdev_issue_flush(inode->i_sb->s_bdev); 180 if (!ret) 181 ret = err; 182 } 183 out: 184 err = file_check_and_advance_wb_err(file); 185 if (ret == 0) 186 ret = err; 187 trace_ext4_sync_file_exit(inode, ret); 188 return ret; 189 } 190