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 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(d_inode(dentry->d_parent)); 60 dput(dentry); 61 if (!next) 62 break; 63 iput(inode); 64 inode = next; 65 /* 66 * The directory inode may have gone through rmdir by now. But 67 * the inode itself and its blocks are still allocated (we hold 68 * a reference to the inode so it didn't go through 69 * ext4_evict_inode()) and so we are safe to flush metadata 70 * blocks and the inode. 71 */ 72 ret = sync_mapping_buffers(inode->i_mapping); 73 if (ret) 74 break; 75 ret = sync_inode_metadata(inode, 1); 76 if (ret) 77 break; 78 } 79 iput(inode); 80 return ret; 81 } 82 83 static int ext4_fsync_nojournal(struct inode *inode, bool datasync, 84 bool *needs_barrier) 85 { 86 int ret, err; 87 88 ret = sync_mapping_buffers(inode->i_mapping); 89 if (!(inode->i_state & I_DIRTY_ALL)) 90 return ret; 91 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 92 return ret; 93 94 err = sync_inode_metadata(inode, 1); 95 if (!ret) 96 ret = err; 97 98 if (!ret) 99 ret = ext4_sync_parent(inode); 100 if (test_opt(inode->i_sb, BARRIER)) 101 *needs_barrier = true; 102 103 return ret; 104 } 105 106 static int ext4_fsync_journal(struct inode *inode, bool datasync, 107 bool *needs_barrier) 108 { 109 struct ext4_inode_info *ei = EXT4_I(inode); 110 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 111 tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 112 113 if (journal->j_flags & JBD2_BARRIER && 114 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 115 *needs_barrier = true; 116 117 return jbd2_complete_transaction(journal, commit_tid); 118 } 119 120 /* 121 * akpm: A new design for ext4_sync_file(). 122 * 123 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 124 * There cannot be a transaction open by this task. 125 * Another task could have dirtied this inode. Its data can be in any 126 * state in the journalling system. 127 * 128 * What we do is just kick off a commit and wait on it. This will snapshot the 129 * inode to disk. 130 */ 131 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 132 { 133 int ret = 0, err; 134 bool needs_barrier = false; 135 struct inode *inode = file->f_mapping->host; 136 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 137 138 if (unlikely(ext4_forced_shutdown(sbi))) 139 return -EIO; 140 141 J_ASSERT(ext4_journal_current_handle() == NULL); 142 143 trace_ext4_sync_file_enter(file, datasync); 144 145 if (sb_rdonly(inode->i_sb)) { 146 /* Make sure that we read updated s_mount_flags value */ 147 smp_rmb(); 148 if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED) 149 ret = -EROFS; 150 goto out; 151 } 152 153 ret = file_write_and_wait_range(file, start, end); 154 if (ret) 155 return ret; 156 157 /* 158 * data=writeback,ordered: 159 * The caller's filemap_fdatawrite()/wait will sync the data. 160 * Metadata is in the journal, we wait for proper transaction to 161 * commit here. 162 * 163 * data=journal: 164 * filemap_fdatawrite won't do anything (the buffers are clean). 165 * ext4_force_commit will write the file data into the journal and 166 * will wait on that. 167 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 168 * (they were dirtied by commit). But that's OK - the blocks are 169 * safe in-journal, which is all fsync() needs to ensure. 170 */ 171 if (!sbi->s_journal) 172 ret = ext4_fsync_nojournal(inode, datasync, &needs_barrier); 173 else if (ext4_should_journal_data(inode)) 174 ret = ext4_force_commit(inode->i_sb); 175 else 176 ret = ext4_fsync_journal(inode, datasync, &needs_barrier); 177 178 if (needs_barrier) { 179 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 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