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 */
ext4_sync_parent(struct inode * inode)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
ext4_fsync_nojournal(struct file * file,loff_t start,loff_t end,int datasync,bool * needs_barrier)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
ext4_fsync_journal(struct inode * inode,bool datasync,bool * needs_barrier)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 */
ext4_sync_file(struct file * file,loff_t start,loff_t end,int datasync)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