Linux kernel mirror (for testing)
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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 */
46static 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 = mmb_sync(&EXT4_I(inode)->i_metadata_bhs);
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
82static 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 = mmb_fsync_noflush(file, &EXT4_I(inode)->i_metadata_bhs,
93 start, end, datasync);
94 if (ret)
95 return ret;
96
97 /* Force writeout of inode table buffer to disk */
98 ret = ext4_write_inode(inode, &wbc);
99 if (ret)
100 return ret;
101
102 ret = ext4_sync_parent(inode);
103
104 if (test_opt(inode->i_sb, BARRIER))
105 *needs_barrier = true;
106
107 return ret;
108}
109
110static int ext4_fsync_journal(struct inode *inode, bool datasync,
111 bool *needs_barrier)
112{
113 struct ext4_inode_info *ei = EXT4_I(inode);
114 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
115 tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
116
117 /*
118 * Fastcommit does not really support fsync on directories or other
119 * special files. Force a full commit.
120 */
121 if (!S_ISREG(inode->i_mode))
122 return ext4_force_commit(inode->i_sb);
123
124 if (journal->j_flags & JBD2_BARRIER &&
125 !jbd2_trans_will_send_data_barrier(journal, commit_tid))
126 *needs_barrier = true;
127
128 return ext4_fc_commit(journal, commit_tid);
129}
130
131/*
132 * akpm: A new design for ext4_sync_file().
133 *
134 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
135 * There cannot be a transaction open by this task.
136 * Another task could have dirtied this inode. Its data can be in any
137 * state in the journalling system.
138 *
139 * What we do is just kick off a commit and wait on it. This will snapshot the
140 * inode to disk.
141 */
142int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
143{
144 int ret = 0, err;
145 bool needs_barrier = false;
146 struct inode *inode = file->f_mapping->host;
147
148 ret = ext4_emergency_state(inode->i_sb);
149 if (unlikely(ret))
150 return ret;
151
152 ASSERT(ext4_journal_current_handle() == NULL);
153
154 trace_ext4_sync_file_enter(file, datasync);
155
156 if (sb_rdonly(inode->i_sb))
157 goto out;
158
159 if (!EXT4_SB(inode->i_sb)->s_journal) {
160 ret = ext4_fsync_nojournal(file, start, end, datasync,
161 &needs_barrier);
162 if (needs_barrier)
163 goto issue_flush;
164 goto out;
165 }
166
167 ret = file_write_and_wait_range(file, start, end);
168 if (ret)
169 goto out;
170
171 /*
172 * The caller's filemap_fdatawrite()/wait will sync the data.
173 * Metadata is in the journal, we wait for proper transaction to
174 * commit here.
175 */
176 ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
177
178issue_flush:
179 if (needs_barrier) {
180 err = blkdev_issue_flush(inode->i_sb->s_bdev);
181 if (!ret)
182 ret = err;
183 }
184out:
185 err = file_check_and_advance_wb_err(file);
186 if (ret == 0)
187 ret = err;
188 trace_ext4_sync_file_exit(inode, ret);
189 return ret;
190}