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 */
ext4_sync_parent(struct inode * inode)45 static int ext4_sync_parent(struct inode *inode)
46 {
47 struct dentry *dentry, *next;
48 int ret = 0;
49
50 if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
51 return 0;
52 dentry = d_find_any_alias(inode);
53 if (!dentry)
54 return 0;
55 while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
56 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
57
58 next = dget_parent(dentry);
59 dput(dentry);
60 dentry = next;
61 inode = dentry->d_inode;
62
63 /*
64 * The directory inode may have gone through rmdir by now. But
65 * the inode itself and its blocks are still allocated (we hold
66 * a reference to the inode via its dentry), so it didn't go
67 * through ext4_evict_inode()) and so we are safe to flush
68 * metadata blocks and the inode.
69 */
70 ret = sync_mapping_buffers(inode->i_mapping);
71 if (ret)
72 break;
73 ret = sync_inode_metadata(inode, 1);
74 if (ret)
75 break;
76 }
77 dput(dentry);
78 return ret;
79 }
80
ext4_fsync_nojournal(struct inode * inode,bool datasync,bool * needs_barrier)81 static int ext4_fsync_nojournal(struct inode *inode, bool datasync,
82 bool *needs_barrier)
83 {
84 int ret, err;
85
86 ret = sync_mapping_buffers(inode->i_mapping);
87 if (!(inode->i_state & I_DIRTY_ALL))
88 return ret;
89 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
90 return ret;
91
92 err = sync_inode_metadata(inode, 1);
93 if (!ret)
94 ret = err;
95
96 if (!ret)
97 ret = ext4_sync_parent(inode);
98 if (test_opt(inode->i_sb, BARRIER))
99 *needs_barrier = true;
100
101 return ret;
102 }
103
ext4_fsync_journal(struct inode * inode,bool datasync,bool * needs_barrier)104 static int ext4_fsync_journal(struct inode *inode, bool datasync,
105 bool *needs_barrier)
106 {
107 struct ext4_inode_info *ei = EXT4_I(inode);
108 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
109 tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
110
111 if (journal->j_flags & JBD2_BARRIER &&
112 !jbd2_trans_will_send_data_barrier(journal, commit_tid))
113 *needs_barrier = true;
114
115 return ext4_fc_commit(journal, commit_tid);
116 }
117
118 /*
119 * akpm: A new design for ext4_sync_file().
120 *
121 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
122 * There cannot be a transaction open by this task.
123 * Another task could have dirtied this inode. Its data can be in any
124 * state in the journalling system.
125 *
126 * What we do is just kick off a commit and wait on it. This will snapshot the
127 * inode to disk.
128 */
ext4_sync_file(struct file * file,loff_t start,loff_t end,int datasync)129 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
130 {
131 int ret = 0, err;
132 bool needs_barrier = false;
133 struct inode *inode = file->f_mapping->host;
134 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
135
136 if (unlikely(ext4_forced_shutdown(sbi)))
137 return -EIO;
138
139 ASSERT(ext4_journal_current_handle() == NULL);
140
141 trace_ext4_sync_file_enter(file, datasync);
142
143 if (sb_rdonly(inode->i_sb)) {
144 /* Make sure that we read updated s_mount_flags value */
145 smp_rmb();
146 if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FS_ABORTED))
147 ret = -EROFS;
148 goto out;
149 }
150
151 ret = file_write_and_wait_range(file, start, end);
152 if (ret)
153 goto out;
154
155 /*
156 * data=writeback,ordered:
157 * The caller's filemap_fdatawrite()/wait will sync the data.
158 * Metadata is in the journal, we wait for proper transaction to
159 * commit here.
160 *
161 * data=journal:
162 * filemap_fdatawrite won't do anything (the buffers are clean).
163 * ext4_force_commit will write the file data into the journal and
164 * will wait on that.
165 * filemap_fdatawait() will encounter a ton of newly-dirtied pages
166 * (they were dirtied by commit). But that's OK - the blocks are
167 * safe in-journal, which is all fsync() needs to ensure.
168 */
169 if (!sbi->s_journal)
170 ret = ext4_fsync_nojournal(inode, datasync, &needs_barrier);
171 else if (ext4_should_journal_data(inode))
172 ret = ext4_force_commit(inode->i_sb);
173 else
174 ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
175
176 if (needs_barrier) {
177 err = blkdev_issue_flush(inode->i_sb->s_bdev);
178 if (!ret)
179 ret = err;
180 }
181 out:
182 err = file_check_and_advance_wb_err(file);
183 if (ret == 0)
184 ret = err;
185 trace_ext4_sync_file_exit(inode, ret);
186 return ret;
187 }
188