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 /*
84 * akpm: A new design for ext4_sync_file().
85 *
86 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
87 * There cannot be a transaction open by this task.
88 * Another task could have dirtied this inode. Its data can be in any
89 * state in the journalling system.
90 *
91 * What we do is just kick off a commit and wait on it. This will snapshot the
92 * inode to disk.
93 */
94
95 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
96 {
97 struct inode *inode = file->f_mapping->host;
98 struct ext4_inode_info *ei = EXT4_I(inode);
99 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
100 int ret = 0, err;
101 tid_t commit_tid;
102 bool needs_barrier = false;
103
104 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
105 return -EIO;
106
107 J_ASSERT(ext4_journal_current_handle() == NULL);
108
109 trace_ext4_sync_file_enter(file, datasync);
110
111 if (sb_rdonly(inode->i_sb)) {
112 /* Make sure that we read updated s_mount_flags value */
113 smp_rmb();
114 if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
115 ret = -EROFS;
116 goto out;
117 }
118
119 if (!journal) {
120 ret = __generic_file_fsync(file, start, end, datasync);
121 if (!ret)
122 ret = ext4_sync_parent(inode);
123 if (test_opt(inode->i_sb, BARRIER))
124 goto issue_flush;
125 goto out;
126 }
127
128 ret = file_write_and_wait_range(file, start, end);
129 if (ret)
130 return ret;
131 /*
132 * data=writeback,ordered:
133 * The caller's filemap_fdatawrite()/wait will sync the data.
134 * Metadata is in the journal, we wait for proper transaction to
135 * commit here.
136 *
137 * data=journal:
138 * filemap_fdatawrite won't do anything (the buffers are clean).
139 * ext4_force_commit will write the file data into the journal and
140 * will wait on that.
141 * filemap_fdatawait() will encounter a ton of newly-dirtied pages
142 * (they were dirtied by commit). But that's OK - the blocks are
143 * safe in-journal, which is all fsync() needs to ensure.
144 */
145 if (ext4_should_journal_data(inode)) {
146 ret = ext4_force_commit(inode->i_sb);
147 goto out;
148 }
149
150 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
151 if (journal->j_flags & JBD2_BARRIER &&
152 !jbd2_trans_will_send_data_barrier(journal, commit_tid))
153 needs_barrier = true;
154 ret = jbd2_complete_transaction(journal, commit_tid);
155 if (needs_barrier) {
156 issue_flush:
157 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
158 if (!ret)
159 ret = err;
160 }
161 out:
162 err = file_check_and_advance_wb_err(file);
163 if (ret == 0)
164 ret = err;
165 trace_ext4_sync_file_exit(inode, ret);
166 return ret;
167 }