Line data Source code
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 : */
46 21 : static int ext4_sync_parent(struct inode *inode)
47 : {
48 21 : struct dentry *dentry, *next;
49 21 : int ret = 0;
50 :
51 21 : if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
52 : return 0;
53 1 : dentry = d_find_any_alias(inode);
54 1 : if (!dentry)
55 : return 0;
56 2 : while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
57 1 : ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
58 :
59 1 : next = dget_parent(dentry);
60 1 : dput(dentry);
61 1 : dentry = next;
62 1 : 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 1 : ret = sync_mapping_buffers(inode->i_mapping);
72 1 : if (ret)
73 : break;
74 1 : ret = sync_inode_metadata(inode, 1);
75 1 : if (ret)
76 : break;
77 : }
78 1 : dput(dentry);
79 1 : return ret;
80 : }
81 :
82 21 : static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
83 : int datasync, bool *needs_barrier)
84 : {
85 21 : struct inode *inode = file->f_inode;
86 21 : int ret;
87 :
88 21 : ret = generic_buffers_fsync_noflush(file, start, end, datasync);
89 21 : if (!ret)
90 21 : ret = ext4_sync_parent(inode);
91 21 : if (test_opt(inode->i_sb, BARRIER))
92 21 : *needs_barrier = true;
93 :
94 21 : return ret;
95 : }
96 :
97 239240 : static int ext4_fsync_journal(struct inode *inode, bool datasync,
98 : bool *needs_barrier)
99 : {
100 239240 : struct ext4_inode_info *ei = EXT4_I(inode);
101 239240 : journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
102 239240 : tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
103 :
104 : /*
105 : * Fastcommit does not really support fsync on directories or other
106 : * special files. Force a full commit.
107 : */
108 239240 : if (!S_ISREG(inode->i_mode))
109 3331 : return ext4_force_commit(inode->i_sb);
110 :
111 471802 : if (journal->j_flags & JBD2_BARRIER &&
112 235905 : !jbd2_trans_will_send_data_barrier(journal, commit_tid))
113 47863 : *needs_barrier = true;
114 :
115 235897 : 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 : */
129 239376 : int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
130 : {
131 239376 : int ret = 0, err;
132 239376 : bool needs_barrier = false;
133 239376 : struct inode *inode = file->f_mapping->host;
134 239376 : struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
135 :
136 478752 : if (unlikely(ext4_forced_shutdown(sbi)))
137 : return -EIO;
138 :
139 239368 : ASSERT(ext4_journal_current_handle() == NULL);
140 :
141 239368 : trace_ext4_sync_file_enter(file, datasync);
142 :
143 239366 : if (sb_rdonly(inode->i_sb)) {
144 : /* Make sure that we read updated s_mount_flags value */
145 0 : smp_rmb();
146 0 : if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FS_ABORTED))
147 0 : ret = -EROFS;
148 0 : goto out;
149 : }
150 :
151 239366 : if (!sbi->s_journal) {
152 21 : ret = ext4_fsync_nojournal(file, start, end, datasync,
153 : &needs_barrier);
154 21 : if (needs_barrier)
155 21 : goto issue_flush;
156 0 : goto out;
157 : }
158 :
159 239345 : ret = file_write_and_wait_range(file, start, end);
160 239355 : if (ret)
161 108 : goto out;
162 :
163 : /*
164 : * The caller's filemap_fdatawrite()/wait will sync the data.
165 : * Metadata is in the journal, we wait for proper transaction to
166 : * commit here.
167 : */
168 239247 : ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
169 :
170 239247 : issue_flush:
171 239247 : if (needs_barrier) {
172 47887 : err = blkdev_issue_flush(inode->i_sb->s_bdev);
173 47875 : if (!ret)
174 47875 : ret = err;
175 : }
176 191360 : out:
177 239343 : err = file_check_and_advance_wb_err(file);
178 239372 : if (ret == 0)
179 239264 : ret = err;
180 239372 : trace_ext4_sync_file_exit(inode, ret);
181 239372 : return ret;
182 : }
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