xref: /openbmc/linux/fs/ext4/fsync.c (revision 565d76cb)
1 /*
2  *  linux/fs/ext4/fsync.c
3  *
4  *  Copyright (C) 1993  Stephen Tweedie (sct@redhat.com)
5  *  from
6  *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
7  *                      Laboratoire MASI - Institut Blaise Pascal
8  *                      Universite Pierre et Marie Curie (Paris VI)
9  *  from
10  *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds
11  *
12  *  ext4fs fsync primitive
13  *
14  *  Big-endian to little-endian byte-swapping/bitmaps by
15  *        David S. Miller (davem@caip.rutgers.edu), 1995
16  *
17  *  Removed unnecessary code duplication for little endian machines
18  *  and excessive __inline__s.
19  *        Andi Kleen, 1997
20  *
21  * Major simplications and cleanup - we only need to do the metadata, because
22  * we can depend on generic_block_fdatasync() to sync the data blocks.
23  */
24 
25 #include <linux/time.h>
26 #include <linux/fs.h>
27 #include <linux/sched.h>
28 #include <linux/writeback.h>
29 #include <linux/jbd2.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 static void dump_completed_IO(struct inode * inode)
38 {
39 #ifdef	EXT4_DEBUG
40 	struct list_head *cur, *before, *after;
41 	ext4_io_end_t *io, *io0, *io1;
42 	unsigned long flags;
43 
44 	if (list_empty(&EXT4_I(inode)->i_completed_io_list)){
45 		ext4_debug("inode %lu completed_io list is empty\n", inode->i_ino);
46 		return;
47 	}
48 
49 	ext4_debug("Dump inode %lu completed_io list \n", inode->i_ino);
50 	spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
51 	list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list){
52 		cur = &io->list;
53 		before = cur->prev;
54 		io0 = container_of(before, ext4_io_end_t, list);
55 		after = cur->next;
56 		io1 = container_of(after, ext4_io_end_t, list);
57 
58 		ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
59 			    io, inode->i_ino, io0, io1);
60 	}
61 	spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
62 #endif
63 }
64 
65 /*
66  * This function is called from ext4_sync_file().
67  *
68  * When IO is completed, the work to convert unwritten extents to
69  * written is queued on workqueue but may not get immediately
70  * scheduled. When fsync is called, we need to ensure the
71  * conversion is complete before fsync returns.
72  * The inode keeps track of a list of pending/completed IO that
73  * might needs to do the conversion. This function walks through
74  * the list and convert the related unwritten extents for completed IO
75  * to written.
76  * The function return the number of pending IOs on success.
77  */
78 extern int ext4_flush_completed_IO(struct inode *inode)
79 {
80 	ext4_io_end_t *io;
81 	struct ext4_inode_info *ei = EXT4_I(inode);
82 	unsigned long flags;
83 	int ret = 0;
84 	int ret2 = 0;
85 
86 	if (list_empty(&ei->i_completed_io_list))
87 		return ret;
88 
89 	dump_completed_IO(inode);
90 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
91 	while (!list_empty(&ei->i_completed_io_list)){
92 		io = list_entry(ei->i_completed_io_list.next,
93 				ext4_io_end_t, list);
94 		/*
95 		 * Calling ext4_end_io_nolock() to convert completed
96 		 * IO to written.
97 		 *
98 		 * When ext4_sync_file() is called, run_queue() may already
99 		 * about to flush the work corresponding to this io structure.
100 		 * It will be upset if it founds the io structure related
101 		 * to the work-to-be schedule is freed.
102 		 *
103 		 * Thus we need to keep the io structure still valid here after
104 		 * convertion finished. The io structure has a flag to
105 		 * avoid double converting from both fsync and background work
106 		 * queue work.
107 		 */
108 		spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
109 		ret = ext4_end_io_nolock(io);
110 		spin_lock_irqsave(&ei->i_completed_io_lock, flags);
111 		if (ret < 0)
112 			ret2 = ret;
113 		else
114 			list_del_init(&io->list);
115 	}
116 	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
117 	return (ret2 < 0) ? ret2 : 0;
118 }
119 
120 /*
121  * If we're not journaling and this is a just-created file, we have to
122  * sync our parent directory (if it was freshly created) since
123  * otherwise it will only be written by writeback, leaving a huge
124  * window during which a crash may lose the file.  This may apply for
125  * the parent directory's parent as well, and so on recursively, if
126  * they are also freshly created.
127  */
128 static void ext4_sync_parent(struct inode *inode)
129 {
130 	struct dentry *dentry = NULL;
131 
132 	while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
133 		ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
134 		dentry = list_entry(inode->i_dentry.next,
135 				    struct dentry, d_alias);
136 		if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode)
137 			break;
138 		inode = dentry->d_parent->d_inode;
139 		sync_mapping_buffers(inode->i_mapping);
140 	}
141 }
142 
143 /*
144  * akpm: A new design for ext4_sync_file().
145  *
146  * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
147  * There cannot be a transaction open by this task.
148  * Another task could have dirtied this inode.  Its data can be in any
149  * state in the journalling system.
150  *
151  * What we do is just kick off a commit and wait on it.  This will snapshot the
152  * inode to disk.
153  *
154  * i_mutex lock is held when entering and exiting this function
155  */
156 
157 int ext4_sync_file(struct file *file, int datasync)
158 {
159 	struct inode *inode = file->f_mapping->host;
160 	struct ext4_inode_info *ei = EXT4_I(inode);
161 	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
162 	int ret;
163 	tid_t commit_tid;
164 
165 	J_ASSERT(ext4_journal_current_handle() == NULL);
166 
167 	trace_ext4_sync_file(file, datasync);
168 
169 	if (inode->i_sb->s_flags & MS_RDONLY)
170 		return 0;
171 
172 	ret = ext4_flush_completed_IO(inode);
173 	if (ret < 0)
174 		return ret;
175 
176 	if (!journal) {
177 		ret = generic_file_fsync(file, datasync);
178 		if (!ret && !list_empty(&inode->i_dentry))
179 			ext4_sync_parent(inode);
180 		return ret;
181 	}
182 
183 	/*
184 	 * data=writeback,ordered:
185 	 *  The caller's filemap_fdatawrite()/wait will sync the data.
186 	 *  Metadata is in the journal, we wait for proper transaction to
187 	 *  commit here.
188 	 *
189 	 * data=journal:
190 	 *  filemap_fdatawrite won't do anything (the buffers are clean).
191 	 *  ext4_force_commit will write the file data into the journal and
192 	 *  will wait on that.
193 	 *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
194 	 *  (they were dirtied by commit).  But that's OK - the blocks are
195 	 *  safe in-journal, which is all fsync() needs to ensure.
196 	 */
197 	if (ext4_should_journal_data(inode))
198 		return ext4_force_commit(inode->i_sb);
199 
200 	commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
201 	if (jbd2_log_start_commit(journal, commit_tid)) {
202 		/*
203 		 * When the journal is on a different device than the
204 		 * fs data disk, we need to issue the barrier in
205 		 * writeback mode.  (In ordered mode, the jbd2 layer
206 		 * will take care of issuing the barrier.  In
207 		 * data=journal, all of the data blocks are written to
208 		 * the journal device.)
209 		 */
210 		if (ext4_should_writeback_data(inode) &&
211 		    (journal->j_fs_dev != journal->j_dev) &&
212 		    (journal->j_flags & JBD2_BARRIER))
213 			blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL,
214 					NULL);
215 		ret = jbd2_log_wait_commit(journal, commit_tid);
216 	} else if (journal->j_flags & JBD2_BARRIER)
217 		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
218 	return ret;
219 }
220