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1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/ext4/fsync.c4 *5 * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com)6 * from7 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr)8 * Laboratoire MASI - Institut Blaise Pascal9 * Universite Pierre et Marie Curie (Paris VI)10 * from11 * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds12 *13 * ext4fs fsync primitive14 *15 * Big-endian to little-endian byte-swapping/bitmaps by16 * David S. Miller (davem@caip.rutgers.edu), 199517 *18 * Removed unnecessary code duplication for little endian machines19 * and excessive __inline__s.20 * Andi Kleen, 199721 *22 * Major simplications and cleanup - we only need to do the metadata, because23 * 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 to40 * sync our parent directory (if it was freshly created) since41 * otherwise it will only be written by writeback, leaving a huge42 * window during which a crash may lose the file. This may apply for43 * the parent directory's parent as well, and so on recursively, if44 * 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. But66 * the inode itself and its blocks are still allocated (we hold67 * a reference to the inode via its dentry), so it didn't go68 * through ext4_evict_inode()) and so we are safe to flush69 * metadata blocks and the inode.70 */71 ret = sync_mapping_buffers(inode->i_mapping);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 int ret;87 88 ret = generic_buffers_fsync_noflush(file, start, end, datasync);89 if (!ret)90 ret = ext4_sync_parent(inode);91 if (test_opt(inode->i_sb, BARRIER))92 *needs_barrier = true;93 94 return ret;95}96 97static int ext4_fsync_journal(struct inode *inode, bool datasync,98 bool *needs_barrier)99{100 struct ext4_inode_info *ei = EXT4_I(inode);101 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;102 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 other106 * special files. Force a full commit.107 */108 if (!S_ISREG(inode->i_mode))109 return ext4_force_commit(inode->i_sb);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 any124 * state in the journalling system.125 *126 * What we do is just kick off a commit and wait on it. This will snapshot the127 * inode to disk.128 */129int 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;134 135 if (unlikely(ext4_forced_shutdown(inode->i_sb)))136 return -EIO;137 138 ASSERT(ext4_journal_current_handle() == NULL);139 140 trace_ext4_sync_file_enter(file, datasync);141 142 if (sb_rdonly(inode->i_sb)) {143 /* Make sure that we read updated s_ext4_flags value */144 smp_rmb();145 if (ext4_forced_shutdown(inode->i_sb))146 ret = -EROFS;147 goto out;148 }149 150 if (!EXT4_SB(inode->i_sb)->s_journal) {151 ret = ext4_fsync_nojournal(file, start, end, datasync,152 &needs_barrier);153 if (needs_barrier)154 goto issue_flush;155 goto out;156 }157 158 ret = file_write_and_wait_range(file, start, end);159 if (ret)160 goto out;161 162 /*163 * The caller's filemap_fdatawrite()/wait will sync the data.164 * Metadata is in the journal, we wait for proper transaction to165 * commit here.166 */167 ret = ext4_fsync_journal(inode, datasync, &needs_barrier);168 169issue_flush:170 if (needs_barrier) {171 err = blkdev_issue_flush(inode->i_sb->s_bdev);172 if (!ret)173 ret = err;174 }175out:176 err = file_check_and_advance_wb_err(file);177 if (ret == 0)178 ret = err;179 trace_ext4_sync_file_exit(inode, ret);180 return ret;181}182