fsync.c (5294B)
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 */ 45static 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 81static 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 104static 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 */ 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 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 } 181out: 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}