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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 0 : static int ext4_sync_parent(struct inode *inode) 46 : { 47 0 : struct dentry *dentry, *next; 48 0 : int ret = 0; 49 : 50 0 : if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) 51 : return 0; 52 0 : dentry = d_find_any_alias(inode); 53 0 : if (!dentry) 54 : return 0; 55 0 : while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 56 0 : ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 57 : 58 0 : next = dget_parent(dentry); 59 0 : dput(dentry); 60 0 : dentry = next; 61 0 : 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 0 : ret = sync_mapping_buffers(inode->i_mapping); 71 0 : if (ret) 72 : break; 73 0 : ret = sync_inode_metadata(inode, 1); 74 0 : if (ret) 75 : break; 76 : } 77 0 : dput(dentry); 78 0 : return ret; 79 : } 80 : 81 0 : static int ext4_fsync_nojournal(struct inode *inode, bool datasync, 82 : bool *needs_barrier) 83 : { 84 0 : int ret, err; 85 : 86 0 : ret = sync_mapping_buffers(inode->i_mapping); 87 0 : if (!(inode->i_state & I_DIRTY_ALL)) 88 : return ret; 89 0 : if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 90 : return ret; 91 : 92 0 : err = sync_inode_metadata(inode, 1); 93 0 : if (!ret) 94 0 : ret = err; 95 : 96 0 : if (!ret) 97 0 : ret = ext4_sync_parent(inode); 98 0 : if (test_opt(inode->i_sb, BARRIER)) 99 0 : *needs_barrier = true; 100 : 101 : return ret; 102 : } 103 : 104 121 : static int ext4_fsync_journal(struct inode *inode, bool datasync, 105 : bool *needs_barrier) 106 : { 107 121 : struct ext4_inode_info *ei = EXT4_I(inode); 108 121 : journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 109 121 : tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 110 : 111 242 : if (journal->j_flags & JBD2_BARRIER && 112 121 : !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 113 71 : *needs_barrier = true; 114 : 115 121 : 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 : */ 129 121 : int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 130 : { 131 121 : int ret = 0, err; 132 121 : bool needs_barrier = false; 133 121 : struct inode *inode = file->f_mapping->host; 134 121 : struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 135 : 136 121 : if (unlikely(ext4_forced_shutdown(sbi))) 137 : return -EIO; 138 : 139 121 : ASSERT(ext4_journal_current_handle() == NULL); 140 : 141 121 : trace_ext4_sync_file_enter(file, datasync); 142 : 143 121 : 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 : 151 121 : ret = file_write_and_wait_range(file, start, end); 152 121 : if (ret) 153 0 : 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 : */ 169 121 : if (!sbi->s_journal) 170 0 : ret = ext4_fsync_nojournal(inode, datasync, &needs_barrier); 171 121 : else if (ext4_should_journal_data(inode)) 172 0 : ret = ext4_force_commit(inode->i_sb); 173 : else 174 121 : ret = ext4_fsync_journal(inode, datasync, &needs_barrier); 175 : 176 121 : if (needs_barrier) { 177 71 : err = blkdev_issue_flush(inode->i_sb->s_bdev); 178 71 : if (!ret) 179 71 : ret = err; 180 : } 181 50 : out: 182 121 : err = file_check_and_advance_wb_err(file); 183 121 : if (ret == 0) 184 121 : ret = err; 185 121 : trace_ext4_sync_file_exit(inode, ret); 186 121 : return ret; 187 : }
