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 static int ext4_sync_parent(struct inode *inode) 46 { 47 struct dentry *dentry = NULL; 48 struct inode *next; 49 int ret = 0; 50 51 if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) 52 return 0; 53 inode = igrab(inode); 54 while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 55 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 56 dentry = d_find_any_alias(inode); 57 if (!dentry) 58 break; 59 next = igrab(d_inode(dentry->d_parent)); 60 dput(dentry); 61 if (!next) 62 break; 63 iput(inode); 64 inode = next; 65 /* 66 * The directory inode may have gone through rmdir by now. But 67 * the inode itself and its blocks are still allocated (we hold 68 * a reference to the inode so it didn't go through 69 * ext4_evict_inode()) and so we are safe to flush metadata 70 * blocks and the inode. 71 */ 72 ret = sync_mapping_buffers(inode->i_mapping); 73 if (ret) 74 break; 75 ret = sync_inode_metadata(inode, 1); 76 if (ret) 77 break; 78 } 79 iput(inode); 80 return ret; 81 } 82 83 /* 84 * akpm: A new design for ext4_sync_file(). 85 * 86 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 87 * There cannot be a transaction open by this task. 88 * Another task could have dirtied this inode. Its data can be in any 89 * state in the journalling system. 90 * 91 * What we do is just kick off a commit and wait on it. This will snapshot the 92 * inode to disk. 93 */ 94 95 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 96 { 97 struct inode *inode = file->f_mapping->host; 98 struct ext4_inode_info *ei = EXT4_I(inode); 99 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 100 int ret = 0, err; 101 tid_t commit_tid; 102 bool needs_barrier = false; 103 104 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) 105 return -EIO; 106 107 J_ASSERT(ext4_journal_current_handle() == NULL); 108 109 trace_ext4_sync_file_enter(file, datasync); 110 111 if (sb_rdonly(inode->i_sb)) { 112 /* Make sure that we read updated s_mount_flags value */ 113 smp_rmb(); 114 if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED) 115 ret = -EROFS; 116 goto out; 117 } 118 119 if (!journal) { 120 ret = __generic_file_fsync(file, start, end, datasync); 121 if (!ret) 122 ret = ext4_sync_parent(inode); 123 if (test_opt(inode->i_sb, BARRIER)) 124 goto issue_flush; 125 goto out; 126 } 127 128 ret = file_write_and_wait_range(file, start, end); 129 if (ret) 130 return ret; 131 /* 132 * data=writeback,ordered: 133 * The caller's filemap_fdatawrite()/wait will sync the data. 134 * Metadata is in the journal, we wait for proper transaction to 135 * commit here. 136 * 137 * data=journal: 138 * filemap_fdatawrite won't do anything (the buffers are clean). 139 * ext4_force_commit will write the file data into the journal and 140 * will wait on that. 141 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 142 * (they were dirtied by commit). But that's OK - the blocks are 143 * safe in-journal, which is all fsync() needs to ensure. 144 */ 145 if (ext4_should_journal_data(inode)) { 146 ret = ext4_force_commit(inode->i_sb); 147 goto out; 148 } 149 150 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 151 if (journal->j_flags & JBD2_BARRIER && 152 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 153 needs_barrier = true; 154 ret = jbd2_complete_transaction(journal, commit_tid); 155 if (needs_barrier) { 156 issue_flush: 157 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 158 if (!ret) 159 ret = err; 160 } 161 out: 162 trace_ext4_sync_file_exit(inode, ret); 163 return ret; 164 } 165