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 #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 to 40 * sync our parent directory (if it was freshly created) since 41 * otherwise it will only be written by writeback, leaving a huge 42 * window during which a crash may lose the file. This may apply for 43 * the parent directory's parent as well, and so on recursively, if 44 * they are also freshly created. 45 */ ext4_sync_parent(struct inode * inode)46 static 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. But 66 * the inode itself and its blocks are still allocated (we hold 67 * a reference to the inode via its dentry), so it didn't go 68 * through ext4_evict_inode()) and so we are safe to flush 69 * 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 ext4_fsync_nojournal(struct file * file,loff_t start,loff_t end,int datasync,bool * needs_barrier)82 static 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 ext4_fsync_journal(struct inode * inode,bool datasync,bool * needs_barrier)97 static 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 other 106 * 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 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 */ ext4_sync_file(struct file * file,loff_t start,loff_t end,int datasync)129 int 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 to 165 * commit here. 166 */ 167 ret = ext4_fsync_journal(inode, datasync, &needs_barrier); 168 169 issue_flush: 170 if (needs_barrier) { 171 err = blkdev_issue_flush(inode->i_sb->s_bdev); 172 if (!ret) 173 ret = err; 174 } 175 out: 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