1 /* 2 * linux/fs/ext4/fsync.c 3 * 4 * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com) 5 * from 6 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr) 7 * Laboratoire MASI - Institut Blaise Pascal 8 * Universite Pierre et Marie Curie (Paris VI) 9 * from 10 * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds 11 * 12 * ext4fs fsync primitive 13 * 14 * Big-endian to little-endian byte-swapping/bitmaps by 15 * David S. Miller (davem@caip.rutgers.edu), 1995 16 * 17 * Removed unnecessary code duplication for little endian machines 18 * and excessive __inline__s. 19 * Andi Kleen, 1997 20 * 21 * Major simplications and cleanup - we only need to do the metadata, because 22 * we can depend on generic_block_fdatasync() to sync the data blocks. 23 */ 24 25 #include <linux/time.h> 26 #include <linux/fs.h> 27 #include <linux/sched.h> 28 #include <linux/writeback.h> 29 #include <linux/blkdev.h> 30 31 #include "ext4.h" 32 #include "ext4_jbd2.h" 33 34 #include <trace/events/ext4.h> 35 36 /* 37 * If we're not journaling and this is a just-created file, we have to 38 * sync our parent directory (if it was freshly created) since 39 * otherwise it will only be written by writeback, leaving a huge 40 * window during which a crash may lose the file. This may apply for 41 * the parent directory's parent as well, and so on recursively, if 42 * they are also freshly created. 43 */ 44 static int ext4_sync_parent(struct inode *inode) 45 { 46 struct dentry *dentry = NULL; 47 struct inode *next; 48 int ret = 0; 49 50 if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) 51 return 0; 52 inode = igrab(inode); 53 while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 54 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 55 dentry = d_find_any_alias(inode); 56 if (!dentry) 57 break; 58 next = igrab(d_inode(dentry->d_parent)); 59 dput(dentry); 60 if (!next) 61 break; 62 iput(inode); 63 inode = next; 64 ret = sync_mapping_buffers(inode->i_mapping); 65 if (ret) 66 break; 67 ret = sync_inode_metadata(inode, 1); 68 if (ret) 69 break; 70 } 71 iput(inode); 72 return ret; 73 } 74 75 /* 76 * akpm: A new design for ext4_sync_file(). 77 * 78 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 79 * There cannot be a transaction open by this task. 80 * Another task could have dirtied this inode. Its data can be in any 81 * state in the journalling system. 82 * 83 * What we do is just kick off a commit and wait on it. This will snapshot the 84 * inode to disk. 85 */ 86 87 int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 88 { 89 struct inode *inode = file->f_mapping->host; 90 struct ext4_inode_info *ei = EXT4_I(inode); 91 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 92 int ret = 0, err; 93 tid_t commit_tid; 94 bool needs_barrier = false; 95 96 J_ASSERT(ext4_journal_current_handle() == NULL); 97 98 trace_ext4_sync_file_enter(file, datasync); 99 100 if (inode->i_sb->s_flags & MS_RDONLY) { 101 /* Make sure that we read updated s_mount_flags value */ 102 smp_rmb(); 103 if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED) 104 ret = -EROFS; 105 goto out; 106 } 107 108 if (!journal) { 109 ret = __generic_file_fsync(file, start, end, datasync); 110 if (!ret && !hlist_empty(&inode->i_dentry)) 111 ret = ext4_sync_parent(inode); 112 if (test_opt(inode->i_sb, BARRIER)) 113 goto issue_flush; 114 goto out; 115 } 116 117 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 118 if (ret) 119 return ret; 120 /* 121 * data=writeback,ordered: 122 * The caller's filemap_fdatawrite()/wait will sync the data. 123 * Metadata is in the journal, we wait for proper transaction to 124 * commit here. 125 * 126 * data=journal: 127 * filemap_fdatawrite won't do anything (the buffers are clean). 128 * ext4_force_commit will write the file data into the journal and 129 * will wait on that. 130 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 131 * (they were dirtied by commit). But that's OK - the blocks are 132 * safe in-journal, which is all fsync() needs to ensure. 133 */ 134 if (ext4_should_journal_data(inode)) { 135 ret = ext4_force_commit(inode->i_sb); 136 goto out; 137 } 138 139 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 140 if (journal->j_flags & JBD2_BARRIER && 141 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 142 needs_barrier = true; 143 ret = jbd2_complete_transaction(journal, commit_tid); 144 if (needs_barrier) { 145 issue_flush: 146 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 147 if (!ret) 148 ret = err; 149 } 150 out: 151 trace_ext4_sync_file_exit(inode, ret); 152 return ret; 153 } 154