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/jbd2.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 static void dump_completed_IO(struct inode * inode) 38 { 39 #ifdef EXT4FS_DEBUG 40 struct list_head *cur, *before, *after; 41 ext4_io_end_t *io, *io0, *io1; 42 unsigned long flags; 43 44 if (list_empty(&EXT4_I(inode)->i_completed_io_list)){ 45 ext4_debug("inode %lu completed_io list is empty\n", inode->i_ino); 46 return; 47 } 48 49 ext4_debug("Dump inode %lu completed_io list \n", inode->i_ino); 50 spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); 51 list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list){ 52 cur = &io->list; 53 before = cur->prev; 54 io0 = container_of(before, ext4_io_end_t, list); 55 after = cur->next; 56 io1 = container_of(after, ext4_io_end_t, list); 57 58 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n", 59 io, inode->i_ino, io0, io1); 60 } 61 spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags); 62 #endif 63 } 64 65 /* 66 * This function is called from ext4_sync_file(). 67 * 68 * When IO is completed, the work to convert unwritten extents to 69 * written is queued on workqueue but may not get immediately 70 * scheduled. When fsync is called, we need to ensure the 71 * conversion is complete before fsync returns. 72 * The inode keeps track of a list of pending/completed IO that 73 * might needs to do the conversion. This function walks through 74 * the list and convert the related unwritten extents for completed IO 75 * to written. 76 * The function return the number of pending IOs on success. 77 */ 78 extern int ext4_flush_completed_IO(struct inode *inode) 79 { 80 ext4_io_end_t *io; 81 struct ext4_inode_info *ei = EXT4_I(inode); 82 unsigned long flags; 83 int ret = 0; 84 int ret2 = 0; 85 86 if (list_empty(&ei->i_completed_io_list)) 87 return ret; 88 89 dump_completed_IO(inode); 90 spin_lock_irqsave(&ei->i_completed_io_lock, flags); 91 while (!list_empty(&ei->i_completed_io_list)){ 92 io = list_entry(ei->i_completed_io_list.next, 93 ext4_io_end_t, list); 94 /* 95 * Calling ext4_end_io_nolock() to convert completed 96 * IO to written. 97 * 98 * When ext4_sync_file() is called, run_queue() may already 99 * about to flush the work corresponding to this io structure. 100 * It will be upset if it founds the io structure related 101 * to the work-to-be schedule is freed. 102 * 103 * Thus we need to keep the io structure still valid here after 104 * conversion finished. The io structure has a flag to 105 * avoid double converting from both fsync and background work 106 * queue work. 107 */ 108 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 109 ret = ext4_end_io_nolock(io); 110 spin_lock_irqsave(&ei->i_completed_io_lock, flags); 111 if (ret < 0) 112 ret2 = ret; 113 else 114 list_del_init(&io->list); 115 } 116 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 117 return (ret2 < 0) ? ret2 : 0; 118 } 119 120 /* 121 * If we're not journaling and this is a just-created file, we have to 122 * sync our parent directory (if it was freshly created) since 123 * otherwise it will only be written by writeback, leaving a huge 124 * window during which a crash may lose the file. This may apply for 125 * the parent directory's parent as well, and so on recursively, if 126 * they are also freshly created. 127 */ 128 static int ext4_sync_parent(struct inode *inode) 129 { 130 struct writeback_control wbc; 131 struct dentry *dentry = NULL; 132 int ret = 0; 133 134 while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { 135 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); 136 dentry = list_entry(inode->i_dentry.next, 137 struct dentry, d_alias); 138 if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode) 139 break; 140 inode = dentry->d_parent->d_inode; 141 ret = sync_mapping_buffers(inode->i_mapping); 142 if (ret) 143 break; 144 memset(&wbc, 0, sizeof(wbc)); 145 wbc.sync_mode = WB_SYNC_ALL; 146 wbc.nr_to_write = 0; /* only write out the inode */ 147 ret = sync_inode(inode, &wbc); 148 if (ret) 149 break; 150 } 151 return ret; 152 } 153 154 /* 155 * akpm: A new design for ext4_sync_file(). 156 * 157 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). 158 * There cannot be a transaction open by this task. 159 * Another task could have dirtied this inode. Its data can be in any 160 * state in the journalling system. 161 * 162 * What we do is just kick off a commit and wait on it. This will snapshot the 163 * inode to disk. 164 * 165 * i_mutex lock is held when entering and exiting this function 166 */ 167 168 int ext4_sync_file(struct file *file, int datasync) 169 { 170 struct inode *inode = file->f_mapping->host; 171 struct ext4_inode_info *ei = EXT4_I(inode); 172 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; 173 int ret; 174 tid_t commit_tid; 175 bool needs_barrier = false; 176 177 J_ASSERT(ext4_journal_current_handle() == NULL); 178 179 trace_ext4_sync_file_enter(file, datasync); 180 181 if (inode->i_sb->s_flags & MS_RDONLY) 182 return 0; 183 184 ret = ext4_flush_completed_IO(inode); 185 if (ret < 0) 186 goto out; 187 188 if (!journal) { 189 ret = generic_file_fsync(file, datasync); 190 if (!ret && !list_empty(&inode->i_dentry)) 191 ret = ext4_sync_parent(inode); 192 goto out; 193 } 194 195 /* 196 * data=writeback,ordered: 197 * The caller's filemap_fdatawrite()/wait will sync the data. 198 * Metadata is in the journal, we wait for proper transaction to 199 * commit here. 200 * 201 * data=journal: 202 * filemap_fdatawrite won't do anything (the buffers are clean). 203 * ext4_force_commit will write the file data into the journal and 204 * will wait on that. 205 * filemap_fdatawait() will encounter a ton of newly-dirtied pages 206 * (they were dirtied by commit). But that's OK - the blocks are 207 * safe in-journal, which is all fsync() needs to ensure. 208 */ 209 if (ext4_should_journal_data(inode)) { 210 ret = ext4_force_commit(inode->i_sb); 211 goto out; 212 } 213 214 commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; 215 if (journal->j_flags & JBD2_BARRIER && 216 !jbd2_trans_will_send_data_barrier(journal, commit_tid)) 217 needs_barrier = true; 218 jbd2_log_start_commit(journal, commit_tid); 219 ret = jbd2_log_wait_commit(journal, commit_tid); 220 if (needs_barrier) 221 blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 222 out: 223 trace_ext4_sync_file_exit(inode, ret); 224 return ret; 225 } 226