/* *  linux/fs/ext4/fsync.c * *  Copyright (C) 1993  Stephen Tweedie (sct@redhat.com) *  from *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr) *                      Laboratoire MASI - Institut Blaise Pascal *                      Universite Pierre et Marie Curie (Paris VI) *  from *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds * *  ext4fs fsync primitive * *  Big-endian to little-endian byte-swapping/bitmaps by *        David S. Miller (davem@caip.rutgers.edu), 1995 * *  Removed unnecessary code duplication for little endian machines *  and excessive __inline__s. *        Andi Kleen, 1997 * * Major simplications and cleanup - we only need to do the metadata, because * we can depend on generic_block_fdatasync() to sync the data blocks. */ #include <linux/time.h>#include <linux/fs.h>#include <linux/sched.h>#include <linux/writeback.h>#include <linux/jbd2.h>#include <linux/blkdev.h> #include "ext4.h"#include "ext4_jbd2.h" #include <trace/events/ext4.h> static void dump_completed_IO(struct inode * inode){#ifdef	EXT4FS_DEBUG	struct list_head *cur, *before, *after;	ext4_io_end_t *io, *io0, *io1;	unsigned long flags; 	if (list_empty(&EXT4_I(inode)->i_completed_io_list)){		ext4_debug("inode %lu completed_io list is empty\n", inode->i_ino);		return;	} 	ext4_debug("Dump inode %lu completed_io list \n", inode->i_ino);	spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);	list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list){		cur = &io->list;		before = cur->prev;		io0 = container_of(before, ext4_io_end_t, list);		after = cur->next;		io1 = container_of(after, ext4_io_end_t, list); 		ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",			    io, inode->i_ino, io0, io1);	}	spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);#endif} /* * This function is called from ext4_sync_file(). * * When IO is completed, the work to convert unwritten extents to * written is queued on workqueue but may not get immediately * scheduled. When fsync is called, we need to ensure the * conversion is complete before fsync returns. * The inode keeps track of a list of pending/completed IO that * might needs to do the conversion. This function walks through * the list and convert the related unwritten extents for completed IO * to written. * The function return the number of pending IOs on success. */int ext4_flush_completed_IO(struct inode *inode){	ext4_io_end_t *io;	struct ext4_inode_info *ei = EXT4_I(inode);	unsigned long flags;	int ret = 0;	int ret2 = 0; 	dump_completed_IO(inode);	spin_lock_irqsave(&ei->i_completed_io_lock, flags);	while (!list_empty(&ei->i_completed_io_list)){		io = list_entry(ei->i_completed_io_list.next,				ext4_io_end_t, list);		list_del_init(&io->list);		io->flag |= EXT4_IO_END_IN_FSYNC;		/*		 * Calling ext4_end_io_nolock() to convert completed		 * IO to written.		 *		 * When ext4_sync_file() is called, run_queue() may already		 * about to flush the work corresponding to this io structure.		 * It will be upset if it founds the io structure related		 * to the work-to-be schedule is freed.		 *		 * Thus we need to keep the io structure still valid here after		 * conversion finished. The io structure has a flag to		 * avoid double converting from both fsync and background work		 * queue work.		 */		spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);		ret = ext4_end_io_nolock(io);		if (ret < 0)			ret2 = ret;		spin_lock_irqsave(&ei->i_completed_io_lock, flags);		io->flag &= ~EXT4_IO_END_IN_FSYNC;	}	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);	return (ret2 < 0) ? ret2 : 0;} /* * If we're not journaling and this is a just-created file, we have to * sync our parent directory (if it was freshly created) since * otherwise it will only be written by writeback, leaving a huge * window during which a crash may lose the file.  This may apply for * the parent directory's parent as well, and so on recursively, if * they are also freshly created. */static int ext4_sync_parent(struct inode *inode){	struct writeback_control wbc;	struct dentry *dentry = NULL;	struct inode *next;	int ret = 0; 	if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))		return 0;	inode = igrab(inode);	while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {		ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);		dentry = NULL;		spin_lock(&inode->i_lock);		if (!list_empty(&inode->i_dentry)) {			dentry = list_first_entry(&inode->i_dentry,						  struct dentry, d_alias);			dget(dentry);		}		spin_unlock(&inode->i_lock);		if (!dentry)			break;		next = igrab(dentry->d_parent->d_inode);		dput(dentry);		if (!next)			break;		iput(inode);		inode = next;		ret = sync_mapping_buffers(inode->i_mapping);		if (ret)			break;		memset(&wbc, 0, sizeof(wbc));		wbc.sync_mode = WB_SYNC_ALL;		wbc.nr_to_write = 0;         /* only write out the inode */		ret = sync_inode(inode, &wbc);		if (ret)			break;	}	iput(inode);	return ret;} /** * __sync_file - generic_file_fsync without the locking and filemap_write * @inode:	inode to sync * @datasync:	only sync essential metadata if true * * This is just generic_file_fsync without the locking.  This is needed for * nojournal mode to make sure this inodes data/metadata makes it to disk * properly.  The i_mutex should be held already. */static int __sync_inode(struct inode *inode, int datasync){	int err;	int ret; 	ret = sync_mapping_buffers(inode->i_mapping);	if (!(inode->i_state & I_DIRTY))		return ret;	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))		return ret; 	err = sync_inode_metadata(inode, 1);	if (ret == 0)		ret = err;	return ret;} /* * akpm: A new design for ext4_sync_file(). * * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). * There cannot be a transaction open by this task. * Another task could have dirtied this inode.  Its data can be in any * state in the journalling system. * * What we do is just kick off a commit and wait on it.  This will snapshot the * inode to disk. * * i_mutex lock is held when entering and exiting this function */ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync){	struct inode *inode = file->f_mapping->host;	struct ext4_inode_info *ei = EXT4_I(inode);	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;	int ret;	tid_t commit_tid;	bool needs_barrier = false; 	J_ASSERT(ext4_journal_current_handle() == NULL); 	trace_ext4_sync_file_enter(file, datasync); 	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);	if (ret)		return ret;	mutex_lock(&inode->i_mutex); 	if (inode->i_sb->s_flags & MS_RDONLY)		goto out; 	ret = ext4_flush_completed_IO(inode);	if (ret < 0)		goto out; 	if (!journal) {		ret = __sync_inode(inode, datasync);		if (!ret && !list_empty(&inode->i_dentry))			ret = ext4_sync_parent(inode);		goto out;	} 	/*	 * data=writeback,ordered:	 *  The caller's filemap_fdatawrite()/wait will sync the data.	 *  Metadata is in the journal, we wait for proper transaction to	 *  commit here.	 *	 * data=journal:	 *  filemap_fdatawrite won't do anything (the buffers are clean).	 *  ext4_force_commit will write the file data into the journal and	 *  will wait on that.	 *  filemap_fdatawait() will encounter a ton of newly-dirtied pages	 *  (they were dirtied by commit).  But that's OK - the blocks are	 *  safe in-journal, which is all fsync() needs to ensure.	 */	if (ext4_should_journal_data(inode)) {		ret = ext4_force_commit(inode->i_sb);		goto out;	} 	commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;	if (journal->j_flags & JBD2_BARRIER &&	    !jbd2_trans_will_send_data_barrier(journal, commit_tid))		needs_barrier = true;	jbd2_log_start_commit(journal, commit_tid);	ret = jbd2_log_wait_commit(journal, commit_tid);	if (needs_barrier)		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); out:	mutex_unlock(&inode->i_mutex);	trace_ext4_sync_file_exit(inode, ret);	return ret;}