Commit 14ece102 authored by Frank Mayhar's avatar Frank Mayhar Committed by Theodore Ts'o
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ext4: Make fsync sync new parent directories in no-journal mode 



Add a new ext4 state to tell us when a file has been newly created; use
that state in ext4_sync_file in no-journal mode to tell us when we need
to sync the parent directory as well as the inode and data itself.  This
fixes a problem in which a panic or power failure may lose the entire
file even when using fsync, since the parent directory entry is lost.

Addresses-Google-Bug: #2480057

Signed-off-by: default avatarFrank Mayhar <fmayhar@google.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 60e6679e

fs/ext4/ext4.h

+1 −0
Original line number Diff line number Diff line
@@ -1180,6 +1180,7 @@ enum { 
	EXT4_STATE_DA_ALLOC_CLOSE,	/* Alloc DA blks on close */

	EXT4_STATE_EXT_MIGRATE,		/* Inode is migrating */

	EXT4_STATE_DIO_UNWRITTEN,	/* need convert on dio done*/

	EXT4_STATE_NEWENTRY,		/* File just added to dir */

};



#define EXT4_INODE_BIT_FNS(name, field)					\

fs/ext4/fsync.c

+29 −2
Original line number Diff line number Diff line
@@ -34,6 +34,29 @@ 


#include <trace/events/ext4.h>



/*

 * 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 void ext4_sync_parent(struct inode *inode)

{

	struct dentry *dentry = NULL;



	while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {

		ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);

		dentry = list_entry(inode->i_dentry.next,

				    struct dentry, d_alias);

		if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode)

			break;

		inode = dentry->d_parent->d_inode;

		sync_mapping_buffers(inode->i_mapping);

	}

}



/*

 * akpm: A new design for ext4_sync_file().

 *
@@ -67,8 +90,12 @@ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync) 
	if (ret < 0)

		return ret;



	if (!journal)

		return simple_fsync(file, dentry, datasync);

	if (!journal) {

		ret = simple_fsync(file, dentry, datasync);

		if (!ret && !list_empty(&inode->i_dentry))

			ext4_sync_parent(inode);

		return ret;

	}



	/*

	 * data=writeback,ordered:

fs/ext4/namei.c

+2 −0
Original line number Diff line number Diff line
@@ -1517,6 +1517,8 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry, 
	de->rec_len = ext4_rec_len_to_disk(blocksize, blocksize);

	retval = add_dirent_to_buf(handle, dentry, inode, de, bh);

	brelse(bh);

	if (retval == 0)

		ext4_set_inode_state(inode, EXT4_STATE_NEWENTRY);

	return retval;

}

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