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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: Frank Mayhar <fmayhar@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Frank Mayhar 2010-05-17 08:00:00 -04:00 committed by Theodore Ts'o
parent 60e6679e28
commit 14ece1028b
3 changed files with 32 additions and 2 deletions
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1
fs/ext4/ext4.h
View File

@ -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) \

31
fs/ext4/fsync.c
View File

@ -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:

2
fs/ext4/namei.c
View File

@ -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;
}