Hi Eric:
On Tue, Apr 5, 2011 at 12:35 PM, Eric Sandeen <sandeen@xxxxxxxxxx> wrote:
> On 4/5/11 12:27 PM, Curt Wohlgemuth wrote:
>> ext4 has taken the stance that, in the absence of a journal,
>> when an fsync/fdatasync of an inode is done, the parent
>> directory should be sync'ed if this inode entry is new.
>> ext4_sync_parent(), which implements this, does indeed sync
>> the dirent pages for parent directories, but it does not
>> sync the directory *inode*. This patch fixes this.
>>
>> I tested this using a power fail test, which panics a
>> machine running a file server getting requests from a
>> client. Without this patch, on about every other test run,
>> the server is missing many, many files that had been synced.
>> With this patch, on > 6 runs, I see zero files being lost.
>>
>> Signed-off-by: Curt Wohlgemuth <curtw@xxxxxxxxxx>
>> ---
>> fs/ext4/fsync.c | 11 ++++++++++-
>> 1 files changed, 10 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
>> index 7f74019..a276348 100644
>> --- a/fs/ext4/fsync.c
>> +++ b/fs/ext4/fsync.c
>> @@ -128,6 +128,7 @@ extern int ext4_flush_completed_IO(struct inode *inode)
>> static void ext4_sync_parent(struct inode *inode)
>> {
>> struct dentry *dentry = NULL;
>> + int ret;
>>
>> while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
>> ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
>> @@ -136,7 +137,15 @@ static void ext4_sync_parent(struct inode *inode)
>> if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode)
>> break;
>> inode = dentry->d_parent->d_inode;
>> - sync_mapping_buffers(inode->i_mapping);
>> + ret = sync_mapping_buffers(inode->i_mapping);
>> + if (! ret) {
>> + struct writeback_control wbc = {
>> + .sync_mode = WB_SYNC_ALL,
>> + .nr_to_write = 0, /* metadata-only; caller
>> + takes care of data */
>> + };
>> + (void)sync_inode(inode, &wbc);
>
> I know ext4_sync_parent was a void already, but why don't we send errors back up through ext4_sync_file?
Well, you could argue that a failure to sync the parent shouldn't
cause the inode's fsync() to fail, but I probably wouldn't :-) . I'll
resend a patch that implements this.
Thanks,
Curt
>
> -Eric
>
>> + }
>> }
>> }
>>
>
>
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