On Tue, Apr 09, 2019 at 11:01:58AM +0800, Hou Tao wrote:
> fsync() needs to make sure the data & meta-data of file are persistent
> after the return of fsync(), even when a power-failure occurs later.
> In the case of fat-fs, the FAT belongs to the meta-data of file,
> so we need to issue a flush after the writeback of FAT instead before.
>
> Also bail out early when any stage of fsync fails.
>
> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
> ---
> fs/fat/file.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/fs/fat/file.c b/fs/fat/file.c
> index b3bed32946b1..0e3ed79fcc3f 100644
> --- a/fs/fat/file.c
> +++ b/fs/fat/file.c
> @@ -193,12 +193,17 @@ static int fat_file_release(struct inode *inode, struct file *filp)
> int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
> {
> struct inode *inode = filp->f_mapping->host;
> - int res, err;
> + int err;
> +
> + err = __generic_file_fsync(filp, start, end, datasync);
> + if (err)
> + return err;
>
> - res = generic_file_fsync(filp, start, end, datasync);
> err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
Huh. I would've thought that flushing the FAT would also be required
at the end of a WB_SYNC_ALL (aka data integrity) writepages call?
The patch itself seems good, though.
--D
> + if (err)
> + return err;
>
> - return res ? res : err;
> + return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
> }
>
>
> --
> 2.16.2.dirty
>
