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Date: Fri, 17 Feb 2017 17:09:38 +0100 From: Miklos Szeredi <mszeredi@...hat.com> To: Al Viro <viro@...iv.linux.org.uk> Cc: linux-unionfs@...r.kernel.org, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org Subject: [PATCH 9/9] vfs: intercept fsync on overlay files Fsync is really an inode operation (AFAICS) so a doing it on a O_RDONLY file descriptor should flush any data written through an O_WRONLY file descriptor for example. To make this work correctly in case the file is copied up after being opened for read, intercept the fsync operation, similarly to read_iter and mmap. Signed-off-by: Miklos Szeredi <mszeredi@...hat.com> --- fs/overlay_util.c | 19 +++++++++++++++++++ include/linux/fs.h | 3 +++ include/linux/overlay_util.h | 2 ++ 3 files changed, 24 insertions(+) diff --git a/fs/overlay_util.c b/fs/overlay_util.c index 063f8c5719d1..dae9d23b1519 100644 --- a/fs/overlay_util.c +++ b/fs/overlay_util.c @@ -37,6 +37,25 @@ ssize_t overlay_read_iter(struct file *file, struct kiocb *kio, } EXPORT_SYMBOL(overlay_read_iter); +int overlay_fsync(struct file *file, loff_t start, loff_t end, + int datasync) +{ + int ret; + + if (likely(overlay_file_consistent(file))) + return file->f_op->fsync(file, start, end, datasync); + + file = filp_clone_open(file); + if (IS_ERR(file)) + return PTR_ERR(file); + + ret = vfs_fsync_range(file, start, end, datasync); + fput(file); + + return ret; +} +EXPORT_SYMBOL(overlay_fsync); + int overlay_mmap(struct file *file, struct vm_area_struct *vma) { if (unlikely(!overlay_file_consistent(file))) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 1293005de2e3..1cfa3b33659c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1748,6 +1748,9 @@ static inline int call_mmap(struct file *file, struct vm_area_struct *vma) static inline int call_fsync(struct file *file, loff_t start, loff_t end, int datasync) { + if (unlikely(is_overlay_file(file))) + return overlay_fsync(file, start, end, datasync); + return file->f_op->fsync(file, start, end, datasync); } diff --git a/include/linux/overlay_util.h b/include/linux/overlay_util.h index 2cd66bc316cc..06a0dd923404 100644 --- a/include/linux/overlay_util.h +++ b/include/linux/overlay_util.h @@ -11,5 +11,7 @@ struct vm_area_struct; extern ssize_t overlay_read_iter(struct file *file, struct kiocb *kio, struct iov_iter *iter); extern int overlay_mmap(struct file *file, struct vm_area_struct *vma); +extern int overlay_fsync(struct file *file, loff_t start, loff_t end, + int datasync); #endif /* _LINUX_OVERLAY_FS_H */ -- 2.5.5
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