On Mon 23-01-17 21:43:16, Amir Goldstein wrote:
> Before calling write f_ops, call file_start_write() instead
> of sb_start_write().
>
> This ensures freeze protection for both overlay and upper fs
> when file is open from an overlayfs mount.
>
> Replace {sb,file}_start_write() for {copy,clone}_file_range() and
> for fallocate().
>
> For dedup_file_range() there is no need for mnt_want_write_file().
> File is already open for write, so we already have mnt_want_write()
> and we only need file_start_write().
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
The patch looks like a good cleanup regardless of your overlayfs work. It
seems we just missed these places when converting freeze protection to
file_start_write(). You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/open.c | 4 ++--
> fs/read_write.c | 12 ++++--------
> include/linux/fs.h | 26 +++++++++++++-------------
> 3 files changed, 19 insertions(+), 23 deletions(-)
>
> diff --git a/fs/open.c b/fs/open.c
> index 9921f70..d3fe1a1 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -316,7 +316,7 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> if (!file->f_op->fallocate)
> return -EOPNOTSUPP;
>
> - sb_start_write(inode->i_sb);
> + file_start_write(file);
> ret = file->f_op->fallocate(file, mode, offset, len);
>
> /*
> @@ -329,7 +329,7 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> if (ret == 0)
> fsnotify_modify(file);
>
> - sb_end_write(inode->i_sb);
> + file_end_write(file);
> return ret;
> }
> EXPORT_SYMBOL_GPL(vfs_fallocate);
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 5816d4c..1e42487 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1538,7 +1538,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> if (len == 0)
> return 0;
>
> - sb_start_write(inode_out->i_sb);
> + file_start_write(file_out);
>
> /*
> * Try cloning first, this is supported by more file systems, and
> @@ -1574,7 +1574,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> inc_syscr(current);
> inc_syscw(current);
>
> - sb_end_write(inode_out->i_sb);
> + file_end_write(file_out);
>
> return ret;
> }
> @@ -1976,11 +1976,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
> }
> dst = file_inode(dst_file);
>
> - ret = mnt_want_write_file(dst_file);
> - if (ret) {
> - info->status = ret;
> - goto next_loop;
> - }
> + file_start_write(dst_file);
>
> dst_off = info->dest_offset;
> ret = clone_verify_area(dst_file, dst_off, len, true);
> @@ -2013,7 +2009,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
> }
>
> next_file:
> - mnt_drop_write_file(dst_file);
> + file_end_write(dst_file);
> next_loop:
> fdput(dst_fd);
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 71811be..8a4dbc6 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1741,19 +1741,6 @@ extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> extern int vfs_dedupe_file_range(struct file *file,
> struct file_dedupe_range *same);
>
> -static inline int do_clone_file_range(struct file *file_in, loff_t pos_in,
> - struct file *file_out, loff_t pos_out,
> - u64 len)
> -{
> - int ret;
> -
> - sb_start_write(file_inode(file_out)->i_sb);
> - ret = vfs_clone_file_range(file_in, pos_in, file_out, pos_out, len);
> - sb_end_write(file_inode(file_out)->i_sb);
> -
> - return ret;
> -}
> -
> struct super_operations {
> struct inode *(*alloc_inode)(struct super_block *sb);
> void (*destroy_inode)(struct inode *);
> @@ -2579,6 +2566,19 @@ static inline void file_end_write(struct file *file)
> __sb_end_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE);
> }
>
> +static inline int do_clone_file_range(struct file *file_in, loff_t pos_in,
> + struct file *file_out, loff_t pos_out,
> + u64 len)
> +{
> + int ret;
> +
> + file_start_write(file_out);
> + ret = vfs_clone_file_range(file_in, pos_in, file_out, pos_out, len);
> + file_end_write(file_out);
> +
> + return ret;
> +}
> +
> /*
> * get_write_access() gets write permission for a file.
> * put_write_access() releases this write permission.
> --
> 2.7.4
>
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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