RE: [PATCH v7 1/11] fs: Add support FALLOC_FL_INSERT_RANGE for fallocate

Namjae Jeon
2015-01-07T05:46:41Z

> On Fri, Jan 02, 2015 at 06:40:33PM +0900, Namjae Jeon wrote:
> > FALLOC_FL_INSERT_RANGE command is the opposite command of
> > FALLOC_FL_COLLAPSE_RANGE that is needed for advertisers or someone who want to
> > add some data in the middle of file. FALLOC_FL_INSERT_RANGE will create space
> > for writing new data within a file after shifting extents to right as given
> > length. and this command also has same limitation as FALLOC_FL_COLLAPSE_RANGE,
> > that is block boundary and use ftruncate(2) for crosses EOF.
> >
> > Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> > Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
> > ---
> > fs/open.c | 8 +++++++-
> > include/uapi/linux/falloc.h | 15 +++++++++++++++
> > 2 files changed, 22 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/open.c b/fs/open.c
> > index 36662d0..74ed498 100644
> > --- a/fs/open.c
> > +++ b/fs/open.c
> > @@ -232,7 +232,8 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> >
> > /* Return error if mode is not supported */
> > if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
> > - FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
> > + FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |
> > + FALLOC_FL_INSERT_RANGE))
> > return -EOPNOTSUPP;
> >
> > /* Punch hole and zero range are mutually exclusive */
> > @@ -250,6 +251,11 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> > (mode & ~FALLOC_FL_COLLAPSE_RANGE))
> > return -EINVAL;
> >
> > + /* Insert range should only be used exclusively. */
> > + if ((mode & FALLOC_FL_INSERT_RANGE) &&
> > + (mode & ~FALLOC_FL_INSERT_RANGE))
> > + return -EINVAL;
> > +
> > if (!(file->f_mode & FMODE_WRITE))
> > return -EBADF;
> >
> > diff --git a/include/uapi/linux/falloc.h b/include/uapi/linux/falloc.h
> > index d1197ae..1f20723 100644
> > --- a/include/uapi/linux/falloc.h
> > +++ b/include/uapi/linux/falloc.h
> > @@ -41,4 +41,19 @@
> > */
> > #define FALLOC_FL_ZERO_RANGE 0x10
> >
> > +/*
> > + * FALLOC_FL_INSERT_RANGE is use to insert space within the file size without
>
> used
>
> > + * overwriting any existing data. The contents of the file beyond offset are
> > + * shifted towards right by len bytes to create a hole. As such, this
> > + * operation will increase the size of the file by len bytes.
>
> I suppose we should split this comment up into a few paragraphs similar
> to the collapse range comment it is based on. That means we split
> here...
>
> > + * Different filesystems may implement different limitations on the granularity
> > + * of the operation. Most will limit operations to filesystem block size
> > + * boundaries, but this boundary may be larger or smaller depending on
> > + * the filesystem and/or the configuration of the filesystem or file.
>
> ... and here.
>
> Otherwise this looks fine to me.
Okay, I will fix them.
>
> Brian
>
> > + * Attempting to insert space using this flag at OR beyond the end of
> > + * the file is considered an illegal operation - just use ftruncate(2) or
> > + * fallocate(2) with mode 0 for such type of operations.
> > + */
> > +#define FALLOC_FL_INSERT_RANGE 0x20
> > +
> > #endif /* _UAPI_FALLOC_H_ */
> > --
> > 1.7.11-rc0
> >