[lustre-devel] [PATCH 1/8] lustre: seq: make seq_proc_write_common() safer

[James Simmons]

> > From: Andreas Dilger <adilger at whamcloud.com>
> >
> > Don't allow seq_proc_write_common() to specify arbitrary ranges,
> > since this can permanently corrupt the sequence controller and/or
> > sequnece server.  That would allow duplicate FID allocation, or
> > possibly prevent any new files to be created or servers to be added
> > to the filesystem.
> >
> > Instead, limit the sequence range that can be written via /proc to
> > a subset of the sequence range currently allocated to that node.
> > Add the "clear" keyword to allow dropping the entire local sequence
> > and force a new one to be fetched from the sequence server.
> >
> > WC-bug-id: https://jira.whamcloud.com/browse/LU-3642
> > Lustre-commit: 05f69f5ee20eeffcc26f643333cedcfb53ba6669
> > Signed-off-by: Andreas Dilger <adilger at whamcloud.com>
> > Reviewed-on: http://review.whamcloud.com/7123
> > Reviewed-by: Jinshan Xiong <jinshan.xiong at gmail.com>
> > Reviewed-by: Alex Zhuravlev <bzzz at whamcloud.com>
> > Reviewed-by: James Simmons <uja.ornl at gmail.com>
> > Reviewed-by: Oleg Drokin <green at whamclould.com>
> > ---
> >  fs/lustre/fid/lproc_fid.c | 12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> I already have this is my backport branch.
>  a8ab6db57383

I pushed the first batch from your backport branch. I remember 
remember pushing some patches before for fid / fld that ended up
being server only patches. Its not really clear what is server or
client in that code. I was hoping for some feedback from Andreas
and / or Oleg about this patch collect being server only.

> > diff --git a/fs/lustre/fid/lproc_fid.c b/fs/lustre/fid/lproc_fid.c
> > index 94869d4..e2e47df 100644
> > --- a/fs/lustre/fid/lproc_fid.c
> > +++ b/fs/lustre/fid/lproc_fid.c
> > @@ -52,14 +52,18 @@
> >  /* Format: [0x64BIT_INT - 0x64BIT_INT] + 32 bytes just in case */
> >  #define MAX_FID_RANGE_STRLEN (32 + 2 * 2 * sizeof(u64))
> >  /*
> > - * Note: this function is only used for testing, it is no safe for production
> > - * use.
> > + * Reduce the SEQ range allocated to a node to a strict subset of the range
> > + * currently-allocated SEQ range.  If the specified range is "clear", then
> > + * drop all allocated sequences and request a new one from the master.
> > + *
> > + * Note: this function should only be used for testing, it is not necessarily
> > + * safe for production use.
> >   */
> >  static int
> >  ldebugfs_fid_write_common(const char __user *buffer, size_t count,
> >  			  struct lu_seq_range *range)
> >  {
> > -	struct lu_seq_range tmp;
> > +	struct lu_seq_range tmp = { 0, };
> >  	int rc;
> >  	char kernbuf[MAX_FID_RANGE_STRLEN];
> >  
> > @@ -82,8 +86,6 @@
> >  	rc = sscanf(kernbuf, "[%llx - %llx]\n",
> >  		    (unsigned long long *)&tmp.lsr_start,
> >  		    (unsigned long long *)&tmp.lsr_end);
> > -	if (rc != 2)
> > -		return -EINVAL;
> >  	if (!lu_seq_range_is_sane(&tmp) || lu_seq_range_is_zero(&tmp) ||
> >  	    tmp.lsr_start < range->lsr_start || tmp.lsr_end > range->lsr_end)
> >  		return -EINVAL;
> > -- 
> > 1.8.3.1
>