Re: [PATCH] io/mremap: modify argument errors of mremap command

[Zorro Lang <zlang@xxxxxxxxxx>]

On Wed, Mar 16, 2016 at 08:31:26AM -0400, Brian Foster wrote:
> On Wed, Mar 16, 2016 at 05:31:47PM +0800, Zorro Lang wrote:
> > There're 2 argument errors in mremap command:
> > 1. If run "mremap 1024 8192", it won't return error and try to
> > do "mremap 1024" silently.
> > 
> > 2. The "-f" option can't be used, due to it need a new address
> > argument as the fifth argument of mremap() syscall(man mremap).
> > 
> > This patch try to fix above two problems.
> > 
> > Signed-off-by: Zorro Lang <zlang@xxxxxxxxxx>
> > ---
> 
> A couple nits...
> 
> > 
> > Hi,
> > 
> > I'm not sure pass a address argument to mremap command is right or
> > wrong. And maybe I should use strtoul() to instead of cvtnum() for
> > address argument.
> > 
> > At least I did some simple test with this patch on my machine, results are:
> > "mremap -f 139946004389888 2048"  PASS
> > "mremap -f 4096k 2048"            PASS
> > "mremap -f 1g 2048"               PASS
> > "mremap -f 4096 2048"             FAIL as 'Permission denied'
> > 
> > What do you think of this patch?
> > 
> > Thanks,
> > Zorro
> > 
> > 
> >  io/mmap.c         | 22 +++++++++++++++-------
> >  man/man8/xfs_io.8 |  5 ++++-
> >  2 files changed, 19 insertions(+), 8 deletions(-)
> > 
> > diff --git a/io/mmap.c b/io/mmap.c
> > index 5970069..672ee61 100644
> > --- a/io/mmap.c
> > +++ b/io/mmap.c
> > @@ -589,7 +589,7 @@ mremap_help(void)
> >  "\n"
> >  " Resizes the mappping, growing or shrinking from the current size.\n"
> >  " The default stored value is 'X', repeated to fill the range specified.\n"
> > -" -f -- use the MREMAP_FIXED flag\n"
> > +" -f <new_address> -- use the MREMAP_FIXED flag to mremap on the new 
> > address\n"
> 
> Exceeds 80 chars.
> 
> >  " -m -- use the MREMAP_MAYMOVE flag\n"
> >  "\n"));
> >  }
> > @@ -600,15 +600,18 @@ mremap_f(
> >     char            **argv)
> >  {
> >     ssize_t         new_length;
> > -   void            *new_addr;
> > +   void            *new_addr = NULL;
> >     int             flags = 0;
> >     int             c;
> >     size_t          blocksize, sectsize;
> >  
> > -   while ((c = getopt(argc, argv, "fm")) != EOF) {
> > +   init_cvtnum(&blocksize, &sectsize);
> > +
> > +   while ((c = getopt(argc, argv, "f:m")) != EOF) {
> >             switch (c) {
> >             case 'f':
> >                     flags = MREMAP_FIXED|MREMAP_MAYMOVE;
> > +                   new_addr = (void *)cvtnum(blocksize, sectsize, optarg);
> >                     break;
> >             case 'm':
> >                     flags = MREMAP_MAYMOVE;
> > @@ -618,7 +621,9 @@ mremap_f(
> >             }
> >     }
> >  
> > -   init_cvtnum(&blocksize, &sectsize);
> > +   if (optind != argc - 1)
> > +           return command_usage(&mremap_cmd);
> > +
> >     new_length = cvtnum(blocksize, sectsize, argv[optind]);
> >     if (new_length < 0) {
> >             printf(_("non-numeric offset argument -- %s\n"),
> > @@ -626,7 +631,10 @@ mremap_f(
> >             return 0;
> >     }
> >  
> > -   new_addr = mremap(mapping->addr, mapping->length, new_length, flags);
> > +   if (!new_addr)
> > +           new_addr = mremap(mapping->addr, mapping->length, new_length, 
> > flags);
> > +   else
> > +           new_addr = mremap(mapping->addr, mapping->length, new_length, 
> > flags, new_addr);
> 
> Both mremap() calls above exceed 80 chars. Otherwise, this looks Ok to
> me:
> 
> Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>

Hi Brian,

Thanks for your review. I will send a V2 patch to fix these "exceed 80
chars" errors.

Thanks,
Zorro

> 
> >     if (new_addr == MAP_FAILED)
> >             perror("mremap");
> >     else {
> > @@ -697,9 +705,9 @@ mmap_init(void)
> >     mremap_cmd.altname = "mrm";
> >     mremap_cmd.cfunc = mremap_f;
> >     mremap_cmd.argmin = 1;
> > -   mremap_cmd.argmax = 2;
> > +   mremap_cmd.argmax = 3;
> >     mremap_cmd.flags = CMD_NOFILE_OK | CMD_FOREIGN_OK;
> > -   mremap_cmd.args = _("[-m|-f] newsize");
> > +   mremap_cmd.args = _("[-m|-f <new_address>] newsize");
> >     mremap_cmd.oneline =
> >             _("alters the size of the current memory mapping");
> >     mremap_cmd.help = mremap_help;
> > diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
> > index 33fbe6a..984b551 100644
> > --- a/man/man8/xfs_io.8
> > +++ b/man/man8/xfs_io.8
> > @@ -581,7 +581,7 @@ See the
> >  .B mmap
> >  command.
> >  .TP
> > -.BI "mremap [ \-f ] [ \-m ] " new_length
> > +.BI "mremap [ \-f <new_address> ] [ \-m ] " new_length
> >  Changes the current mapping size to
> >  .IR new_length .
> >  Whether the mapping may be moved is controlled by the flags passed;
> > @@ -589,6 +589,9 @@ MREMAP_FIXED
> >  .RB ( \-f ),
> >  or MREMAP_MAYMOVE
> >  .RB ( \-m ).
> > +.IR new_length
> > +specifies a page-aligned address to which the mapping must be moved. It
> > +can be setted to 139946004389888, 4096k or 1g etc.
> >  .TP
> >  .B mrm
> >  See the
> 
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