On Wed, Aug 14, 2019 at 09:53:33AM +0800, Qu Wenruo wrote:
>
>
> On 2019/8/14 上午9:04, Jeff Mahoney wrote:
> > If a user attempts to resize a file system to a size under 256MiB,
> > it will be rejected with EINVAL and get then unhelpful error message
> > "ERROR: unable to resize '/path': Invalid argument."
> >
> > This commit performs that check before issuing the ioctl to report
> > a more sensible error message. We also do overflow/underflow
> > checking when -/+ size is used and report those errors as well.
> >
> > Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
> > ---
> > cmds/filesystem.c | 41 +++++++++++++++++++++++++++++++++++++++++
> > common/utils.c | 2 +-
> > common/utils.h | 2 +-
> > 3 files changed, 43 insertions(+), 2 deletions(-)
> >
> > diff --git a/cmds/filesystem.c b/cmds/filesystem.c
> > index 4f22089a..e3415126 100644
> > --- a/cmds/filesystem.c
> > +++ b/cmds/filesystem.c
> > @@ -34,10 +34,12 @@
> > #include "kerncompat.h"
> > #include "ctree.h"
> > #include "common/utils.h"
> > +#include "common/device-utils.h"
> > #include "volumes.h"
> > #include "cmds/commands.h"
> > #include "cmds/filesystem-usage.h"
> > #include "kernel-lib/list_sort.h"
> > +#include "kernel-lib/overflow.h"
> > #include "disk-io.h"
> > #include "common/help.h"
> > #include "common/fsfeatures.h"
> > @@ -1062,6 +1064,41 @@ next:
> > }
> > static DEFINE_SIMPLE_COMMAND(filesystem_defrag, "defragment");
> >
> > +static int check_resize_size(const char *path, const char *amount)
> > +{
> > + int mod = 0;
> > + u64 oldsize = 0, size, newsize;
> > +
> > + if (*amount == '-')
> > + mod = -1;
> > + else if (*amount == '+')
> > + mod = 1;
> > +
> > + if (mod) {
> > + amount++;
> > + oldsize = disk_size(path);
> > + if (oldsize == 0)
> > + return -1;
> > + }
> > +
> > + size = parse_size(amount);
> > +
> > + if (mod == -1 && check_sub_overflow(oldsize, size, &newsize)) {
> > + error("can't resize to negative size");
> > + return -1;
> > + } else if (mod == 1 && check_add_overflow(oldsize, size, &newsize)) {
> > + error("can't resize to larger than 16EiB");
> > + return -1;
> > + } else
> > + newsize = size;
> > +
> > + if (newsize < SZ_256M) {
> > + error("can't resize to size smaller than 256MiB");
> > + return -1;
> > + }
> > + return 0;
> > +}
> > +
> > static const char * const cmd_filesystem_resize_usage[] = {
> > "btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max <path>",
> > "Resize a filesystem",
> > @@ -1110,6 +1147,10 @@ static int cmd_filesystem_resize(const struct cmd_struct *cmd,
> > if (fd < 0)
> > return 1;
> >
> > + res = check_resize_size(path, amount);
> > + if (res < 0)
> > + return 1;
> > +
> > printf("Resize '%s' of '%s'\n", path, amount);
> > memset(&args, 0, sizeof(args));
> > strncpy_null(args.name, amount);
> > diff --git a/common/utils.c b/common/utils.c
> > index ad938409..f2a10ccc 100644
> > --- a/common/utils.c
> > +++ b/common/utils.c
> > @@ -638,7 +638,7 @@ static int fls64(u64 x)
> > return 64 - i;
> > }
> >
> > -u64 parse_size(char *s)
> > +u64 parse_size(const char *s)
>
> Although a good change, not sure if David will ask for an explict patch
> for that.
I've split that from the patch.
> Despite that, looks good.
Well, no. The resize specifier is more complex and has eg. formats like
1:+1G, max, 2:-2G, 3:max. Moreover the relative change must not be
compared to the 256M limit, 'resize -128M' fails while it should not for
a filesystem that's eg. 2G.
