e2fsprogs: debugfs: set_inode_field fails to set block[IND]...

e2fsprogs: debugfs: set_inode_field fails to set block[IND]...

[Jun He]

Hi,
I hope this is the right place to report problems of e2fsprogs.

When trying to update block[IND], block[DIND], and block[TIND], it
gives the similar error message:

jhe@node001:~$ sudo debugfs /dev/loop0 -w -R 'set_inode_field
firstfile block[IND] 2'
debugfs 1.42 (29-Nov-2011)
set_inode_field: invalid field specifier: block[IND]

I looked at the code and found the problem in the following code in
find_field() in debugfs/set_fields.c.

    idx = strchr(arg, '[');
    if (idx) {
        *idx++ = 0;
        delim = idx + strlen(idx) - 1;
        if (!*idx || *delim != ']')
            idx = 0;
        else
            *delim = 0;
    }
    /*
     * Can we parse the number?
     */
    if (idx) {
        array_idx = strtol(idx, &tmp, 0);
        if (*tmp)
            idx = 0;
    }


When the field name is something like "block[4]", this works. It sets
'[' and ']' to 0 and converts the number between them.
When the field name is block[IND], it still replaces '[' and ']' with
0. So arg becomes 'block' and will always fail the following test of
  if (strcmp(ss->name, arg) != 0).

One possible fix is to change the max limit for field 'block', use
number to index IND, DIND, and TIND.
Or, name 'block[IND]', 'block[DIND]', and 'block[TIND]' differently
without the '[' ']'. Such as 'block.IND', 'block.DIND', 'block.TIND'.

If it's just a usage problem, please let me know how to use
set_inode_field to set block[IND].. correctly.

Thanks,
Jun

Re: e2fsprogs: debugfs: set_inode_field fails to set block[IND]...

[Darrick J. Wong]

On Mon, Aug 18, 2014 at 11:32:10PM -0500, Jun He wrote:
> Hi,
> I hope this is the right place to report problems of e2fsprogs.
> 
> When trying to update block[IND], block[DIND], and block[TIND], it
> gives the similar error message:
> 
> jhe@node001:~$ sudo debugfs /dev/loop0 -w -R 'set_inode_field
> firstfile block[IND] 2'
> debugfs 1.42 (29-Nov-2011)
> set_inode_field: invalid field specifier: block[IND]
> 
> I looked at the code and found the problem in the following code in
> find_field() in debugfs/set_fields.c.
> 
>     idx = strchr(arg, '[');
>     if (idx) {
>         *idx++ = 0;
>         delim = idx + strlen(idx) - 1;
>         if (!*idx || *delim != ']')
>             idx = 0;
>         else
>             *delim = 0;
>     }
>     /*
>      * Can we parse the number?
>      */
>     if (idx) {
>         array_idx = strtol(idx, &tmp, 0);
>         if (*tmp)
>             idx = 0;
>     }
> 
> 
> When the field name is something like "block[4]", this works. It sets
> '[' and ']' to 0 and converts the number between them.
> When the field name is block[IND], it still replaces '[' and ']' with
> 0. So arg becomes 'block' and will always fail the following test of
>   if (strcmp(ss->name, arg) != 0).
> 
> One possible fix is to change the max limit for field 'block', use
> number to index IND, DIND, and TIND.
> Or, name 'block[IND]', 'block[DIND]', and 'block[TIND]' differently
> without the '[' ']'. Such as 'block.IND', 'block.DIND', 'block.TIND'.
> 
> If it's just a usage problem, please let me know how to use
> set_inode_field to set block[IND].. correctly.

Seems pretty broken to me.  I'll review any patch you send. :)

FWIW, I've been using modify_inode to mess with those fields.

Not that either command does much good for an extent files.

--D
> 
> Thanks,
> Jun
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH] debugfs: fix set_inode_field block[IND|DIND|TIND]

[Theodore Ts'o]

After we determine that we can't parse the array value as an integer,
we need to restore the square brackets to the field name, so that we
can find a match with block[IND], block[DIND], and block[TIND] in the
inode field table.

Reported-by: Jun He <jhe@cs.wisc.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 debugfs/set_fields.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/debugfs/set_fields.c b/debugfs/set_fields.c
index 40dc5e7..6104b2b 100644
--- a/debugfs/set_fields.c
+++ b/debugfs/set_fields.c
@@ -321,8 +321,11 @@ static struct field_set_info *find_field(struct field_set_info *fields,
 	 */
 	if (idx) {
 		array_idx = strtol(idx, &tmp, 0);
-		if (*tmp)
+		if (*tmp) {
+			*(--idx) = '[';
+			*delim = ']';
 			idx = 0;
+		}
 	}
 
 	/*
-- 
2.1.0