REISERFS_MAX_NAME and ENAMETOOLONG

REISERFS_MAX_NAME and ENAMETOOLONG

[Xuân Baldauf]

Hello,

when downloading something from java.sun.com (e.g. 
http://javashoplm.sun.com/ECom/docs/Welcome.jsp?StoreId=22&PartDetailId=jdk-1.5.0-doc-oth-JPR&SiteId=JSC&TransactionId=noreg 
), very long URLs are encountered. When trying to download using "wget", 
wget tries to open a file with those long filenames, and fails with 
ENAMETOOLONG (File name too long).

I think that the limit is due to the REISERFS_MAX_NAME macro 
(http://lxr.linux.no/source/include/linux/reiserfs_fs.h?v=2.6.10#L1107), 
which currently resolves to "255" (which supposedly means 255 bytes).

Is it safe to change REISERFS_MAX_NAME to something larger, or does this 
change the disk layout in an unexpected or incompatible way?

Thanks,

Xuân Baldauf.

Re: REISERFS_MAX_NAME and ENAMETOOLONG

[Vladimir V. Saveliev]

Hello

Xuân Baldauf wrote:
> Hello,
> 
> when downloading something from java.sun.com (e.g.
> http://javashoplm.sun.com/ECom/docs/Welcome.jsp?StoreId=22&PartDetailId=jdk-1.5.0-doc-oth-JPR&SiteId=JSC&TransactionId=noreg
> ), very long URLs are encountered. When trying to download using "wget",
> wget tries to open a file with those long filenames, and fails with
> ENAMETOOLONG (File name too long).
> 
> I think that the limit is due to the REISERFS_MAX_NAME macro
> (http://lxr.linux.no/source/include/linux/reiserfs_fs.h?v=2.6.10#L1107),
> which currently resolves to "255" (which supposedly means 255 bytes).
> 
> Is it safe to change REISERFS_MAX_NAME to something larger, or does this
> change the disk layout in an unexpected or incompatible way?
> 

Yes. Max long name in reiserfs used to be much longer and then it was changed for compilability with something.
I believe you can easlily change it to 3500.

> Thanks,
> 
> Xuân Baldauf.
> 
> 
> 

Re: REISERFS_MAX_NAME and ENAMETOOLONG

[Jeff Mahoney]

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Hash: SHA1

Vladimir V. Saveliev wrote:
> Hello
> 
> Xuân Baldauf wrote:
>>Hello,
>>
>>when downloading something from java.sun.com (e.g.
>>http://javashoplm.sun.com/ECom/docs/Welcome.jsp?StoreId=22&PartDetailId=jdk-1.5.0-doc-oth-JPR&SiteId=JSC&TransactionId=noreg
>>), very long URLs are encountered. When trying to download using "wget",
>>wget tries to open a file with those long filenames, and fails with
>>ENAMETOOLONG (File name too long).
>>
>>I think that the limit is due to the REISERFS_MAX_NAME macro
>>(http://lxr.linux.no/source/include/linux/reiserfs_fs.h?v=2.6.10#L1107),
>>which currently resolves to "255" (which supposedly means 255 bytes).
>>
>>Is it safe to change REISERFS_MAX_NAME to something larger, or does this
>>change the disk layout in an unexpected or incompatible way?
>>
> 
> Yes. Max long name in reiserfs used to be much longer and then it was changed for compilability with something.
> I believe you can easlily change it to 3500.

Just as a data point:

http://marc.theaimsgroup.com/?l=reiserfs&m=97908551206263&w=2

The current state:

The kernel doesn't care about the length of a file name, so long as the
maximum path used to access it is below PATH_MAX (currently 4k). dirents
are dynamically sized, so there is no more 255 byte limit inside the kernel.

Glibc still defines dirent->d_name as char[256] for backward
compatibility. If the kernel supports d_reclen (which it has for a very
long time), dirents are treated as dynamically sized. Since glibc
allocates an 8k (_IO_BUFSIZE) buffer and passes it to sys_getdents,
proper bounds checking is done, and the max length is supported.

I did a quick test using your suggestion on my development machine, and
got proper results back.

- -Jeff

- --
Jeff Mahoney
SuSE Labs
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Re: REISERFS_MAX_NAME and ENAMETOOLONG

[Xuân Baldauf]

Jeff Mahoney wrote:
> Vladimir V. Saveliev wrote:
> >Hello
>
> >Xuân Baldauf wrote:
> >>Hello,
> >>
> >>when downloading something from java.sun.com (e.g.
> >>http://javashoplm.sun.com/ECom/docs/Welcome.jsp?StoreId=22&PartDetailId=jdk-1.5.0-doc-oth-JPR&SiteId=JSC&TransactionId=noreg
> >>), very long URLs are encountered. When trying to download using "wget",
> >>wget tries to open a file with those long filenames, and fails with
> >>ENAMETOOLONG (File name too long).
> >>
> >>I think that the limit is due to the REISERFS_MAX_NAME macro
> >>(http://lxr.linux.no/source/include/linux/reiserfs_fs.h?v=2.6.10#L1107),
> >>which currently resolves to "255" (which supposedly means 255 bytes).
> >>
> >>Is it safe to change REISERFS_MAX_NAME to something larger, or does this
> >>change the disk layout in an unexpected or incompatible way?
> >>
> >Yes. Max long name in reiserfs used to be much longer and then it was
> changed for compilability with something.
> >I believe you can easlily change it to 3500.
>
> Just as a data point:
>
> http://marc.theaimsgroup.com/?l=reiserfs&m=97908551206263&w=2
Interesting story. :-) It also tells how imposed (arbitrary) limits get
spread (by a kind of "limits group dynamics") instead of getting
removed. :-|
>
> The current state:
>
> The kernel doesn't care about the length of a file name, so long as the
> maximum path used to access it is below PATH_MAX (currently 4k). dirents
> are dynamically sized, so there is no more 255 byte limit inside the
> kernel.
>
> Glibc still defines dirent->d_name as char[256] for backward
> compatibility. If the kernel supports d_reclen (which it has for a very
> long time), dirents are treated as dynamically sized. Since glibc
> allocates an 8k (_IO_BUFSIZE) buffer and passes it to sys_getdents,
> proper bounds checking is done, and the max length is supported.
>
> I did a quick test using your suggestion on my development machine, and
> got proper results back.
So even a full userland recompile is not needed anymore in these days,
because the kernel (REISERFS_MAX_NAME) is the only limiting component
(up to the next limit PATH_MAX)?
>
> -Jeff
Xuân.
>
> --
> Jeff Mahoney
> SuSE Labs

Re: REISERFS_MAX_NAME and ENAMETOOLONG

[Chet Hosey]

On Mon, Aug 22, 2005 at 11:42:44AM +0200, Xu?n Baldauf wrote:
> Hello,
> 
> when downloading something from java.sun.com (e.g. 
> http://javashoplm.sun.com/ECom/docs/Welcome.jsp?StoreId=22&PartDetailId=jdk-1.5.0-doc-oth-JPR&SiteId=JSC&TransactionId=noreg 
> ), very long URLs are encountered. When trying to download using "wget", 
> wget tries to open a file with those long filenames, and fails with 
> ENAMETOOLONG (File name too long).
> 
> I think that the limit is due to the REISERFS_MAX_NAME macro 
> (http://lxr.linux.no/source/include/linux/reiserfs_fs.h?v=2.6.10#L1107), 
> which currently resolves to "255" (which supposedly means 255 bytes).
> 
> Is it safe to change REISERFS_MAX_NAME to something larger, or does this 
> change the disk layout in an unexpected or incompatible way?
> 
> Thanks,
> 
> Xu?n Baldauf.
> 

I'm sure you've investigated this, but you might also consider the -O
option to wget -- it probably isn't quite what you're looking for if you
are fetching multiple files (such as with --mirror), but when fetching
one file at a time it's quite a bit less drastic than recompiling the
kernel and putting extremely long file names on disk.

Chet

Re: REISERFS_MAX_NAME and ENAMETOOLONG

[michael chang]

On 8/22/05, Xuân Baldauf
<xuan--2005.08.22--reiserfs-list--namesys.com@baldauf.org> wrote:
> when downloading something from java.sun.com (e.g.
> http://javashoplm.sun.com/ECom/docs/Welcome.jsp?StoreId=22&PartDetailId=jdk-1.5.0-doc-oth-JPR&SiteId=JSC&TransactionId=noreg
> ), very long URLs are encountered. When trying to download using "wget",
> wget tries to open a file with those long filenames, and fails with
> ENAMETOOLONG (File name too long).

You may want to also try using a different way of downloading files --
for example, most of the files from the download center will supply
much shorter filenames to many standard browsers (e.g. Mozilla
Firefox, Mozilla, Opera, perhaps Konquerer and whatever GNOME uses,
and maybe lynx/links/links2/elinks (dunno which)).  Also, if you're
mirroring, try looking at HTTrack.  [Although, yes, wget is much
smaller. ^^]

-- 
~Mike
 - Just my two cents
 - No man is an island, and no man is unable.