[Samba] File Locking, Access - Inconsistencies

[Ravi Channavajhala]

On Wed, Aug 12, 2009 at 11:01 AM, Ravi
Channavajhala<ravi.channavajhala at dciera.com> wrote:
> On Wed, Aug 12, 2009 at 9:53 AM, Jeremy Allison<jra at samba.org> wrote:
>> On Wed, Aug 12, 2009 at 08:51:51AM +0530, ravi channavajhala wrote:
>>> Hi Jeremy,
>>>
>>> Why would the file name be an issue here?  It is not just one file, several
>>> files are getting affected.  I followed your earlier discussion on the issue
>>> way back in 2002, can you suggest something to try.  Really, I will take
>>> whatever I can get.
>>
>> Firstly, let's keep the list CC:ed so we keep
>> everyone up to date. I'm asking what file name
>> the fcntl is blocked in, as I want to know if
>> this is a Samba tdb, or a file the server is
>> trying to access. The Samba server should never
>> make a blocking fcntl lock call on a user data
>> file, but will make such calls on tdb files.
>>
>> So please let me know what file the fcntl syscall
>> is blocked in. Thanks,
>>
>> Jeremy.
>
> Sorry I must have not used reply to all.  Anyway, here is how I
> trussed.  I had the user open a file, and then capture the system
> calls made  with truss.  The fcntl appears blocking on a user file,
> but I might be incorrect because I didnt really see which file the
> file descriptor belonged to (the very first two lines of truss show
> fcntl, no other information).  Either way, if this is blocking on tbd
> file what possible recourse I can apply?  Thanks for your help.

FWIW, this is what I see on Solaris 10 (Sun's stock Samba bundled with OS)

# pstack 1968
1968:   /usr/sfw/sbin/smbd -D
 ff049c64 fcntl    (a, 23, ffbff750)
 ff0398c0 fcntl    (a, 23, ffbff750, a, fee02a00, ff0c72b4) + 18
 00272ec0 tdb_brlock (448180, 22dc, 2, 23, 0, 1) + 90
 002731dc tdb_lock (448180, 88d, 2, 20, 18ec34, 401c98) + 17c
 001ff048 ???????? (fffa7038, 43d960, 1d3d8, 453660, 9ea5, 453670)
 001f8538 is_locked (43d960, feff, 0, 1000, 0, 0) + 1e8
 000926a4 reply_read_and_X (495ca8, 4751f0, 3f, 43d960, 20000, 0) + 2ec
 000d4c64 ???????? (495ca8, 454da0, 4751f0, 3f, 20000, 0)
 000d4db8 ???????? (9400, 4751f0, 3f, 20000, 9400, 32cf4c)
 000d5060 ???????? (454da0, 4751f0, 0, 1, 401c98, 6c00)
 000d634c smbd_process (fff58830, 6c7c, 401c98, 93a80, 20441, 17d) + 1e4
 0032f028 main     (0, 392800, 1, 40aacc, 40ca28, 0) + afc
 0004dda8 _start   (0, 0, 0, 0, 0, 0) + 108

# truss -v all -aef -p 1968
1968:       *** SUID: ruid/euid/suid = 0 / 2110 / 2110  ***
1968:       *** SGID: rgid/egid/sgid = 0 / 2110 / 2110  ***
1968:   psargs: /usr/sfw/sbin/smbd -D
1968:   fcntl(10, F_SETLKW64, 0xFFBFF750) (sleeping...)
1968:           typ=F_WRLCK  whence=SEEK_SET start=8924  len=1     sys=3  pid=0

Now on Solaris 9 (Compiled with gcc)

#truss -aef -v all -p 3623
3623:       *** SUID: ruid/euid/suid = 0 / 1598 / 1598  ***
3623:       *** SGID: rgid/egid/sgid = 0 / 1598 / 1598  ***
3623:   psargs: /usr/local/samba/sbin/smbd -D -d 3 -s
/usr/local/samba/etc/smb.conf
3623:   fcntl(25, F_GETLK64, 0xFFBFF100) (sleeping...)
3623:           typ=F_RDLCK  whence=SEEK_SET start=0     len=512   sys=0  pid=0

#pstack 3623
3623:   /usr/local/samba/sbin/smbd -D -d 3 -s /usr/local/samba/etc/smb.conf
 00000000 fcntl    (19, 21, ffbff100)

 #pflags 3623
3623:   /usr/local/samba/sbin/smbd -D -d 3 -s /usr/local/samba/etc/smb.conf
        data model = _ILP32  flags = PR_ORPHAN
  /1:   flags = PR_PCINVAL|PR_ASLEEP [ fcntl(0x19,0x21,0xffbff100) ]
  sigmask = 0x00011080,0x00000000

-- 
Ravi Channavajhala
http://www.dciera.com