archive mirror
 help / color / mirror / Atom feed
From: James W McMechan <>
Subject: Re: Oops with tmpfs on both 2.4.22 & 2.6.0-test11
Date: Wed, 3 Dec 2003 03:06:14 -0800	[thread overview]
Message-ID: <> (raw)

> Hi,
> I hope nobody minds me jumping in this thread. I have been looking 
> at this code for some time and hope I have got the facts correct.
Thank you, so far it is no longer crashing :)

> The two list_xxx macros as mentioned (fs/libfs.c:line 137) adjusts 
> the cursor dentry to the beginning of the d_subdirs list needed for 
> (file->f_pos == 2) as there can be additions in the d_subdirs list 
> after the open call and before ->lseek or ->readdir call.
> The cursor adjustment in dcache_dir_lseek() (fs/libfs.c: line 90) 
> always puts the cursor just before the last looked dentry in the
> while loop. 
> But it is problematic when we have an empty directory and 
> (file->f_pos == 2)
> In this case we have the loop counter p pointing to the cursor and 
> doing list_del and list_add_tail of the same list node results in oops.
This is where I get mildly lost, from what you are saying here I
would have expected a test on list_empty rather than on
fpos==2 also this occurs in every file, will starting in a different
pos in the list cause problems?

With further testing it also Oops even when the dir is not empty
I did a "touch /dev/shm/1 /dev/shm/2 /dev/shm/3" to put some
entries in the dir first and the original still oops at offset 2

I should do more testing, to see if I can find out what happens
on non empty dirs, because I was thinking it was due to the
dir being empty, which now appears not to be true.

> The following patch takes (file->f_post == 2) as a special case and 
> adjusts the cursor dentry by putting it right at the beginning of the 
> d_subdirs list.
Also is the new variable dentry needed or just a optimization?
It looks functionally equivalent, but perhaps it is needed for 
something I am not seeing at the moment.
> Thanks
> Maneesh

The best thing to hit the internet in years - Juno SpeedBand!
Surf the web up to FIVE TIMES FASTER!
Only $14.95/ month - visit to sign up today!

             reply	other threads:[~2003-12-03 11:15 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-03 11:06 James W McMechan [this message]
2003-12-03 12:02 ` Oops with tmpfs on both 2.4.22 & 2.6.0-test11 Maneesh Soni
     [not found] <>
2003-12-08  5:10 ` Maneesh Soni
  -- strict thread matches above, loose matches on Subject: below --
2003-12-07 22:48 James McMechan
2003-12-01  2:59 James W McMechan
2003-12-01 11:37 ` Maneesh Soni
2003-12-01  2:06 James W McMechan
2003-12-01  4:51 ` William Lee Irwin III
2003-12-01  1:06 James W McMechan
2003-12-01  3:43 ` William Lee Irwin III
2003-11-30 21:17 James W McMechan
2003-12-01  1:21 ` William Lee Irwin III
2003-12-01  7:58   ` Andries Brouwer
2003-12-01  8:00     ` William Lee Irwin III
2003-11-30 17:34 James W McMechan
2003-11-30 20:06 ` William Lee Irwin III
2003-11-30 21:21   ` Oleg Drokin
2003-11-30 16:57 James W McMechan
2003-11-30 19:27 ` William Lee Irwin III

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).