patch-2.1.122 linux/fs/umsdos/README-WIP.txt

• Lines: 247
• Date: Wed Sep 16 15:12:31 1998
• Orig file: v2.1.121/linux/fs/umsdos/README-WIP.txt
• Orig date: Sat Sep 5 16:46:41 1998

diff -u --recursive --new-file v2.1.121/linux/fs/umsdos/README-WIP.txt linux/fs/umsdos/README-WIP.txt
@@ -1,21 +1,31 @@
 Changes by Matija Nalis (mnalis@jagor.srce.hr) on umsdos dentry fixing
 (started by Peter T. Waltenberg <peterw@karaka.chch.cri.nz>)
+Final conversion to dentries Bill Hawes <whawes@star.net>
 
 ---------- WARNING --------- WARNING --------- WARNING -----------
-THIS IS TRULY EXPERIMENTAL.  IT IS NOT BETA YET.  PLEASE EXCUSE MY
-YELLING, BUT ANY USE OF THIS MODULE MAY VERY WELL DESTROY YOUR
-UMSDOS FILESYSTEM, AND MAYBE EVEN OTHER FILESYSTEMS IN USE.
-YOU'VE BEEN WARNED.
+There is no warning any more.
+Both read-only and read-write stuff is fixed, both in
+msdos-compatibile mode, and in umsdos EMD mode, and it seems stable.
+There are still few symlink/hardlink nuisances, but those are not fatal.
+
+I'd call it wide beta, and ask for as many people as possible to
+come and test it! See notes below for some more information, or if
+you are trying to use UMSDOS as root partition.
 ---------- WARNING --------- WARNING --------- WARNING -----------
 
-Current status (980901) - UMSDOS dentry-WIP-Beta 0.82-7:
+Legend: those lines marked with '+' on the beggining of line indicates it
+passed all of my tests, and performed perfect in all of them.
+
+Current status (980915) - UMSDOS dentry-Beta 0.83:
 
 (1) pure MSDOS (no --linux-.--- EMD file):
 
+READ:
 + readdir			- works
 + lookup			- works
 + read file			- works
 
+WRITE:
 + creat file			- works
 + delete file			- works
 + write file			- works
@@ -24,145 +34,93 @@
 + rename dir (same dir)		- works
 + rename dir (dif. dir)		- works
 + mkdir				- works
-- rmdir 			- QUESTIONABLE. probable problem on non-empty dirs.
-
-Notes: possible very minor problems with dentry/inode/... kernel structures (very rare)
++ rmdir 			- works
 
 
 (2) umsdos (with --linux-.--- EMD file):
 
+READ:
 + readdir			- works
 + lookup 			- works
 + permissions/owners stuff	- works
 + long file names		- works
 + read file			- works
-- switching MSDOS/UMSDOS	- works?
-- switching UMSDOS/MSDOS	- works?
-- pseudo root things		- COMPLETELY UNTESTED (commented out currently!)
++ switching MSDOS/UMSDOS	- works
++ switching UMSDOS/MSDOS	- works
+- pseudo root things		- DOES NOT WORK. COMMENTED OUT. See Notes below.
 + resolve symlink		- works
 + dereference symlink		- works
-- hard links			- broken again...
-+ special files (block/char devices, FIFOs, sockets...)	- seems to work.
-- other ioctls			- some UNTESTED
 + dangling symlink		- works
+- hard links			- DOES NOT WORK CORRECTLY ALWAYS.
++ special files (block/char devices, FIFOs, sockets...)	- works
+- various umsdos ioctls		- works
 
-- create symlink		- seems to work both on short & long names now !
-- create hardlink		- WARNING: NOT FIXED YET!
-- create file			- seems to work both on short & long names now !
-- create special file		- seems to work both on short & long names now !
-- write to file			- seems to work both on short & long names now !
-- rename file (same dir)	- seems to work, but with i_count PROBLEMS
-- rename file (dif. dir)	- seems to work, but with i_count PROBLEMS
-- rename dir (same dir)		- seems to work, but with i_count PROBLEMS
-- rename dir (dif. dir)		- seems to work, but with i_count PROBLEMS
-- delete file			- seems to work fully now!
-- notify_change (chown,perms)	- seems to work!
-- delete hardlink		- WARNING: NOT FIXED YET!
-- mkdir				- seems to work both on short & long names now !
-- rmdir 			- may work, but readdir blocks linux afterwards. to be FIXED!
-- umssyncing			- seems to work, but NEEDS MORE TESTING
 
-+ CVF-FAT stuff (compressed DOS filesystem) - there is some support from Frank
+WRITE:
+- create symlink		- sometimes works, but see WARNING below
+- create hardlink		- works
++ create file			- works
++ create special file		- works
++ write to file			- works
++ rename file (same dir)	- works
++ rename file (dif. dir)	- works
+- rename hardlink (same dir)	-
+- rename hardlink (dif. dir)	-
+- rename symlink (same dir)	- 
+- rename symlink (dif. dir)	- problems sometimes. see warning below.
++ rename dir (same dir)		- works
++ rename dir (dif. dir)		- works
++ delete file			- works
++ notify_change (chown,perms)	- works
++ delete hardlink		- works
++ mkdir				- works
+- rmdir 			- HMMM. see with clean --linux-.--- files...
+- umssyncing (many ioctls)	- works
+
+
+- CVF-FAT stuff (compressed DOS filesystem) - there is some support from Frank
   Gockel <gockel@sent13.uni-duisburg.de> to use it even under umsdosfs, but I
   have no way of testing it -- please let me know if there are problems specific
   to umsdos (for instance, it works under msdosfs, but not under umsdosfs).
 
 
+Some current notes:
 
-Notes:  there is moderate trashing of dentry/inode kernel structures.  Probably
-some other kernel structures are compromised.  You should have SysRq support
-compiled in, and use Sync/Emergency-remount-RO.  If you don't try mounting
-read/write, you should have no big problems. When most things begin to work,
-I'll get to finding/fixing those inode/dentry ?_count leakages.
-
-Note 4:  rmdir(2) fails with EBUSY - sdir->i_count > 1 (like 7 ??).  It may be
-some error with dir->i_count++, or something related to iput().  See if
-number changes if we access the directory in different ways.
-
-Note 5:  there is a problem with unmounting umsdosfs.  It seems to stay
-registered or something.  Remounting the same device on any mount point with a
-different fstype (such as msdos or vfat) ignores the new fstype and umsdosfs
-kicks back in. Should be fixed in 0.82-6 (at least, with nothing in between)!
-Much of inode/dentry corruption is fixed in 0.82-7, especially when mounting
-read-only.
-
-Note 6:  also we screwed umount(2)-ing the fs at times (EBUSY), by missing
-some of those iput/dput's. When most of the rest of the code is fixed, we'll
-put them back at the correct places (hopefully). Also much better in 0.82-7.
+Note: creating and using pseudo-hardlinks is always non-perfect, especially
+in filesystems that might be externally modified like umsdos. There is
+example is specs file about it.
+
+Warning: moving symlinks around may break them until umount/remount.
+
+Warning: I seem to able to reproduce one problem with creting symlink after
+I rm -rf directory: it is manifested as symlink apperantly being regular
+file instead of symlink until next umount/mount pair. Tracking this one
+down...
+
+Wanted: I am currently looking for volunteers that already have UMSDOS
+filesystems in pseudo-root, or are able to get them, to test PSEUDO-ROOT
+stuff (and get new patches from me), which I currently can't do. Anyone know
+of URL of nice UMSDOS pseudo-root ready image ? As always, any patches or
+pointer to things done in wrong way (or ideas of better ways) are greatly
+appreciated !
+
+Note: If you are currently trying to use UMSDOS as root partition (with
+linux installed in c:\linux) it will not work. Pseudo-root is currently
+commented out. See 'wanted' above and contact me if you are interested in
+testing it.
 
 ------------------------------------------------------------------------------
 
 Some general notes:
 
-There is a great amount of kernel log messages.  Use SysRq log-level 5 to turn
-most of them off, or 4 to turn all but really fatal ones off.  Probably good
-idea to kill klogd/syslogd so it will only go to console. You can also
-comment out include/linux/umsdos_fs.h definition of UMS_DEBUG to get rid of
-most debugging messages. Please don't turn it off without good reason.
-
-It should work enough to test it, even enough to give you a few chances to
-umount/rmmod module, recompile it, and reinsert it again (but probably
-screaming about still used inodes on device and stuff).  This is first on
-my list of things to get fixed, as it would greatly improve speed of
-compile/test/reboot/set_environment/recompile cycle by removing
-'reboot/set_environment' component that now occurs every few cycles.
-
-I need some help from someone who knows more than I about the use of dentries
-and inodes.  If you can help, please contact me.  I'm mostly worried about
-iget/iput and dget/dput, and deallocating temporary dentries we create.
-Should we destroy temp dentries? using d_invalidate? using d_drop? just
-dput them?
-
-I'm unfortunately somewhat out of time to read linux-kernel, but I do check
-for messages having "UMSDOS" in the subject, and read them.  I might miss
-some in all that volume, though.  I should reply to any direct e-mail in few
-days.  If I don't, probably I never got your message.  You can try
-mnalis@voyager.hr; however mnalis@jagor.srce.hr is preferable.
-
-
-------------------------------------------------------------------------------
-some of my notes for myself /mn/:
+Good idea when running development kernels is to have SysRq support compiled
+in kernel, and use Sync/Emergency-remount-RO if you bump into problems (like
+not being able to umount(2) umsdosfs, and because of it root partition also,
+or panics which force you to reboot etc.)
+
+I'm unfortunately somewhat out of time to read linux-kernel@vger, but I do
+check for messages having "UMSDOS" in the subject, and read them.  I might
+miss some in all that volume, though.  I should reply to any direct e-mail
+in few days.  If I don't, probably I never got your message.  You can try
+mnalis-umsdos@voyager.hr; however mnalis@jagor.srce.hr is preferable.
 
-+ hardlinks/symlinks. test with files in not_the_same_dir
-- also test not_the_same_dir for other file operations like rename etc.
-- iput: device 00:00 inode 318 still has aliases! problem. Check in iput()
-  for device 0,0. Probably null pointer passed around when it shouldn't be ?
-- dput/iput problem...
-- What about .dotfiles? Are they working? How about multiple dots?
-- fix stuff like dir->i_count++ to atomic_inc(&dir->i_count) and similar?
-
-- should check what happen when multiple UMSDOSFS are mounted
-
-- chase down all "FIXME", "DELME", "CNT", check_dentry, check_inode, kill_dentry
-  and fix it properly.
-
-- umsdos_create_any - calling msdos_create will create dentry for short name. Hmmmm..?
-
-- what is dir->i_count++ ? locking directory ? should this be lock_parent or
-something ?
-
-+ i_binary=2 is for CVF (compressed filesystem).
-
-- SECURITY WARNING: short dentries should be invalidated, or they could be
-  accessed instead of proper long names.
-
-- I've put many check_dentry_path(), check_inode() calls to trace down
-  problems. those should be removed in final version.
-
-- iput()s with a "FIXME?" comment are uncommented and probably OK. Those with
-  "FIXME??" should be tested but probably work. Commented iput()s with
-  any "FIXME" comments should probably be uncommented and tested. At some
-  places we may need dput() instead of iput(), but that should be checked.
-
-+ as for iput(): (my only pointer so far. anyone else?)
-
->development I only know about iput. All functions that get an inode as
->argument and don't return it have to call iput on it before exit, i.e. when
->it is no longer needed and the code returns to vfs layer. The rest is quite
->new to me, but it might be similar for dput. Typical side effect of a
->missing iput was a memory runout (but no crash). You also couldn't unmount
->the filesystem later though no process was using it. On the other hand, one
->iput too much lead to serious pointer corruption and crashed the system
->very soon. I used to look at the FAT filesystem and copy those pieces of
->
-> Frank