1 Changes by Matija Nalis (mnalis@jagor.srce.hr) on umsdos dentry fixing
2 (started by Peter T. Waltenberg <peterw@karaka.chch.cri.nz>)
3 (Final conversion to dentries Bill Hawes <whawes@star.net>)
4
5 There is no warning any more.
6 Both read-only and read-write stuff is fixed, both in
7 msdos-compatibile mode, and in umsdos EMD mode, and it seems stable.
8 There are still few hardlink nuisances, but those are not fatal.
9
10 I'd call it pre-release, and ask for as many people as possible to
11 come and test it! See notes below for some more information, or if
12 you are trying to use UMSDOS as root partition.
13
14 Userland NOTE: new umsdos_progs (umssync, umssetup, udosctl & friends) that
15 will compile and work on 2.2.x kernels and glibc based systems may be found
16 at http://cvs.linux.hr/
17
18 Also look at the quick-hack "homepage" for umsdos filesystem at
19 http://www.voyager.hr/~mnalis/umsdos
20
21 Information below is getting outdated slowly -- I'll fix it one day when I
22 get enough time - there are more important things to fix right now.
23
24 Legend: those lines marked with '+' on the beggining of line indicates it
25 passed all of my tests, and performed perfect in all of them.
26
27 Current status (990202) - UMSDOS 0.85:
28
29 (1) pure MSDOS (no --linux-.--- EMD file):
30
31 READ:
32 + readdir - works
33 + lookup - works
34 + read file - works
35
36 WRITE:
37 + creat file - works
38 + delete file - works
39 + write file - works
40 + rename file (same dir) - works
41 + rename file (dif. dir) - works
42 + rename dir (same dir) - works
43 + rename dir (dif. dir) - works
44 + mkdir - works
45 + rmdir - works
46
47
48 (2) umsdos (with --linux-.--- EMD file):
49
50 READ:
51 + readdir - works
52 + lookup - works
53 + permissions/owners stuff - works
54 + long file names - works
55 + read file - works
56 + switching MSDOS/UMSDOS - works
57 + switching UMSDOS/MSDOS - works
58 - pseudo root things - works mostly. See notes below.
59 + resolve symlink - works
60 + dereference symlink - works
61 + dangling symlink - works
62 + hard links - works
63 + special files (block/char devices, FIFOs, sockets...) - works
64 + various umsdos ioctls - works
65
66
67 WRITE:
68 + create symlink - works
69 - create hardlink - works
70 + create file - works
71 + create special file - works
72 + write to file - works
73 + rename file (same dir) - works
74 + rename file (dif. dir) - works
75 - rename hardlink (same dir) -
76 - rename hardlink (dif. dir) -
77 + rename symlink (same dir) - works
78 + rename symlink (dif. dir) - works
79 + rename dir (same dir) - works
80 + rename dir (dif. dir) - works
81 + delete file - works
82 + notify_change (chown,perms) - works
83 + delete hardlink - works
84 + mkdir - works
85 + rmdir - works
86 + umssyncing (many ioctls) - works
87
88
89 - CVF-FAT stuff (compressed DOS filesystem) - there is some support from Frank
90 Gockel <gockel@sent13.uni-duisburg.de> to use it even under umsdosfs, but I
91 have no way of testing it -- please let me know if there are problems specific
92 to umsdos (for instance, it works under msdosfs, but not under umsdosfs).
93
94
95 Some current notes:
96
97 Note: creating and using pseudo-hardlinks is always non-perfect, especially
98 in filesystems that might be externally modified like umsdos. There is
99 example is specs file about it. Specifically, moving directory which
100 contains hardlinks will break them.
101
102 Note: (about pseudoroot) If you are currently trying to use UMSDOS as root
103 partition (with linux installed in c:\linux) it will boot, but there may be
104 some problems. Volunteers ready to test pseudoroot are needed (preferably
105 ones with working backups or unimportant data). For example, '/DOS' pseudo
106 directory is only partially re-implemented and buggy. It works most of the
107 time, though. Update: should work ok in 0.84, although it still does not
108 work correctly in combination with initrd featere. Working on this!
109
110 Note: (about creating hardlinks in pseudoroot mode) - hardlinks created in
111 pseudoroot mode are now again compatibile with 'normal' hardlinks, and vice
112 versa. Thanks to Sorin Iordachescu <sorin@rodae.ro> for providing fix.
113
114 Warning: (about hardlinks) - modifying hardlinks (esp. if they are in
115 different directories) are currently somewhat broken, I'm working on it.
116 Problem seems to be that code uses and updates EMD of directory where 'real
117 hardlink' is stored, not EMD of directory where our pseudo-hardlink is
118 located! I'm looking for ideas how to work around this in clean way, since
119 without it modifying hardlinks in any but most simple ways is broken!
120
121 ------------------------------------------------------------------------------
122
123 Some general notes:
124
125 Good idea when running development kernels is to have SysRq support compiled
126 in kernel, and use Sync/Emergency-remount-RO if you bump into problems (like
127 not being able to umount(2) umsdosfs, and because of it root partition also,
128 or panics which force you to reboot etc.)
129
130 I'm unfortunately somewhat out of time to read linux-kernel@vger, but I do
131 check for messages having "UMSDOS" in the subject, and read them. I might
132 miss some in all that volume, though. I should reply to any direct e-mail
133 in few days. If I don't, probably I never got your message. You can try
134 mnalis-umsdos@voyager.hr; however mnalis@jagor.srce.hr is preferable.
135
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