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1 | Read/Write HPFS 2.09 |
2 | 1998-2004, Mikulas Patocka |
3 | |
4 | email: mikulas@artax.karlin.mff.cuni.cz |
5 | homepage: http://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/index-e.cgi |
6 | |
7 | CREDITS: |
8 | Chris Smith, 1993, original read-only HPFS, some code and hpfs structures file |
9 | is taken from it |
10 | Jacques Gelinas, MSDos mmap, Inspired by fs/nfs/mmap.c (Jon Tombs 15 Aug 1993) |
11 | Werner Almesberger, 1992, 1993, MSDos option parser & CR/LF conversion |
12 | |
13 | Mount options |
14 | |
15 | uid=xxx,gid=xxx,umask=xxx (default uid=gid=0 umask=default_system_umask) |
16 | Set owner/group/mode for files that do not have it specified in extended |
17 | attributes. Mode is inverted umask - for example umask 027 gives owner |
18 | all permission, group read permission and anybody else no access. Note |
19 | that for files mode is anded with 0666. If you want files to have 'x' |
20 | rights, you must use extended attributes. |
21 | case=lower,asis (default asis) |
22 | File name lowercasing in readdir. |
23 | conv=binary,text,auto (default binary) |
24 | CR/LF -> LF conversion, if auto, decision is made according to extension |
25 | - there is a list of text extensions (I thing it's better to not convert |
26 | text file than to damage binary file). If you want to change that list, |
27 | change it in the source. Original readonly HPFS contained some strange |
28 | heuristic algorithm that I removed. I thing it's danger to let the |
29 | computer decide whether file is text or binary. For example, DJGPP |
30 | binaries contain small text message at the beginning and they could be |
31 | misidentified and damaged under some circumstances. |
32 | check=none,normal,strict (default normal) |
33 | Check level. Selecting none will cause only little speedup and big |
34 | danger. I tried to write it so that it won't crash if check=normal on |
35 | corrupted filesystems. check=strict means many superfluous checks - |
36 | used for debugging (for example it checks if file is allocated in |
37 | bitmaps when accessing it). |
38 | errors=continue,remount-ro,panic (default remount-ro) |
39 | Behaviour when filesystem errors found. |
40 | chkdsk=no,errors,always (default errors) |
41 | When to mark filesystem dirty so that OS/2 checks it. |
42 | eas=no,ro,rw (default rw) |
43 | What to do with extended attributes. 'no' - ignore them and use always |
44 | values specified in uid/gid/mode options. 'ro' - read extended |
45 | attributes but do not create them. 'rw' - create extended attributes |
46 | when you use chmod/chown/chgrp/mknod/ln -s on the filesystem. |
47 | timeshift=(-)nnn (default 0) |
48 | Shifts the time by nnn seconds. For example, if you see under linux |
49 | one hour more, than under os/2, use timeshift=-3600. |
50 | |
51 | |
52 | File names |
53 | |
54 | As in OS/2, filenames are case insensitive. However, shell thinks that names |
55 | are case sensitive, so for example when you create a file FOO, you can use |
56 | 'cat FOO', 'cat Foo', 'cat foo' or 'cat F*' but not 'cat f*'. Note, that you |
57 | also won't be able to compile linux kernel (and maybe other things) on HPFS |
58 | because kernel creates different files with names like bootsect.S and |
59 | bootsect.s. When searching for file thats name has characters >= 128, codepages |
60 | are used - see below. |
61 | OS/2 ignores dots and spaces at the end of file name, so this driver does as |
62 | well. If you create 'a. ...', the file 'a' will be created, but you can still |
63 | access it under names 'a.', 'a..', 'a . . . ' etc. |
64 | |
65 | |
66 | Extended attributes |
67 | |
68 | On HPFS partitions, OS/2 can associate to each file a special information called |
69 | extended attributes. Extended attributes are pairs of (key,value) where key is |
70 | an ascii string identifying that attribute and value is any string of bytes of |
71 | variable length. OS/2 stores window and icon positions and file types there. So |
72 | why not use it for unix-specific info like file owner or access rights? This |
73 | driver can do it. If you chown/chgrp/chmod on a hpfs partition, extended |
74 | attributes with keys "UID", "GID" or "MODE" and 2-byte values are created. Only |
75 | that extended attributes those value differs from defaults specified in mount |
76 | options are created. Once created, the extended attributes are never deleted, |
77 | they're just changed. It means that when your default uid=0 and you type |
78 | something like 'chown luser file; chown root file' the file will contain |
79 | extended attribute UID=0. And when you umount the fs and mount it again with |
80 | uid=luser_uid, the file will be still owned by root! If you chmod file to 444, |
81 | extended attribute "MODE" will not be set, this special case is done by setting |
82 | read-only flag. When you mknod a block or char device, besides "MODE", the |
83 | special 4-byte extended attribute "DEV" will be created containing the device |
84 | number. Currently this driver cannot resize extended attributes - it means |
85 | that if somebody (I don't know who?) has set "UID", "GID", "MODE" or "DEV" |
86 | attributes with different sizes, they won't be rewritten and changing these |
87 | values doesn't work. |
88 | |
89 | |
90 | Symlinks |
91 | |
92 | You can do symlinks on HPFS partition, symlinks are achieved by setting extended |
93 | attribute named "SYMLINK" with symlink value. Like on ext2, you can chown and |
94 | chgrp symlinks but I don't know what is it good for. chmoding symlink results |
95 | in chmoding file where symlink points. These symlinks are just for Linux use and |
96 | incompatible with OS/2. OS/2 PmShell symlinks are not supported because they are |
97 | stored in very crazy way. They tried to do it so that link changes when file is |
98 | moved ... sometimes it works. But the link is partly stored in directory |
99 | extended attributes and partly in OS2SYS.INI. I don't want (and don't know how) |
100 | to analyze or change OS2SYS.INI. |
101 | |
102 | |
103 | Codepages |
104 | |
105 | HPFS can contain several uppercasing tables for several codepages and each |
106 | file has a pointer to codepage its name is in. However OS/2 was created in |
107 | America where people don't care much about codepages and so multiple codepages |
108 | support is quite buggy. I have Czech OS/2 working in codepage 852 on my disk. |
109 | Once I booted English OS/2 working in cp 850 and I created a file on my 852 |
110 | partition. It marked file name codepage as 850 - good. But when I again booted |
111 | Czech OS/2, the file was completely inaccessible under any name. It seems that |
112 | OS/2 uppercases the search pattern with its system code page (852) and file |
113 | name it's comparing to with its code page (850). These could never match. Is it |
114 | really what IBM developers wanted? But problems continued. When I created in |
115 | Czech OS/2 another file in that directory, that file was inaccessible too. OS/2 |
116 | probably uses different uppercasing method when searching where to place a file |
117 | (note, that files in HPFS directory must be sorted) and when searching for |
118 | a file. Finally when I opened this directory in PmShell, PmShell crashed (the |
119 | funny thing was that, when rebooted, PmShell tried to reopen this directory |
120 | again :-). chkdsk happily ignores these errors and only low-level disk |
121 | modification saved me. Never mix different language versions of OS/2 on one |
122 | system although HPFS was designed to allow that. |
123 | OK, I could implement complex codepage support to this driver but I think it |
124 | would cause more problems than benefit with such buggy implementation in OS/2. |
125 | So this driver simply uses first codepage it finds for uppercasing and |
126 | lowercasing no matter what's file codepage index. Usually all file names are in |
127 | this codepage - if you don't try to do what I described above :-) |
128 | |
129 | |
130 | Known bugs |
131 | |
132 | HPFS386 on OS/2 server is not supported. HPFS386 installed on normal OS/2 client |
133 | should work. If you have OS/2 server, use only read-only mode. I don't know how |
134 | to handle some HPFS386 structures like access control list or extended perm |
135 | list, I don't know how to delete them when file is deleted and how to not |
136 | overwrite them with extended attributes. Send me some info on these structures |
137 | and I'll make it. However, this driver should detect presence of HPFS386 |
138 | structures, remount read-only and not destroy them (I hope). |
139 | |
140 | When there's not enough space for extended attributes, they will be truncated |
141 | and no error is returned. |
142 | |
143 | OS/2 can't access files if the path is longer than about 256 chars but this |
144 | driver allows you to do it. chkdsk ignores such errors. |
145 | |
146 | Sometimes you won't be able to delete some files on a very full filesystem |
147 | (returning error ENOSPC). That's because file in non-leaf node in directory tree |
148 | (one directory, if it's large, has dirents in tree on HPFS) must be replaced |
149 | with another node when deleted. And that new file might have larger name than |
150 | the old one so the new name doesn't fit in directory node (dnode). And that |
151 | would result in directory tree splitting, that takes disk space. Workaround is |
152 | to delete other files that are leaf (probability that the file is non-leaf is |
153 | about 1/50) or to truncate file first to make some space. |
154 | You encounter this problem only if you have many directories so that |
155 | preallocated directory band is full i.e. |
156 | number_of_directories / size_of_filesystem_in_mb > 4. |
157 | |
158 | You can't delete open directories. |
159 | |
160 | You can't rename over directories (what is it good for?). |
161 | |
162 | Renaming files so that only case changes doesn't work. This driver supports it |
163 | but vfs doesn't. Something like 'mv file FILE' won't work. |
164 | |
165 | All atimes and directory mtimes are not updated. That's because of performance |
166 | reasons. If you extremely wish to update them, let me know, I'll write it (but |
167 | it will be slow). |
168 | |
169 | When the system is out of memory and swap, it may slightly corrupt filesystem |
170 | (lost files, unbalanced directories). (I guess all filesystem may do it). |
171 | |
172 | When compiled, you get warning: function declaration isn't a prototype. Does |
173 | anybody know what does it mean? |
174 | |
175 | |
176 | What does "unbalanced tree" message mean? |
177 | |
178 | Old versions of this driver created sometimes unbalanced dnode trees. OS/2 |
179 | chkdsk doesn't scream if the tree is unbalanced (and sometimes creates |
180 | unbalanced trees too :-) but both HPFS and HPFS386 contain bug that it rarely |
181 | crashes when the tree is not balanced. This driver handles unbalanced trees |
182 | correctly and writes warning if it finds them. If you see this message, this is |
183 | probably because of directories created with old version of this driver. |
184 | Workaround is to move all files from that directory to another and then back |
185 | again. Do it in Linux, not OS/2! If you see this message in directory that is |
186 | whole created by this driver, it is BUG - let me know about it. |
187 | |
188 | |
189 | Bugs in OS/2 |
190 | |
191 | When you have two (or more) lost directories pointing each to other, chkdsk |
192 | locks up when repairing filesystem. |
193 | |
194 | Sometimes (I think it's random) when you create a file with one-char name under |
195 | OS/2, OS/2 marks it as 'long'. chkdsk then removes this flag saying "Minor fs |
196 | error corrected". |
197 | |
198 | File names like "a .b" are marked as 'long' by OS/2 but chkdsk "corrects" it and |
199 | marks them as short (and writes "minor fs error corrected"). This bug is not in |
200 | HPFS386. |
201 | |
202 | Codepage bugs described above. |
203 | |
204 | If you don't install fixpacks, there are many, many more... |
205 | |
206 | |
207 | History |
208 | |
209 | 0.90 First public release |
210 | 0.91 Fixed bug that caused shooting to memory when write_inode was called on |
211 | open inode (rarely happened) |
212 | 0.92 Fixed a little memory leak in freeing directory inodes |
213 | 0.93 Fixed bug that locked up the machine when there were too many filenames |
214 | with first 15 characters same |
215 | Fixed write_file to zero file when writing behind file end |
216 | 0.94 Fixed a little memory leak when trying to delete busy file or directory |
217 | 0.95 Fixed a bug that i_hpfs_parent_dir was not updated when moving files |
218 | 1.90 First version for 2.1.1xx kernels |
219 | 1.91 Fixed a bug that chk_sectors failed when sectors were at the end of disk |
220 | Fixed a race-condition when write_inode is called while deleting file |
221 | Fixed a bug that could possibly happen (with very low probability) when |
222 | using 0xff in filenames |
223 | Rewritten locking to avoid race-conditions |
224 | Mount option 'eas' now works |
225 | Fsync no longer returns error |
226 | Files beginning with '.' are marked hidden |
227 | Remount support added |
228 | Alloc is not so slow when filesystem becomes full |
229 | Atimes are no more updated because it slows down operation |
230 | Code cleanup (removed all commented debug prints) |
231 | 1.92 Corrected a bug when sync was called just before closing file |
232 | 1.93 Modified, so that it works with kernels >= 2.1.131, I don't know if it |
233 | works with previous versions |
234 | Fixed a possible problem with disks > 64G (but I don't have one, so I can't |
235 | test it) |
236 | Fixed a file overflow at 2G |
237 | Added new option 'timeshift' |
238 | Changed behaviour on HPFS386: It is now possible to operate on HPFS386 in |
239 | read-only mode |
240 | Fixed a bug that slowed down alloc and prevented allocating 100% space |
241 | (this bug was not destructive) |
242 | 1.94 Added workaround for one bug in Linux |
243 | Fixed one buffer leak |
244 | Fixed some incompatibilities with large extended attributes (but it's still |
245 | not 100% ok, I have no info on it and OS/2 doesn't want to create them) |
246 | Rewritten allocation |
247 | Fixed a bug with i_blocks (du sometimes didn't display correct values) |
248 | Directories have no longer archive attribute set (some programs don't like |
249 | it) |
250 | Fixed a bug that it set badly one flag in large anode tree (it was not |
251 | destructive) |
252 | 1.95 Fixed one buffer leak, that could happen on corrupted filesystem |
253 | Fixed one bug in allocation in 1.94 |
254 | 1.96 Added workaround for one bug in OS/2 (HPFS locked up, HPFS386 reported |
255 | error sometimes when opening directories in PMSHELL) |
256 | Fixed a possible bitmap race |
257 | Fixed possible problem on large disks |
258 | You can now delete open files |
259 | Fixed a nondestructive race in rename |
260 | 1.97 Support for HPFS v3 (on large partitions) |
261 | Fixed a bug that it didn't allow creation of files > 128M (it should be 2G) |
262 | 1.97.1 Changed names of global symbols |
263 | Fixed a bug when chmoding or chowning root directory |
264 | 1.98 Fixed a deadlock when using old_readdir |
265 | Better directory handling; workaround for "unbalanced tree" bug in OS/2 |
266 | 1.99 Corrected a possible problem when there's not enough space while deleting |
267 | file |
268 | Now it tries to truncate the file if there's not enough space when deleting |
269 | Removed a lot of redundant code |
270 | 2.00 Fixed a bug in rename (it was there since 1.96) |
271 | Better anti-fragmentation strategy |
272 | 2.01 Fixed problem with directory listing over NFS |
273 | Directory lseek now checks for proper parameters |
274 | Fixed race-condition in buffer code - it is in all filesystems in Linux; |
275 | when reading device (cat /dev/hda) while creating files on it, files |
276 | could be damaged |
277 | 2.02 Workaround for bug in breada in Linux. breada could cause accesses beyond |
278 | end of partition |
279 | 2.03 Char, block devices and pipes are correctly created |
280 | Fixed non-crashing race in unlink (Alexander Viro) |
281 | Now it works with Japanese version of OS/2 |
282 | 2.04 Fixed error when ftruncate used to extend file |
283 | 2.05 Fixed crash when got mount parameters without = |
284 | Fixed crash when allocation of anode failed due to full disk |
285 | Fixed some crashes when block io or inode allocation failed |
286 | 2.06 Fixed some crash on corrupted disk structures |
287 | Better allocation strategy |
288 | Reschedule points added so that it doesn't lock CPU long time |
289 | It should work in read-only mode on Warp Server |
290 | 2.07 More fixes for Warp Server. Now it really works |
291 | 2.08 Creating new files is not so slow on large disks |
292 | An attempt to sync deleted file does not generate filesystem error |
293 | 2.09 Fixed error on extremely fragmented files |
294 | |
295 | |
296 | vim: set textwidth=80: |
297 |
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