Based on kernel version 4.1. Page generated on 2015-06-28 12:12 EST.
1 Read/Write HPFS 2.09 2 1998-2004, Mikulas Patocka 3 4 email: firstname.lastname@example.org 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: