| Read/Write HPFS 2.09 | |
| 1998-2004, Mikulas Patocka | |
| email: mikulas@artax.karlin.mff.cuni.cz | |
| homepage: http://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/index-e.cgi | |
| CREDITS: | |
| Chris Smith, 1993, original read-only HPFS, some code and hpfs structures file | |
| is taken from it | |
| Jacques Gelinas, MSDos mmap, Inspired by fs/nfs/mmap.c (Jon Tombs 15 Aug 1993) | |
| Werner Almesberger, 1992, 1993, MSDos option parser & CR/LF conversion | |
| Mount options | |
| uid=xxx,gid=xxx,umask=xxx (default uid=gid=0 umask=default_system_umask) | |
| Set owner/group/mode for files that do not have it specified in extended | |
| attributes. Mode is inverted umask - for example umask 027 gives owner | |
| all permission, group read permission and anybody else no access. Note | |
| that for files mode is anded with 0666. If you want files to have 'x' | |
| rights, you must use extended attributes. | |
| case=lower,asis (default asis) | |
| File name lowercasing in readdir. | |
| conv=binary,text,auto (default binary) | |
| CR/LF -> LF conversion, if auto, decision is made according to extension | |
| - there is a list of text extensions (I thing it's better to not convert | |
| text file than to damage binary file). If you want to change that list, | |
| change it in the source. Original readonly HPFS contained some strange | |
| heuristic algorithm that I removed. I thing it's danger to let the | |
| computer decide whether file is text or binary. For example, DJGPP | |
| binaries contain small text message at the beginning and they could be | |
| misidentified and damaged under some circumstances. | |
| check=none,normal,strict (default normal) | |
| Check level. Selecting none will cause only little speedup and big | |
| danger. I tried to write it so that it won't crash if check=normal on | |
| corrupted filesystems. check=strict means many superfluous checks - | |
| used for debugging (for example it checks if file is allocated in | |
| bitmaps when accessing it). | |
| errors=continue,remount-ro,panic (default remount-ro) | |
| Behaviour when filesystem errors found. | |
| chkdsk=no,errors,always (default errors) | |
| When to mark filesystem dirty so that OS/2 checks it. | |
| eas=no,ro,rw (default rw) | |
| What to do with extended attributes. 'no' - ignore them and use always | |
| values specified in uid/gid/mode options. 'ro' - read extended | |
| attributes but do not create them. 'rw' - create extended attributes | |
| when you use chmod/chown/chgrp/mknod/ln -s on the filesystem. | |
| timeshift=(-)nnn (default 0) | |
| Shifts the time by nnn seconds. For example, if you see under linux | |
| one hour more, than under os/2, use timeshift=-3600. | |
| File names | |
| As in OS/2, filenames are case insensitive. However, shell thinks that names | |
| are case sensitive, so for example when you create a file FOO, you can use | |
| 'cat FOO', 'cat Foo', 'cat foo' or 'cat F*' but not 'cat f*'. Note, that you | |
| also won't be able to compile linux kernel (and maybe other things) on HPFS | |
| because kernel creates different files with names like bootsect.S and | |
| bootsect.s. When searching for file thats name has characters >= 128, codepages | |
| are used - see below. | |
| OS/2 ignores dots and spaces at the end of file name, so this driver does as | |
| well. If you create 'a. ...', the file 'a' will be created, but you can still | |
| access it under names 'a.', 'a..', 'a . . . ' etc. | |
| Extended attributes | |
| On HPFS partitions, OS/2 can associate to each file a special information called | |
| extended attributes. Extended attributes are pairs of (key,value) where key is | |
| an ascii string identifying that attribute and value is any string of bytes of | |
| variable length. OS/2 stores window and icon positions and file types there. So | |
| why not use it for unix-specific info like file owner or access rights? This | |
| driver can do it. If you chown/chgrp/chmod on a hpfs partition, extended | |
| attributes with keys "UID", "GID" or "MODE" and 2-byte values are created. Only | |
| that extended attributes those value differs from defaults specified in mount | |
| options are created. Once created, the extended attributes are never deleted, | |
| they're just changed. It means that when your default uid=0 and you type | |
| something like 'chown luser file; chown root file' the file will contain | |
| extended attribute UID=0. And when you umount the fs and mount it again with | |
| uid=luser_uid, the file will be still owned by root! If you chmod file to 444, | |
| extended attribute "MODE" will not be set, this special case is done by setting | |
| read-only flag. When you mknod a block or char device, besides "MODE", the | |
| special 4-byte extended attribute "DEV" will be created containing the device | |
| number. Currently this driver cannot resize extended attributes - it means | |
| that if somebody (I don't know who?) has set "UID", "GID", "MODE" or "DEV" | |
| attributes with different sizes, they won't be rewritten and changing these | |
| values doesn't work. | |
| Symlinks | |
| You can do symlinks on HPFS partition, symlinks are achieved by setting extended | |
| attribute named "SYMLINK" with symlink value. Like on ext2, you can chown and | |
| chgrp symlinks but I don't know what is it good for. chmoding symlink results | |
| in chmoding file where symlink points. These symlinks are just for Linux use and | |
| incompatible with OS/2. OS/2 PmShell symlinks are not supported because they are | |
| stored in very crazy way. They tried to do it so that link changes when file is | |
| moved ... sometimes it works. But the link is partly stored in directory | |
| extended attributes and partly in OS2SYS.INI. I don't want (and don't know how) | |
| to analyze or change OS2SYS.INI. | |
| Codepages | |
| HPFS can contain several uppercasing tables for several codepages and each | |
| file has a pointer to codepage its name is in. However OS/2 was created in | |
| America where people don't care much about codepages and so multiple codepages | |
| support is quite buggy. I have Czech OS/2 working in codepage 852 on my disk. | |
| Once I booted English OS/2 working in cp 850 and I created a file on my 852 | |
| partition. It marked file name codepage as 850 - good. But when I again booted | |
| Czech OS/2, the file was completely inaccessible under any name. It seems that | |
| OS/2 uppercases the search pattern with its system code page (852) and file | |
| name it's comparing to with its code page (850). These could never match. Is it | |
| really what IBM developers wanted? But problems continued. When I created in | |
| Czech OS/2 another file in that directory, that file was inaccessible too. OS/2 | |
| probably uses different uppercasing method when searching where to place a file | |
| (note, that files in HPFS directory must be sorted) and when searching for | |
| a file. Finally when I opened this directory in PmShell, PmShell crashed (the | |
| funny thing was that, when rebooted, PmShell tried to reopen this directory | |
| again :-). chkdsk happily ignores these errors and only low-level disk | |
| modification saved me. Never mix different language versions of OS/2 on one | |
| system although HPFS was designed to allow that. | |
| OK, I could implement complex codepage support to this driver but I think it | |
| would cause more problems than benefit with such buggy implementation in OS/2. | |
| So this driver simply uses first codepage it finds for uppercasing and | |
| lowercasing no matter what's file codepage index. Usually all file names are in | |
| this codepage - if you don't try to do what I described above :-) | |
| Known bugs | |
| HPFS386 on OS/2 server is not supported. HPFS386 installed on normal OS/2 client | |
| should work. If you have OS/2 server, use only read-only mode. I don't know how | |
| to handle some HPFS386 structures like access control list or extended perm | |
| list, I don't know how to delete them when file is deleted and how to not | |
| overwrite them with extended attributes. Send me some info on these structures | |
| and I'll make it. However, this driver should detect presence of HPFS386 | |
| structures, remount read-only and not destroy them (I hope). | |
| When there's not enough space for extended attributes, they will be truncated | |
| and no error is returned. | |
| OS/2 can't access files if the path is longer than about 256 chars but this | |
| driver allows you to do it. chkdsk ignores such errors. | |
| Sometimes you won't be able to delete some files on a very full filesystem | |
| (returning error ENOSPC). That's because file in non-leaf node in directory tree | |
| (one directory, if it's large, has dirents in tree on HPFS) must be replaced | |
| with another node when deleted. And that new file might have larger name than | |
| the old one so the new name doesn't fit in directory node (dnode). And that | |
| would result in directory tree splitting, that takes disk space. Workaround is | |
| to delete other files that are leaf (probability that the file is non-leaf is | |
| about 1/50) or to truncate file first to make some space. | |
| You encounter this problem only if you have many directories so that | |
| preallocated directory band is full i.e. | |
| number_of_directories / size_of_filesystem_in_mb > 4. | |
| You can't delete open directories. | |
| You can't rename over directories (what is it good for?). | |
| Renaming files so that only case changes doesn't work. This driver supports it | |
| but vfs doesn't. Something like 'mv file FILE' won't work. | |
| All atimes and directory mtimes are not updated. That's because of performance | |
| reasons. If you extremely wish to update them, let me know, I'll write it (but | |
| it will be slow). | |
| When the system is out of memory and swap, it may slightly corrupt filesystem | |
| (lost files, unbalanced directories). (I guess all filesystem may do it). | |
| When compiled, you get warning: function declaration isn't a prototype. Does | |
| anybody know what does it mean? | |
| What does "unbalanced tree" message mean? | |
| Old versions of this driver created sometimes unbalanced dnode trees. OS/2 | |
| chkdsk doesn't scream if the tree is unbalanced (and sometimes creates | |
| unbalanced trees too :-) but both HPFS and HPFS386 contain bug that it rarely | |
| crashes when the tree is not balanced. This driver handles unbalanced trees | |
| correctly and writes warning if it finds them. If you see this message, this is | |
| probably because of directories created with old version of this driver. | |
| Workaround is to move all files from that directory to another and then back | |
| again. Do it in Linux, not OS/2! If you see this message in directory that is | |
| whole created by this driver, it is BUG - let me know about it. | |
| Bugs in OS/2 | |
| When you have two (or more) lost directories pointing each to other, chkdsk | |
| locks up when repairing filesystem. | |
| Sometimes (I think it's random) when you create a file with one-char name under | |
| OS/2, OS/2 marks it as 'long'. chkdsk then removes this flag saying "Minor fs | |
| error corrected". | |
| File names like "a .b" are marked as 'long' by OS/2 but chkdsk "corrects" it and | |
| marks them as short (and writes "minor fs error corrected"). This bug is not in | |
| HPFS386. | |
| Codepage bugs described above. | |
| If you don't install fixpacks, there are many, many more... | |
| History | |
| 0.90 First public release | |
| 0.91 Fixed bug that caused shooting to memory when write_inode was called on | |
| open inode (rarely happened) | |
| 0.92 Fixed a little memory leak in freeing directory inodes | |
| 0.93 Fixed bug that locked up the machine when there were too many filenames | |
| with first 15 characters same | |
| Fixed write_file to zero file when writing behind file end | |
| 0.94 Fixed a little memory leak when trying to delete busy file or directory | |
| 0.95 Fixed a bug that i_hpfs_parent_dir was not updated when moving files | |
| 1.90 First version for 2.1.1xx kernels | |
| 1.91 Fixed a bug that chk_sectors failed when sectors were at the end of disk | |
| Fixed a race-condition when write_inode is called while deleting file | |
| Fixed a bug that could possibly happen (with very low probability) when | |
| using 0xff in filenames | |
| Rewritten locking to avoid race-conditions | |
| Mount option 'eas' now works | |
| Fsync no longer returns error | |
| Files beginning with '.' are marked hidden | |
| Remount support added | |
| Alloc is not so slow when filesystem becomes full | |
| Atimes are no more updated because it slows down operation | |
| Code cleanup (removed all commented debug prints) | |
| 1.92 Corrected a bug when sync was called just before closing file | |
| 1.93 Modified, so that it works with kernels >= 2.1.131, I don't know if it | |
| works with previous versions | |
| Fixed a possible problem with disks > 64G (but I don't have one, so I can't | |
| test it) | |
| Fixed a file overflow at 2G | |
| Added new option 'timeshift' | |
| Changed behaviour on HPFS386: It is now possible to operate on HPFS386 in | |
| read-only mode | |
| Fixed a bug that slowed down alloc and prevented allocating 100% space | |
| (this bug was not destructive) | |
| 1.94 Added workaround for one bug in Linux | |
| Fixed one buffer leak | |
| Fixed some incompatibilities with large extended attributes (but it's still | |
| not 100% ok, I have no info on it and OS/2 doesn't want to create them) | |
| Rewritten allocation | |
| Fixed a bug with i_blocks (du sometimes didn't display correct values) | |
| Directories have no longer archive attribute set (some programs don't like | |
| it) | |
| Fixed a bug that it set badly one flag in large anode tree (it was not | |
| destructive) | |
| 1.95 Fixed one buffer leak, that could happen on corrupted filesystem | |
| Fixed one bug in allocation in 1.94 | |
| 1.96 Added workaround for one bug in OS/2 (HPFS locked up, HPFS386 reported | |
| error sometimes when opening directories in PMSHELL) | |
| Fixed a possible bitmap race | |
| Fixed possible problem on large disks | |
| You can now delete open files | |
| Fixed a nondestructive race in rename | |
| 1.97 Support for HPFS v3 (on large partitions) | |
| Fixed a bug that it didn't allow creation of files > 128M (it should be 2G) | |
| 1.97.1 Changed names of global symbols | |
| Fixed a bug when chmoding or chowning root directory | |
| 1.98 Fixed a deadlock when using old_readdir | |
| Better directory handling; workaround for "unbalanced tree" bug in OS/2 | |
| 1.99 Corrected a possible problem when there's not enough space while deleting | |
| file | |
| Now it tries to truncate the file if there's not enough space when deleting | |
| Removed a lot of redundant code | |
| 2.00 Fixed a bug in rename (it was there since 1.96) | |
| Better anti-fragmentation strategy | |
| 2.01 Fixed problem with directory listing over NFS | |
| Directory lseek now checks for proper parameters | |
| Fixed race-condition in buffer code - it is in all filesystems in Linux; | |
| when reading device (cat /dev/hda) while creating files on it, files | |
| could be damaged | |
| 2.02 Workaround for bug in breada in Linux. breada could cause accesses beyond | |
| end of partition | |
| 2.03 Char, block devices and pipes are correctly created | |
| Fixed non-crashing race in unlink (Alexander Viro) | |
| Now it works with Japanese version of OS/2 | |
| 2.04 Fixed error when ftruncate used to extend file | |
| 2.05 Fixed crash when got mount parameters without = | |
| Fixed crash when allocation of anode failed due to full disk | |
| Fixed some crashes when block io or inode allocation failed | |
| 2.06 Fixed some crash on corrupted disk structures | |
| Better allocation strategy | |
| Reschedule points added so that it doesn't lock CPU long time | |
| It should work in read-only mode on Warp Server | |
| 2.07 More fixes for Warp Server. Now it really works | |
| 2.08 Creating new files is not so slow on large disks | |
| An attempt to sync deleted file does not generate filesystem error | |
| 2.09 Fixed error on extremely fragmented files | |
| vim: set textwidth=80: |