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