Commit graph

297 commits

Author SHA1 Message Date
Ben Gras
a9f55a2e46 VFS, FSes: add REQ_PEEK request type
REQ_PEEK behaves just like REQ_READ except that it does not copy
data anywhere, just obtains the blocks from the FS into the cache.

To be used by the future mmap implementation.

Change-Id: I1b56de304f0a7152b69a72c8962d04258adb44f9
2013-03-07 10:57:38 +00:00
Lionel Sambuc
8f3fbf7cc1 Cleanup: Remove minix.bootprog.mk
The build system distinction between "bootprog" and "service" is
meaningless as boot programs are standard services.

As minix.service.mk simply imports minix.bootprog.mk, reduce confusion
by removing minix.bootprog.mk and placing the rules in minix.service.mk.

Change-Id: I4056b1e574bed59a8c890239b41b1a7c7cad63e8
2013-03-06 11:56:56 +01:00
Thomas Veerman
49ad4e8888 Spring cleanup
Remove old versions of system calls and system calls that don't have
a libc api interface anymore (dup, dup2, creat).

VFS still contains support for old system call numbers for the new stat
system calls (i.e., 65, 66, 67) to keep supporting old binaries built for
MINIX 3.2.1 (prior to the release).

Change-Id: I721779b58a50c7eeae20669de24658d55d69b25b
2013-03-06 09:56:08 +00:00
Thomas Veerman
473547c777 VFS: implement pipe2
Change-Id: Iedc8042dd73a903456b25ba665d12577f5589ca2
2013-02-28 10:08:53 +00:00
Thomas Veerman
fa78dc389f socket: implement SOCK_CLOEXEC and SOCK_NONBLOCK
Change-Id: I3fa36fa999c82a192d402cb4d913bd397e106e53
2013-02-28 10:08:53 +00:00
Thomas Veerman
fd610ba1b0 VFS: add ability to open files O_CLOEXEC
.adjust libc to make use of it (undo __minix diff)

Change-Id: I90a1aa219fcd1b12b6bc60e72176f326eac8184a
2013-02-28 10:08:53 +00:00
Lionel Sambuc
f640210005 Removing obsolete _NBSD_LIBC define
Change-Id: Ia6ce84ccdf36cf6f64540b990baaa7d85c53533d
2013-02-26 09:44:24 +00:00
Lionel Sambuc
8e4736f2df Removing obsolete _MINIX define
Change-Id: Id33ac7e973d1c0e249b690fe44a597474fac6076
2013-02-26 09:44:20 +00:00
Thomas Veerman
2b90964e33 VFS: don't garbage collect if file is already closed 2013-02-21 10:29:08 +00:00
Thomas Veerman
cfcce207c1 VFS: prevent unmapping drivers that don't support reopening
libchardriver does not support DEV_REOPEN and will return ERESTART
when you do try it. This made VFS unhappy and concluded erroneously
that the driver was EDEADEPT.
2013-02-21 10:29:08 +00:00
Ben Gras
298b41b523 libexec: detect short files
if an exec() fails partway through reading in the sections, the target
process is already gone and a defunct process remains. sanity checking
the binary beforehand helps that.

test10 mutilates binaries and exec()s them on purpose; making an exec()
fail cleanly in such cases seems like acceptable behaviour.

fixes test10 on ARM.

Change-Id: I1ed9bb200ce469d4d349073cadccad5503b2fcb0
2013-02-04 12:04:35 +01:00
Thomas Veerman
06e2adbeaa VFS: fix select again
Change-Id: Ia5e26cdbfe38e3fb293dd57269a76b15c1fe236b
2013-01-25 17:42:36 +00:00
Thomas Veerman
b180f32ab3 VFS/PFS: remove remnants of file position in pipes 2013-01-23 11:14:34 +00:00
Thomas Veerman
306f3ccd6f VFS: fix select bug on pipes 2013-01-23 11:14:34 +00:00
Lionel Sambuc
f14fb60209 Libraries updates and cleanup
* Updating common/lib
 * Updating lib/csu
 * Updating lib/libc
 * Updating libexec/ld.elf_so
 * Corrected test on __minix in featuretest to actually follow the
   meaning of the comment.
 * Cleaned up _REENTRANT-related defintions.
 * Disabled -D_REENTRANT for libfetch
 * Removing some unneeded __NBSD_LIBC defines and tests

Change-Id: Ic1394baef74d11b9f86b312f5ff4bbc3cbf72ce2
2013-01-14 11:36:26 +01:00
Thomas Veerman
bdfef53dbf VFS: initialize variables 2013-01-11 12:46:44 +00:00
Thomas Veerman
aa521228a5 VFS: Coverity appeasements 2013-01-11 09:42:01 +00:00
Thomas Veerman
ea8ff9284a Add stack trace dumps for VFS over serial 2013-01-11 09:18:36 +00:00
Thomas Veerman
625f4ae4a3 VFS: add documentation about internal working 2013-01-11 09:18:36 +00:00
Thomas Veerman
23c5f56e32 VFS: change locking to ease concurrent FSes
This patch uses stricter locking for REQ_LINK, REQ_MKDIR, REQ_MKNOD,
REQ_RENAME, REQ_RMDIR, REQ_SLINK and REQ_UNLINK. For all requests, VFS
locks the directory in which we add or remove an inode with VNODE_WRITE.
I.e., the operations have exclusive access to that directory.

Furthermore, REQ_CHOWN, REQ_CHMOD, and REQ_FTRUNC now lock the vmnt
VMNT_READ; VMNT_WRITE was unnecessary.
2013-01-11 09:18:35 +00:00
Thomas Veerman
3de8d1cf6e VFS/PFS: remove notion of position in pipes
Because pipes have no file position. VFS maintained (file) offsets into a
buffer internal to PFS and stored them in vnodes for simplicity, mixing
the responsibilities of filp and vnode objects.

With this patch PFS ignores the position field in REQ_READ and REQ_WRITE
requests making VFS' job a lot simpler.
2013-01-11 09:18:35 +00:00
Thomas Veerman
7c8b3ddfed VFS: fix locking bugs
.sync and fsync used unnecessarily restrictive locking type
.fsync violated locking order by obtaining a vmnt lock after a filp lock
.fsync contained a TOCTOU bug
.new_node violated locking rules (didn't upgrade lock upon file creation)
.do_pipe used unnecessarily restrictive locking type
.always lock pipes exclusively; even a read operation might require to do
 a write on a vnode object (update pipe size)
.when opening a file with O_TRUNC, upgrade vnode lock when truncating
.utime used unnecessarily restrictive locking type
.path parsing:
  .always acquire VMNT_WRITE or VMNT_EXCL on vmnt and downgrade to
   VMNT_READ if that was what was actually requested. This prevents the
   following deadlock scenario:
   thread A:
     lock_vmnt(vmp, TLL_READSER);
     lock_vnode(vp, TLL_READSER);
     upgrade_vmnt_lock(vmp, TLL_WRITE);

   thread B:
     lock_vmnt(vmp, TLL_READ);
     lock_vnode(vp, TLL_READSER);

   thread A will be stuck in upgrade_vmnt_lock and thread B is stuck in
   lock_vnode. This happens when, for example, thread A tries create a
   new node (open.c:new_node) and thread B tries to do eat_path to
   change dir (stadir.c:do_chdir). When the path is being resolved, a
   vnode is always locked with VNODE_OPCL (TLL_READSER) and then
   downgraded to VNODE_READ if read-only is actually requested. Thread
   A locks the vmnt with VMNT_WRITE (TLL_READSER) which still allows
   VMNT_READ locks. Thread B can't acquire a lock on the vnode because
   thread A has it; Thread A can't upgrade its vmnt lock to VMNT_WRITE
   (TLL_WRITE) because thread B has a VMNT_READ lock on it.

   By serializing vmnt locks during path parsing, thread B can only
   acquire a lock on vmp when thread A has completely finished its
   operation.
2013-01-11 09:18:35 +00:00
Kees Jongenburger
c0c581a635 vfs:fix for variable 'rfp' set but not used.
mount.c: In function 'mount_pfs':
mount.c:395:17: error: variable 'rfp' set but not used [-Werror=unused-but-set-variable]

Change-Id: I2f22590ab4e3a4a1678e9096626ebca53d2660e6
2013-01-07 09:12:27 +01:00
Ben Gras
8aeac26999 vfs: fix clobbering fd_nr
dumpcore: fd_nr can be in use as blocking fd but will then be clobbered
by common_open, causing disaster for exiting unpause().
2012-12-11 12:00:57 +01:00
David van Moolenbroek
766047123a VFS: fix off-by-one in get_name() 2012-11-30 12:24:47 +00:00
Thomas Veerman
179261a9b6 mtab: support moving mount points
Also fix canonical_path function; it fails to parse some paths
2012-11-29 10:50:51 +00:00
Thomas Veerman
d9f4f71916 Implement dynamic mtab support
With this patch /etc/mtab becomes obsolete.
2012-11-26 15:20:18 +00:00
Thomas Veerman
de83b2a9d9 VFS: change 'last_dir' to match locking assumption
new_node makes the assumption that when it does last_dir on a path, a
successive advance would not yield a lock on a vmnt, because last_dir
already locked the vmnt. This is true except when last_dir resolves
to a directory on the parent vmnt of the file that was the result of
advance. For example,
 # cd /
 # echo foo > home
where home is on a different (sub) partition than / is (default
install). last_dir would resolve to / and advance would resolve to
/home.

With this change, last_dir resolves to the root node on the /home
partition, making the assumption valid again.
2012-11-26 15:20:18 +00:00
David van Moolenbroek
7dd286e6b8 VFS: do not save device node for new regular files
The VFS/FS protocol does not require the file server to supply a
special device node number in response to a REQ_CREATE request, as
this call creates only regular files. Therefore, VFS should not
erroneously save this piece of information from the REQ_CREATE reply
either.
2012-11-15 14:29:59 +00:00
Thomas Veerman
14e470be81 VFS: fix TOCTOU bug in sync 2012-11-14 13:24:53 +00:00
Thomas Veerman
ed23a7a7d2 VFS: fix reboot panic with mounted FUSE FS
Upon reboot VFS semi-exits all processes and unmounts the file system.
However, upon unmount, exiting FUSE file systems might need service from
the file system (due to libc). As the FUSE process is halfway the exit
procedure, it doesn't have a valid root directory and working directory.
Trying to do system calls then triggers a sanity check in VFS.

This fix first exits normal processes which should then allow for
unmounting FUSE file systems. Then VFS exits all processes including
File Servers and unmounts the rest of the file system.
2012-11-14 13:18:16 +00:00
Thomas Veerman
badec36b33 VFS: fix deadlock when out of worker threads
There is a deadlock vulnerability when there are no worker threads
available and all of them blocked on a worker thread that's waiting for a
reply from a driver or a reply from an FS that needs to make a back call. In
these cases the deadlock resolver thread should kick in, but didn't in all
cases. Moreover, POSIX calls from File Servers weren't handled properly
anymore, which also could lead to deadlocks.
2012-11-14 13:12:37 +00:00
Arne Welzel
e35c4f78d2 VFS: fix check_bsf() locking
The check_bsf() macro uses assert(mutex_trylock(&bsf_lock)) and
assumes bsf_lock is locked afterwards. This breaks when compiling
with NOASSERTS="yes". Also: macro to function transition.
2012-09-28 14:57:34 +02:00
Arne Welzel
7e1074732b VFS: resolve unused parameter if NOASSERTS="yes"
If VFS is compiled with NOASSERTS="yes", ctty_opcl() does not
use the op parameter. Change to "non-assert()" sanity check.
2012-09-28 14:57:32 +02:00
Ben Gras
60014efb3e vfs: pm_dumpcore: always clean up process
. whenever this function is called, pm will expect
	  the process to be cleaned up
	. so don't abort the process entirely on error
	. fixes a later 'forking on top of in-use child' vfs panic
2012-09-19 17:13:17 +02:00
Thomas Veerman
c087a60ed2 VFS: fix GCC compilation error 2012-09-17 15:29:38 +00:00
Thomas Veerman
3881e732a9 VFS: panic when unmount_all fails 2012-09-17 11:01:46 +00:00
Thomas Veerman
992799b91f VFS: make all IPC asynchronous
By decoupling synchronous drivers from VFS, we are a big step closer to
supporting driver crashes under all circumstances. That is, VFS can't
become stuck on IPC with a synchronous driver (e.g., INET) and can
recover from crashing block drivers during open/close/ioctl or during
communication with an FS.

In order to maintain serialized communication with a synchronous driver,
the communication is wrapped by a mutex on a per driver basis (not major
numbers as there can be multiple majors with identical endpoints). Majors
that share a driver endpoint point to a single mutex object.

In order to support crashes from block drivers, the file reopen tactic
had to be changed; first reopen files associated with the crashed
driver, then send the new driver endpoint to FSes. This solves a
deadlock between the FS and the block driver;
  - VFS would send REQ_NEW_DRIVER to an FS, but he FS only receives it
    after retrying the current request to the newly started driver.
  - The block driver would refuse the retried request until all files
    had been reopened.
  - VFS would reopen files only after getting a reply from the initial
    REQ_NEW_DRIVER.

When a character special driver crashes, all associated files have to
be marked invalid and closed (or reopened if flagged as such). However,
they can only be closed if a thread holds exclusive access to it. To
obtain exclusive access, the worker thread (which handles the new driver
endpoint event from DS) schedules a new job to garbage collect invalid
files. This way, we can signal the worker thread that was talking to the
crashed driver and will release exclusive access to a file associated
with the crashed driver and prevent the garbage collecting worker thread
from dead locking on that file.

Also, when a character special driver crashes, RS will unmap the driver
and remap it upon restart. During unmapping, associated files are marked
invalid instead of waiting for an endpoint up event from DS, as that
event might come later than new read/write/select requests and thus
cause confusion in the freshly started driver.

When locking a filp, the usage counters are no longer checked. The usage
counter can legally go down to zero during filp invalidation while there
are locks pending.

DS events are handled by a separate worker thread instead of the main
thread as reopening files could lead to another crash and a stuck thread.
An additional worker thread is then necessary to unlock it.

Finally, with everything asynchronous a race condition in do_select
surfaced. A select entry was only marked in use after succesfully sending
initial select requests to drivers and having to wait. When multiple
select() calls were handled there was opportunity that these entries
were overwritten. This had as effect that some select results were
ignored (and select() remained blocking instead if returning) or do_select
tried to access filps that were not present (because thrown away by
secondary select()). This bug manifested itself with sendrecs, but was
very hard to reproduce. However, it became awfully easy to trigger with
asynsends only.
2012-09-17 11:01:45 +00:00
Ben Gras
e4ac80eb60 various warning/errorwarning fixes for gcc47
. warnings (sometimes promoted to errors) in servers/ and kernel/
 . -Os for ext2 boot module to make it small enough
2012-08-27 16:19:18 +02:00
Ben Gras
31d8526346 libexec: add load_offset feature, used for ld.so
. ld.so is linked at 0 but it can relocate itself; we
	  wish to load ld.so higher though to trap NULL dereferences.
	  if we know we have to execute ld.so, vfs tells libexec to put it
	  higher.
2012-08-12 23:22:54 +02:00
Thomas Veerman
66dbf73049 VFS: fix locking bug in clone_opcl
When VFS runs out of vnodes after closing a vnode in opcl, common_open
will try to unlock a vnode through unlock_filp that has already been
unlocked in clone_opcl. By first obtaining and locking a new vnode this
situation is prevented; if there are no free vnodes, common_open will
unlock a still locked vnode.
2012-07-30 10:01:16 +00:00
Thomas Veerman
f6b0d662b5 VFS: check path components for NAME_MAX length 2012-07-30 09:44:58 +00:00
David van Moolenbroek
0b4c154160 VFS: call req_inhibread again 2012-07-19 14:36:51 +00:00
David van Moolenbroek
e0742978f1 VFS: do not resolve symlinks in rename(2) 2012-07-18 14:59:45 +00:00
Thomas Veerman
0d3ccd8908 VFS: fix coverity defects 2012-07-17 10:29:22 +00:00
Thomas Veerman
fd60f03129 VFS: remove support for sync FS communication 2012-07-17 10:12:53 +00:00
Thomas Veerman
06f49fe167 VFS: prevent buffer overflow
If an FS returns faulty struct dirent data, VFS could overflow
a buffer that holds this data.
2012-07-17 08:49:41 +00:00
Ben Gras
cbcdb838f1 various coverity-inspired fixes
. some strncpy/strcpy to strlcpy conversions
	. new <minix/param.h> to avoid including other minix headers
	  that have colliding definitions with library and commands code,
	  causing parse warnings
	. removed some dead code / assignments
2012-07-16 14:00:56 +02:00
Thomas Veerman
77dbd766c1 VFS: Use safe string copy functions 2012-07-16 10:57:43 +00:00
Ben Gras
50e2064049 No more intel/minix segments.
This commit removes all traces of Minix segments (the text/data/stack
memory map abstraction in the kernel) and significance of Intel segments
(hardware segments like CS, DS that add offsets to all addressing before
page table translation). This ultimately simplifies the memory layout
and addressing and makes the same layout possible on non-Intel
architectures.

There are only two types of addresses in the world now: virtual
and physical; even the kernel and processes have the same virtual
address space. Kernel and user processes can be distinguished at a
glance as processes won't use 0xF0000000 and above.

No static pre-allocated memory sizes exist any more.

Changes to booting:
        . The pre_init.c leaves the kernel and modules exactly as
          they were left by the bootloader in physical memory
        . The kernel starts running using physical addressing,
          loaded at a fixed location given in its linker script by the
          bootloader.  All code and data in this phase are linked to
          this fixed low location.
        . It makes a bootstrap pagetable to map itself to a
          fixed high location (also in linker script) and jumps to
          the high address. All code and data then use this high addressing.
        . All code/data symbols linked at the low addresses is prefixed by
          an objcopy step with __k_unpaged_*, so that that code cannot
          reference highly-linked symbols (which aren't valid yet) or vice
          versa (symbols that aren't valid any more).
        . The two addressing modes are separated in the linker script by
          collecting the unpaged_*.o objects and linking them with low
          addresses, and linking the rest high. Some objects are linked
          twice, once low and once high.
        . The bootstrap phase passes a lot of information (e.g. free memory
          list, physical location of the modules, etc.) using the kinfo
          struct.
        . After this bootstrap the low-linked part is freed.
        . The kernel maps in VM into the bootstrap page table so that VM can
          begin executing. Its first job is to make page tables for all other
          boot processes. So VM runs before RS, and RS gets a fully dynamic,
          VM-managed address space. VM gets its privilege info from RS as usual
          but that happens after RS starts running.
        . Both the kernel loading VM and VM organizing boot processes happen
	  using the libexec logic. This removes the last reason for VM to
	  still know much about exec() and vm/exec.c is gone.

Further Implementation:
        . All segments are based at 0 and have a 4 GB limit.
        . The kernel is mapped in at the top of the virtual address
          space so as not to constrain the user processes.
        . Processes do not use segments from the LDT at all; there are
          no segments in the LDT any more, so no LLDT is needed.
        . The Minix segments T/D/S are gone and so none of the
          user-space or in-kernel copy functions use them. The copy
          functions use a process endpoint of NONE to realize it's
          a physical address, virtual otherwise.
        . The umap call only makes sense to translate a virtual address
          to a physical address now.
        . Segments-related calls like newmap and alloc_segments are gone.
        . All segments-related translation in VM is gone (vir2map etc).
        . Initialization in VM is simpler as no moving around is necessary.
        . VM and all other boot processes can be linked wherever they wish
          and will be mapped in at the right location by the kernel and VM
          respectively.

Other changes:
        . The multiboot code is less special: it does not use mb_print
          for its diagnostics any more but uses printf() as normal, saving
          the output into the diagnostics buffer, only printing to the
          screen using the direct print functions if a panic() occurs.
        . The multiboot code uses the flexible 'free memory map list'
          style to receive the list of free memory if available.
        . The kernel determines the memory layout of the processes to
          a degree: it tells VM where the kernel starts and ends and
          where the kernel wants the top of the process to be. VM then
          uses this entire range, i.e. the stack is right at the top,
          and mmap()ped bits of memory are placed below that downwards,
          and the break grows upwards.

Other Consequences:
        . Every process gets its own page table as address spaces
          can't be separated any more by segments.
        . As all segments are 0-based, there is no distinction between
          virtual and linear addresses, nor between userspace and
          kernel addresses.
        . Less work is done when context switching, leading to a net
          performance increase. (8% faster on my machine for 'make servers'.)
	. The layout and configuration of the GDT makes sysenter and syscall
	  possible.
2012-07-15 22:30:15 +02:00