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24 commits

Author SHA1 Message Date
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
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
Thomas Veerman
77dbd766c1 VFS: Use safe string copy functions 2012-07-16 10:57:43 +00:00
Ben Gras
0fb2f83da9 drop from segments physcopy/vircopy invocations
. sys_vircopy always uses D for both src and dst
	. sys_physcopy uses PHYS_SEG if and only if corresponding
	  endpoint is NONE, so we can derive the mode (PHYS_SEG or D)
	  from the endpoint arg in the kernel, dropping the seg args
	. fields in msg still filled in for backwards compatability,
	  using same NONE-logic in the library
2012-06-18 12:28:40 +00:00
Thomas Veerman
91a38b6d4e VFS: fix dead lock
When running out of worker threads to handle device replies a dead
lock resolver thread is used. However, it was only used for FS
endpoints; it is now used for "system processes" (drivers and FS
endpoints). Also, drivers were marked as system process when they
were not "forced" to map (i.e., mapping was done before endpoint was
alive).
2012-04-13 13:19:10 +00:00
Thomas Veerman
8f55767619 VFS: make m_in job local
By making m_in job local (i.e., each job has its own copy of m_in instead
of refering to the global m_in) we don't have to store and restore m_in
on every thread yield. This reduces overhead. Moreover, remove the
assumption that m_in is preserved. Do_XXX functions have to copy the
system call parameters as soon as possible and only pass those copies to
other functions.

Furthermore, this patch cleans up some code and uses better types in a lot
of places.
2012-04-13 12:50:38 +00:00
Ben Gras
7336a67dfe retire PUBLIC, PRIVATE and FORWARD 2012-03-25 21:58:14 +02:00
Thomas Veerman
80c4685324 VFS: replace VFS with AVFS 2012-02-13 16:53:21 +00:00
David van Moolenbroek
b4d909d415 Split block/character protocols and libdriver
This patch separates the character and block driver communication
protocols. The old character protocol remains the same, but a new
block protocol is introduced. The libdriver library is replaced by
two new libraries: libchardriver and libblockdriver. Their exposed
API, and drivers that use them, have been updated accordingly.
Together, libbdev and libblockdriver now completely abstract away
the message format used by the block protocol. As the memory driver
is both a character and a block device driver, it now implements its
own message loop.

The most important semantic change made to the block protocol is that
it is no longer possible to return both partial results and an error
for a single transfer. This simplifies the interaction between the
caller and the driver, as the I/O vector no longer needs to be copied
back. Also, drivers are now no longer supposed to decide based on the
layout of the I/O vector when a transfer should be cut short. Put
simply, transfers are now supposed to either succeed completely, or
result in an error.

After this patch, the state of the various pieces is as follows:
- block protocol: stable
- libbdev API: stable for synchronous communication
- libblockdriver API: needs slight revision (the drvlib/partition API
  in particular; the threading API will also change shortly)
- character protocol: needs cleanup
- libchardriver API: needs cleanup accordingly
- driver restarts: largely unsupported until endpoint changes are
  reintroduced

As a side effect, this patch eliminates several bugs, hacks, and gcc
-Wall and -W warnings all over the place. It probably introduces a
few new ones, too.

Update warning: this patch changes the protocol between MFS and disk
drivers, so in order to use old/new images, the MFS from the ramdisk
must be used to mount all file systems.
2011-11-23 14:06:37 +01:00
Thomas Veerman
ece4c9d565 Add DEV_CLONE_A dev type 2011-07-27 12:23:03 +00:00
Thomas Veerman
aba392e630 Clean up and fix multiple bugs in select:
- Remove redundant code.
 - Always wait for the initial reply from an asynchronous select request,
   even if the select has been satisfied on another file descriptor or
   was canceled due to a serious error.
 - Restart asynchronous selects if upon reply from the driver turns out
   that there are deferred operations (and do not forget we're still
   interested in the results of the deferred operations).
 - Do not hang a non-blocking select when another blocking select on
   the same filp is still blocking.
 - Split blocking operations in read, write, and exceptions (i.e.,
   blocking on read does not imply the write will block as well).
 - Some loops would iterate over OPEN_MAX file descriptors instead of
   the "highest" file descriptor.
 - Use proper internal error return values.
 - A secondary reply from a synchronous driver is essentially the same
   as from an asynchronous driver (the only difference being how the 
   answer is received). Merge.
 - Return proper error code after a driver failure.
 - Auto-detect whether a driver is synchronous or asynchronous.
 - Remove some code duplication.
 - Clean up code (coding style, add missing comments, put all select
   related code together).
2011-04-13 13:25:34 +00:00
Kees van Reeuwijk
bc314bda91 Remove the types Dev_t, _mnx_Gui, _mnx_Uid, and similar.
Use ANSI-style function declarations where necessary.
2010-04-13 10:58:41 +00:00
Cristiano Giuffrida
65ef539739 Driver mapping refactory.
VFS CHANGES:
- dmap table no longer statically initialized in VFS
- Dropped FSSIGNON svrctl call no longer used by INET

INET CHANGES:
- INET announces its presence to VFS just like any other driver

RS CHANGES:
- The boot image dev table contains all the data to initialize VFS' dmap table
- RS interface supports asynchronous up and update operations now
- RS interface extended to support driver style and flags
2010-04-09 21:56:44 +00:00
Cristiano Giuffrida
48c6bb79f4 Driver refactory for live update and crash recovery.
SYSLIB CHANGES:
- DS calls to publish / retrieve labels consider endpoints instead of u32_t.

VFS CHANGES:
- mapdriver() only adds an entry in the dmap table in VFS.
- dev_up() is only executed upon reception of a driver up event.

INET CHANGES:
- INET no longer searches for existing drivers instances at startup.
- A newtwork driver is (re)initialized upon reception of a driver up event.
- Networking startup is now race-free by design. No need to waste 5 seconds
at startup any more.

DRIVER CHANGES:
- Every driver publishes driver up events when starting for the first time or
in case of restart when recovery actions must be taken in the upper layers.
- Driver up events are published by drivers through DS. 
- For regular drivers, VFS is normally the only subscriber, but not necessarily.
For instance, when the filter driver is in use, it must subscribe to driver
up events to initiate recovery.
- For network drivers, inet is the only subscriber for now.
- Every VFS driver is statically linked with libdriver, every network driver
is statically linked with libnetdriver.

DRIVER LIBRARIES CHANGES:
- Libdriver is extended to provide generic receive() and ds_publish() interfaces
for VFS drivers.
- driver_receive() is a wrapper for sef_receive() also used in driver_task()
to discard spurious messages that were meant to be delivered to a previous
version of the driver.
- driver_receive_mq() is the same as driver_receive() but integrates support
for queued messages.
- driver_announce() publishes a driver up event for VFS drivers and marks
the driver as initialized and expecting a DEV_OPEN message.
- Libnetdriver is introduced to provide similar receive() and ds_publish()
interfaces for network drivers (netdriver_announce() and netdriver_receive()).
- Network drivers all support live update with no state transfer now.

KERNEL CHANGES:
- Added kernel call statectl for state management. Used by driver_announce() to
unblock eventual callers sendrecing to the driver.
2010-04-08 13:41:35 +00:00
Cristiano Giuffrida
cb176df60f New RS and new signal handling for system processes.
UPDATING INFO:
20100317:
        /usr/src/etc/system.conf updated to ignore default kernel calls: copy
        it (or merge it) to /etc/system.conf.
        The hello driver (/dev/hello) added to the distribution:
        # cd /usr/src/commands/scripts && make clean install
        # cd /dev && MAKEDEV hello

KERNEL CHANGES:
- Generic signal handling support. The kernel no longer assumes PM as a signal
manager for every process. The signal manager of a given process can now be
specified in its privilege slot. When a signal has to be delivered, the kernel
performs the lookup and forwards the signal to the appropriate signal manager.
PM is the default signal manager for user processes, RS is the default signal
manager for system processes. To enable ptrace()ing for system processes, it
is sufficient to change the default signal manager to PM. This will temporarily
disable crash recovery, though.
- sys_exit() is now split into sys_exit() (i.e. exit() for system processes,
which generates a self-termination signal), and sys_clear() (i.e. used by PM
to ask the kernel to clear a process slot when a process exits).
- Added a new kernel call (i.e. sys_update()) to swap two process slots and
implement live update.

PM CHANGES:
- Posix signal handling is no longer allowed for system processes. System
signals are split into two fixed categories: termination and non-termination
signals. When a non-termination signaled is processed, PM transforms the signal
into an IPC message and delivers the message to the system process. When a
termination signal is processed, PM terminates the process.
- PM no longer assumes itself as the signal manager for system processes. It now
makes sure that every system signal goes through the kernel before being
actually processes. The kernel will then dispatch the signal to the appropriate
signal manager which may or may not be PM.

SYSLIB CHANGES:
- Simplified SEF init and LU callbacks.
- Added additional predefined SEF callbacks to debug crash recovery and
live update.
- Fixed a temporary ack in the SEF init protocol. SEF init reply is now
completely synchronous.
- Added SEF signal event type to provide a uniform interface for system
processes to deal with signals. A sef_cb_signal_handler() callback is
available for system processes to handle every received signal. A
sef_cb_signal_manager() callback is used by signal managers to process
system signals on behalf of the kernel.
- Fixed a few bugs with memory mapping and DS.

VM CHANGES:
- Page faults and memory requests coming from the kernel are now implemented
using signals.
- Added a new VM call to swap two process slots and implement live update.
- The call is used by RS at update time and in turn invokes the kernel call
sys_update().

RS CHANGES:
- RS has been reworked with a better functional decomposition.
- Better kernel call masks. com.h now defines the set of very basic kernel calls
every system service is allowed to use. This makes system.conf simpler and
easier to maintain. In addition, this guarantees a higher level of isolation
for system libraries that use one or more kernel calls internally (e.g. printf).
- RS is the default signal manager for system processes. By default, RS
intercepts every signal delivered to every system process. This makes crash
recovery possible before bringing PM and friends in the loop.
- RS now supports fast rollback when something goes wrong while initializing
the new version during a live update.
- Live update is now implemented by keeping the two versions side-by-side and
swapping the process slots when the old version is ready to update.
- Crash recovery is now implemented by keeping the two versions side-by-side
and cleaning up the old version only when the recovery process is complete.

DS CHANGES:
- Fixed a bug when the process doing ds_publish() or ds_delete() is not known
by DS.
- Fixed the completely broken support for strings. String publishing is now
implemented in the system library and simply wraps publishing of memory ranges.
Ideally, we should adopt a similar approach for other data types as well.
- Test suite fixed.

DRIVER CHANGES:
- The hello driver has been added to the Minix distribution to demonstrate basic
live update and crash recovery functionalities.
- Other drivers have been adapted to conform the new SEF interface.
2010-03-17 01:15:29 +00:00
Ben Gras
35a108b911 panic() cleanup.
this change
   - makes panic() variadic, doing full printf() formatting -
     no more NO_NUM, and no more separate printf() statements
     needed to print extra info (or something in hex) before panicing
   - unifies panic() - same panic() name and usage for everyone -
     vm, kernel and rest have different names/syntax currently
     in order to implement their own luxuries, but no longer
   - throws out the 1st argument, to make source less noisy.
     the panic() in syslib retrieves the server name from the kernel
     so it should be clear enough who is panicing; e.g.
         panic("sigaction failed: %d", errno);
     looks like:
         at_wini(73130): panic: sigaction failed: 0
         syslib:panic.c: stacktrace: 0x74dc 0x2025 0x100a
   - throws out report() - printf() is more convenient and powerful
   - harmonizes/fixes the use of panic() - there were a few places
     that used printf-style formatting (didn't work) and newlines
     (messes up the formatting) in panic()
   - throws out a few per-server panic() functions
   - cleans up a tie-in of tty with panic()

merging printf() and panic() statements to be done incrementally.
2010-03-05 15:05:11 +00:00
Cristiano Giuffrida
c5b309ff07 Merge of Wu's GSOC 09 branch (src.20090525.r4372.wu)
Main changes:
- COW optimization for safecopy.
- safemap, a grant-based interface for sharing memory regions between processes.
- Integration with safemap and complete rework of DS, supporting new data types
  natively (labels, memory ranges, memory mapped ranges).
- For further information:
  http://wiki.minix3.org/en/SummerOfCode2009/MemoryGrants

Additional changes not included in the original Wu's branch:
- Fixed unhandled case in VM when using COW optimization for safecopy in case
  of a block that has already been shared as SMAP.
- Better interface and naming scheme for sys_saferevmap and ds_retrieve_map
  calls.
- Better input checking in syslib: check for page alignment when creating
  memory mapping grants.
- DS notifies subscribers when an entry is deleted.
- Documented the behavior of indirect grants in case of memory mapping.
- Test suite in /usr/src/test/safeperf|safecopy|safemap|ds/* reworked
  and extended.
- Minor fixes and general cleanup.
- TO-DO: Grant ids should be generated and managed the way endpoints are to make
sure grant slots are never misreused.
2010-01-14 15:24:16 +00:00
David van Moolenbroek
b31119abf5 Mount updates:
- allow mounting with "none" block device
- allow unmounting by mountpoint
- make VFS aware of file system process labels
- allow m3_ca1 to use the full available message size
- use *printf in u/mount(1), as mount(2) uses it already
- fix reference leaks for some mount error cases in VFS
2010-01-12 23:08:50 +00:00
David van Moolenbroek
ac9ab099c8 General cleanup:
- clean up kernel section of minix/com.h somewhat
- remove ALLOCMEM and VM_ALLOCMEM calls
- remove non-safecopy and minix-vmd support from Inet
- remove SYS_VIRVCOPY and SYS_PHYSVCOPY calls
- remove obsolete segment encoding in SYS_SAFECOPY*
- remove DEVCTL call, svrctl(FSDEVUNMAP), map_driverX
- remove declarations of unimplemented svrctl requests
- remove everything related to swapping to disk
- remove floppysetup.sh
- remove traces of rescue device
- update DESCRIBE.sh with new devices
- some other small changes
2010-01-05 19:39:27 +00:00
David van Moolenbroek
be2087ecf9 Filter driver by Wu Bingzheng et al 2009-12-02 10:08:58 +00:00
Tomas Hruby
8590ac260d Removed dependency of vfs on NR_TASKS macro
- all macros in consts.h that depend on NR_TASKS replaced by a FP_BLOCKED_ON_*

- fp_suspended removed and replaced by fp_blocked_on. Testing whether a process
  is supended is qeual to testing whether fp_blocked_on is FP_BLOCKED_ON_NONE or
  not

- fp_task is valid only if fp_blocked_on == FP_BLOCKED_ON_OTHER

- no need of special values that do not colide with valid and special endpoints
  since they are not used as endpoints anymore

- suspend only takes FP_BLOCKED_ON_* values not endpoints anymore

- suspend(task) replaced by wait_for(task) which sets fp_task so we remember who
  are we waiting for and suspend sets fp_blocked_on to FP_BLOCKED_ON_OTHER to
  signal that we are waiting for some other process

- some functions should take endpoint_t instead of int, fixed
2009-09-22 21:48:26 +00:00
Philip Homburg
d9a9b727e2 Added dmap_async_driver and dmap_sel_filp fields. Support for asynch character
drivers (needs cleaning up).
2008-02-22 15:01:00 +00:00
Philip Homburg
f46319037b New VFS interface 2007-08-07 12:52:47 +00:00
Ben Gras
fa0ba56bc9 Merge of VFS by Balasz Gerofi with Minix trunk. 2006-10-25 13:40:36 +00:00
Renamed from servers/fs/dmap.c (Browse further)