Commit graph

17 commits

Author SHA1 Message Date
Thomas Veerman
0e537f1085 AVFS: initialize root FS before receiving new work 2012-01-30 15:16:20 +00:00
Thomas Veerman
0bd011affd PM: extend srv_fork to set a specific UID
Currently, all servers and drivers run as root as they are forks of
RS. srv_fork now tells PM with which credentials to run the resulting
fork. Subsequently, PM lets VFS now as well.

This patch also fixes the following bugs:
 - RS doesn't initialize the setugid variable during exec, causing the
   servers and drivers to run setuid rendering the srv_fork extension
   useless.
 - PM erroneously tells VFS to run processes setuid. This doesn't
   actually lead to setuid processes as VFS sets {r,e}uid and {r,e}gid
   properly before checking PM's approval.
2012-01-30 15:16:19 +00:00
Thomas Veerman
de5a9a3e8b AVFS: Use scratchpad instead of m_in to pass around file descriptors
Some code relies on having the file descriptor in m_in.fd. Consequently,
m_in is not only used to provide syscall parameters from user space to
VFS, but also as a global variable to store temporary data within VFS.
This has the ugly side effect that m_in gets overwritten during core
dumping.*

To work around this problem VFS now uses a so called "scratchpad" to
store temporary data that has to be globally accessible. This is a simple
table indexed by process number, just like fproc. The scratchpad allows
us to store the buffer pointer and buffer size for suspended system calls
(i.e., read, write, open, lock) instead of using fproc. This makes fproc
a bit smaller and fproc iterators a bit faster. Moreover, suspension of
processes becomes simpler altogether and suspended operations on pipes
are now less of a special case.

* This patch fixes a bug where due to unexpected m_in overwriting a
coredump would fail, and consequently resources are leaked. The coredump
was triggered with:
$ a() { a; }
$ a
2011-12-21 10:52:51 +00:00
Thomas Veerman
94da86cbee Discard process' pending request upon incoming PM request
When a process wants something done from VFS, but VFS has no worker
threads available, the request is stored and executed later. However,
when PM also sends a request for that process at the same time, discard
the pending request from the process and give priority to PM. The request
PM sends is either an EXIT or a DUMPCORE request, so we're not interested
in executing the pending request anyway.
2011-12-12 08:20:35 +00:00
David van Moolenbroek
9701e9dfd2 Servers: cleanup of some gcc -W warnings 2011-12-11 22:33:37 +01:00
Thomas Veerman
5cbbfc69e7 Change asserts with side effects into panics 2011-12-09 14:46:10 +00:00
Thomas Veerman
0a61519eea Provide core dumping support for AVFS 2011-12-08 10:47:11 +00:00
David van Moolenbroek
e8f944d3ca avfs: unbreak process termination on PM_DUMPCORE 2011-11-24 13:04:52 +01:00
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
febb4403ff Reenable backcall detection 2011-10-27 15:29:37 +00:00
Thomas Veerman
823e42c3e3 Make AVFS deal intelligently with back calling FSes
PUFFS file systems need to make back calls for every operation we
send to them. Consequently, they cannot handle block reads and writes
themselves. Instead, the root file system has to do it (for now).

When the mount operation causes an FS to make a back call, AVFS now
concludes that every block read and write for that FS has to go
through the root file system.
2011-10-27 15:29:23 +00:00
Thomas Veerman
90cde23c19 Cleanup more resources upon exit 2011-09-16 10:16:57 +00:00
Thomas Veerman
7db039347a Make AVFS resilient against failing back calls 2011-09-06 10:38:16 +00:00
Thomas Veerman
7f24c2b3ca Unverbose mount 2011-08-26 15:49:37 +00:00
Thomas Veerman
e09714ab53 Turn off block read debugs and turn on mount debugs 2011-08-22 13:24:35 +00:00
Thomas Veerman
ae2159c371 Fix locking issues with back calls from FSes 2011-08-19 14:17:35 +00:00
Thomas Veerman
a6bd3f4a22 Merge AVFS and APFS 2011-08-17 13:40:36 +00:00