Commit Graph

109 Commits

Author SHA1 Message Date
Kyle Fuller
615ab66d18 Provide a rc.d script for archlinux
Unlike most other Linux distributions archlinux installs its
init scripts in /etc/rc.d insead of /etc/init.d.  This commit
provides an archlinux rc.d script for zfs and extends the
build infrastructure to ensure it get's installed in the
correct place.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #322
2011-07-11 14:12:23 -07:00
Brian Behlendorf
b1c932d318 Add proper library versioning
The zfs libraries were never properly versioned.  Since the API has
remained static for quite some time this we never an issue.  However,
going forward they should be versioned.  This commit versions all
of the libraries to 1.0.0.  From here on out this version must be
updated to reflect changes to the library.
2011-07-06 09:20:28 -07:00
Gunnar Beutner
52e7c3a2e5 Link libshare directly to libzfs
Drop usage of dlopen/dlsym for libshare.  There is no need to do
this because the zfs packages provide libshare.  Unlike on Solaris
we are guaranteed it will be available.

This avoids possible problems with hardcoding the libshare path in
the code (e.g. when users specify a different install path via
configure options).  It additionally simplifies the code which is
good for maintainability.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2011-07-06 09:20:28 -07:00
Gunnar Beutner
46e18b3f0f Implemented sharing datasets via NFS using libshare.
The sharenfs and sharesmb properties depend on the libshare library
to export datasets via NFS and SMB. This commit implements the base
libshare functionality as well as support for managing NFS shares.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2011-07-06 09:20:28 -07:00
Brian Behlendorf
f2cfee80e3 Fix implicit declaration of 'mkdirp'
The lib/libspl/include/libgen.h header file was being mistakenly
left out of the 'make dist' tarball.  It just happens this doesn't
cause a build failure when creating packages because the system
libgen/h is included instead.  This simply results in the following
warning due to the missing forward declaration of mkdirp().

  ../../lib/libzfs/libzfs_mount.c:417:3: warning: implicit declaration
  of function 'mkdirp' [-Wimplicit-function-declaration]
2011-07-01 13:39:47 -07:00
Brian Behlendorf
2cf7f52bc4 Linux compat 2.6.39: mount_nodev()
The .get_sb callback has been replaced by a .mount callback
in the file_system_type structure.  When using the new
interface the caller must now use the mount_nodev() helper.

Unfortunately, the new interface no longer passes the vfsmount
down to the zfs layers.  This poses a problem for the existing
implementation because we currently save this pointer in the
super block for latter use.  It provides our only entry point
in to the namespace layer for manipulating certain mount options.

This needed to be done originally to allow commands like
'zfs set atime=off tank' to work properly.  It also allowed me
to keep more of the original Solaris code unmodified.  Under
Solaris there is a 1-to-1 mapping between a mount point and a
file system so this is a fairly natural thing to do.  However,
under Linux they many be multiple entries in the namespace
which reference the same filesystem.  Thus keeping a back
reference from the filesystem to the namespace is complicated.

Rather than introduce some ugly hack to get the vfsmount and
continue as before.  I'm leveraging this API change to update
the ZFS code to do things in a more natural way for Linux.
This has the upside that is resolves the compatibility issue
for the long term and fixes several other minor bugs which
have been reported.

This commit updates the code to remove this vfsmount back
reference entirely.  All modifications to filesystem mount
options are now passed in to the kernel via a '-o remount'.
This is the expected Linux mechanism and allows the namespace
to properly handle any options which apply to it before passing
them on to the file system itself.

Aside from fixing the compatibility issue, removing the
vfsmount has had the benefit of simplifying the code.  This
change which fairly involved has turned out nicely.

Closes #246
Closes #217
Closes #187
Closes #248
Closes #231
2011-07-01 13:36:39 -07:00
Brian Behlendorf
5c03efc379 Linux compat 2.6.39: security_inode_init_security()
The security_inode_init_security() function now takes an additional
qstr argument which must be passed in from the dentry if available.
Passing a NULL is safe when no qstr is available the relevant
security checks will just be skipped.

Closes #246
Closes #217
Closes #187
2011-07-01 12:40:08 -07:00
Prasad Joshi
b312979252 Tear down and flush the mmap region
The inode eviction should unmap the pages associated with the inode.
These pages should also be flushed to disk to avoid the data loss.
Therefore, use truncate_setsize() in evict_inode() to release the
pagecache.

The API truncate_setsize() was added in 2.6.35 kernel. To ensure
compatibility with the old kernel, the patch defines its own
truncate_setsize function.

Signed-off-by: Prasad Joshi <pjoshi@stec-inc.com>
Closes #255
2011-06-27 09:59:19 -07:00
Christian Kohlschütter
df30f56639 Add "ashift" property to zpool create
Some disks with internal sectors larger than 512 bytes (e.g., 4k) can
suffer from bad write performance when ashift is not configured
correctly.  This is caused by the disk not reporting its actual sector
size, but a sector size of 512 bytes.  The drive may behave this way
for compatibility reasons.  For example, the WDC WD20EARS disks are
known to exhibit this behavior.

When creating a zpool, ZFS takes that wrong sector size and sets the
"ashift" property accordingly (to 9: 1<<9=512), whereas it should be
set to 12 for 4k sectors (1<<12=4096).

This patch allows an adminstrator to manual specify the known correct
ashift size at 'zpool create' time.  This can significantly improve
performance in certain cases.  However, it will have an impact on your
total pool capacity.  See the updated ashift property description
in the zpool.8 man page for additional details.

Valid values for the ashift property range from 9 to 17 (512B-128KB).
Additionally, you may set the ashift to 0 if you wish to auto-detect
the sector size based on what the disk reports, this is the default
behavior.  The most common ashift values are 9 and 12.

  Example:
  zpool create -o ashift=12 tank raidz2 sda sdb sdc sdd

Closes #280

Original-patch-by: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2011-06-17 16:35:49 -07:00
Brian Behlendorf
2e08aedba4 Always check -Wno-unused-but-set-variable gcc support
The previous commit 8a7e1ceefa wasn't
quite right.  This check applies to both the user and kernel space
build and as such we must make sure it runs regardless of what
the --with-config option is set too.

For example, if --with-config=kernel then the autoconf test does
not run and we generate build warnings when compiling the kernel
packages.
2011-06-14 16:40:35 -07:00
Brian Behlendorf
8a7e1ceefa Check for -Wno-unused-but-set-variable gcc support
Gcc versions 4.3.2 and earlier do not support the compiler flag
-Wno-unused-but-set-variable.  This can lead to build failures
on older Linux platforms such as Debian Lenny.  Since this is
an optional build argument this changes add a new autoconf check
for the option.  If it is supported by the installed version of
gcc then it is used otherwise it is omited.

See commit's 12c1acde76 and
79713039a2 for the reason the
-Wno-unused-but-set-variable options was originally added.
2011-06-14 14:43:22 -07:00
Brian Behlendorf
1b9d8c340f Fix 'zfs send -D' segfault
Sending pools with dedup results in a segfault due to a Solaris
portability issue.  Under Solaris the pipe(2) library call
creates a bidirectional data channel.  Unfortunately, on Linux
pipe(2) call creates unidirection data channel.  The fix is to
use the socketpair(2) function to create the expected
bidirectional channel.

Seth Heeren did the original leg work on this issue for zfs-fuse.
We finally just rediscovered the same portability issue and
dfurphy was able to point me at the original issue for the fix.

Closes #268
2011-06-09 13:58:48 -07:00
Brian Behlendorf
df554c148e Fix 'zfs set volsize=N pool/dataset'
This change fixes a kernel panic which would occur when resizing
a dataset which was not open.  The objset_t stored in the
zvol_state_t will be set to NULL when the block device is closed.
To avoid this issue we pass the correct objset_t as the third arg.

The code has also been updated to correctly notify the kernel
when the block device capacity changes.  For 2.6.28 and newer
kernels the capacity change will be immediately detected.  For
earlier kernels the capacity change will be detected when the
device is next opened.  This is a known limitation of older
kernels.

Online ext3 resize test case passes on 2.6.28+ kernels:
$ dd if=/dev/zero of=/tmp/zvol bs=1M count=1 seek=1023
$ zpool create tank /tmp/zvol
$ zfs create -V 500M tank/zd0
$ mkfs.ext3 /dev/zd0
$ mkdir /mnt/zd0
$ mount /dev/zd0 /mnt/zd0
$ df -h /mnt/zd0
$ zfs set volsize=800M tank/zd0
$ resize2fs /dev/zd0
$ df -h /mnt/zd0

Original-patch-by: Fajar A. Nugraha <github@fajar.net>
Closes #68
Closes #84
2011-05-02 08:54:40 -07:00
Alejandro R. Sedeño
e90a3de3e8 Add zpl_export.c to the list of targets. 2011-04-29 19:50:35 -07:00
Brian Behlendorf
94e954257a Correct MAXUID
The uid_t on most systems is in fact and unsigned 32-bit value.
This is almost always correct, however you could compile your
kernel to use an unsigned 16-bit value for uid_t.  In practice
I've never encountered a distribution which does this so I'm
willing to overlook this corner case for now.

Closes #165
2011-04-29 14:03:12 -07:00
Gunnar Beutner
055656d4f4 Implemented NFS export_operations.
Implemented the required NFS operations for exporting ZFS datasets
using the in-kernel NFS daemon.
2011-04-29 12:36:13 -07:00
Darik Horn
492b8e9e7b Use gethostid in the Linux convention.
Disable the gethostid() override for Solaris behavior because Linux systems
implement the POSIX standard in a way that allows a negative result.

Mask the gethostid() result to the lower four bytes, like coreutils does in
/usr/bin/hostid, to prevent junk bits or sign-extension on systems that have an
eight byte long type. This can cause a spurious hostid mismatch that prevents
zpool import on 64-bit systems.
2011-04-25 10:36:17 -05:00
Brian Behlendorf
a1cc0b3290 Fix 32-bit MAXOFFSET_T definition
Having MAXOFFSET_T defined to 0x7fffffffl was artificially limiting
the maximum file size on 32-bit systems.  In reality MAXOFFSET_T is
used when working with 'long long' types and as such we now define
it as LLONG_MAX.  This resolves the 2GB file size limit for files
and additionally allows zvols greater than 2GB on 32-bit systems.

Closes #136
Closes #81
2011-04-22 16:21:26 -07:00
Richard Laager
826ab7ad19 Support IEC base-2 prefixes
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2011-04-19 12:56:21 -07:00
Brian Behlendorf
12c1acde76 Set -Wno-unused-but-set-variable globally
As of gcc-4.6 the option -Wunused-but-set-variable is enabled by
default.  While this is a useful warning there are numerous places
in the ZFS code when a variable is set and then only checked in an
ASSERT().  To avoid having to update every instance of this in the
code we now set -Wno-unused-but-set-variable to suppress the warning.

Additionally, when building with --enable-debug and -Werror set these
warning also become fatal.  We can reevaluate the suppression of these
error at a later time if it becomes an issue.  For now we are basically
just reverting to the previous gcc behavior.
2011-04-19 10:44:10 -07:00
Brian Behlendorf
bdf4328b04 Linux 2.6.28 compat, insert_inode_locked()
Added insert_inode_locked() helper function, prior to this most callers
used insert_inode_hash().  The older method doesn't check for collisions
in the inode_hashtable but it still acceptible for use.  Fallback to
using insert_inode_hash() when insert_inode_locked() is unavailable.
2011-03-22 12:15:54 -07:00
Brian Behlendorf
1073d746d6 Linux compat, umount2(2) flags
Older glibc <sys/mount.h> headers did not define all the available
umount2(2) flags.  Both MNT_FORCE and MNT_DETACH are supported in the
kernel back to 2.4.11 so we define them correctly if they are missing.

Closes #95
2011-03-22 12:15:54 -07:00
Brian Behlendorf
f47c42e214 Merge branch 'dracut' 2011-03-22 12:13:04 -07:00
Brian Behlendorf
716895b161 Fix 'LDFLAGS=-Wl,--as-needed' build error
Compiling with 'LDFLAGS=-Wl,--as-needed' exposed the fact that
there were some library linking problems introduced by mount_zfs.
In particular, the libzfs library does use nvpair symbols, and
mount_zfs contains no dependencies on libzpool.

Closes #161
Closes #162
2011-03-18 14:47:19 -07:00
Brian Behlendorf
01c0e61da0 Add init scripts
To support automatically mounting your zfs on filesystem on boot
a basic init script is needed.  Unfortunately, every distribution
has their own idea of the _right_ way to do things.  Rather than
write one very complicated portable init script, which would be
invariably replaced by the distributions own anyway.  I have
instead added support to provide multiple distribution specific
init scripts.

The correct init script for your distribution will be selected
by ZFS_AC_DEFAULT_PACKAGE which will set DEFAULT_INIT_SCRIPT.
During 'make install' the correct script for your system will
be installed from zfs/etc/init.d/zfs.DEFAULT_INIT_SCRIPT to the
usual /etc/init.d/zfs location.

Currently, there is zfs.fedora and a more generic zfs.lsb init
script.  Hopefully, the distribution maintainers who know best
how they want their init scripts to function will feedback their
approved versions to be included in the project.

This change does not consider upstart jobs but I'm not at all
opposed to add that sort of thing.
2011-03-17 16:51:54 -07:00
Brian Behlendorf
9ac97c2a93 Print mount/umount errors
Because we are dependent of the system mount/umount utilities to
ensure correct mtab locking, we should not suppress their error
output.  During a successful mount/umount they will be silent,
but during a failure the error message they print is the only sure
way to know why a mount failed.  This is because the (u)mount(8)
return code does not contain the result of the system call issued.
The only way to clearly idenify why thing failed is to rely on
the error message printed by the tool.

Longer term once libmount is available we can issue the mount/umount
system calls within the tool and still be ensured correct mtab locking.

Closed #107
2011-03-09 15:26:48 -08:00
Brian Behlendorf
d53368f675 Fix mount helper
Several issues related to strange mount/umount behavior were reported
and this commit should address most of them.  The original idea was
to put in place a zfs mount helper (mount.zfs).  This helper is used
to enforce 'legacy' mount behavior, and perform any extra mount argument
processing (selinux, zfsutil, etc).  This helper wasn't ready for the
0.6.0-rc1 release but with this change it's functional but needs to
extensively tested.

This change addresses the following open issues.
Closes #101
Closes #107
Closes #113
Closes #115
Closes #119
2011-03-09 15:26:48 -08:00
Brian Behlendorf
5075c7ea69 Add missing libspl+libzpool libs to libzfs
The libspl and libzpool libraries were missing from the libzfs
Makefile.am.  They should be explicitly listed to avoid build
issues when compiling static libraries and binaries.

Additionally, ensure libzpool is built before libzfs because
libzfs is dependent on libzpool.  This was also exposed as an
issue when forcing static linking.
2011-03-03 15:48:57 -08:00
Brian Behlendorf
45066d1f20 Linux 2.6.38 compat, blkdev_get_by_path()
The open_bdev_exclusive() function has been replaced (again) by the
more generic blkdev_get_by_path() function.  Additionally, the
counterpart function close_bdev_exclusive() has been replaced by
blkdev_put().  Because these functions are more generic versions
of the functions they replaced the compatibility macro must add
the FMODE_EXCL mask to ensure they are exclusive.

Closes #114
2011-02-23 12:29:38 -08:00
Brian Behlendorf
f03e41e8da Improve 'zpool import' safety
There are three improvements here to 'zpool import' proposed by Fajar
in Github issue #98.  They are all good so I'm commiting all three.

1) Add descriptions for "hpet" and "core" blacklist entries.

2) Add "core" to the blacklist, as described in the issue accessing
this device will crash Xen dom0.

3) Refine probing behavior to use fstatat64().  This allows us to
determine if a device is a block device or a regular file without
having to open it.  This is the safest appraoch when probing /dev/
because the simple act of opening a device may have unexpected
consequences.

Closes #98
2011-02-17 09:35:43 -08:00
Brian Behlendorf
07bd86718b Suppress share error on mount
Until code is added to support automatically sharing datasets
we should return success instead of failure.  This prevents the
command line tools from returning a non-zero error code.  While
a user likely won't notice this, test scripts like zconfig.sh
do and correctly fail because of it.
2011-02-16 11:05:55 -08:00
Brian Behlendorf
2c395def27 Linux 2.6.36 compat, sops->evict_inode()
The new prefered inteface for evicting an inode from the inode cache
is the ->evict_inode() callback.  It replaces both the ->delete_inode()
and ->clear_inode() callbacks which were previously used for this.
2011-02-11 13:47:51 -08:00
Brian Behlendorf
7268e1bec8 Linux 2.6.35 compat, fops->fsync()
The fsync() callback in the file_operations structure used to take
3 arguments.  The callback now only takes 2 arguments because the
dentry argument was determined to be unused by all consumers.  To
handle this a compatibility prototype was added to ensure the right
prototype is used.  Our implementation never used the dentry argument
either so it's just a matter of using the right prototype.
2011-02-11 09:05:51 -08:00
Brian Behlendorf
777d4af891 Linux 2.6.35 compat, const struct xattr_handler
The const keyword was added to the 'struct xattr_handler' in the
generic Linux super_block structure.  To handle this we define an
appropriate xattr_handler_t typedef which can be used.  This was
the preferred solution because it keeps the code clean and readable.
2011-02-10 16:29:00 -08:00
Brian Behlendorf
afffb5cd10 MS_DIRSYNC and MS_REC compat
It turns out that older versions of the glibc headers do not
properly define MS_DIRSYNC despite it being explicitly mentioned
in the man pages.  They instead call it S_WRITE, so for system
where this is not correct defined map MS_DIRSYNC to S_WRITE.
At the time of this commit both Ubuntu Lucid, and Debian Squeeze
both use the out of date glibc headers.

As for MS_REC this field is also not available in the older headers.
Since there is no obvious mapping in this case we simply disable
the recursive mount option which used it.
2011-02-10 12:14:57 -08:00
Brian Behlendorf
1ac0ea38a5 Add missing -ldl linker option
The inclusion on dlsym(), dlopen(), and dlclose() symbols require
us to link against the dl library.  Be careful to add the flag to
both the libzfs library and the commands which depend on the library.
2011-02-10 11:05:44 -08:00
Brian Behlendorf
b3b4f547f9 Remove useless libefi warnings
These two warnings in libefi serve no real purpose.  When running
without DEBUG they are already supressed, and even when DEBUG is
enabled all they indicate is the device doesn't already have an
EFI label.  For a Linux machine this is probably the common case.
2011-02-10 09:27:22 -08:00
Brian Behlendorf
1efb473f89 Add Hooks for Linux File Operations
The Linux specific file operations have all been located in the
file zpl_file.c.  These functions primarily rely on the reworked
zfs_* functions to do their job.  They are also responsible for
converting the possible Solaris style error codes to negative
Linux errors.

This first zpl_* commit also includes a common zpl.h header with
minimal entries to register the Linux specific hooks.  In also
adds all the new zpl_* file to the Makefile.in.  This is not a
standalone commit, you required the following zpl_* commits.
2011-02-10 09:27:21 -08:00
Brian Behlendorf
bcf308227c Remove zfs_ctldir.[ch]
This code is used for snapshot and heavily leverages Solaris
functionality we do not want to reimplement.  These files have
been removed, including references to them, and will be replaced
by a zfs_snap.c/zpl_snap.c implementation which handles snapshots.
2011-02-10 09:27:21 -08:00
Brian Behlendorf
590329b50c Add basic uio support
This code originates in OpenSolaris and was modified by KQ Infotech
to be compatible with Linux.  While supporting uios in the short
term is useful to get something working this is not an abstraction
we want to keep.  This code is expected to be short lived and
removed as soon as all the remaining uio based APIs and updated.
2011-02-10 09:21:43 -08:00
Brian Behlendorf
b4ead57cfb Remove HAVE_ZPL from commands and libraries
Thanks to the previous few commits we can now build all of the
user space commands and libraries with support for the zpl.
2011-02-04 16:14:34 -08:00
Brian Behlendorf
9a616b5d17 Documentation updates
Minor Linux specific documentation updates to the comments and
man pages.
2011-02-04 16:14:34 -08:00
Brian Behlendorf
c5d915f423 Minimal libshare infrastructure
ZFS even under Solaris does not strictly require libshare to be
available.  The current implementation attempts to dlopen() the
library to access the needed symbols.  If this fails libshare
support is simply disabled.

This means that on Linux we only need the most minimal libshare
implementation.  In fact just enough to prevent the build from
failing.  Longer term we can decide if we want to implement a
libshare library like Solaris.  At best this would be an abstraction
layer between ZFS and NFS/SMB.  Alternately, we can drop libshare
entirely and directly integrate ZFS with Linux's NFS/SMB.

Finally the bare bones user-libshare.m4 test was dropped.  If we
do decide to implement libshare at some point it will surely be
as part of this package so the check is not needed.
2011-02-04 16:14:29 -08:00
Brian Behlendorf
3fb1fcdea1 Add 'zfs mount' support
By design the zfs utility is supposed to handle mounting and unmounting
a zfs filesystem.  We could allow zfs to do this directly.  There are
system calls available to mount/umount a filesystem.  And there are
library calls available to manipulate /etc/mtab.  But there are a
couple very good reasons not to take this appraoch... for now.

Instead of directly calling the system and library calls to (u)mount
the filesystem we fork and exec a (u)mount process.  The principle
reason for this is to delegate the responsibility for locking and
updating /etc/mtab to (u)mount(8).  This ensures maximum portability
and ensures the right locking scheme for your version of (u)mount
will be used.  If we didn't do this we would have to resort to an
autoconf test to determine what locking mechanism is used.

The downside to using mount(8) instead of mount(2) is that we lose
the exact errno which was returned by the kernel.  The return code
from mount(8) provides some insight in to what went wrong but it
not quite as good.  For the moment this is translated as a best
guess in to a errno for the higher layers of zfs.

In the long term a shared library called libmount is under development
which provides a common API to address the locking and errno issues.
Once the standard mount utility has been updated to use this library
we can then leverage it.  Until then this is the only safe solution.

  http://www.kernel.org/pub/linux/utils/util-linux/libmount-docs/index.html
2011-02-04 16:11:58 -08:00
Brian Behlendorf
feb46b92a7 Open up libzfs_run_process/libzfs_load_module
Recently helper functions were added to libzfs_util to load a kernel
module or execute a process.  Initially this functionality was limited
to libzfs but it has become clear there will be other consumers.  This
change opens up the interface so it may be used where appropriate.
2011-01-28 12:47:57 -08:00
Brian Behlendorf
b3259b6a2b Autoconf selinux support
If libselinux is detected on your system at configure time link
against it.  This allows us to use a library call to detect if
selinux is enabled and if it is to pass the mount option:

  "context=\"system_u:object_r:file_t:s0"

For now this is required because none of the existing selinux
policies are aware of the zfs filesystem type.  Because of this
they do not properly enable xattr based labeling even though
zfs supports all of the required hooks.

Until distro's add zfs as a known xattr friendly fs type we
must use mntpoint labeling.  Alternately, end users could modify
their existing selinux policy with a little guidance.
2011-01-28 12:45:19 -08:00
Brian Behlendorf
149e873ab1 Fix minor compiler warnings
These compiler warnings were introduced when code which was
previously #ifdef'ed out by HAVE_ZPL was re-added for use
by the posix layer.  All of the following changes should be
obviously correct and will cause no semantic changes.
2011-01-06 15:04:28 -08:00
Brian Behlendorf
683fe41fc7 Add missing mkdirp prototype
For while now mkdirp has been built as part of libspl however
the protoype was never added to libgen.h.  This went unnoticed
until enabling the mount support which uses mkdirp().
2010-12-14 10:06:44 -08:00
Ricardo M. Correia
8d4e8140ef Fix block device-related issues in zdb.
Specifically, this fixes the two following errors in zdb when a pool
is composed of block devices:

1) 'Value too large for defined data type' when running 'zdb <dataset>'.
2) 'character device required' when running 'zdb -l <block-device>'.

Signed-off-by: Ricardo M. Correia <ricardo.correia@oracle.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2010-12-14 09:52:46 -08:00
Brian Behlendorf
5e7affae52 Skip /dev/hpet during 'zpool import'
If libblkid does not contain ZFS support, then 'zpool import' will scan
all block devices in /dev/ to determine which ones are components of a
ZFS filesystem.  It does this by opening all the devices and stat'ing
them to determine which ones are block devices.  If the device turns
out not to be a block device it is skipped.

Usually, this whole process is pretty harmless (although slow).  But
there are certain devices in /dev/ which must be handled in a very
specific way or your system may crash.  For example, if /dev/watchdog
is simply opened the watchdog timer will be started and your system
will panic when the timer expires.

It turns out the /dev/hpet causes similiar problems although only when
accessed under a virtual machine.  For some reason accessing /dev/hpet
causes qemu to crash.  To address this issue this commit adds /dev/hpet
to the device blacklist, it will be skipped solely based on its name.
2010-11-12 09:33:17 -08:00