| fbde7c6119f99a0e316ad1a8fe0788bd76d277b1 |
|
16-Nov-2013 |
Axel Lin <axel.lin@ingics.com> |
devtmpfs: Calling delete_path() only when necessary
The deleted variable is always 1 in current code.
Initialize deleted variable to be 0, so delete_path() will be called only when
necessary.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
| 27ac0ffeac80ba6b9580529568d06144df044366 |
|
20-Sep-2011 |
J. Bruce Fields <bfields@redhat.com> |
locks: break delegations on any attribute modification
NFSv4 uses leases to guarantee that clients can cache metadata as well
as data.
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| b21996e36c8e3b92a84e972378bde80b43acd890 |
|
20-Sep-2011 |
J. Bruce Fields <bfields@redhat.com> |
locks: break delegations on unlink
We need to break delegations on any operation that changes the set of
links pointing to an inode. Start with unlink.
Such operations also hold the i_mutex on a parent directory. Breaking a
delegation may require waiting for a timeout (by default 90 seconds) in
the case of a unresponsive NFS client. To avoid blocking all directory
operations, we therefore drop locks before waiting for the delegation.
The logic then looks like:
acquire locks
...
test for delegation; if found:
take reference on inode
release locks
wait for delegation break
drop reference on inode
retry
It is possible this could never terminate. (Even if we take precautions
to prevent another delegation being acquired on the same inode, we could
get a different inode on each retry.) But this seems very unlikely.
The initial test for a delegation happens after the lock on the target
inode is acquired, but the directory inode may have been acquired
further up the call stack. We therefore add a "struct inode **"
argument to any intervening functions, which we use to pass the inode
back up to the caller in the case it needs a delegation synchronously
broken.
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 4e4098a3e08783cfd75f9fcdab276dc1d46931da |
|
11-Apr-2013 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
driver core: handle user namespaces properly with the uid/gid devtmpfs change
Now that devtmpfs is caring about uid/gid, we need to use the correct
internal types so users who have USER_NS enabled will have things work
properly for them.
Thanks to Eric for pointing this out, and the patch review.
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
| d81c8d19da8fb6514c75d5c19334f4236856c561 |
|
10-Apr-2013 |
Ming Lei <ming.lei@canonical.com> |
driver core: devtmpfs: fix compile failure with CONFIG_UIDGID_STRICT_TYPE_CHECKS
If CONFIG_UIDGID_STRICT_TYPE_CHECKS is enalbed, the below compile
failure will be triggered:
drivers/base/devtmpfs.c: In function 'handle_create':
drivers/base/devtmpfs.c:214:19: error: incompatible types when assigning to type 'kuid_t' from type 'uid_t'
drivers/base/devtmpfs.c:215:19: error: incompatible types when assigning to type 'kgid_t' from type 'gid_t'
make[2]: *** [drivers/base/devtmpfs.o] Error 1
This patch fixes the compile failure.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
| c3a30420902de10bcc4c8474766cb5f97f4c4dfc |
|
10-Apr-2013 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
devtmpfs: add base.h include
This fixes a sparse warning, and is a good idea given that the
devtmpfs_init() prototype is in this file.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
| 3c2670e6515cf584810f417db9b00992c8b2d75a |
|
06-Apr-2013 |
Kay Sievers <kay@vrfy.org> |
driver core: add uid and gid to devtmpfs
Some drivers want to tell userspace what uid and gid should be used for
their device nodes, so allow that information to percolate through the
driver core to userspace in order to make this happen. This means that
some systems (i.e. Android and friends) will not need to even run a
udev-like daemon for their device node manager and can just rely in
devtmpfs fully, reducing their footprint even more.
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
| 3dadecce20603aa380023c65e6f55f108fd5e952 |
|
24-Jan-2013 |
Al Viro <viro@zeniv.linux.org.uk> |
switch vfs_getattr() to struct path
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 1ac12b4b6d707937f9de6d09622823b2fd0c93ef |
|
11-Dec-2012 |
Jeff Layton <jlayton@redhat.com> |
vfs: turn is_dir argument to kern_path_create into a lookup_flags arg
Where we can pass in LOOKUP_DIRECTORY or LOOKUP_REVAL. Any other flags
passed in here are currently ignored.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 91fa2ccaa87368314527ea7518c545063662d67f |
|
25-Apr-2012 |
Eric W. Biederman <ebiederm@xmission.com> |
userns: Convert devtmpfs to use GLOBAL_ROOT_UID and GLOBAL_ROOT_GID
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
|
| 921a1650de9eed40dd64d681aba4a4d98856f289 |
|
19-Jul-2012 |
Al Viro <viro@zeniv.linux.org.uk> |
new helper: done_path_create()
releases what needs to be released after {kern,user}_path_create()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 79714f72d3b964611997de512cb29198c9f2dbbb |
|
15-Jun-2012 |
Al Viro <viro@zeniv.linux.org.uk> |
get rid of kern_path_parent()
all callers want the same thing, actually - a kinda-sorta analog of
kern_path_create(). I.e. they want parent vfsmount/dentry (with
->i_mutex held, to make sure the child dentry is still their child)
+ the child dentry.
Signed-off-by Al Viro <viro@zeniv.linux.org.uk>
|
| 02fbe5e61df654b2b39a1ddc1ae912c9e14c3ddd |
|
17-Apr-2012 |
Peter Korsgaard <jacmet@sunsite.dk> |
devtmpfs: fix 'the the' typo
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
| fbd48a69a0b576dd8cba01b2b4fc24fad76f1b68 |
|
24-Jul-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
switch devtmpfs to umode_t
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 2c9ede55ecec58099b72e4bb8eab719f32f72c31 |
|
24-Jul-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
switch device_get_devnode() and ->devnode() to umode_t *
both callers of device_get_devnode() are only interested in lower 16bits
and nobody tries to return anything wider than 16bit anyway.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 65e6757be42ddf0a9115ec0e6af268fec9727359 |
|
15-Nov-2011 |
Kautuk Consul <consul.kautuk@gmail.com> |
devtmpfsd: fix task state handling
- Set the state to TASK_INTERRUPTIBLE using __set_current_state()
instead of set_current_state() as the spin_unlock is an implicit memory
barrier.
- After return from schedule(), there is no need to set the current
state to TASK_RUNNING - a call to schedule() always returns in
TASK_RUNNING state.
Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| f9e0b159dbff693bacb64a929e04f442df985b50 |
|
21-Jul-2011 |
Arnaud Lacombe <lacombar@gmail.com> |
drivers/base/devtmpfs.c: correct annotation of `setup_done'
This fixes the following section mismatch issue:
WARNING: vmlinux.o(.text+0x1192bf): Section mismatch in reference from the function devtmpfsd() to the variable .init.data:setup_done
The function devtmpfsd() references the variable __initdata setup_done.
This is often because devtmpfsd lacks a __initdata annotation or the annotation of setup_done is wrong.
WARNING: vmlinux.o(.text+0x119342): Section mismatch in reference from the function devtmpfsd() to the variable .init.data:setup_done
The function devtmpfsd() references the variable __initdata setup_done.
This is often because devtmpfsd lacks a __initdata annotation or the annotation of setup_done is wrong.
Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 9d108d25487bf958f8093409a4c0bee6169edba6 |
|
28-Jul-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
devtmpfs: missing initialialization in never-hit case
create_path() on something without a single / in it will return err
without initializing it. It actually can't happen (we call that thing
only if create on the same path returns -ENOENT, which won't happen
happen for single-component path), but in this case initializing err
to 0 is more than making compiler to STFU - would be the right thing
to return on such paths; the function creates a parent directory of
given pathname and in that case it has no work to do...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| e13889bab3c6b5c839075086d28fe05f71984dda |
|
25-Jul-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
fix devtmpfs race
After we's done complete(&req->done), there's nothing to prevent the
scope containing *req from being gone and *req overwritten by any
kind of junk. So we must read req->next before that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 5da4e689449ad99ab31cf2208d99eddfce0498ba |
|
27-Jun-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
devtmpfs: get rid of bogus mkdir in create_path()
We do _NOT_ want to mkdir the path itself - we are preparing to
mknod it, after all. Normally it'll fail with -ENOENT and
just do nothing, but if somebody has created the parent in
the meanwhile, we'll get buggered...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 69753a0f14d3cb2e8a70e559ef8d409e4deeac8a |
|
27-Jun-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
switch devtmpfs to kern_path_create()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| 2780f1ff6aec0cf708a61c022d475bfcaa648965 |
|
27-Jun-2011 |
Al Viro <viro@zeniv.linux.org.uk> |
switch devtmpfs object creation/removal to separate kernel thread
... and give it a namespace where devtmpfs would be mounted on root,
thus avoiding abuses of vfs_path_lookup() (it was never intended to
be used with LOOKUP_PARENT). Games with credentials are also gone.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| fc14f2fef682df677d64a145256dbd263df2aa7b |
|
24-Jul-2010 |
Al Viro <viro@zeniv.linux.org.uk> |
convert get_sb_single() users
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
| da5e4ef7fdb8f2fb0878dee3bd9d4dd10cea8cf1 |
|
16-Mar-2010 |
Peter Korsgaard <jacmet@sunsite.dk> |
devtmpfs: support !CONFIG_TMPFS
Make devtmpfs available on (embedded) configurations without SHMEM/TMPFS,
using ramfs instead.
Saves ~15KB.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 5a0e3ad6af8660be21ca98a971cd00f331318c05 |
|
24-Mar-2010 |
Tejun Heo <tj@kernel.org> |
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
|
| 5e31d76f2817bd50258a092a7c5b15b3006fd61c |
|
13-Jan-2010 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver-Core: devtmpfs - reset inode permissions before unlinking
Before unlinking the inode, reset the current permissions of possible
references like hardlinks, so granted permissions can not be retained
across the device lifetime by creating hardlinks, in the unusual case
that there is a user-writable directory on the same filesystem.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| f776c5ec4690b21b3668ad5956774a22c86f541a |
|
18-Jan-2010 |
Heiko Carstens <heiko.carstens@de.ibm.com> |
driver-core: fix devtmpfs crash on s390
On Mon, Jan 18, 2010 at 05:26:20PM +0530, Sachin Sant wrote:
> Hello Heiko,
>
> Today while trying to boot next-20100118 i came across
> the following Oops :
>
> Brought up 4 CPUs
> Unable to handle kernel pointer dereference at virtual kernel address 0000000000
> 543000
> Oops: 0004 #1 SMP
> Modules linked in:
> CPU: 0 Not tainted 2.6.33-rc4-autotest-next-20100118-5-default #1
> Process swapper (pid: 1, task: 00000000fd792038, ksp: 00000000fd797a30)
> Krnl PSW : 0704200180000000 00000000001eb0b8 (shmem_parse_options+0xc0/0x328)
> R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:2 PM:0 EA:3
> Krnl GPRS: 000000000054388a 000000000000003d 0000000000543836 000000000000003d
> 0000000000000000 0000000000483f28 0000000000536112 00000000fd797d00
> 00000000fd4ba100 0000000000000100 0000000000483978 0000000000543832
> 0000000000000000 0000000000465958 00000000001eb0b0 00000000fd797c58
> Krnl Code: 00000000001eb0aa: c0e5000994f1 brasl %r14,31da8c
> 00000000001eb0b0: b9020022 ltgr %r2,%r2
> 00000000001eb0b4: a784010b brc 8,1eb2ca
> >00000000001eb0b8: 92002000 mvi 0(%r2),0
> 00000000001eb0bc: a7080000 lhi %r0,0
> 00000000001eb0c0: 41902001 la %r9,1(%r2)
> 00000000001eb0c4: b9040016 lgr %r1,%r6
> 00000000001eb0c8: b904002b lgr %r2,%r11
> Call Trace:
> (<00000000fd797c50> 0xfd797c50)
> <00000000001eb5da> shmem_fill_super+0x13a/0x25c
> <0000000000228cfa> get_sb_single+0xbe/0xdc
> <000000000034ffc0> dev_get_sb+0x2c/0x38
> <000000000066c602> devtmpfs_init+0x46/0xc0
> <000000000066c53e> driver_init+0x22/0x60
> <000000000064d40a> kernel_init+0x24e/0x3d0
> <000000000010a7ea> kernel_thread_starter+0x6/0xc
> <000000000010a7e4> kernel_thread_starter+0x0/0xc
>
> I never tried to boot a kernel with DEVTMPFS enabled on a s390 box.
> So am wondering if this is supported or not ? If you think this
> is supported i will send a mail to community on this.
There is nothing arch specific to devtmpfs. This part crashes because the
kernel tries to modify the data read-only section which is write protected
on s390.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 8042273801059884da2d53bbca34575d090b6f4e |
|
22-Dec-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
devtmpfs: unlock mutex in case of string allocation error
Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| f1f76f865b5f66db5b5c7f2d19874f2bb9b43b8d |
|
16-Dec-2009 |
Thomas Gleixner <tglx@linutronix.de> |
devtmpfs: Convert dirlock to a mutex
devtmpfs has a rw_lock dirlock which serializes delete_path and
create_path.
This code was obviously never tested with the usual set of debugging
facilities enabled. In the dirlock held sections the code calls:
- vfs functions which take mutexes
- kmalloc(, GFP_KERNEL)
In both code pathes the might sleep warning triggers and spams dmesg.
Convert the rw_lock to a mutex. There is no reason why this needs to
be a rwlock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 03d673e6af6490371aaf64dfe1f84c658c48b71d |
|
30-Oct-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver-Core: devtmpfs - set root directory mode to 0755
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Mark Rosenstand <rosenstand@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 015bf43b07158668c2f38af463939afcc6d19403 |
|
28-Oct-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver Core: devtmpfs: do not remove non-kernel-created directories
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 073120cc28ad9f6003452c8bb9d15a87b1820201 |
|
28-Oct-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver Core: devtmpfs: use sys_mount()
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| ed413ae6e7813d3227eef43bc6d84ca4f4fe6b21 |
|
28-Oct-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver core: devtmpfs: prevent concurrent subdirectory creation and removal
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 0092699643703aefca6af0aa758a73f1624d53be |
|
28-Oct-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver Core: devtmpfs: ignore umask while setting file mode
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| e454cea20bdcff10ee698d11b8882662a0153a47 |
|
18-Sep-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver-Core: extend devnode callbacks to provide permissions
This allows subsytems to provide devtmpfs with non-default permissions
for the device node. Instead of the default mode of 0600, null, zero,
random, urandom, full, tty, ptmx now have a mode of 0666, which allows
non-privileged processes to access standard device nodes in case no
other userspace process applies the expected permissions.
This also fixes a wrong assignment in pktcdvd and a checkpatch.pl complain.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
| 2b2af54a5bb6f7e80ccf78f20084b93c398c3a8b |
|
30-Apr-2009 |
Kay Sievers <kay.sievers@vrfy.org> |
Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev
Devtmpfs lets the kernel create a tmpfs instance called devtmpfs
very early at kernel initialization, before any driver-core device
is registered. Every device with a major/minor will provide a
device node in devtmpfs.
Devtmpfs can be changed and altered by userspace at any time,
and in any way needed - just like today's udev-mounted tmpfs.
Unmodified udev versions will run just fine on top of it, and will
recognize an already existing kernel-created device node and use it.
The default node permissions are root:root 0600. Proper permissions
and user/group ownership, meaningful symlinks, all other policy still
needs to be applied by userspace.
If a node is created by devtmps, devtmpfs will remove the device node
when the device goes away. If the device node was created by
userspace, or the devtmpfs created node was replaced by userspace, it
will no longer be removed by devtmpfs.
If it is requested to auto-mount it, it makes init=/bin/sh work
without any further userspace support. /dev will be fully populated
and dynamic, and always reflect the current device state of the kernel.
With the commonly used dynamic device numbers, it solves the problem
where static devices nodes may point to the wrong devices.
It is intended to make the initial bootup logic simpler and more robust,
by de-coupling the creation of the inital environment, to reliably run
userspace processes, from a complex userspace bootstrap logic to provide
a working /dev.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Jan Blunck <jblunck@suse.de>
Tested-By: Harald Hoyer <harald@redhat.com>
Tested-By: Scott James Remnant <scott@ubuntu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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