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When the autofs protocol version 5 packet type was added in commit
5c0a32fc2cd0 ("autofs4: add new packet type for v5 communications"), it
obvously tried quite hard to be word-size agnostic, and uses explicitly
sized fields that are all correctly aligned.
However, with the final "char name[NAME_MAX+1]" array at the end, the
actual size of the structure ends up being not very well defined:
because the struct isn't marked 'packed', doing a "sizeof()" on it will
align the size of the struct up to the biggest alignment of the members
it has.
And despite all the members being the same, the alignment of them is
different: a "__u64" has 4-byte alignment on x86-32, but native 8-byte
alignment on x86-64. And while 'NAME_MAX+1' ends up being a nice round
number (256), the name[] array starts out a 4-byte aligned.
End result: the "packed" size of the structure is 300 bytes: 4-byte, but
not 8-byte aligned.
As a result, despite all the fields being in the same place on all
architectures, sizeof() will round up that size to 304 bytes on
architectures that have 8-byte alignment for u64.
Note that this is *not* a problem for 32-bit compat mode on POWER, since
there __u64 is 8-byte aligned even in 32-bit mode. But on x86, 32-bit
and 64-bit alignment is different for 64-bit entities, and as a result
the structure that has exactly the same layout has different sizes.
So on x86-64, but no other architecture, we will just subtract 4 from
the size of the structure when running in a compat task. That way we
will write the properly sized packet that user mode expects.
Not pretty. Sadly, this very subtle, and unnecessary, size difference
has been encoded in user space that wants to read packets of *exactly*
the right size, and will refuse to touch anything else.
Reported-and-tested-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I don't know how I missed this obvious mistake when I
reviewed Als' patches, sorry.
[ Quoting Al:
Grr... Note to self: do git status *and* git stash show -p
before git push. Nothing like "WTF? I'd fixed that braino"
feeling ;-/
Al sent the same patch - it got broken in commit d668dc56631d:
"autofs4: deal with autofs4_write/autofs4_write races". ]
Reported-and-tested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Just serialize the actual writing of packets into pipe on
a new mutex, independent from everything else in the locking
hierarchy. As soon as something has started feeding a piece
of packet into the pipe to daemon, we *want* everything else
about to try the same to wait until we are done.
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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we need to hold ->wq_mutex while we are forming the packet to send,
lest we have autofs4_catatonic_mode() setting wq->name.name to NULL
just as autofs4_notify_daemon() decides to memcpy() from it...
We do have check for catatonic mode immediately after that (under
->wq_mutex, as it ought to be) and packet won't be actually sent,
but it'll be too late for us if we oops on that memcpy() from NULL...
Fix is obvious - just extend the area covered by ->wq_mutex over
that switch and check whether it's catatonic *before* doing anything
else.
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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We need to recheck ->catatonic after autofs4_wait() got ->wq_mutex
for good, or we might end up with wq inserted into queue after
autofs4_catatonic_mode() had done its thing. It will stick there
forever, since there won't be anything to clear its ->name.name.
A bit of a complication: validate_request() drops and regains ->wq_mutex.
It actually ends up the most convenient place to stick the check into...
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The previous comit made the autofs4 debug printouts check types against
the printout format, and uncovered this bug:
fs/autofs4/waitq.c:106:2: warning: format ‘%08lx’ expects type ‘long unsigned int’, but argument 4 has type ‘autofs_wqt_t’
which is due to the insane type for wait_queue_token. That thing should
be some fixed well-defined size (preferably just 'unsigned int' or
'u32') but for unexplained reasons it is randomly either 'unsigned long'
or 'unsigned int' depending on the architecture.
For now, cast it to 'unsigned long' for printing, the way we do
elsewhere. Somebody else can try to explain the typedef mess.
(There's a reason we don't support excessive use of typedefs in the
kernel: it's usually just a good way of confusing yourself).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The autofs4_lock introduced by the rcu-walk changes has unnecessarily
broad scope. The locking is better handled by the per-autofs super
block lookup_lock.
Signed-off-by: Ian Kent <raven@themaw.net>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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It is possible for the check in wait.c:validate_request() to return
an incorrect result if the dentry that was mounted upon has changed
during the callback.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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dcache_lock no longer protects anything. remove it.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
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The remaining usages for dcache_lock is to allow atomic, multi-step read-side
operations over the directory tree by excluding modifications to the tree.
Also, to walk in the leaf->root direction in the tree where we don't have
a natural d_lock ordering.
This could be accomplished by taking every d_lock, but this would mean a
huge number of locks and actually gets very tricky.
Solve this instead by using the rename seqlock for multi-step read-side
operations, retry in case of a rename so we don't walk up the wrong parent.
Concurrent dentry insertions are not serialised against. Concurrent deletes
are tricky when walking up the directory: our parent might have been deleted
when dropping locks so also need to check and retry for that.
We can also use the rename lock in cases where livelock is a worry (and it
is introduced in subsequent patch).
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
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The recent ->lookup() deadlock correction required the directory inode
mutex to be dropped while waiting for expire completion. We were
concerned about side effects from this change and one has been identified.
I saw several error messages.
They cause autofs to become quite confused and don't really point to the
actual problem.
Things like:
handle_packet_missing_direct:1376: can't find map entry for (43,1827932)
which is usually totally fatal (although in this case it wouldn't be
except that I treat is as such because it normally is).
do_mount_direct: direct trigger not valid or already mounted
/test/nested/g3c/s1/ss1
which is recoverable, however if this problem is at play it can cause
autofs to become quite confused as to the dependencies in the mount tree
because mount triggers end up mounted multiple times. It's hard to
accurately check for this over mounting case and automount shouldn't need
to if the kernel module is doing its job.
There was one other message, similar in consequence of this last one but I
can't locate a log example just now.
When checking if a mount has already completed prior to adding a new mount
request to the wait queue we check if the dentry is hashed and, if so, if
it is a mount point. But, if a mount successfully completed while we
slept on the wait queue mutex the dentry must exist for the mount to have
completed so the test is not really needed.
Mounts can also be done on top of a global root dentry, so for the above
case, where a mount request completes and the wait queue entry has already
been removed, the hashed test returning false can cause an incorrect
callback to the daemon. Also, d_mountpoint() is not sufficient to check
if a mount has completed for the multi-mount case when we don't have a
real mount at the base of the tree.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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- the type assigned at mount when no type is given is changed
from 0 to AUTOFS_TYPE_INDIRECT. This was done because 0 and
AUTOFS_TYPE_INDIRECT were being treated implicitly as the same
type.
- previously, an offset mount had it's type set to
AUTOFS_TYPE_DIRECT|AUTOFS_TYPE_OFFSET but the mount control
re-implementation needs to be able distinguish all three types.
So this was changed to make the type setting explicit.
- a type AUTOFS_TYPE_ANY was added for use by the re-implementation
when checking if a given path is a mountpoint. It's not really a
type as we use this to ask if a given path is a mountpoint in the
autofs_dev_ioctl_ismountpoint() function.
- functions to set and test the autofs mount types have been added to
improve readability and make the type usage explicit.
- the mount type is used from user space for the mount control
re-implementtion so, for consistency, all the definitions have
been moved to the user space include file include/linux/auto_fs4.h.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.
Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().
Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Ian Kent <raven@themaw.net>
Cc: autofs@linux.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
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Track the uid and gid of the last process to request a mount for on an
autofs dentry.
[akpm@linux-foundation.org: fix tpyo in comment]
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Usage of the AUTOFS_TYPE_* defines is a little confusing and appears
inconsistent.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We have been seeing mount requests comming to the automount daemon for
keys of the form "<map key>/<non key directory>" which are lookups for
invalid map keys. But we can check for this in the kernel module and
return a fail immediately, without having to send a request to the daemon.
It is possible to recognise these requests are invalid based on whether
the request dentry is negative and its relation to the autofs file system
root.
For example, given the indirect multi-mount map entry:
idm1 \
/mm1 <server>:/<path1>
/mm2 <server>:/<path2>
For a request to mount idm1, IS_ROOT((idm1)->d_parent) will be always be
true and the dentry may be negative. But directories idm1/mm1 and
idm1/mm2 will always be created as part of the mount request for idm1. So
any mount request within idm1 itself must have a positive dentry otherwise
the map key is invalid.
In version 4 these multi-mount entries are all mounted and umounted as a
single request and in version 5 the directories idm1/mm1 and idm1/mm2 are
created and an autofs fs mounted on them to act as a mount trigger so the
above is also true.
This also holds true for the autofs version 4 pseudo direct mount feature.
When this feature is used without the "--ghost" option automount(8) will
create internal submounts as we go down the map key paths which are
essentially normal indirect mounts for which the above holds. If the
"--ghost" option is given the directories for map keys are created at
daemon startup so valid map entries correspond to postive dentries in the
autofs fs.
autofs version 5 direct mount maps are similar except that the IS_ROOT
check is not needed. This has been addressed in a previous patch tittled
"autofs4 - detect invalid direct mount requests".
For example, given the direct multi-mount map entry:
/test/dm1 \
/mm1 <server>:/<path1>
/mm2 <server>:/<path2>
An autofs fs is mounted on /test/dm1 as a trigger mount and when a mount
is triggered for /test/dm1, the multi-mount offset directories
/test/dm1/mm1 and /test/dm1/mm2 are created and an autofs fs is mounted on
them to act as mount triggers. So valid direct mount requests must always
have a positive dentry if they correspond to a valid map entry.
Signed-off-by: Ian Kent <raven@themaw.net>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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autofs v5 direct and offset mounts within an autofs filesystem are
triggered by existing autofs triger mounts so the mount point dentry must
be positive. If the mount point dentry is negative then the trigger
doesn't exist so we can return fail immediately.
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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If an autofs mount becomes catatonic before autofs4_wait_release() is
called the wait queue counter will not be decremented down to zero and the
entry will never be freed. There are also races decrementing the wait
counter in the wait release function. To deal with this the counter needs
to be updated while holding the wait queue mutex and waiters need to be
woken up unconditionally when the wait is removed from the queue to ensure
we eventually free the wait.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It is possible for an autofs mount to become catatonic (and for the daemon
communication pipe to become NULL) after a wait has been initiallized but
before the request has been sent to the daemon. We need to check for this
before sending the request packet.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It see that the patch tittled "autofs4 - fix pending mount race" is
missing a change that I had recently made.
It's missing a kfree for the case mutex_lock_interruptible() fails
to aquire the wait queue mutex.
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Close a race between a pending mount that is about to finish and a new
lookup for the same directory.
Process P1 triggers a mount of directory foo. It sets
DCACHE_AUTOFS_PENDING in the ->lookup routine, creates a waitq entry for
'foo', and calls out to the daemon to perform the mount. The autofs
daemon will then create the directory 'foo', using a new dentry that will
be hashed in the dcache.
Before the mount completes, another process, P2, tries to walk into the
'foo' directory. The vfs path walking code finds an entry for 'foo' and
calls the revalidate method. Revalidate finds that the entry is not
PENDING (because PENDING was never set on the dentry created by the
mkdir), but it does find the directory is empty. Revalidate calls
try_to_fill_dentry, which sets the PENDING flag and then calls into the
autofs4 wait code to trigger or wait for a mount of 'foo'. The wait code
finds the entry for 'foo' and goes to sleep waiting for the completion of
the mount.
Yet another process, P3, tries to walk into the 'foo' directory. This
process again finds a dentry in the dcache for 'foo', and calls into the
autofs revalidate code.
The revalidate code finds that the PENDING flag is set, and so calls
try_to_fill_dentry.
a) try_to_fill_dentry sets the PENDING flag redundantly for this
dentry, then calls into the autofs4 wait code.
b) the autofs4 wait code takes the waitq mutex and searches for an
entry for 'foo'
Between a and b, P1 is woken up because the mount completed. P1 takes the
wait queue mutex, clears the PENDING flag from the dentry, and removes the
waitqueue entry for 'foo' from the list.
When it releases the waitq mutex, P3 (eventually) acquires it. At this
time, it looks for an existing waitq for 'foo', finds none, and so creates
a new one and calls out to the daemon to mount the 'foo' directory.
Now, the reason that three processes are required to trigger this race is
that, because the PENDING flag is not set on the dentry created by mkdir,
the window for the race would be way to slim for it to ever occur.
Basically, between the testing of d_mountpoint(dentry) and the taking of
the waitq mutex, the mount would have to complete and the daemon would
have to be woken up, and that in turn would have to wake up P1. This is
simply impossible. Add the third process, though, and it becomes slightly
more likely.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The autofs4_catatonic_mode() function accesses the wait queue without any
locking but can be called at any time. This could lead to a possible
double free of the name field of the wait and a double fput of the daemon
communication pipe or an fput of a NULL file pointer.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The autofs_wait_queue already contains all of the fields of the
struct qstr, so change it into a qstr.
This patch, from Jeff Moyer, has been modified a liitle by myself.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Catch invalid dentry when calculating its path.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Get rid of sparse related warnings from places that use integer as NULL
pointer.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The current header file definitions for autofs version 5 have caused a couple
of problems for application builds downstream.
This fixes the problem by separating the definitions.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Resolve the panic on failed mount of an autofs filesystem originally
reported by Mao Bibo.
It addresses two issues that happen after the mount fail. The first a NULL
pointer reference to a field (pipe) in the autofs superblock info structure
and second the lack of super block cleanup by the autofs and autofs4
modules.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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kill_anon_super()
Make sure all dentries refs are released before calling kill_anon_super() so
that the assumption that generic_shutdown_super() can completely destroy the
dentry tree for there will be no external references holds true.
What was being done in the put_super() superblock op, is now done in the
kill_sb() filesystem op instead, prior to calling kill_anon_super().
This makes the struct autofs_sb_info::root member variable redundant (since
sb->s_root is still available), and so that is removed. The calls to
shrink_dcache_sb() are also removed since they're also redundant as
shrink_dcache_for_umount() will now be called after the cleanup routine.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch fixes two problems.
First, the comparison of entries in the waitq.c was incorrect.
Second, the NFY_NONE check was incorrect. The test of whether the dentry
is mounted if ineffective, for example, if an expire fails then we could
wait forever on a non existant expire. The bug was identified by Jeff
Moyer.
The patch changes autofs4 to wait on expires only as this is all that's
needed. If there is no existing wait when autofs4_wait is call with a type
of NFY_NONE it delays until either a wait appears or the the expire flag is
cleared.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix accidental underflow of the atomic counter.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch define a new autofs packet for autofs v5 and updates the waitq.c
functions to handle the additional packet type.
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Whitespace and formating changes to waitq code.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Semaphore to mutex conversion.
The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This is the fs/ part of the big kfree cleanup patch.
Remove pointless checks for NULL prior to calling kfree() in fs/.
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix debugging printk.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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At the tail end of an expire it's possible for a process to enter
autofs4_wait, with a waitq type of NFY_NONE but find that the expire is
finished. In this cause autofs4_wait will try to create a new wait but not
notify the daemon leading to a hang. As the wait type is meant to delay mount
requests from revalidate or lookup during an expire and the expire is done all
we need to do is check if the dentry is a mountpoint. If it's not then we're
done.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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It's possible for an event wait request to arive before the event
requestor. If this happens the daemon never gets notified and autofs
hangs.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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