linux-toradex.git/fs/autofs4, branch v3.0.24

autofs: work around unhappy compat problem on x86-64

2012-03-12T17:32:38+00:00

commit a32744d4abae24572eff7269bc17895c41bd0085 upstream.

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 
Signed-off-by: Ian Kent 
Signed-off-by: Linus Torvalds 
Cc: Jonathan Nieder 
Signed-off-by: Greg Kroah-Hartman

autofs4: bogus dentry_unhash() added in ->unlink()

2011-05-30T05:50:53+00:00

Signed-off-by: Al Viro

vfs: push dentry_unhash on rmdir into file systems

2011-05-26T11:26:47+00:00

Only a few file systems need this.  Start by pushing it down into each
fs rmdir method (except gfs2 and xfs) so it can be dealt with on a per-fs
basis.

This does not change behavior for any in-tree file systems.

Acked-by: Christoph Hellwig 
Signed-off-by: Sage Weil 
Signed-off-by: Al Viro

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi

autofs4: Do not potentially dereference NULL pointer returned by fget() in autofs_dev_ioctl_setpipefd()

2011-03-24T18:54:35+00:00

In fs/autofs4/dev-ioctl.c::autofs_dev_ioctl_setpipefd() we call fget(),
which may return NULL, but we do not explicitly test for that NULL return
so we may end up dereferencing a NULL pointer - bad.

When I originally submitted this patch I had chosen EBUSY as the return
value to use if this happens. Ian Kent was kind enough to explain why that
would most likely be wrong and why EBADF should most likely be used
instead. This version of the patch uses EBADF.

Signed-off-by: Jesper Juhl 
Signed-off-by: Ian Kent 
Signed-off-by: Al Viro

autofs4 - remove autofs4_lock

2011-03-24T18:54:35+00:00

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 
Acked-by: David Howells 
Signed-off-by: Al Viro

autofs4 - fix d_manage() return on rcu-walk

2011-03-24T18:54:34+00:00

The daemon never needs to block and, in the rcu-walk case an error
return isn't used, so always return zero.

Signed-off-by: Ian Kent 
Signed-off-by: Al Viro

autofs4 - fix autofs4_expire_indirect() traversal

2011-03-24T18:54:34+00:00

The vfs-scale changes changed the traversal used in
autofs4_expire_indirect() from a list to a depth first tree traversal
which isn't right.

Signed-off-by: Ian Kent 
Signed-off-by: Al Viro

autofs4 - fix dentry leak in autofs4_expire_direct()

2011-03-24T18:54:34+00:00

There is a missing dput() when returning from autofs4_expire_direct()
when we see that the dentry is already a pending mount.

Signed-off-by: Ian Kent 
Acked-by: David Howells 
Signed-off-by: Al Viro

autofs4 - reinstate last used update on access

2011-03-24T18:54:34+00:00

When direct (and offset) mounts were introduced the the last used
timeout could no longer be updated in ->d_revalidate(). This is
because covered direct mounts would be followed over without calling
the autofs file system. As a result the definition of the busyness
check for all entries was changed to be "actually busy" being an open
file or working directory within the automount. But now we have a call
back in the follow so the last used update on any access can be
re-instated. This requires DCACHE_MANAGE_TRANSIT to always be set.

Signed-off-by: Ian Kent 
Signed-off-by: Al Viro