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  1. 14 7月, 2012 12 次提交
  3. 02 6月, 2012 11 次提交
  5. 30 5月, 2012 1 次提交
    • A
      brlocks/lglocks: API cleanups · 962830df
      由 Andi Kleen 提交于 
      lglocks and brlocks are currently generated with some complicated macros
in lglock.h.  But there's no reason to not just use common utility
functions and put all the data into a common data structure.

In preparation, this patch changes the API to look more like normal
function calls with pointers, not magic macros.

The patch is rather large because I move over all users in one go to keep
it bisectable.  This impacts the VFS somewhat in terms of lines changed.
But no actual behaviour change.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      962830df
  7. 27 5月, 2012 1 次提交
    • L
      word-at-a-time: make the interfaces truly generic · 36126f8f
      由 Linus Torvalds 提交于 
      This changes the interfaces in <asm/word-at-a-time.h> to be a bit more
complicated, but a lot more generic.

In particular, it allows us to really do the operations efficiently on
both little-endian and big-endian machines, pretty much regardless of
machine details.  For example, if you can rely on a fast population
count instruction on your architecture, this will allow you to make your
optimized <asm/word-at-a-time.h> file with that.

NOTE! The "generic" version in include/asm-generic/word-at-a-time.h is
not truly generic, it actually only works on big-endian.  Why? Because
on little-endian the generic algorithms are wasteful, since you can
inevitably do better. The x86 implementation is an example of that.

(The only truly non-generic part of the asm-generic implementation is
the "find_zero()" function, and you could make a little-endian version
of it.  And if the Kbuild infrastructure allowed us to pick a particular
header file, that would be lovely)

The <asm/word-at-a-time.h> functions are as follows:

 - WORD_AT_A_TIME_CONSTANTS: specific constants that the algorithm
   uses.

 - has_zero(): take a word, and determine if it has a zero byte in it.
   It gets the word, the pointer to the constant pool, and a pointer to
   an intermediate "data" field it can set.

   This is the "quick-and-dirty" zero tester: it's what is run inside
   the hot loops.

 - "prep_zero_mask()": take the word, the data that has_zero() produced,
   and the constant pool, and generate an *exact* mask of which byte had
   the first zero.  This is run directly *outside* the loop, and allows
   the "has_zero()" function to answer the "is there a zero byte"
   question without necessarily getting exactly *which* byte is the
   first one to contain a zero.

   If you do multiple byte lookups concurrently (eg "hash_name()", which
   looks for both NUL and '/' bytes), after you've done the prep_zero_mask()
   phase, the result of those can be or'ed together to get the "either
   or" case.

 - The result from "prep_zero_mask()" can then be fed into "find_zero()"
   (to find the byte offset of the first byte that was zero) or into
   "zero_bytemask()" (to find the bytemask of the bytes preceding the
   zero byte).

   The existence of zero_bytemask() is optional, and is not necessary
   for the normal string routines.  But dentry name hashing needs it, so
   if you enable DENTRY_WORD_AT_A_TIME you need to expose it.

This changes the generic strncpy_from_user() function and the dentry
hashing functions to use these modified word-at-a-time interfaces.  This
gets us back to the optimized state of the x86 strncpy that we lost in
the previous commit when moving over to the generic version.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      36126f8f
  9. 25 5月, 2012 1 次提交
  11. 05 5月, 2012 1 次提交
    • L
      vfs: clean up __d_lookup_rcu() and dentry_cmp() interfaces · 12f8ad4b
      由 Linus Torvalds 提交于 
      The calling conventions for __d_lookup_rcu() and dentry_cmp() are
annoying in different ways, and there is actually one single underlying
reason for both of the annoyances.

The fundamental reason is that we do the returned dentry sequence number
check inside __d_lookup_rcu() instead of doing it in the caller.  This
results in two annoyances:

 - __d_lookup_rcu() now not only needs to return the dentry and the
   sequence number that goes along with the lookup, it also needs to
   return the inode pointer that was validated by that sequence number
   check.

 - and because we did the sequence number check early (to validate the
   name pointer and length) we also couldn't just pass the dentry itself
   to dentry_cmp(), we had to pass the counted string that contained the
   name.

So that sequence number decision caused two separate ugly calling
conventions.

Both of these problems would be solved if we just did the sequence
number check in the caller instead.  There's only one caller, and that
caller already has to do the sequence number check for the parent
anyway, so just do that.

That allows us to stop returning the dentry->d_inode in that in-out
argument (pointer-to-pointer-to-inode), so we can make the inode
argument just a regular input inode pointer.  The caller can just load
the inode from dentry->d_inode, and then do the sequence number check
after that to make sure that it's synchronized with the name we looked
up.

And it allows us to just pass in the dentry to dentry_cmp(), which is
what all the callers really wanted.  Sure, dentry_cmp() has to be a bit
careful about the dentry (which is not stable during RCU lookup), but
that's actually very simple.

And now that dentry_cmp() can clearly see that the first string argument
is a dentry, we can use the direct word access for that, instead of the
careful unaligned zero-padding.  The dentry name is always properly
aligned, since it is a single path component that is either embedded
into the dentry itself, or was allocated with kmalloc() (see __d_alloc).

Finally, this also uninlines the nasty slow-case for dentry comparisons:
that one *does* need to do a sequence number check, since it will call
in to the low-level filesystems, and we want to give those a stable
inode pointer and path component length/start arguments.  Doing an extra
sequence check for that slow case is not a problem, though.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      12f8ad4b
  13. 04 5月, 2012 1 次提交
    • L
      vfs: make word-at-a-time accesses handle a non-existing page · e419b4cc
      由 Linus Torvalds 提交于 
      It turns out that there are more cases than CONFIG_DEBUG_PAGEALLOC that
can have holes in the kernel address space: it seems to happen easily
with Xen, and it looks like the AMD gart64 code will also punch holes
dynamically.

Actually hitting that case is still very unlikely, so just do the
access, and take an exception and fix it up for the very unlikely case
of it being a page-crosser with no next page.

And hey, this abstraction might even help other architectures that have
other issues with unaligned word accesses than the possible missing next
page.  IOW, this could do the byte order magic too.

Peter Anvin fixed a thinko in the shifting for the exception case.
Reported-and-tested-by: NJana Saout <jana@saout.de>
Cc:  Peter Anvin <hpa@zytor.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e419b4cc
  15. 03 5月, 2012 1 次提交
  17. 29 4月, 2012 1 次提交
    • L
      VFS: clean up and simplify getname_flags() · 3f9f0aa6
      由 Linus Torvalds 提交于 
      This removes a number of silly games around strncpy_from_user() in
do_getname(), and removes that helper function entirely.  We instead
make getname_flags() just use strncpy_from_user() properly directly.

Removing the wrapper function simplifies things noticeably, mostly
because we no longer play the unnecessary games with segments (x86
strncpy_from_user() no longer needs the hack), but also because the
empty path handling is just much more obvious.  The return value of
"strncpy_to_user()" is much more obvious than checking an odd error
return case from do_getname().

[ non-x86 architectures were notified of this change several weeks ago,
  since it is possible that they have copied the old broken x86
  strncpy_from_user. But nobody reacted, so .. See

    http://www.spinics.net/lists/linux-arch/msg17313.html

  for details ]

Cc: linux-arch@vger.kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3f9f0aa6
  19. 08 4月, 2012 1 次提交
    • E
      userns: Replace the hard to write inode_userns with inode_capable. · 1a48e2ac
      由 Eric W. Biederman 提交于 
      This represents a change in strategy of how to handle user namespaces.
Instead of tagging everything explicitly with a user namespace and bulking
up all of the comparisons of uids and gids in the kernel,  all uids and gids
in use will have a mapping to a flat kuid and kgid spaces respectively.  This
allows much more of the existing logic to be preserved and in general
allows for faster code.

In this new and improved world we allow someone to utiliize capabilities
over an inode if the inodes owner mapps into the capabilities holders user
namespace and the user has capabilities in their user namespace.  Which
is simple and efficient.

Moving the fs uid comparisons to be comparisons in a flat kuid space
follows in later patches, something that is only significant if you
are using user namespaces.
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
      1a48e2ac
  21. 07 4月, 2012 1 次提交
    • L
      Make the "word-at-a-time" helper functions more commonly usable · f68e556e
      由 Linus Torvalds 提交于 
      I have a new optimized x86 "strncpy_from_user()" that will use these
same helper functions for all the same reasons the name lookup code uses
them.  This is preparation for that.

This moves them into an architecture-specific header file.  It's
architecture-specific for two reasons:

 - some of the functions are likely to want architecture-specific
   implementations.  Even if the current code happens to be "generic" in
   the sense that it should work on any little-endian machine, it's
   likely that the "multiply by a big constant and shift" implementation
   is less than optimal for an architecture that has a guaranteed fast
   bit count instruction, for example.

 - I expect that if architectures like sparc want to start playing
   around with this, we'll need to abstract out a few more details (in
   particular the actual unaligned accesses).  So we're likely to have
   more architecture-specific stuff if non-x86 architectures start using
   this.

   (and if it turns out that non-x86 architectures don't start using
   this, then having it in an architecture-specific header is still the
   right thing to do, of course)
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f68e556e
  23. 03 4月, 2012 1 次提交
  25. 01 4月, 2012 7 次提交