linux.git/block, branch v3.12-rc1

partitions/efi: loosen check fot pmbr size in lba

2013-09-15T11:10:16+00:00

Matt found that commit 27a7c642174e ("partitions/efi: account for pmbr
size in lba") caused his GPT formatted eMMC device not to boot.  The
reason is that this commit enforced Linux to always check the lesser of
the whole disk or 2Tib for the pMBR size in LBA.  While most disk
partitioning tools out there create a pMBR with these characteristics,
Microsoft does not, as it always sets the entry to the maximum 32-bit
limitation - even though a drive may be smaller than that[1].

Loosen this check and only verify that the size is either the whole disk
or 0xFFFFFFFF.  No tool in its right mind would set it to any value
other than these.

[1] http://thestarman.pcministry.com/asm/mbr/GPT.htm#GPTPT

Reported-and-tested-by: Matt Porter 
Signed-off-by: Davidlohr Bueso 
Signed-off-by: Linus Torvalds

lib/radix-tree.c: make radix_tree_node_alloc() work correctly within interrupt

2013-09-11T22:59:36+00:00

With users of radix_tree_preload() run from interrupt (block/blk-ioc.c is
one such possible user), the following race can happen:

radix_tree_preload()
...
radix_tree_insert()
  radix_tree_node_alloc()
    if (rtp->nr) {
      ret = rtp->nodes[rtp->nr - 1];

...
radix_tree_preload()
...
radix_tree_insert()
  radix_tree_node_alloc()
    if (rtp->nr) {
      ret = rtp->nodes[rtp->nr - 1];

And we give out one radix tree node twice.  That clearly results in radix
tree corruption with different results (usually OOPS) depending on which
two users of radix tree race.

We fix the problem by making radix_tree_node_alloc() always allocate fresh
radix tree nodes when in interrupt.  Using preloading when in interrupt
doesn't make sense since all the allocations have to be atomic anyway and
we cannot steal nodes from process-context users because some users rely
on radix_tree_insert() succeeding after radix_tree_preload().
in_interrupt() check is somewhat ugly but we cannot simply key off passed
gfp_mask as that is acquired from root_gfp_mask() and thus the same for
all preload users.

Another part of the fix is to avoid node preallocation in
radix_tree_preload() when passed gfp_mask doesn't allow waiting.  Again,
preallocation in such case doesn't make sense and when preallocation would
happen in interrupt we could possibly leak some allocated nodes.  However,
some users of radix_tree_preload() require following radix_tree_insert()
to succeed.  To avoid unexpected effects for these users,
radix_tree_preload() only warns if passed gfp mask doesn't allow waiting
and we provide a new function radix_tree_maybe_preload() for those users
which get different gfp mask from different call sites and which are
prepared to handle radix_tree_insert() failure.

Signed-off-by: Jan Kara 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

block/partitions/efi.c: consistently use pr_foo()

2013-09-11T22:59:19+00:00

Cc: Davidlohr Bueso 
Cc: Karel Zak 
Cc: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

partitions/efi: some style cleanups

2013-09-11T22:59:19+00:00

Trivial coding style cleanups - still plenty left.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso 
Reviewed-by: Karel Zak 
Acked-by: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

partitions/efi: delete annoying emacs style comments

2013-09-11T22:59:18+00:00

I love emacs, but these settings for coding style are annoying when trying
to open the efi.h file.  More important, we already have checkpatch for
that.

Signed-off-by: Davidlohr Bueso 
Reviewed-by: Karel Zak 
Acked-by: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

partitions/efi: compare first and last usable LBAs

2013-09-11T22:59:18+00:00

When verifying GPT header integrity, make sure that first usable LBA is
smaller than last usable LBA.

Signed-off-by: Davidlohr Bueso 
Reviewed-by: Karel Zak 
Acked-by: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

partitions/efi: account for pmbr size in lba

2013-09-11T22:59:17+00:00

The partition that has the 0xEE (GPT protective), must have the size in
lba field set to the lesser of the size of the disk minus one or
0xFFFFFFFF for larger disks.

Signed-off-by: Davidlohr Bueso 
Reviewed-by: Karel Zak 
Acked-by: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

partitions/efi: detect hybrid MBRs

2013-09-11T22:59:16+00:00

One of the biggest problems with GPT is compatibility with older, non-GPT
systems.  The problem is addressed by creating hybrid mbrs, an extension,
or variant, of the traditional protective mbr.  This contains, apart from
the 0xEE partition, up three additional primary partitions that point to
the same space marked by up to three GPT partitions.  The result is that
legacy OSs can see the three required MBR partitions and at the same time
ignore the GPT-aware partitions that protect the GPT structures.

While hybrid MBRs are hacks, workarounds and simply not part of the GPT
standard, they do exist and we have no way around them.  For instance, by
default, OSX creates a hybrid scheme when using multi-OS booting.

In order for Linux to properly discover protective MBRs, it must be made
aware of devices that have hybrid MBRs.  No functionality is changed by
this patch, just a debug message informing the user of the MBR scheme that
is being used.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso 
Reviewed-by: Karel Zak 
Acked-by: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

partitions/efi: do not require gpt partition to begin at sector 1

2013-09-11T22:59:16+00:00

When detecting a valid protective MBR, the Linux kernel isn't picky about
the partition (1-4) the 0xEE is at, but, unlike other operating systems,
it does require it to begin at the second sector (sector 1).  This check,
apart from it not being enforced by UEFI, and causing Linux to potentially
fail to detect any *valid* partitions on the disk, can present problems
when dealing with hybrid MBRs[1].

For compatibility reasons, if the first partition is hybridized, the 0xEE
partition must be small enough to ensure that it only protects the GPT
data structures - as opposed to the the whole disk in a protective MBR.
This problem is very well described by Rod Smith[1]: where MBR-only
partitioning programs (such as older versions of fdisk) can see some of
the disk space as unallocated, thus loosing the purpose of the 0xEE
partition's protection of GPT data structures.

By dropping this check, this patch enables Linux to be more flexible when
probing for GPT disklabels.

[1] http://www.rodsbooks.com/gdisk/hybrid.html#reactions

Signed-off-by: Davidlohr Bueso 
Reviewed-by: Karel Zak 
Acked-by: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

partitions/efi: check pmbr record's starting lba

2013-09-11T22:59:15+00:00

Per the UEFI Specs 2.4, June 2013, the starting lba of the partition that
has the EFI GPT (0xEE) must be set to 0x00000001 - this is obviously the
LBA of the GPT Partition Header.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso 
Reviewed-by: Karel Zak 
Acked-by: Matt Fleming 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds