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  1. Dec 18, 2010
    • Chris Metcalf's avatar
      arch/tile: handle rt_sigreturn() more cleanly · 81711cee
      Chris Metcalf authored 
      

The current tile rt_sigreturn() syscall pattern uses the common idiom
of loading up pt_regs with all the saved registers from the time of
the signal, then anticipating the fact that we will clobber the ABI
"return value" register (r0) as we return from the syscall by setting
the rt_sigreturn return value to whatever random value was in the pt_regs
for r0.

However, this breaks in our 64-bit kernel when running "compat" tasks,
since we always sign-extend the "return value" register to properly
handle returned pointers that are in the upper 2GB of the 32-bit compat
address space.  Doing this to the sigreturn path then causes occasional
random corruption of the 64-bit r0 register.

Instead, we stop doing the crazy "load the return-value register"
hack in sigreturn.  We already have some sigreturn-specific assembly
code that we use to pass the pt_regs pointer to C code.  We extend that
code to also set the link register to point to a spot a few instructions
after the usual syscall return address so we don't clobber the saved r0.
Now it no longer matters what the rt_sigreturn syscall returns, and the
pt_regs structure can be cleanly and completely reloaded.

Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
      81711cee
    • Chris Metcalf's avatar
      arch/tile: handle CLONE_SETTLS in copy_thread(), not user space · bc4cf2bb
      Chris Metcalf authored 
      

Previously we were just setting up the "tp" register in the
new task as started by clone() in libc.  However, this is not
quite right, since in principle a signal might be delivered to
the new task before it had its TLS set up.  (Of course, this race
window still exists for resetting the libc getpid() cached value
in the new task, in principle.  But in any case, we are now doing
this exactly the way all other architectures do it.)

This change is important for 2.6.37 since the tile glibc we will
be submitting upstream will not set TLS in user space any more,
so it will only work on a kernel that has this fix.  It should
also be taken for 2.6.36.x in the stable tree if possible.

Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
Cc: stable <stable@kernel.org>
      bc4cf2bb
  3. Dec 15, 2010
  5. Dec 14, 2010
    • Chris Mason's avatar
      Btrfs: prevent RAID level downgrades when space is low · 83a50de9
      Chris Mason authored 
      

The extent allocator has code that allows us to fill
allocations from any available block group, even if it doesn't
match the raid level we've requested.

This was put in because adding a new drive to a filesystem
made with the default mkfs options actually upgrades the metadata from
single spindle dup to full RAID1.

But, the code also allows us to allocate from a raid0 chunk when we
really want a raid1 or raid10 chunk.  This can cause big trouble because
mkfs creates a small (4MB) raid0 chunk for data and metadata which then
goes unused for raid1/raid10 installs.

The allocator will happily wander in and allocate from that chunk when
things get tight, which is not correct.

The fix here is to make sure that we provide duplication when the
caller has asked for it.  It does all the dups to be any raid level,
which preserves the dup->raid1 upgrade abilities.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      83a50de9
    • Chris Mason's avatar
      Btrfs: account for missing devices in RAID allocation profiles · cd02dca5
      Chris Mason authored 
      

When we mount in RAID degraded mode without adding a new device to
replace the failed one, we can end up using the wrong RAID flags for
allocations.

This results in strange combinations of block groups (raid1 in a raid10
filesystem) and corruptions when we try to allocate blocks from single
spindle chunks on drives that are actually missing.

The first device has two small 4MB chunks in it that mkfs creates and
these are usually unused in a raid1 or raid10 setup.  But, in -o degraded,
the allocator will fall back to these because the mask of desired raid groups
isn't correct.

The fix here is to count the missing devices as we build up the list
of devices in the system.  This count is used when picking the
raid level to make sure we continue using the same levels that were
in place before we lost a drive.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      cd02dca5
    • Chris Mason's avatar
      Btrfs: EIO when we fail to read tree roots · 68433b73
      Chris Mason authored 
      

If we just get a plain IO error when we read tree roots, the code
wasn't properly sending that error up the chain.  This allowed mounts to
continue when they should failed, and allowed operations
on partially setup root structs.  The end result was usually oopsen
on spinlocks that hadn't been spun up correctly.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      68433b73
  7. Dec 11, 2010
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