When we recover from crash via write-ahead log tree and process
the inode refs, for each btrfs_inode_ref item, we will
1) check if we already have a perfect match in fs/file tree, if
   we have, then we're done.
2) search the corresponding back reference in fs/file tree, and
   check all the names in this back reference to see if they are
   also in the log to avoid conflict corners.
3) recover the logged inode refs to fs/file tree.

In current btrfs, however,
- for 2)'s check, once is enough, since the checked back reference
  will remain unchanged after processing all the inode refs belonged
  to the key.
- it has no need to do another 1) between 2) and 3).

I've made a small test to show how it improves,

$dd if=/dev/zero of=foobar bs=4K count=1
$sync
$make 100 hard links continuously, like ln foobar link_i
$fsync foobar
$echo b > /proc/sysrq-trigger
after reboot
$time mount DEV PATH

without patch:
real    0m0.285s
user    0m0.001s
sys     0m0.009s

with patch:
real    0m0.123s
user    0m0.000s
sys     0m0.010s

Changelog v1->v2:
- fix double free - pointed by David Sterba
Changelog v2->v3:
- adjust free order
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

We take an free extent out from allocator, trim it, then put it back,
but before we trim the block group, we should make sure the block group is
cached, so plus a little change to make cache_block_group() run without a
transaction.
Signed-off-by: Li Dongyang <lidongyang@novell.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Callers of btrfs_discard_extent() should check if we are mounted with -o discard,
as we want to make fitrim to work even the fs is not mounted with -o discard.
Also we should use REQ_DISCARD to map the free extent to get a full mapping,
last we only return errors if
1. the error is not a EOPNOTSUPP
2. no device supports discard
Signed-off-by: Li Dongyang <lidongyang@novell.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

btrfs_map_block() will only return a single stripe length, but we want the
full extent be mapped to each disk when we are trimming the extent,
so we add length to btrfs_bio_stripe and fill it if we are mapping for REQ_DISCARD.
Signed-off-by: Li Dongyang <lidongyang@novell.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Make the function public as we should update the reserved extents calculations
after taking out an extent for trimming.
Signed-off-by: Li Dongyang <lidongyang@novell.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

btrfs_link returns EPERM if a cross-subvolume link is attempted.

However, in this case I believe EXDEV to be the more appropriate value.
>From the link(2) man page:

EXDEV  oldpath and newpath are not on the same mounted file system.  (Linux
       permits a file system to be mounted at multiple points, but link()
       does not work across different mount points, even if the same file
       system is mounted on both.)

This matters because an application may have different behaviors based on
return codes.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Data compression and data cow are controlled across the entire FS by mount
options right now.  ioctls are needed to set this on a per file or per
directory basis.  This has been proposed previously, but VFS developers
wanted us to use generic ioctls rather than btrfs-specific ones.

According to Chris's comment, there should be just one true compression
method(probably LZO) stored in the super.  However, before this, we would
wait for that one method is stable enough to be adopted into the super.
So I list it as a long term goal, and just store it in ram today.

After applying this patch, we can use the generic "FS_IOC_SETFLAGS" ioctl to
control file and directory's datacow and compression attribute.

NOTE:
 - The compression type is selected by such rules:
   If we mount btrfs with compress options, ie, zlib/lzo, the type is it.
   Otherwise, we'll use the default compress type (zlib today).

v1->v2:
- rebase to the latest btrfs.
v2->v3:
- fix a problem, i.e. when a file is set NOCOW via mount option, then this NOCOW
  will be screwed by inheritance from parent directory.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

For datacow control, the corresponding inode flags are needed.
This is for btrfs use.

v1->v2:
Change FS_COW_FL to another bit due to conflict with the upstream e2fsprogs
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

In the filesystem context, we must allocate memory by GFP_NOFS,
or we may start another filesystem operation and make kswap thread hang up.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

This patch is checking return value of read_tree_block(),
and if it is NULL, error processing.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

On Fri, Mar 18, 2011 at 11:56:53AM -0400, Chris Mason wrote:
> Thanks for fielding this one.  Does put_unaligned_le32 optimize away on
> platforms with efficient access?  It would be great if we didn't need
> the #ifdef.

(quicktest: assembly output is same for put_unaligned_le32 and direct
assignment on my x86_64)
I was originally following examples in
Documentation/unaligned-memory-access.txt. From other code it seems to me that
the define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is intended for larger
portions of code. Macros/wrappers for {put,get}_unaligned* are chosen via
arch/<arch>/include/asm/unaligned.h accordingly, therefore it's safe to use
put_unaligned_le32 without the ifdef.

dave
Signed-off-by: Chris Mason <chris.mason@oracle.com>

This patch changes some BUG_ON() to the error return.
(but, most callers still use BUG_ON())
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Tracepoints can provide insight into why btrfs hits bugs and be greatly
helpful for debugging, e.g
              dd-7822  [000]  2121.641088: btrfs_inode_request: root = 5(FS_TREE), gen = 4, ino = 256, blocks = 8, disk_i_size = 0, last_trans = 8, logged_trans = 0
              dd-7822  [000]  2121.641100: btrfs_inode_new: root = 5(FS_TREE), gen = 8, ino = 257, blocks = 0, disk_i_size = 0, last_trans = 0, logged_trans = 0
 btrfs-transacti-7804  [001]  2146.935420: btrfs_cow_block: root = 2(EXTENT_TREE), refs = 2, orig_buf = 29368320 (orig_level = 0), cow_buf = 29388800 (cow_level = 0)
 btrfs-transacti-7804  [001]  2146.935473: btrfs_cow_block: root = 1(ROOT_TREE), refs = 2, orig_buf = 29364224 (orig_level = 0), cow_buf = 29392896 (cow_level = 0)
 btrfs-transacti-7804  [001]  2146.972221: btrfs_transaction_commit: root = 1(ROOT_TREE), gen = 8
   flush-btrfs-2-7821  [001]  2155.824210: btrfs_chunk_alloc: root = 3(CHUNK_TREE), offset = 1103101952, size = 1073741824, num_stripes = 1, sub_stripes = 0, type = DATA
   flush-btrfs-2-7821  [001]  2155.824241: btrfs_cow_block: root = 2(EXTENT_TREE), refs = 2, orig_buf = 29388800 (orig_level = 0), cow_buf = 29396992 (cow_level = 0)
   flush-btrfs-2-7821  [001]  2155.824255: btrfs_cow_block: root = 4(DEV_TREE), refs = 2, orig_buf = 29372416 (orig_level = 0), cow_buf = 29401088 (cow_level = 0)
   flush-btrfs-2-7821  [000]  2155.824329: btrfs_cow_block: root = 3(CHUNK_TREE), refs = 2, orig_buf = 20971520 (orig_level = 0), cow_buf = 20975616 (cow_level = 0)
 btrfs-endio-wri-7800  [001]  2155.898019: btrfs_cow_block: root = 5(FS_TREE), refs = 2, orig_buf = 29384704 (orig_level = 0), cow_buf = 29405184 (cow_level = 0)
 btrfs-endio-wri-7800  [001]  2155.898043: btrfs_cow_block: root = 7(CSUM_TREE), refs = 2, orig_buf = 29376512 (orig_level = 0), cow_buf = 29409280 (cow_level = 0)

Here is what I have added:

1) ordere_extent:
        btrfs_ordered_extent_add
        btrfs_ordered_extent_remove
        btrfs_ordered_extent_start
        btrfs_ordered_extent_put

These provide critical information to understand how ordered_extents are
updated.

2) extent_map:
        btrfs_get_extent

extent_map is used in both read and write cases, and it is useful for tracking
how btrfs specific IO is running.

3) writepage:
        __extent_writepage
        btrfs_writepage_end_io_hook

Pages are cirtical resourses and produce a lot of corner cases during writeback,
so it is valuable to know how page is written to disk.

4) inode:
        btrfs_inode_new
        btrfs_inode_request
        btrfs_inode_evict

These can show where and when a inode is created, when a inode is evicted.

5) sync:
        btrfs_sync_file
        btrfs_sync_fs

These show sync arguments.

6) transaction:
        btrfs_transaction_commit

In transaction based filesystem, it will be useful to know the generation and
who does commit.

7) back reference and cow:
	btrfs_delayed_tree_ref
	btrfs_delayed_data_ref
	btrfs_delayed_ref_head
	btrfs_cow_block

Btrfs natively supports back references, these tracepoints are helpful on
understanding btrfs's COW mechanism.

8) chunk:
	btrfs_chunk_alloc
	btrfs_chunk_free

Chunk is a link between physical offset and logical offset, and stands for space
infomation in btrfs, and these are helpful on tracing space things.

9) reserved_extent:
	btrfs_reserved_extent_alloc
	btrfs_reserved_extent_free

These can show how btrfs uses its space.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

The pointer to the extent buffer for the root of each tree
is protected by a spinlock so that we can safely read the pointer
and take a reference on the extent buffer.

But now that the extent buffers are freed via RCU, we can safely
use rcu_read_lock instead.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

I noticed that dio_end_io calls the appropriate endio function with an error,
but the endio functions don't actually do anything with that error, they assume
that if there was an error then the bio will not be uptodate.  So if we had
checksum failures we would never pass back EIO.  So if there is an error in our
endio functions make sure to clear the uptodate flag on the bio.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

When doing direct writes we store the checksums in the ordered sum stuff in the
ordered extent for writing them when the write completes, so we don't even use
the dip->csums array.  So if we're writing, don't bother allocating dip->csums
since we won't use it anyway.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

This patch makes the free space cluster refilling code a little easier to
understand, and fixes some things with the bitmap part of it.  Currently we
either want to refill a cluster with

1) All normal extent entries (those without bitmaps)
2) A bitmap entry with enough space

The current code has this ugly jump around logic that will first try and fill up
the cluster with extent entries and then if it can't do that it will try and
find a bitmap to use.  So instead split this out into two functions, one that
tries to find only normal entries, and one that tries to find bitmaps.

This also fixes a suboptimal thing we would do with bitmaps.  If we used a
bitmap we would just tell the cluster that we were pointing at a bitmap and it
would do the tree search in the block group for that entry every time we tried
to make an allocation.  Instead of doing that now we just add it to the clusters
group.

I tested this with my ENOSPC tests and xfstests and it survived.
Signed-off-by: Josef Bacik <josef@redhat.com>

We have been creating bitmaps for small extents unconditionally forever.  This
was great when testing to make sure the bitmap stuff was working, but is
overkill normally.  So instead of always adding small chunks of free space to
bitmaps, only start doing it if we go past half of our extent threshold.  This
will keeps us from creating a bitmap for just one small free extent at the front
of the block group, and will make the allocator a little faster as a result.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

We do all this fun stuff with min_bytes, but either don't use it in the case of
just normal extents, or use it completely wrong in the case of bitmaps.  So fix
this for both cases

1) In the extent case, stop looking for space with window_free >= min_bytes
instead of bytes + empty_size.

2) In the bitmap case, we were looking for streches of free space that was at
least min_bytes in size, which was not right at all.  So instead search for
stretches of free space that are at least bytes in size (this will make a
difference when we have > page size blocks) and then only search for min_bytes
amount of free space.

Thanks,
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Josef Bacik <josef@redhat.com>

The free space cluster stuff is heavy duty, so there is no sense in going
through the entire song and dance if there isn't enough space in the block group
to begin with.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

We need to make sure the dir items we get are valid dir items.  So any time we
try and read one check it with verify_dir_item, which will do various sanity
checks to make sure it looks sane.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Doing an audit of where we use btrfs_search_slot only showed one place where we
don't check the return value of btrfs_search_slot properly.  Just fix
mark_extent_written to see if btrfs_search_slot failed and act accordingly.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Currently if we have corrupted items things will blow up in spectacular ways.
So as we read in blocks and they are leaves, check the entire leaf to make sure
all of the items are correct and point to valid parts in the leaf for the item
data the are responsible for.  If the item is corrupt we will kick back EIO and
not read any of the copies since they are likely to not be correct either.  This
will catch generic corruptions, it will be up to the individual callers of
btrfs_search_slot to make sure their items are right.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Currently if we have corrupt metadata map_extent_buffer will complain about it,
but not return an error so the caller has no idea a problem was hit.  Fix this.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Everytime I have to deal with btrfs_cont_expand I stare at it for 20 minutes
trying to remember what exactly it does and why the hell we need it.  So add a
comment to save future-Josef some time.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Mark_inode_dirty will call btrfs_dirty_inode which will take care of updating
the inode.  This makes setsize a little cleaner since we don't have to start a
transaction and update the inode in there, we can just call mark_inode_dirty.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

We don't need an orphan item when expanding files, we just need them for
truncating them, so only add the orphan item in btrfs_truncate instead of in
btrfs_setsize.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

This fixes a problem where if truncate fails the inode will still be on the in
memory orphan list.  This is will make us complain when the inode gets destroyed
because it's still on the orphan list.  So if we fail just remove us from the in
memory list and carry on.
Signed-off-by: Josef Bacik <josef@redhat.com>

If we cannot truncate an inode for some reason we will never delete the orphan
item associated with that inode, which means that we will loop forever in
btrfs_orphan_cleanup.  Instead of doing this just return error so we fail to
mount.  It sucks, but hey it's better than hanging.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Now that we can handle having errors in the truncate path lets make sure we
return errors instead of doing BUG_ON() and such.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

->truncate() is going away, instead all of the work needs to be done in
->setattr().  So this converts us over to do this.  It's fairly straightforward,
just get rid of our .truncate inode operation and call btrfs_truncate() directly
from btrfs_setsize.  This works out better for us since truncate can technically
return ENOSPC, and before we had no way of letting anybody know.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Since we alloc/free free space entries a whole lot, lets use a slab to keep
track of them.  This makes some of my tests slightly faster.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

We track delayed allocation per inodes via 2 counters, one is
outstanding_extents and reserved_extents.  Outstanding_extents is already an
atomic_t, but reserved_extents is not and is protected by a spinlock.  So
convert this to an atomic_t and instead of using a spinlock, use atomic_cmpxchg
when releasing delalloc bytes.  This makes our inode 72 bytes smaller, and
reduces locking overhead (albiet it was minimal to begin with).  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Really we don't need to memset the pages array at all, since we know how many
pages we're going to use in the array and pass that around.  So don't memset,
just trust we're not idiots and we pass num_pages around properly.
Signed-off-by: Josef Bacik <josef@redhat.com>

Our aio_write function is huge and kind of hard to follow at times.  So this
patch fixes this by breaking out the buffered and direct write paths out into
seperate functions so it's a little clearer what's going on.  I've also fixed
some wrong typing that we had and added the ability to handle getting an error
back from btrfs_set_extent_delalloc.  Tested this with xfstests and everything
came out fine.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Sorry, but these were bugging me.  Just cleanup some of the formatting in
file.c.
Signed-off-by: Josef Bacik <josef@redhat.com>

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-mn10300:
  MN10300: atomic_read() should ensure it emits a load
  MN10300: The SMP_ICACHE_INV_FLUSH_RANGE IPI command does not exist
  MN10300: Proper use of macros get_user() in the case of incremented pointers

* 'upstream' of git://git.linux-mips.org/pub/scm/upstream-linus: (26 commits)
  MIPS: Alchemy: Fix reset for MTX-1 and XXS1500
  MIPS: MTX-1: Make au1000_eth probe all PHY addresses
  MIPS: Jz4740: Add HAVE_CLK
  MIPS: Move idle task creation to work queue
  MIPS, Perf-events: Use unsigned delta for right shift in event update
  MIPS, Perf-events: Work with the new callchain interface
  MIPS, Perf-events: Fix event check in validate_event()
  MIPS, Perf-events: Work with the new PMU interface
  MIPS, Perf-events: Work with irq_work
  MIPS: Fix always CONFIG_LOONGSON_UART_BASE=y
  MIPS: Loongson: Fix potentially wrong string handling
  MIPS: Fix GCC-4.6 'set but not used' warning in arch/mips/mm/init.c
  MIPS: Fix GCC-4.6 'set but not used' warning in ieee754int.h
  MIPS: Remove unused code from arch/mips/kernel/syscall.c
  MIPS: Fix GCC-4.6 'set but not used' warning in signal*.c
  MIPS: MSP: Fix MSP71xx bpci interrupt handler return value
  MIPS: Select R4K timer lib for all MSP platforms
  MIPS: Loongson: Remove ad-hoc cmdline default
  MIPS: Clear the correct flag in sysmips(MIPS_FIXADE, ...).
  MIPS: Add an unreachable return statement to satisfy buggy GCCs.
  ...

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: ce4100: Set pci ops via callback instead of module init
  x86/mm: Fix pgd_lock deadlock
  x86/mm: Handle mm_fault_error() in kernel space
  x86: Don't check for BIOS corruption in first 64K when there's no need to