root_item->flags and root_item->byte_limit are not initialized when
a subvolume is created. This bug is not revealed until we added
readonly snapshot support - now you mount a btrfs filesystem and you
may find the subvolumes in it are readonly.

To work around this problem, we steal a bit from root_item->inode_item->flags,
and use it to indicate if those fields have been properly initialized.
When we read a tree root from disk, we check if the bit is set, and if
not we'll set the flag and initialize the two fields of the root item.
Reported-by: NAndreas Philipp <philipp.andreas@gmail.com>
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Tested-by: NAndreas Philipp <philipp.andreas@gmail.com>
cc: stable@kernel.org
Signed-off-by: NChris Mason <chris.mason@oracle.com>

the object id of the space cache inode's key is allocated from the relative
root, just like the regular file. So we can't identify space cache inode by
checking the object id of the inode's key, and we have to clear __GFP_FS flag
at the time we look up the space cache inode.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Free btrfs_trans_handle when join_transaction() fails
in start_transaction()
Signed-off-by: NYoshinori Sano <yoshinori.sano@gmail.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Call btrfs_end_transaction() if btrfs_commit_transaction_async() fails.
Signed-off-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

btrfs_rename() does not release the subvol_sem if the transaction failed to start.
Signed-off-by: NJohann Lombardi <johann@whamcloud.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

When we defrag a file, whose size can be fit into an inline extent,
with compression enabled, the compress type is set to be
fs_info->compress_type, which is 0 if the btrfs filesystem is mounted
without compress option. This leads to oops.
Reported-by: NDaniel Blueman <daniel.blueman@gmail.com>
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Some mount options are not displayed by /proc/mounts.
This patch displays the option such as compress_type by /proc/mounts.

Ex.
  [before]
    $ mount | grep sdc2
    /dev/sdc2 on /test12 type btrfs (rw,space_cache,compress=lzo)
    $ cat /proc/mounts | grep sdc2
    /dev/sdc2 /test12 btrfs rw,relatime,compress 0 0

  [after]
    $ mount | grep sdc2
    /dev/sdc2 on /test12 type btrfs (rw,space_cache,compress=lzo)
    $ cat /proc/mounts | grep sdc2
    /dev/sdc2 /test12 btrfs rw,relatime,compress=lzo,space_cache 0 0
Signed-off-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

While compiling Btrfs, I got following messages:

  CC [M]  fs/btrfs/file.o
fs/btrfs/file.c: In function '__btrfs_buffered_write':
fs/btrfs/file.c:909: warning: 'ret' may be used uninitialized in this function
  CC [M]  fs/btrfs/tree-defrag.o

This patch fixes compiler warning.
Signed-off-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Recent changes for discard support didn't compile,
this fixes them not to try and % 64 bit numbers.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Using the GFP_HIGHUSER_MOVABLE flag to allocate the metadata's page may cause
deadlock.
  Task1
  open()
    ...
    btrfs_search_slot()
      ...
      btrfs_cow_block()
	...
	alloc_page()
	  wait for reclaiming
					shrink_slab()
					  ...
					  shrink_icache_memory()
					    ...
					    btrfs_evict_inode()
					      ...
					      btrfs_search_slot()

If the path is locked by task1, the deadlock happens.

So the btree's page cache is different with the file's page cache, it can not
allocate pages by GFP_HIGHUSER_MOVABLE flag, we must clear __GFP_FS flag in
GFP_HIGHUSER_MOVABLE flag.
Reported-by: NItaru Kitayama <kitayama@cl.bb4u.ne.jp>
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

old_inode is not locked; it's not safe to play with its link
count.  Instead of bumping it and calling btrfs_unlink_inode(),
add a variant of the latter that does not do btrfs_drop_nlink()/
btrfs_update_inode(), call it instead of btrfs_inc_nlink()/
btrfs_unlink_inode() and do btrfs_update_inode() ourselves.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

Adding the check on the return value of btrfs_alloc_path() to several places.
And, some of callers are modified by this change.
Signed-off-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

btrfs will remove unused block groups after balance.
When a empty filesystem is balanced, the block group with tag "DATA" may be
dropped, and after umount and mount again, it will not find "DATA" space_info
and lead to OOPS.
So we initial the necessary space_infos(DATA, SYSTEM, METADATA) to avoid OOPS.
Reported-by: NDaniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

After Josef's patch(commit 3c14874a),
btrfs will exclude super bytes when reading block groups(by marking a extent
state UPTODATE).  However, these bytes do not get freed while balance remove
unused block groups, and we won't process those removed ones any more, when
we do umount and unload the btrfs module,  btrfs hits a memory leak.

This patch add the missing free operation.

Reproduce steps:
$ mkfs.btrfs disk
$ mount disk /mnt/btrfs -o loop
$ btrfs filesystem balance /mnt/btrfs
$ umount /mnt/btrfs
$ rmmod btrfs
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

setflags ioctl should return error when any checks fail.
Signed-off-by: NLiu Bo <liubo2009@cn.fujitsu.com>
Reviewed-by: NDavid Sterba <dsterba@suse.cz>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

To make Btrfs code more robust, several return value checks where memory
allocation can fail are introduced. I use BUG_ON where I don't know how
to handle the error properly, which increases the number of using the
notorious BUG_ON, though.
Signed-off-by: NYoshinori Sano <yoshinori.sano@gmail.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

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: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris 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: NLi Dongyang <lidongyang@novell.com>
Signed-off-by: NChris 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: NLi Dongyang <lidongyang@novell.com>
Signed-off-by: NChris 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: NLi Dongyang <lidongyang@novell.com>
Signed-off-by: NChris 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: NLi Dongyang <lidongyang@novell.com>
Signed-off-by: NChris 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: NMark Fasheh <mfasheh@suse.com>
Signed-off-by: NChris 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: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris 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: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris 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: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NChris 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: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NChris 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: NChris 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: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NChris 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: NLiu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: NChris 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: NChris 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: NJosef 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: NJosef 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: NJosef 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: NJosef 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: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NJosef 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: NJosef 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: NJosef 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: NJosef 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: NJosef Bacik <josef@redhat.com>