I've been working on making our O_DIRECT latency not suck and I noticed we were
taking the trans_mutex in btrfs_end_transaction.  So to do this we convert
num_writers and use_count to atomic_t's and just decrement them in
btrfs_end_transaction.  Instead of deleting the transaction from the trans list
in put_transaction we do that in btrfs_commit_transaction() since that's the
only time it actually needs to be removed from the list.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Apparently it is ok to submit a read to an IDE device with the same target page
for different offsets.  This is what Windows does under qemu.  The problem is
under DIO we expect them to be different buffers for checksumming reasons, and
so this sort of thing will result in checksum errors, when in reality the file
is fine.  So when reading, check to make sure that all iov bases are different,
and if they aren't fall back to buffered mode, since that will work out right.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

In btrfs_get_block_direct we call btrfs_get_extent to lookup the extent for the
range that we are looking for.  If we don't find an extent, btrfs_get_extent
will insert a extent_map for that area and mark it as a hole.  So it does the
job of allocating a new extent map and inserting it into the io tree.  But if
we're creating a new extent we free it up and redo all of that work.  So instead
pass the em to btrfs_new_extent_direct(), and if it will work just allocate the
disk space and set it up properly and bypass the freeing/allocating of a new
extent map and the expensive operation of inserting the thing into the io_tree.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

When looking at our DIO performance Chris said that for small IO's doing the
async submit stuff tends to be more overhead than it's worth.  With this on top
of my other fixes I get about a 17-20% speedup doing a sequential dd with 4k
IO's.  Basically if we don't have to split the bio for the map length it's small
enough to be directly submitted, otherwise go back to the async submit.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

We have been unconditionally allocating a new bio and re-adding all pages from
our original bio to the new bio.  This is needed if our original bio is larger
than our stripe size, but if it is smaller than the stripe size then there is no
need to do this.  So check the map length and if we are under that then go ahead
and submit the original bio.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

In the DIO code we often don't update the i_disk_size because the i_size isn't
updated until after the DIO is completed, so basically we are allocating a path,
doing a search, and updating the inode item for no reason since nothing changed.
btrfs_ordered_update_i_size will return 1 if it didn't update i_disk_size, so
only run btrfs_update_inode if btrfs_ordered_update_i_size returns 0.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Instead of calling kmap_atomic for every thing we set in the inode item, map the
entire inode item at the start and unmap it at the end.  This makes a sequential
dd of 400mb O_DIRECT something like 1% faster.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

I saw a lockup where we kept getting into this start transaction->commit
transaction loop because of enospce.  The fact is if we fail to make our
reservation, we've tried _everything_ several times, so we only need to try and
commit the transaction once, and if that doesn't work then we really are out of
space and need to just exit.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Currently we don't handle running out of space in the cache, so to fix this we
keep track of how far in the cache we are.  Then we only dirty the pages if we
successfully modify all of them, otherwise if we have an error or run out of
space we can just drop them and not worry about the vm writing them out.
Thanks,

Tested-by Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de>
Signed-off-by: Josef Bacik <josef@redhat.com>

When I moved the orphan adding to btrfs_truncate I missed the fact that during
orphan cleanup we just add the orphan items to the orphan list without going
through btrfs_orphan_add, which results in lots of warnings on mount if you have
any orphan items that need to be truncated.  Just remove this warning since it's
ok, this will allow all of the normal space accounting take place.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

I noticed a huge problem with the free space cache that was presenting
as an early ENOSPC.  Turns out when writing the free space cache out I
forgot to take into account pinned extents and more importantly
clusters.  This would result in us leaking free space everytime we
unmounted the filesystem and remounted it.

I fix this by making sure to check and see if the current block group
has a cluster and writing out any entries that are in the cluster to the
cache, as well as writing any pinned extents we currently have to the
cache since those will be available for us to use the next time the fs
mounts.

This patch also adds a check to the end of load_free_space_cache to make
sure we got the right amount of free space cache, and if not make sure
to clear the cache and re-cache the old fashioned way.
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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: Andreas Philipp <philipp.andreas@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Tested-by: Andreas Philipp <philipp.andreas@gmail.com>
cc: stable@kernel.org
Signed-off-by: Chris 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: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

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

btrfs_rename() does not release the subvol_sem if the transaction failed to start.
Signed-off-by: Johann Lombardi <johann@whamcloud.com>
Signed-off-by: Chris 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: Daniel Blueman <daniel.blueman@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris 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: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris 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: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris 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: Chris 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: Itaru Kitayama <kitayama@cl.bb4u.ne.jp>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chris 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: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chris 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: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris 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: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris 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: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

setflags ioctl should return error when any checks fail.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris 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: Yoshinori Sano <yoshinori.sano@gmail.com>
Signed-off-by: Chris 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: 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>