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>

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>

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>

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>

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>

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>

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>

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>

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>

Code has been converted over to the new explicit on-stack plugging,
and delay users have been converted to use the new API for that.
So lets kill off the old plugging along with aops->sync_page().
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

There is a race where btrfs_releasepage can drop the
page->private contents just as alloc_extent_buffer is setting
up pages for metadata.  Because of how the Btrfs page flags work,
this results in us skipping the crc on the page during IO.

This patch sovles the race by waiting until after the extent buffer
is inserted into the radix tree before it sets page private.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

The error check of btrfs_join_transaction()/btrfs_join_transaction_nolock()
is added, and the mistake of the error check in several places is
corrected.

For more stable Btrfs, I think that we should reduce BUG_ON().
But, I think that long time is necessary for this.
So, I propose this patch as a short-term solution.

With this patch:
 - To more stable Btrfs, the part that should be corrected is clarified.
 - The panic isn't done by the NULL pointer reference etc. (even if
   BUG_ON() is increased temporarily)
 - The error code is returned in the place where the error can be easily
   returned.

As a long-term plan:
 - BUG_ON() is reduced by using the forced-readonly framework, etc.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs_info, which is allocated in open_ctree(), should be freed
in close_ctree().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

This patch comes from "Forced readonly mounts on errors" ideas.

As we know, this is the first step in being more fault tolerant of disk
corruptions instead of just using BUG() statements.

The major content:
- add a framework for generating errors that should result in filesystems
  going readonly.
- keep FS state in disk super block.
- make sure that all of resource will be freed and released at umount time.
- make sure that fter FS is forced readonly on error, there will be no more
  disk change before FS is corrected. For this, we should stop write operation.

After this patch is applied, the conversion from BUG() to such a framework can
happen incrementally.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

In btrfs_read_fs_root_no_radix(), 'root' is not freed if
btrfs_search_slot() returns error.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Should check if functions returns NULL or not.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

I happened to pass swap partition as root partition in cmdline,
then kernel panic and tell me about "Cannot open root device".
It is not correct, in fact it is a fs type mismatch instead of 'no device'.

Eventually I found btrfs mounting failed with -EIO, it should be -EINVAL.
The logic in init/do_mounts.c:
        for (p = fs_names; *p; p += strlen(p)+1) {
                int err = do_mount_root(name, p, flags, root_mount_data);
                switch (err) {
                        case 0:
                                goto out;
                        case -EACCES:
                                flags |= MS_RDONLY;
                                goto retry;
                        case -EINVAL:
                                continue;
                }
		print "Cannot open root device"
		panic
	}
SO fs type after btrfs will have no chance to mount

Here fix the return value as -EINVAL
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Lzo is a much faster compression algorithm than gzib, so would allow
more users to enable transparent compression, and some users can
choose from compression ratio and speed for different applications

Usage:

 # mount -t btrfs -o compress[=<zlib,lzo>] dev /mnt
or
 # mount -t btrfs -o compress-force[=<zlib,lzo>] dev /mnt

"-o compress" without argument is still allowed for compatability.

Compatibility:

If we mount a filesystem with lzo compression, it will not be able be
mounted in old kernels. One reason is, otherwise btrfs will directly
dump compressed data, which sits in inline extent, to user.

Performance:

The test copied a linux source tarball (~400M) from an ext4 partition
to the btrfs partition, and then extracted it.

(time in second)
           lzo        zlib        nocompress
copy:      10.6       21.7        14.9
extract:   70.1       94.4        66.6

(data size in MB)
           lzo        zlib        nocompress
copy:      185.87     108.69      394.49
extract:   193.80     132.36      381.21

Changelog:

v1 -> v2:
- Select LZO_COMPRESS and LZO_DECOMPRESS in btrfs Kconfig.
- Add incompability flag.
- Fix error handling in compress code.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

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: Chris Mason <chris.mason@oracle.com>

... regarding an unused function when !MIGRATION, and regarding a
printk() format string vs argument mismatch.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Fixes compile error
Signed-off-by: Chris Mason <chris.mason@oracle.com>

There is a problem with how we use sget, it searches through the list of supers
attached to the fs_type looking for a super with the same fs_devices as what
we're trying to mount.  This depends on sb->s_fs_info being filled, but we don't
fill that in until we get to btrfs_fill_super, so we could hit supers on the
fs_type super list that have a null s_fs_info.  In order to fix that we need to
go ahead and setup a blank root with a blank fs_info to hold fs_devices, that
way our test will work out right and then we can set s_fs_info in
btrfs_set_super, and then open_ctree will simply use our pre-allocated root and
fs_info when setting everything up.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Migrate page will directly call the btrfs btree writepage function,
which isn't actually allowed.

Our writepage assumes that you have locked the extent_buffer and
flagged the block as written.  Without doing these steps, we can
corrupt metadata blocks.

A later commit will remove the btree writepage function since
it is really only safely used internally by btrfs.  We
use writepages for everything else.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Add support for an async transaction commit that is ordered such that any
subsequent operations will join the following transaction, but does not
wait until the current commit is fully on disk.  This avoids much of the
latency associated with the btrfs_commit_transaction for callers concerned
with serialization and not safety.

The wait_for_unblock flag controls whether we wait for the 'middle' portion
of commit_transaction to complete, which is necessary if the caller expects
some of the modifications contained in the commit to be available (this is
the case for subvol/snapshot creation).
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

These are all the cases where a variable is set, but not read which are
not bugs as far as I can see, but simply leftovers.

Still needs more review.

Found by gcc 4.6's new warnings
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

This is a simple bit, just dump the free space cache out to our preallocated
inode when we're writing out dirty block groups.  There are a bunch of changes
in inode.c in order to account for special cases.  Mostly when we're doing the
writeout we're holding trans_mutex, so we need to use the nolock transacation
functions.  Also we can't do asynchronous completions since the async thread
could be blocked on already completed IO waiting for the transaction lock.  This
has been tested with xfstests and btrfs filesystem balance, as well as my ENOSPC
tests.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

In order to save free space cache, we need an inode to hold the data, and we
need a special item to point at the right inode for the right block group.  So
first, create a special item that will point to the right inode, and the number
of extent entries we will have and the number of bitmaps we will have.  We
truncate and pre-allocate space everytime to make sure it's uptodate.

This feature will be turned on as soon as you mount with -o space_cache, however
it is safe to boot into old kernels, they will just generate the cache the old
fashion way.  When you boot back into a newer kernel we will notice that we
modified and not the cache and automatically discard the cache.
Signed-off-by: Josef Bacik <josef@redhat.com>

Switch to the WRITE_FLUSH_FUA flag for log writes, remove the EOPNOTSUPP
detection for barriers and stop setting the barrier flag for discards.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

Remove the current bio flags and reuse the request flags for the bio, too.
This allows to more easily trace the type of I/O from the filesystem
down to the block driver.  There were two flags in the bio that were
missing in the requests:  BIO_RW_UNPLUG and BIO_RW_AHEAD.  Also I've
renamed two request flags that had a superflous RW in them.

Note that the flags are in bio.h despite having the REQ_ name - as
blkdev.h includes bio.h that is the only way to go for now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

btrfs_read_fs_root_no_name() returns ERR_PTRs on error so I added a
check for that.  It's not clear to me if it can also return NULL
pointers or not so I left the original NULL pointer check as is.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Unwind and return -ENOMEM if the allocation fails here.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

The async helper threads offload crc work onto all the
CPUs, and make streaming writes much faster.  This
changes the O_DIRECT write code to use them.  The only
small complication was that we need to pass in the
logical offset in the file for each bio, because we can't
find it in the bio's pages.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Previous patches make the allocater return -ENOSPC if there is no
unreserved free metadata space. This patch updates tree log code
and various other places to propagate/handle the ENOSPC error.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

reserve metadata space for handling orphan inodes
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Reserve metadata space for extent tree, checksum tree and root tree
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Besides simplify the code, this change makes sure all metadata
reservation for normal metadata operations are released after
committing transaction.

Changes since V1:

Add code that check if unlink and rmdir will free space.

Add ENOSPC handling for clone ioctl.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Introducing metadata reseravtion contexts has two major advantages.
First, it makes metadata reseravtion more traceable. Second, it can
reclaim freed space and re-add them to the itself after transaction
committed.

Besides add btrfs_block_rsv structure and related helper functions,
This patch contains following changes:

Move code that decides if freed tree block should be pinned into
btrfs_free_tree_block().

Make space accounting more accurate, mainly for handling read only
block groups.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Shrink delayed allocation space in a synchronized manner is more
controllable than flushing all delay allocated space in an async
thread.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>