It's a bug, but it happens to work, as BTRFS_COMPRESS_LZO == 2, which
has only one bit set.
Signed-off-by: Li Zefan <lizefan@huawei.com>

If a file has 3 small extents:

| ext1 | ext2 | ext3 |

Running "btrfs fi defrag" will only defrag the last two extents, if those
extent mappings hasn't been read into memory from disk.

This bug was introduced by commit 17ce6ef8
("Btrfs: add a check to decide if we should defrag the range")

The cause is, that commit looked into previous and next extents using
lookup_extent_mapping() only.

While at it, remove the code that checks the previous extent, since
it's sufficient to check the next extent.
Signed-off-by: Li Zefan <lizefan@huawei.com>

I removed this in an earlier commit and I was wrong.  Because compression
can return from filemap_fdatawrite() without having actually set any of it's
pages as writeback() it can make filemap_fdatawait() do essentially nothing,
and then we won't find any ordered extents because they may not have been
created yet.  So not only does this make fsync() completely useless, but it
will also screw up if you truncate on a non-page aligned offset since we
zero out the end and then wait on ordered extents and then call drop caches.
We can drop the cache before the io completes and then we try to unpin the
extent we just wrote we won't find it and everything goes sideways.  So fix
this by putting it back and put a giant comment there to keep me from trying
to remove it in the future.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

A user reported lots of problems using compression on the new code and it
turns out part of the problem was that igrab() was failing when we added a
new ordered extent.  This is because when writing out an inode under
compression we immediately return without actually doing anything to the
pages, and then in another thread at some point down the line actually do
the ordered dance.  The problem is between the point that we start writeback
and we actually add the ordered extent we could be trying to reclaim the
inode, which makes igrab() return NULL.  So we need to do an igrab() when we
create the async extent and then drop it when we are done with it.  This
makes sure we stay pinned in memory until the ordered extent can get a
reference on it and we are good to go.  With this patch we no longer panic
in btrfs_finish_ordered_io().  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Because btrfs can remove the device that was mounted we need to have a
->show_devname so that in this case we can print out some other device in
the file system to /proc/mount.  So if there are multiple devices in a btrfs
file system we will just print the device with the lowest devid that we can
find.  This will make everything consistent and deal with device removal
properly.  The drawback is if you mount with a device that is higher than
the lowest devicd it won't show up as the mounted device in /proc/mounts,
but this is a small price to pay. This was inspired by Miao Xie's patch.
Thanks,
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <josef@redhat.com>

Al pointed out that we can just toss out the old name on a device and add a
new one arbitrarily, so anybody who uses device->name in printk could
possibly use free'd memory.  Instead of adding locking around all of this he
suggested doing it with RCU, so I've introduced a struct rcu_string that
does just that and have gone through and protected all accesses to
device->name that aren't under the uuid_mutex with rcu_read_lock().  This
protects us and I will use it for dealing with removing the device that we
used to mount the file system in a later patch.  Thanks,
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>

I was getting hung on umount when a transaction was aborted because a range
of one of the free space inodes was still locked.  This is because the nocow
stuff doesn't unlock anything on error.  This fixed the problem and I
verified that is what was happening.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

So we're forcing the eb's to have their ref count set to 1 so invalidatepage
works but this breaks lots of things, for example root nodes, and is just
plain wrong, we don't need to just evict all of this stuff.  Also drop the
invalidatepage altogether and add a page_cache_release().  With this patch
we no longer hang when trying to access the root nodes after an aborted
transaction and we no longer leak memory.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

If a transaction commit fails we don't abort it so we don't set an error on
the file system.  This patch fixes that by actually calling the abort stuff
and then adding a check for a fs error in the transaction start stuff to
make sure it is caught properly.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

I was getting lots of hung tasks and a NULL pointer dereference because we
are not cleaning up the transaction properly when it aborts.  First we need
to reset the running_transaction to NULL so we don't get a bad dereference
for any start_transaction callers after this.  Also we cannot rely on
waitqueue_active() since it's just a list_empty(), so just call wake_up()
directly since that will do the barrier for us and such.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

The transaction abort stuff was throwing warnings from the list debugging
code because we do a list_del_init outside of the delayed_refs spin lock.
The delayed refs locking makes baby Jesus cry so it's not hard to get wrong,
but we need to take the ref head mutex to make sure it's not being processed
currently, and so if it is we need to drop the spin lock and then take and
drop the mutex and do the search again.  If we can take the mutex then we
can safely remove the head from the list and carry on.  Now when the
transaction aborts I don't get the list debugging warnings.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

While doing my enospc work I got a transaction abortion that resulted in a
panic when we tried to unlock_page() an already unlocked page.  This is
because we aren't calling extent_clear_unlock_delalloc with the locked page
so it was unlocking all the pages in the range.  This is wrong since
__extent_writepage expects to have the page locked still unless we return
*page_started as 1.  This should keep us from panicing.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

When adding to the tree modification log, we grab two locks at different
stages. We must not drop the outer lock until we're done with section
protected by the inner lock. This moves the unlock call for the outer lock
to the appropriate position.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

To make sense of the tree mod log, the backref walker not only needs
btrfs_search_old_slot, but it also called btrfs_next_leaf, which in turn was
calling btrfs_search_slot. This obviously didn't give the correct result.

This commit adds btrfs_next_old_leaf, a drop-in replacement for
btrfs_next_leaf with a time_seq parameter. If it is zero, it behaves exactly
like btrfs_next_leaf. If it is non-zero, it will use btrfs_search_old_slot
with this time_seq parameter.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

In __tree_mod_log_oldest_root() we must return the found operation even if
it's not a ROOT_REPLACE operation. Otherwise, the caller assumes that there
are no operations to be rewinded and returns immediately.

The code in the caller is modified to improve readability.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

get_old_root could race with root node updates because we weren't locking
the node early enough. Use btrfs_read_lock_root_node to grab the root locked
in the very beginning and release the lock as soon as possible (just like
btrfs_search_slot does).
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

When resolving indirect refs, we used to call btrfs_next_leaf in case we
didn't find an exact match. While we should find exact matches most of the
time, in case we don't, we must continue searching. Treating those matches
differently depending on the level we're searching doesn't make sense.

Even worse, we might end up searching for a key larger than the largest, in
which case there is no next_leaf and subsequent jobs would fail. This commit
drops the bogous lines.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

This is a leftover from cleanup patch 559af821. Before the cleanup,
btrfs_header_nritems was called inside an if condition. As it has no side
effects we need to preserve here, it should simply be dropped.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Conflicts:
	fs/btrfs/ulist.h
Signed-off-by: Chris Mason <chris.mason@oracle.com>

When we rewind REMOVE_WHILE_FREEING operations, there's code that allocates
a fresh buffer instead of cloning the old one. Setting that buffer's level
correctly was missing in this case.

When rewinding a MOVE_KEYS operation, btrfs_node_key_ptr_offset(slot) was
missing for memmove_extent_buffer()'s arguments.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Logging for del_ptr when we're not deleting the last pointer was wrong. This
fixes both, duplicate log entries and log sequence.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Replace duplicate code by small inline helper function.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

tree_mod_alloc calls __get_tree_mod_seq and must acquire a spinlock before
doing so.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

We must build up the inode list with the extent lock held after following
indirect refs.

This also requires an extension to ulists, which allows to modify the stored
aux value in case a key already exists in the list.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

The sequence number for delayed refs is needed to postpone certain delayed
refs for a very short period while walking backrefs. Before the tree
modification log, we thought we'd only have to hold back those references
that don't have a counter operation.

While now we've the tree mod log, we're rewinding fs tree blocks to a
defined consistent state. We cannot know in advance for which tree block
we'll be doing rewind operations later. Therefore, we must postpone all the
delayed refs for fs-tree blocks, even those having a counter operation.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

Merge branch 'for-chris' of git://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-next into HEAD

During unmount, it could happen that the integrity checker printed a
warning message "attempt to free ... on umount which is not yet iodone"
which turned out to be a false positive.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>

If a file_extent_item was located at the very end of a leaf and there was
not enough space to hold a full item, but there was enough space to hold
one of type BTRFS_FILE_EXTENT_INLINE or PREALLOC, and it was only such a
short item, a warning was printed anyway. This check is now fixed.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>

Reduce ioprio class of scrub readahead threads to idle priority.
This setting is fixed. This priority has shown the best performance
during all measurements.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>

So dpkg fsync()'s the file and the directory containing the file whenever it
writes to a file which is really slow in btrfs.  This is partly because
fsync()'ing a directory _always_ committed the transaction instead of just
going to the tree log.  This is because drop_objectid_items() would return 1
since it does a btrfs_search_slot() which returns 1.  In tree-log jargon
this means that we have to commit the transaction to be safe.  So just check
if ret is greater than 0 and set it to 0 if it does.  With this patch we now
use the tree-log instead of committing the entire transaction, which is
twice as fast on my box.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

We have this check down in the actual logging code, but this is after we
start a transaction and all that good stuff.  So move the helper
inode_in_log() out so we can call it in fsync() and avoid starting a
transaction altogether and just exit if we've already fsync()'ed this file
recently.  You would notice this issue if you fsync()'ed a file over and
over again until the transaction committed.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

btrfs_read_buffer() has the possibility of returning the error.
Therefore, I add the code in which the return value of btrfs_read_buffer()
is checked.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>

The device statistics are written into the device tree with each
transaction commit. Only modified statistics are written.
When a filesystem is mounted, the device statistics for each involved
device are read from the device tree and used to initialize the
counters.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>

An ioctl interface is added to get the device statistic counters.
A second ioctl is added to atomically get and reset these counters.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>

The goal is to detect when drives start to get an increased error rate,
when drives should be replaced soon. Therefore statistic counters are
added that count IO errors (read, write and flush). Additionally, the
software detected errors like checksum errors and corrupted blocks are
counted.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>

1) This function is not used anywhere.

2) Using the blk_abort_queue() to abort the queue seems not correct.
blk_abort_queue() is used for timeout handling (block/blk-timeout.c).

Cc: Chris Mason <chris.mason@oracle.com>
Cc: linux-btrfs@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Asias He <asias@redhat.com>

Two files in the different subvolumes may have the same inode id, so
The rb-tree which is used to manage the defragment object must take it
into account. This patch fix this problem.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>

If cow_file_range_inline fails with ENOSPC we abort the transaction which
isn't very nice.  This really shouldn't be happening anyways but there's no
sense in making it a horrible error when we can easily just go allocate
normal data space for this stuff.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Ceph was hitting this race where we would remove an inode from the per-root
orphan list before we would release the space we had reserved for the inode.
We actually don't need a list or anything, we just need to make sure the
root doesn't try to free up the orphan reserve until after the inodes have
released their reservations.  So use an atomic counter instead of a list on
the root and only decrement the counter after we've released our
reservation.  I've tested this as well as several others and we no longer
see the warnings that you would see while running ceph.  Thanks,
Btrfs: fix how we deal with the orphan block rsv

Ceph was hitting this race where we would remove an inode from the per-root
orphan list before we would release the space we had reserved for the inode.
We actually don't need a list or anything, we just need to make sure the
root doesn't try to free up the orphan reserve until after the inodes have
released their reservations.  So use an atomic counter instead of a list on
the root and only decrement the counter after we've released our
reservation.  I've tested this as well as several others and we no longer
see the warnings that you would see while running ceph.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>