Btrfs: incompatible format change to remove hole extents

Btrfs has always had these filler extent data items for holes in inodes.  This
has made somethings very easy, like logging hole punches and sending hole
punches.  However for large holey files these extent data items are pure
overhead.  So add an incompatible feature to no longer add hole extents to
reduce the amount of metadata used by these sort of files.  This has a few
changes for logging and send obviously since they will need to detect holes and
log/send the holes if there are any.  I've tested this thoroughly with xfstests
and it doesn't cause any issues with and without the incompat format set.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
Btrfs: fix check-integrity to look at the referenced data properly

We were looking at file_extent_num_bytes unconditionally when looking at
referenced data bytes, but this isn't correct for compression.  Fix this by
checking the compression of the file extent we are and setting num_bytes to
disk_num_bytes in the case of compression so that we are marking the proper
bytes as referenced.  This fixes check_int_data freaking out when running
btrfs/004.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
Btrfs: introduce a head ref rbtree

The way how we process delayed refs is
1) get a bunch of head refs,
2) pick up one head ref,
3) go one node back for any delayed ref updates.

The head ref is also linked in the same rbtree as the delayed ref is,
so in 1) stage, we have to walk one by one including not only head refs, but
delayed refs.

When we have a great number of delayed refs pending to process,
this'll cost time a lot.

Here we introduce a head ref specific rbtree, it only has head refs, so troubles
go away.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
Btrfs: skip merge part for delayed data refs

When we have data deduplication on, we'll hang on the merge part
because it needs to verify every queued delayed data refs related to
this disk offset but we may have millions refs.

And in the case of delayed data refs, we don't usually have too much
data refs to merge.

So it's safe to shut it down for data refs.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: add ioctls to query/change feature bits online

There are some feature bits that require no offline setup and can
be enabled online. I've only reviewed extended irefs, but there will
probably be more.

We introduce three new ioctls:
- BTRFS_IOC_GET_SUPPORTED_FEATURES: query the kernel for supported features.
- BTRFS_IOC_GET_FEATURES: query the kernel for enabled features on a per-fs
  basis, as well as querying for which features are changeable with mounted.
- BTRFS_IOC_SET_FEATURES: change features on a per-fs basis.

We introduce two new masks per feature set (_SAFE_SET and _SAFE_CLEAR) that
allow us to define which features are safe to change at runtime.

The failure modes for BTRFS_IOC_SET_FEATURES are as follows:
- Enabling a completely unsupported feature: warns and returns -ENOTSUPP
- Enabling a feature that can only be done offline: warns and returns -EPERM

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
kobject: export kobj_sysfs_ops

struct kobj_attribute implements the baseline attribute functionality
that can be used all over the place. We should export the ops associated
with it.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: publish supported featured in sysfs

This patch adds the ability to publish supported features to sysfs under
/sys/fs/btrfs/features.

The files are module-wide and export which features the kernel supports.

The content, for now, is just "0\n".

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: publish per-super attributes in sysfs

This patch adds per-super attributes to sysfs.

It doesn't publish any attributes yet, but does the proper lifetime
handling as well as the basic infrastructure to add new attributes.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: publish per-super features in sysfs

This patch publishes information on which features are enabled in the
file system on a per-super basis. At this point, it only publishes
information on features supported by the file system implementation.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: publish unknown feature bits in sysfs

With the compat and compat-ro bits, it's possible for file systems to
exist that have features that aren't supported by the kernel's file system
implementation yet still be mountable.

This patch publishes read-only info on those features using a prefix:number
format, where the number is the bit number rather than the shifted value.
e.g. "compat:12"

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: add ability to change features via sysfs

This patch adds the ability to change (set/clear) features while the file
system is mounted. A bitmask is added for each feature set for the
support to set and clear the bits. A message indicating which bit
has been set or cleared is issued when it's been changed and also when
permission or support for a particular bit has been denied.

Since the the attributes can now be writable, we need to introduce
another struct attribute to hold the different permissions.

If neither set or clear is supported, the file will have 0444 permissions.
If either set or clear is supported, the file will have 0644 permissions
and the store handler will filter out the write based on the bitmask.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: use feature attribute names to print better error messages

Now that we have the feature name strings available in the kernel via
the sysfs attributes, we can use them for printing better failure
messages from the ioctl path.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: add ioctl to export size of global metadata reservation

btrfs filesystem df output will show the size of the metadata space
and how much of it is used, and the user assumes that the difference
is all usable space. Since that's not actually the case due to the
global metadata reservation, we should provide the full picture to the
user.

This patch adds an ioctl that exports the size of the global metadata
reservation so that btrfs filesystem df can report it.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: publish allocation data in sysfs

While trying to debug ENOSPC issues, it's helpful to understand what the
kernel's view of the available space is. We export this information
via ioctl, but sysfs files are more easily used.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: publish device membership in sysfs

Now that we have the infrastructure for per-super attributes, we can
publish device membership in /sys/fs/btrfs/<fsid>/devices. The information
is published as symlinks to the block devices.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: publish fs label in sysfs

This adds a writeable attribute which describes the label.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: remove unused variable from btrfs_new_inode

Variable owner in btrfs_new_inode is unused since commit
d82a6f1d7e8b61ed5996334d0db66651bb43641d
(Btrfs: kill BTRFS_I(inode)->block_group)

Signed-off-by: Valentina Giusti <valentina.giusti@microon.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: remove unused variables from disk-io.c

Remove unused variables:
* tree from csum_dirty_buffer,
* tree from btree_readpage_end_io_hook,
* tree from btree_writepages,
* bytenr from btrfs_create_tree,
* fs_info from end_workqueue_fn.

Signed-off-by: Valentina Giusti <valentina.giusti@microon.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: remove unused variable from find_free_extent

The variable found_uncached_bg in find_free_extent is not used since commit
285ff5af6ce358e73f53b55c9efadd4335f4c2ff
(Btrfs: remove the ideal caching code)

Signed-off-by: Valentina Giusti <valentina.giusti@microon.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs: remove unused variables from extent_io.c

Remove unused variables:
* tree from end_bio_extent_writepage,
* item from extent_fiemap.

Signed-off-by: Valentina Giusti <valentina.giusti@microon.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>