Commit Graph

73 Commits

Author SHA1 Message Date
Chris Mason ac8e9819d7 Btrfs: add search and inode lookup ioctls
The search ioctl is a generic tool for doing btree searches from
userland applications.  The first user of the search ioctl is a
subvolume listing feature, but we'll also use it to find new
files in a subvolume.

The search ioctl allows you to specify min and max keys to search for,
along with min and max transid.  It returns the items along with a
header that includes the item key.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-03-15 10:55:10 -04:00
TARUISI Hiroaki 98d377a089 Btrfs: add a function to lookup a directory path by following backrefs
This will be used by the inode lookup ioctl.

Signed-off-by: TARUISI Hiroaki <taruishi.hiroak@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2010-03-15 10:55:09 -04:00
Yan, Zheng 86b9f2eca5 Btrfs: Fix per root used space accounting
The bytes_used field in root item was originally planned to
trace the amount of used data and tree blocks. But it never
worked right since we can't trace freeing of data accurately.
This patch changes it to only trace the amount of tree blocks.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-12-17 12:33:35 -05:00
Yan, Zheng 2e4bfab970 Btrfs: Avoid orphan inodes cleanup during committing transaction
btrfs_lookup_dentry may trigger orphan cleanup, so it's not good
to call it while committing a transaction.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-12-17 12:33:33 -05:00
Yan, Zheng 920bbbfb05 Btrfs: Rewrite btrfs_drop_extents
Rewrite btrfs_drop_extents by using btrfs_duplicate_item, so we can
avoid calling lock_extent within transaction.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-12-15 21:24:52 -05:00
Chris Mason ac6889cbb2 Btrfs: fix file clone ioctl for bookend extents
The file clone ioctl was incorrectly taking the offset into the
extent on disk into account when calculating the length of the
cloned extent.

The length never changes based on the offset into the physical extent.

Test case:

fallocate -l 1g image
mke2fs image
bcp image image2
e2fsck -f image2

(errors on image2)

The math bug ends up wrapping the length of the extent, and things
go wrong from there.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-10-09 11:29:53 -04:00
Yan, Zheng efefb1438b Btrfs: remove negative dentry when deleting subvolumne
The use of btrfs_dentry_delete is removing dentries from the
dcache when deleting subvolumne. btrfs_dentry_delete ignores
negative dentries. This is incorrect since if we don't remove
the negative dentry, its parent dentry can't be removed.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-10-09 09:25:16 -04:00
Sage Weil 1ab86aedbc Btrfs: fix error cases for ioctl transactions
Fix leak of vfsmount write reference and open_ioctl_trans reference on
ENOMEM.  Clean up the error paths while we're at it.

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-29 18:38:44 -04:00
Josef Bacik 9ed74f2dba Btrfs: proper -ENOSPC handling
At the start of a transaction we do a btrfs_reserve_metadata_space() and
specify how many items we plan on modifying.  Then once we've done our
modifications and such, just call btrfs_unreserve_metadata_space() for
the same number of items we reserved.

For keeping track of metadata needed for data I've had to add an extent_io op
for when we merge extents.  This lets us track space properly when we are doing
sequential writes, so we don't end up reserving way more metadata space than
what we need.

The only place where the metadata space accounting is not done is in the
relocation code.  This is because Yan is going to be reworking that code in the
near future, so running btrfs-vol -b could still possibly result in a ENOSPC
related panic.  This patch also turns off the metadata_ratio stuff in order to
allow users to more efficiently use their disk space.

This patch makes it so we track how much metadata we need for an inode's
delayed allocation extents by tracking how many extents are currently
waiting for allocation.  It introduces two new callbacks for the
extent_io tree's, merge_extent_hook and split_extent_hook.  These help
us keep track of when we merge delalloc extents together and split them
up.  Reservations are handled prior to any actually dirty'ing occurs,
and then we unreserve after we dirty.

btrfs_unreserve_metadata_for_delalloc() will make the appropriate
unreservations as needed based on the number of reservations we
currently have and the number of extents we currently have.  Doing the
reservation outside of doing any of the actual dirty'ing lets us do
things like filemap_flush() the inode to try and force delalloc to
happen, or as a last resort actually start allocation on all delalloc
inodes in the fs.  This has survived dbench, fs_mark and an fsx torture
test.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-28 16:29:42 -04:00
Sage Weil 1fb58a6051 Btrfs: fix arithmetic error in clone ioctl
Fix an arithmetic error that was breaking extents cloned via the clone
ioctl starting in the second half of a file.

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-21 16:00:27 -04:00
Yan, Zheng 76dda93c6a Btrfs: add snapshot/subvolume destroy ioctl
This patch adds snapshot/subvolume destroy ioctl.  A subvolume that isn't being
used and doesn't contains links to other subvolumes can be destroyed.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-21 16:00:26 -04:00
Yan, Zheng 4df27c4d5c Btrfs: change how subvolumes are organized
btrfs allows subvolumes and snapshots anywhere in the directory tree.
If we snapshot a subvolume that contains a link to other subvolume
called subvolA, subvolA can be accessed through both the original
subvolume and the snapshot. This is similar to creating hard link to
directory, and has the very similar problems.

The aim of this patch is enforcing there is only one access point to
each subvolume. Only the first directory entry (the one added when
the subvolume/snapshot was created) is treated as valid access point.
The first directory entry is distinguished by checking root forward
reference. If the corresponding root forward reference is missing,
we know the entry is not the first one.

This patch also adds snapshot/subvolume rename support, the code
allows rename subvolume link across subvolumes.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-21 15:56:00 -04:00
Chris Mason 83ebade34b Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2009-09-11 19:07:25 -04:00
Chris Mason a1ed835e1a Btrfs: Fix extent replacment race
Data COW means that whenever we write to a file, we replace any old
extent pointers with new ones.  There was a window where a readpage
might find the old extent pointers on disk and cache them in the
extent_map tree in ram in the middle of a given write replacing them.

Even though both the readpage and the write had their respective bytes
in the file locked, the extent readpage inserts may cover more bytes than
it had locked down.

This commit closes the race by keeping the new extent pinned in the extent
map tree until after the on-disk btree is properly setup with the new
extent pointers.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-11 13:31:07 -04:00
Alexey Dobriyan 405f55712d headers: smp_lock.h redux
* Remove smp_lock.h from files which don't need it (including some headers!)
* Add smp_lock.h to files which do need it
* Make smp_lock.h include conditional in hardirq.h
  It's needed only for one kernel_locked() usage which is under CONFIG_PREEMPT

  This will make hardirq.h inclusion cheaper for every PREEMPT=n config
  (which includes allmodconfig/allyesconfig, BTW)

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-07-12 12:22:34 -07:00
Chris Mason c8a894d77d Btrfs: fix the file clone ioctl for preallocated extents 2009-07-02 13:41:16 -04:00
Chris Mason 0b4dcea579 Btrfs: fix oops when btrfs_inherit_iflags called with a NULL dir
This happens during subvol creation.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-06-11 11:13:35 -04:00
Christoph Hellwig 6cbff00f46 Btrfs: implement FS_IOC_GETFLAGS/SETFLAGS/GETVERSION
Add support for the standard attributes set via chattr and read via
lsattr.  Currently we store the attributes in the flags value in
the btrfs inode, but I wonder whether we should split it into two so
that we don't have to keep converting between the two formats.

Remove the btrfs_clear_flag/btrfs_set_flag/btrfs_test_flag macros
as they were confusing the existing code and got in the way of the
new additions.

Also add the FS_IOC_GETVERSION ioctl for getting i_generation as it's
trivial.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-06-10 11:29:52 -04:00
Yan Zheng 5d4f98a28c Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE)
This commit introduces a new kind of back reference for btrfs metadata.
Once a filesystem has been mounted with this commit, IT WILL NO LONGER
BE MOUNTABLE BY OLDER KERNELS.

When a tree block in subvolume tree is cow'd, the reference counts of all
extents it points to are increased by one.  At transaction commit time,
the old root of the subvolume is recorded in a "dead root" data structure,
and the btree it points to is later walked, dropping reference counts
and freeing any blocks where the reference count goes to 0.

The increments done during cow and decrements done after commit cancel out,
and the walk is a very expensive way to go about freeing the blocks that
are no longer referenced by the new btree root.  This commit reduces the
transaction overhead by avoiding the need for dead root records.

When a non-shared tree block is cow'd, we free the old block at once, and the
new block inherits old block's references. When a tree block with reference
count > 1 is cow'd, we increase the reference counts of all extents
the new block points to by one, and decrease the old block's reference count by
one.

This dead tree avoidance code removes the need to modify the reference
counts of lower level extents when a non-shared tree block is cow'd.
But we still need to update back ref for all pointers in the block.
This is because the location of the block is recorded in the back ref
item.

We can solve this by introducing a new type of back ref. The new
back ref provides information about pointer's key, level and in which
tree the pointer lives. This information allow us to find the pointer
by searching the tree. The shortcoming of the new back ref is that it
only works for pointers in tree blocks referenced by their owner trees.

This is mostly a problem for snapshots, where resolving one of these
fuzzy back references would be O(number_of_snapshots) and quite slow.
The solution used here is to use the fuzzy back references in the common
case where a given tree block is only referenced by one root,
and use the full back references when multiple roots have a reference
on a given block.

This commit adds per subvolume red-black tree to keep trace of cached
inodes. The red-black tree helps the balancing code to find cached
inodes whose inode numbers within a given range.

This commit improves the balancing code by introducing several data
structures to keep the state of balancing. The most important one
is the back ref cache. It caches how the upper level tree blocks are
referenced. This greatly reduce the overhead of checking back ref.

The improved balancing code scales significantly better with a large
number of snapshots.

This is a very large commit and was written in a number of
pieces.  But, they depend heavily on the disk format change and were
squashed together to make sure git bisect didn't end up in a
bad state wrt space balancing or the format change.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-06-10 11:29:46 -04:00
Linus Torvalds 5732c46849 Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: Spelling fix in btrfs_lookup_first_block_group comments
  Btrfs: make show_options result match actual option names
  Btrfs: remove outdated comment in btrfs_ioctl_resize()
  Btrfs: remove some WARN_ONs in the IO failure path
  Btrfs: Don't loop forever on metadata IO failures
  Btrfs: init inode ordered_data_close flag properly
2009-05-14 19:18:44 -07:00
Li Hong 5d847a8ed9 Btrfs: remove outdated comment in btrfs_ioctl_resize()
In Li Zefan's commit dae7b665cf,
a combination call of kmalloc() and copy_from_user() is replaced by
memdup_user(). So btrfs_ioctl_resize() doesn't use GFP_NOFS any more.

Signed-off-by: Li Hong <lihong.hi@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-05-14 14:00:33 -04:00
Linus Torvalds 4ebf662337 Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: look for acls during btrfs_read_locked_inode
  Btrfs: fix acl caching
  Btrfs: Fix a bunch of printk() warnings.
  Btrfs: Fix a trivial warning using max() of u64 vs ULL.
  Btrfs: remove unused btrfs_bit_radix slab
  Btrfs: ratelimit IO error printks
  Btrfs: remove #if 0 code
  Btrfs: When shrinking, only update disk size on success
  Btrfs: fix deadlocks and stalls on dead root removal
  Btrfs: fix fallocate deadlock on inode extent lock
  Btrfs: kill btrfs_cache_create
  Btrfs: don't export symbols
  Btrfs: simplify makefile
  Btrfs: try to keep a healthy ratio of metadata vs data block groups
2009-04-27 11:16:33 -07:00
Joel Becker 21380931eb Btrfs: Fix a bunch of printk() warnings.
Just happened to notice a bunch of %llu vs u64 warnings.  Here's a patch
to cast them all.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-27 08:37:49 -04:00
Chris Mason e980b50cda Btrfs: fix fallocate deadlock on inode extent lock
The btrfs fallocate call takes an extent lock on the entire range
being fallocated, and then runs through insert_reserved_extent on each
extent as they are allocated.

The problem with this is that btrfs_drop_extents may decide to try
and take the same extent lock fallocate was already holding.  The solution
used here is to push down knowledge of the range that is already locked
going into btrfs_drop_extents.

It turns out that at least one other caller had the same bug.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-24 15:46:05 -04:00
Li Zefan dae7b665cf btrfs: use memdup_user()
Remove open-coded memdup_user().

Note this changes some GFP_NOFS to GFP_KERNEL, since copy_from_user() may
cause pagefault, it's pointless to pass GFP_NOFS to kmalloc().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-04-20 23:02:50 -04:00
Al Viro ce3b0f8d5c New helper - current_umask()
current->fs->umask is what most of fs_struct users are doing.
Put that into a helper function.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-03-31 23:00:26 -04:00
Josef Bacik 6a63209fc0 Btrfs: add better -ENOSPC handling
This is a step in the direction of better -ENOSPC handling.  Instead of
checking the global bytes counter we check the space_info bytes counters to
make sure we have enough space.

If we don't we go ahead and try to allocate a new chunk, and then if that fails
we return -ENOSPC.  This patch adds two counters to btrfs_space_info,
bytes_delalloc and bytes_may_use.

bytes_delalloc account for extents we've actually setup for delalloc and will
be allocated at some point down the line. 

bytes_may_use is to keep track of how many bytes we may use for delalloc at
some point.  When we actually set the extent_bit for the delalloc bytes we
subtract the reserved bytes from the bytes_may_use counter.  This keeps us from
not actually being able to allocate space for any delalloc bytes.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
2009-02-20 11:00:09 -05:00
Huang Weiyi 7eaebe7d50 Btrfs: removed unused #include <version.h>'s
Removed unused #include <version.h>'s in btrfs

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-01-21 10:49:16 -05:00
Chris Mason d397712bcc Btrfs: Fix checkpatch.pl warnings
There were many, most are fixed now.  struct-funcs.c generates some warnings
but these are bogus.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-01-05 21:25:51 -05:00
Yan Zheng 52c2617990 Btrfs: update directory's size when creating subvol/snapshot
Make sure directory's size properly updated when creating
subvol/snapshot.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2009-01-05 15:43:43 -05:00
Chris Mason e441d54de4 Btrfs: add permission checks to the ioctls
Only root can add/remove devices
Only root can defrag subtrees
Only files open for writing can be defragged
Only files open for writing can be the destination for a clone

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-01-05 16:57:23 -05:00
Yan Zheng ab67b7c1f7 Btrfs: Add missing mnt_drop_write in ioctl.c
This patch adds the missing mnt_drop_write to match
mnt_want_write in btrfs_ioctl_defrag and btrfs_ioctl_clone

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-12-19 10:58:39 -05:00
Yan Zheng d2fb3437e4 Btrfs: fix leaking block group on balance
The block group structs are referenced in many different
places, and it's not safe to free while balancing.  So, those block
group structs were simply leaked instead.

This patch replaces the block group pointer in the inode with the starting byte
offset of the block group and adds reference counting to the block group
struct.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-12-11 16:30:39 -05:00
Sage Weil cfc8ea8720 Btrfs: mnt_drop_write in ioctl_trans_end
Add missing mnt_drop_write to match the mnt_want_write in
btrfs_ioctl_trans_start.

Signed-off-by: Sage Weil <sage@newdream.net>
2008-12-11 16:30:06 -05:00
Chris Mason d20f7043fa Btrfs: move data checksumming into a dedicated tree
Btrfs stores checksums for each data block.  Until now, they have
been stored in the subvolume trees, indexed by the inode that is
referencing the data block.  This means that when we read the inode,
we've probably read in at least some checksums as well.

But, this has a few problems:

* The checksums are indexed by logical offset in the file.  When
compression is on, this means we have to do the expensive checksumming
on the uncompressed data.  It would be faster if we could checksum
the compressed data instead.

* If we implement encryption, we'll be checksumming the plain text and
storing that on disk.  This is significantly less secure.

* For either compression or encryption, we have to get the plain text
back before we can verify the checksum as correct.  This makes the raid
layer balancing and extent moving much more expensive.

* It makes the front end caching code more complex, as we have touch
the subvolume and inodes as we cache extents.

* There is potentitally one copy of the checksum in each subvolume
referencing an extent.

The solution used here is to store the extent checksums in a dedicated
tree.  This allows us to index the checksums by phyiscal extent
start and length.  It means:

* The checksum is against the data stored on disk, after any compression
or encryption is done.

* The checksum is stored in a central location, and can be verified without
following back references, or reading inodes.

This makes compression significantly faster by reducing the amount of
data that needs to be checksummed.  It will also allow much faster
raid management code in general.

The checksums are indexed by a key with a fixed objectid (a magic value
in ctree.h) and offset set to the starting byte of the extent.  This
allows us to copy the checksum items into the fsync log tree directly (or
any other tree), without having to invent a second format for them.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-12-08 16:58:54 -05:00
Josef Bacik 607d432da0 Btrfs: add support for multiple csum algorithms
This patch gives us the space we will need in order to have different csum
algorithims at some point in the future.  We save the csum algorithim type
in the superblock, and use those instead of define's.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
2008-12-02 07:17:45 -05:00
Christoph Hellwig 7a865e8ac3 Btrfs: btrfs: pass void __user * to btrfs_ioctl_clone_range
Cleans the code up a little and also avoids a sparse warning due to the
incorrect cast in the current version of the code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
2008-12-02 09:52:24 -05:00
Christoph Hellwig 4bcabaa30a Btrfs: clean up btrfs_ioctl a little bit
Provide a void __user *argp pointer so that we can avoid duplicating
the cast for various sub-command calls.

Signed-off-by: Christoph Hellwig <hch@lst.de>
2008-12-02 06:36:08 -05:00
Christoph Hellwig b2950863c6 Btrfs: make things static and include the right headers
Shut up various sparse warnings about symbols that should be either
static or have their declarations in scope.

Signed-off-by: Christoph Hellwig <hch@lst.de>
2008-12-02 09:54:17 -05:00
Sage Weil 1ffa4f426c Btrfs: remove unneeded btrfs_start_delalloc_inodes call
It is called by btrfs_sync_fs.

Signed-off-by: Sage Weil <sage@newdream.net>
2008-12-02 09:53:09 -05:00
Chris Mason 4b4e25f2a6 Btrfs: compat code fixes
The btrfs git kernel trees is used to build a standalone tree for
compiling against older kernels.  This commit makes the standalone tree
work with 2.6.27

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-20 10:22:27 -05:00
Chris Mason ea9e8b11bd Btrfs: prevent loops in the directory tree when creating snapshots
For a directory tree:

/mnt/subvolA/subvolB

btrfsctl -s /mnt/subvolA/subvolB /mnt

Will create a directory loop with subvolA under subvolB.  This
commit uses the forward refs for each subvol and snapshot to error out
before creating the loop.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-17 21:14:24 -05:00
Chris Mason 0660b5af3f Btrfs: Add backrefs and forward refs for subvols and snapshots
Subvols and snapshots can now be referenced from any point in the directory
tree.  We need to maintain back refs for them so we can find lost
subvols.

Forward refs are added so that we know all of the subvols and
snapshots referenced anywhere in the directory tree of a single subvol.  This
can be used to do recursive snapshotting (but they aren't yet) and it is
also used to detect and prevent directory loops when creating new snapshots.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-17 20:37:39 -05:00
Chris Mason 3394e1607e Btrfs: Give each subvol and snapshot their own anonymous devid
Each subvolume has its own private inode number space, and so we need
to fill in different device numbers for each subvolume to avoid confusing
applications.

This commit puts a struct super_block into struct btrfs_root so it can
call set_anon_super() and get a different device number generated for
each root.

btrfs_rename is changed to prevent renames across subvols.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-17 20:42:26 -05:00
Chris Mason 3de4586c52 Btrfs: Allow subvolumes and snapshots anywhere in the directory tree
Before, all snapshots and subvolumes lived in a single flat directory.  This
was awkward and confusing because the single flat directory was only writable
with the ioctls.

This commit changes the ioctls to create subvols and snapshots at any
point in the directory tree.  This requires making separate ioctls for
snapshot and subvol creation instead of a combining them into one.

The subvol ioctl does:

btrfsctl -S subvol_name parent_dir

After the ioctl is done subvol_name lives inside parent_dir.

The snapshot ioctl does:

btrfsctl -s path_for_snapshot root_to_snapshot

path_for_snapshot can be an absolute or relative path.  btrfsctl breaks it up
into directory and basename components.

root_to_snapshot can be any file or directory in the FS.  The snapshot
is taken of the entire root where that file lives.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-17 21:02:50 -05:00
Yan Zheng 2b82032c34 Btrfs: Seed device support
Seed device is a special btrfs with SEEDING super flag
set and can only be mounted in read-only mode. Seed
devices allow people to create new btrfs on top of it.

The new FS contains the same contents as the seed device,
but it can be mounted in read-write mode.

This patch does the following:

1) split code in btrfs_alloc_chunk into two parts. The first part does makes
the newly allocated chunk usable, but does not do any operation that modifies
the chunk tree. The second part does the the chunk tree modifications. This
division is for the bootstrap step of adding storage to the seed device.

2) Update device management code to handle seed device.
The basic idea is: For an FS grown from seed devices, its
seed devices are put into a list. Seed devices are
opened on demand at mounting time. If any seed device is
missing or has been changed, btrfs kernel module will
refuse to mount the FS.

3) make btrfs_find_block_group not return NULL when all
block groups are read-only.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-11-17 21:11:30 -05:00
Yan Zheng c146afad2c Btrfs: mount ro and remount support
This patch adds mount ro and remount support. The main
changes in patch are: adding btrfs_remount and related
helper function; splitting the transaction related code
out of close_ctree into btrfs_commit_super; updating
allocator to properly handle read only block group.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-11-12 14:34:12 -05:00
Sage Weil c5c9cd4d1b Btrfs: allow clone of an arbitrary file range
This patch adds an additional CLONE_RANGE ioctl to clone an arbitrary 
(block-aligned) file range to another file.  The original CLONE ioctl 
becomes a special case of cloning the entire file range.  The logic is a 
bit more complex now since ranges may be cloned to different offsets, and 
because we may only be cloning the beginning or end of a particular extent 
or checksum item.

An additional sanity check ensures the source and destination files aren't 
the same (which would previously deadlock), although eventually this could 
be extended to allow the duplication of file data at a different offset 
within the same file.

Any extents within the destination range in the target file are dropped.

We currently do not cope with the case where a compressed inline extent 
needs to be split.  This will probably require decompressing the extent 
into a temporary address_space, and inserting just the cloned portion as a 
new compressed inline extent.  For now, just return -EINVAL in this case.  
Note that this never comes up in the more common case of cloning an entire 
file.
    
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-11-12 14:32:25 -05:00
Yan Zheng d899e05215 Btrfs: Add fallocate support v2
This patch updates btrfs-progs for fallocate support.

fallocate is a little different in Btrfs because we need to tell the
COW system that a given preallocated extent doesn't need to be
cow'd as long as there are no snapshots of it.  This leverages the
-o nodatacow checks.
 
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-10-30 14:25:28 -04:00
Yan Zheng 80ff385665 Btrfs: update nodatacow code v2
This patch simplifies the nodatacow checker. If all references
were created after the latest snapshot, then we can avoid COW
safely. This patch also updates run_delalloc_nocow to do more
fine-grained checking.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
2008-10-30 14:20:02 -04:00