The data read retry code needs to find the logical disk block before it
can resubmit new bios.  But, finding this block isn't allowed to take
the fs_mutex because that will deadlock with a number of different callers.

This changes the retry code to use the extent map cache instead, but
that requires the extent map cache to have the extent we're looking for.
This is a problem because btrfs_drop_extent_cache just drops the entire
extent instead of the little tiny part it is invalidating.

The bulk of the code in this patch changes btrfs_drop_extent_cache to
invalidate only a portion of the extent cache, and changes btrfs_get_extent
to deal with the results.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

This isn't required anymore because we don't reallocate blocks that
have already been written in this transaction.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

This significantly improves streaming write performance by allowing
concurrency in the data checksumming.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

This allows checksumming to happen in parallel among many cpus, and
keeps us from bogging down pdflush with the checksumming code.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

Block headers now store the chunk tree uuid

Chunk items records the device uuid for each stripes

Device extent items record better back refs to the chunk tree

Block groups record better back refs to the chunk tree

The chunk tree format has also changed.  The objectid of BTRFS_CHUNK_ITEM_KEY
used to be the logical offset of the chunk.  Now it is a chunk tree id,
with the logical offset being stored in the offset field of the key.

This allows a single chunk tree to record multiple logical address spaces,
upping the number of bytes indexed by a chunk tree from 2^64 to
2^128.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

This includes fixing a missing spinlock init call that caused oops on mount
for most kernels other than 2.6.25.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

On huge machines, delayed allocation may try to allocate massive extents.
This change allows btrfs_alloc_extent to return something smaller than
the caller asked for, and the data allocation routines will loop over
the allocations until it fills the whole delayed alloc.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

bio_endio() changed prototype on linux 2.6.24, support older kernels
using the older prototype.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

write_cache_pages doesn't exist in linux 2.6.20,  change the #if
condition to match that.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Fix for a endianess BUG when using btrfs v0.13 with kernels older than 2.6.23

Problem:

Has of v0.13, btrfs-progs is using crc32c.c equivalent to the one found on
linux-2.6.23/lib/libcrc32c.c Since crc32c_le() changed in linux-2.6.23, when
running btrfs v0.13 with older kernels we have a missmatch between the versions
of crc32c_le() from btrfs-progs and libcrc32c in the kernel.  This missmatch
causes a bug when using btrfs on big endian machines.

Solution:
btrfs_crc32c() macro that when compiling for kernels older than 2.6.23, does
endianess conversion to parameters and return value of crc32c().
This endianess conversion nullifies the differences in implementation
of crc32c_le().
If kernel 2.6.23 or better, it calls crc32c().
Signed-off-by: Miguel Sousa Filipe <miguel.filipe@gmail.com>
---
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

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

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

This adds basic O_DIRECT read and write support.  In the write case, we
just do a normal buffered write followed by a cache flush.  O_DIRECT +
O_SYNC are required to trigger metadata syncs.

In the read case, there is a basic btrfs_get_block call for use by
the generic O_DIRECT code.  This does honor multi-volume mapping rules
but it skips all checksumming.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

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

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

Before it was done by the bio end_io routine, the work queue code is able
to scale much better with faster IO subsystems.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Before, metadata checksumming was done by the callers of read_tree_block,
which would set EXTENT_CSUM bits in the extent tree to show that a given
range of pages was already checksummed and didn't need to be verified
again.

But, those bits could go away via try_to_releasepage, and the end
result was bogus checksum failures on pages that never left the cache.

The new code validates checksums when the page is read.  It is a little
tricky because metadata blocks can span pages and a single read may
end up going via multiple bios.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

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

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

When a block is freed, it can be immediately reused if it is from
the current transaction.  But, an extra check is required to make sure
the block had not been written yet.  If it were reused after being written,
the transid in the block header might match the transid of the
next time the block was allocated.

The parent node records the transaction ID of the block it is pointing to,
and this is used as part of validating the block on reads.  So, there
can only be one version of a block per transaction.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

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

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

Checksums were only verified by btrfs_read_tree_block, which meant the
functions to probe the page cache for blocks were not validating checksums.
Normally this is fine because the buffers will only be in cache if they
have already been validated.

But, there is a window while the buffer is being read from disk where
it could be up to date in the cache but not yet verified.  This patch
makes sure all buffers go through checksum verification before they
are used.

This is safer, and it prevents modification of buffers before they go
through the csum code.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

There was an optimization to drop the fs_mutex when doing snapshot deletion
reads, but this can lead to false positives on checksumming errors.  Keep
the lock for now.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

In btrfs_name_hash, Local variable 'buf' is declared as

	__u32 buf[2];

but we then try to do this:

	buf[0] = 0x67452301;
	buf[1] = 0xefcdab89;
	buf[2] = 0x98badcfe;
	buf[3] = 0x10325476;

Oops. Fix buf to be the proper size.
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Signed-off-by: Peter Teoh <htmldeveloper@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

This allows detection of blocks that have already been written in the
running transaction so they can be recowed instead of modified again.
It is step one in trusting the transid field of the block pointers.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

This also fixes one leak around the super block when failing to mount the
FS.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

This allows intelligent versions of unplug and congestion functions
Signed-off-by: Chris Mason <chris.mason@oracle.com>

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

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

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