Instead of overflowing the XDR send buffer with our extent list allocate
pages and pre-encode the layoutupdate payload into them. We optimistically
allocate a single page use alloc_page and only switch to vmalloc when we
have more extents outstanding. Currently there is only a single testcase
(xfstests generic/113) which can reproduce large enough extent lists for
this to occur.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
The kbuild test robot complained that we got the printk format wrong.
Let's just kill these printks instead of fixing them as there is not
point after the initial tree algorithm debugging.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Currently the block layout driver tracks extents in three separate
data structures:
- the two list of pnfs_block_extent structures returned by the server
- the list of sectors that were in invalid state but have been written to
- a list of pnfs_block_short_extent structures for LAYOUTCOMMIT
All of these share the property that they are not only highly inefficient
data structures, but also that operations on them are even more inefficient
than nessecary.
In addition there are various implementation defects like:
- using an int to track sectors, causing corruption for large offsets
- incorrect normalization of page or block granularity ranges
- insufficient error handling
- incorrect synchronization as extents can be modified while they are in
use
This patch replace all three data with a single unified rbtree structure
tracking all extents, as well as their in-memory state, although we still
need to instance for read-only and read-write extent due to the arcane
client side COW feature in the block layouts spec.
To fix the problem of extent possibly being modified while in use we make
sure to return a copy of the extent for use in the write path - the
extent can only be invalidated by a layout recall or return which has
to wait until the I/O operations finished due to refcounts on the layout
segment.
The new extent tree work similar to the schemes used by block based
filesystems like XFS or ext4.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Stephen Rothwell