summaryrefslogtreecommitdiffstats
path: root/fs/xfs/libxfs/xfs_refcount_btree.c
Commit message (Collapse)AuthorAgeFilesLines
* xfs: preallocate blocks for worst-case btree expansionDarrick J. Wong2016-10-051-3/+65
| | | | | | | | | | | | | | | | | | | | | | | | | To gracefully handle the situation where a CoW operation turns a single refcount extent into a lot of tiny ones and then run out of space when a tree split has to happen, use the per-AG reserved block pool to pre-allocate all the space we'll ever need for a maximal btree. For a 4K block size, this only costs an overhead of 0.3% of available disk space. When reflink is enabled, we have an unfortunate problem with rmap -- since we can share a block billions of times, this means that the reverse mapping btree can expand basically infinitely. When an AG is so full that there are no free blocks with which to expand the rmapbt, the filesystem will shut down hard. This is rather annoying to the user, so use the AG reservation code to reserve a "reasonable" amount of space for rmap. We'll prevent reflinks and CoW operations if we think we're getting close to exhausting an AG's free space rather than shutting down, but this permanent reservation should be enough for "most" users. Hopefully. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> [hch@lst.de: ensure that we invalidate the freed btree buffer] Signed-off-by: Christoph Hellwig <hch@lst.de>
* xfs: add refcount btree operationsDarrick J. Wong2016-10-031-0/+211
| | | | | | | | | | | | | Implement the generic btree operations required to manipulate refcount btree blocks. The implementation is similar to the bmapbt, though it will only allocate and free blocks from the AG. Since the refcount root and level fields are separate from the existing roots and levels array, they need a separate logging flag. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> [hch: fix logging of AGF refcount btree fields] Signed-off-by: Christoph Hellwig <hch@lst.de>
* xfs: define the on-disk refcount btree formatDarrick J. Wong2016-10-031-0/+178
Start constructing the refcount btree implementation by establishing the on-disk format and everything needed to read, write, and manipulate the refcount btree blocks. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de>
OpenPOWER on IntegriCloud