Hi all, This is a first pass at sparse inode chunk support for XFS. Some background on this work is available here: http://oss.sgi.com/archives/xfs/2013-08/msg00346.html The basic idea is to allow the partial allocation of inode chunks into fragmented regions of free space. This is accomplished through addition of a holemask field into the inobt record that defines what portion(s) of an inode chunk are invalid (i.e., holes in the chunk). This work is not quite complete, but is at a point where I'd like to start getting feedback on the design and what direction to take for some of the known gaps. The basic breakdown of functionality in this set is as follows: - Patches 1-2 - A couple generic cleanups that are dependencies for later patches in the series. - Patches 3-5 - Basic data structure update, feature bit and minor helper introduction. - Patches 6-7 - Update v5 icreate logging and recovery to handle sparse inode records. - Patches 8-13 - Allocation support for sparse inode records. Physical chunk allocation and individual inode allocation. - Patches 14-16 - Deallocation support for sparse inode chunks. Physical chunk deallocation, individual inode free and cluster free. - Patch 17 - Fixes for bulkstat/inumbers. - Patch 18 - Activate support for sparse chunk allocation and processing. This work is lightly tested for regression (some xfstests failures due to repair) and basic functionality. I have a new xfstests test I'll forward along for demonstration purposes. Some notes on gaps in the design: - Sparse inode chunk allocation granularity: The current minimum sparse chunk allocation granularity is the cluster size. My initial attempts at this work tried to redefine to the minimum chunk length based on the holemask granularity (a la the stale macro I seemingly left in this series ;), but this involves tweaking the codepaths that use the cluster size (i.e., imap) which proved rather hairy. This also means we need a solution where an imap can change if an inode was initially mapped as a sparse chunk and said chunk is subsequently made full. E.g., we'd perhaps need to invalidate the inode buffers for sparse chunks at the time where they are made full. Given that, I landed on using the cluster size and leaving those codepaths as is for the time being. There is a tradeoff here for v5 superblocks because we've recently made a change to scale the cluster size based on the factor increase in the inode size from the default (see xfsprogs commit 7b5f9801). This means that effectiveness of sparse chunks is tied to whether the level of free space fragmentation matches the cluster size. By that I mean effectivess is good (near 100% utilization possible) if free space fragmentation leaves free extents around that at least match the cluster size. If fragmentation is worse than the cluster size, effectiveness is reduced. This can also be demonstrated with the forthcoming xfstests test. - On-disk lifecycle of the sparse inode chunks feature bit: We set an incompatible feature bit once a sparse inode chunk is allocated because older revisions of code will interpret the non-zero holemask bits in the higher order bytes of the record freecount. The feature bit must be removed once all sparse inode chunks are eliminated one way or another. This series does not currently remove the feature bit once set simply because I hadn't thought through the mechanism quite yet. For the next version, I'm thinking about adding an inobt walk mechanism that can be conditionally invoked (i.e., feature bit is currently set and a sparse inode chunk has been eliminated) either via workqueue on an interval or during unmount if necessary. Thoughts or alternative suggestions on that appreciated. That's about it for now. Thoughts, reviews, flames appreciated. Thanks. Brian Brian Foster (18): xfs: refactor xfs_inobt_insert() to eliminate loop and support variable count xfs: pass xfs_mount directly to xfs_ialloc_cluster_alignment() xfs: define sparse inode chunks v5 sb feature bit and helper function xfs: introduce inode record hole mask for sparse inode chunks xfs: create macros/helpers for dealing with sparse inode chunks xfs: pass inode count through ordered icreate log item xfs: handle sparse inode chunks in icreate log recovery xfs: create helper to manage record overlap for sparse inode chunks xfs: allocate sparse inode chunks on full chunk allocation failure xfs: set sparse inodes feature bit when a sparse chunk is allocated xfs: reduce min. inode allocation space requirement for sparse inode chunks xfs: helper to convert inobt record holemask to inode alloc. bitmap xfs: filter out sparse regions from individual inode allocation xfs: update free inode record logic to support sparse inode records xfs: only free allocated regions of inode chunks xfs: skip unallocated regions of inode chunks in xfs_ifree_cluster() xfs: use actual inode count for sparse records in bulkstat/inumbers xfs: enable sparse inode chunks for v5 superblocks fs/xfs/libxfs/xfs_format.h | 17 +- fs/xfs/libxfs/xfs_ialloc.c | 441 +++++++++++++++++++++++++++++++++------ fs/xfs/libxfs/xfs_ialloc.h | 17 +- fs/xfs/libxfs/xfs_ialloc_btree.c | 4 +- fs/xfs/libxfs/xfs_sb.h | 9 +- fs/xfs/xfs_inode.c | 28 ++- fs/xfs/xfs_itable.c | 12 +- fs/xfs/xfs_log_recover.c | 23 +- 8 files changed, 460 insertions(+), 91 deletions(-) -- 1.8.3.1 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
