2 * Currently the check code (bref.methods / crc, sha, etc) is being checked
3 every single blasted time a chain is locked, even if the underlying buffer
4 was previously checked for that chain. This needs an optimization to
5 (significantly) improve performance.
7 * flush synchronization boundary crossing check and current flush chain
10 * snapshot creation must allocate and separately pass a new pmp for the pfs
11 degenerate 'cluster' representing the snapshot. This theoretically will
12 also allow a snapshot to be generated inside a cluster of more than one
15 * snapshot copy currently also copies uuids and can confuse cluster code
17 * hidden dir or other dirs/files/modifications made to PFS before
18 additional cluster entries added.
20 * transaction on cluster - multiple trans structures, subtrans
22 * inode always contains target cluster/chain, not hardlink
24 * cluster_modify_ip -> data returned mod to all chains
25 * and hammer2_cluster_data() -> same thing
27 * chain refs in cluster, cluster refs
29 * check inode shared lock ... can end up in endless loop if following
30 hardlink because ip->chain is not updated in the exclusive lock cycle
31 when following hardlink.
33 cpdup /build/boomdata/jails/bleeding-edge/usr/share/man/man4 /mnt/x3
36 * The block freeing code. At the very least a bulk scan is needed
37 to implement freeing blocks.
39 * Crash stability. Right now the allocation table on-media is not
40 properly synchronized with the flush. This needs to be adjusted
41 such that H2 can do an incremental scan on mount to fixup
42 allocations on mount as part of its crash recovery mechanism.
44 * We actually have to start checking and acting upon the CRCs being
47 * Remaining known hardlink issues need to be addressed.
49 * Core 'copies' mechanism needs to be implemented to support multiple
50 copies on the same media.
52 * Core clustering mechanism needs to be implemented to support
53 mirroring and basic multi-master operation from a single host
54 (multi-host requires additional network protocols and won't
57 * make sure we aren't using a shared lock during RB_SCAN's?
59 * overwrite in write_file case w/compression - if device block size changes
60 the block has to be deleted and reallocated. See hammer2_assign_physical()
63 * freemap / clustering. Set block size on 2MB boundary so the cluster code
64 can be used for reading.
66 * need API layer for shared buffers (unfortunately).
68 * add magic number to inode header, add parent inode number too, to
69 help with brute-force recovery.
71 * modifications past our flush point do not adjust vchain.
72 need to make vchain dynamic so we can (see flush_scan2).??
74 * MINIOSIZE/RADIX set to 1KB for now to avoid buffer cache deadlocks
75 on multiple locked inodes. Fix so we can use LBUFSIZE! Or,
76 alternatively, allow a smaller I/O size based on the sector size
79 * When making a snapshot, do not allow the snapshot to be mounted until
80 the in-memory chain has been freed in order to break the shared core.
82 * Snapshotting a sub-directory does not snapshot any
83 parent-directory-spanning hardlinks.
85 * Snapshot / flush-synchronization point. remodified data that crosses
86 the synchronization boundary is not currently reallocated. see
87 hammer2_chain_modify(), explicit check (requires logical buffer cache
90 * on fresh mount with multiple hardlinks present separate lookups will
91 result in separate vnodes pointing to separate inodes pointing to a
92 common chain (the hardlink target).
94 When the hardlink target consolidates upward only one vp/ip will be
95 adjusted. We need code to fixup the other chains (probably put in
96 inode_lock_*()) which will be pointing to an older deleted hardlink
99 * Filesystem must ensure that modify_tid is not too large relative to
100 the iterator in the volume header, on load, or flush sequencing will
101 not work properly. We should be able to just override it, but we
102 should complain if it happens.
104 * Kernel-side needs to clean up transaction queues and make appropriate
107 * Userland side needs to do the same for any initiated transactions.
109 * Nesting problems in the flusher.
111 * Inefficient vfsync due to thousands of file buffers, one per-vnode.
112 (need to aggregate using a device buffer?)
114 * Use bp->b_dep to interlock the buffer with the chain structure so the
115 strategy code can calculate the crc and assert that the chain is marked
116 modified (not yet flushed).
118 * Deleted inode not reachable via tree for volume flush but still reachable
119 via fsync/inactive/reclaim. Its tree can be destroyed at that point.
121 * The direct write code needs to invalidate any underlying physical buffers.
122 Direct write needs to be implemented.
124 * Make sure a resized block (hammer2_chain_resize()) calculates a new
125 hash code in the parent bref
127 * The freemap allocator needs to getblk/clrbuf/bdwrite any partial
128 block allocations (less than 64KB) that allocate out of a new 64K
129 block, to avoid causing a read-before-write I/O.
131 * Check flush race upward recursion setting SUBMODIFIED vs downward
132 recursion checking SUBMODIFIED then locking (must clear before the
133 recursion and might need additional synchronization)
135 * There is definitely a flush race in the hardlink implementation between
136 the forwarding entries and the actual (hidden) hardlink inode.
138 This will require us to associate a small hard-link-adjust structure
139 with the chain whenever we create or delete hardlinks, on top of
140 adjusting the hardlink inode itself. Any actual flush to the media
141 has to synchronize the correct nlinks value based on whether related
142 created or deleted hardlinks were also flushed.
144 * When a directory entry is created and also if an indirect block is
145 created and entries moved into it, the directory seek position can
146 potentially become incorrect during a scan.
148 * When a directory entry is deleted a directory seek position depending
149 on that key can cause readdir to skip entries.
151 * TWO PHASE COMMIT - store two data offsets in the chain, and
152 hammer2_chain_delete() needs to leave the chain intact if MODIFIED2 is
153 set on its buffer until the flusher gets to it?
158 * If a file is unlinked buts its descriptors is left open and used, we
159 should allow data blocks on-media to be reused since there is no
160 topology left to point at them.