path: root/fs/ncpfs/dir.c
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authorNick Piggin <npiggin@kernel.dk>2011-01-07 17:49:37 +1100
committerNick Piggin <npiggin@kernel.dk>2011-01-07 17:50:22 +1100
commit949854d02455080d20cd3e1db28a3a18daf7599d (patch)
tree9b13a6f86c1d0b91e462a471e53b0e717036b18e /fs/ncpfs/dir.c
parent9abca36087288fe28de4749c71ca003d4b9e3ed0 (diff)
fs: Use rename lock and RCU for multi-step operations
The remaining usages for dcache_lock is to allow atomic, multi-step read-side operations over the directory tree by excluding modifications to the tree. Also, to walk in the leaf->root direction in the tree where we don't have a natural d_lock ordering. This could be accomplished by taking every d_lock, but this would mean a huge number of locks and actually gets very tricky. Solve this instead by using the rename seqlock for multi-step read-side operations, retry in case of a rename so we don't walk up the wrong parent. Concurrent dentry insertions are not serialised against. Concurrent deletes are tricky when walking up the directory: our parent might have been deleted when dropping locks so also need to check and retry for that. We can also use the rename lock in cases where livelock is a worry (and it is introduced in subsequent patch). Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Diffstat (limited to 'fs/ncpfs/dir.c')
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