j_state_lock, j_list_lock, remove-bitlocks
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- v1 Latest3 patches 26 repliesIn review
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/3 | j_state_lock -> j_state_semfs/ fs/ fs/ +3 more | +115 | 0 replies | |
| 2/3 | j_list_lock -> j_list_semfs/ fs/ fs/ +3 more | +105 | 0 replies | |
| 3/3 | remove bitlocksfs/ include/ include/ | +46 | 0 replies |
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Cover letter [patch 0/3] j_state_lock, j_list_lock, remove-bitlocks
Quoted 10 lines · Andrew Morton
Quoted 6 lines
Quoted 3 lines
Damn! The answer was right there in front of my eyes! Here's the cleanest solution. I forgot about
wait_on_bit_lock. I've converted all the locks to use this instead. [...]ah, indeed, this looks really nifty. Andrew?
There's a little lock ranking diagram in
jbd.hwhich tells us that these locks nest insidej_list_lockandj_state_lock. So I guess you'll need to turn those into semaphores.
indeed. I did this (see the three followup patches, against BK-curr), and it builds/boots/works just fine on an ext3 box. Do we want to try this in -mm?
one worry would be that while spinlocks are NOP on UP, semaphores are not. OTOH, this could relax some of the preemptability constraints within ext3 and could make it more hackable. These patches enabled the removal of some of the lock-break code for example and could likely solve some of the remaining ext3 latencies.
Ingo