Re: [patch 29/52] fs: icache lock i_count

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From: Theodore Tso

Subject: Re: [patch 29/52] fs: icache lock i_count

Date: Tuesday, July 6, 2010 - 3:38 am

On Jul 6, 2010, at 12:34 AM, Nick Piggin wrote:
quoted text> On Tue, Jul 06, 2010 at 08:41:06AM +1000, Dave Chinner wrote:
>> 
>> 
>> I don't disagree with this approach - I object to the fact that you
>> repurpose an existing lock and change it's locking rules to "rule
>> the inode". We don't have any one lock that "rules the inode",
>> anyway, so adding a new "i_list_lock" for the new VFS level locking
>> strategies makes it a lot more self-contained. Fundamentally I'm
>> less concerned about the additional memory usage than I am about
>> having landmines planted around i_lock...
> 
> If some filesystem introduces a lock ordering problem from not
> reading the newly added documentation, lockdep should catch it pretty
> quick.

I assume you mean inline documentation in the source, because I
quickly scanned the source and couldn't find any significant changes
to any files in Documentation.

It would be nice if the new state of affairs is documented in a single file,
so that people who want to understand this new locking system don't
have to go crawling through the code, or searching mailing list archives
to figure out what's going on.

A lot of the text in this mail thread, including your discussion of the new
locking hierarchy, and why things are the way they are, would be good
fodder for a new documentation file.   And if you don't want to rename
i_lock, because no better name can be found, we should at least
document that starting as of 2.6.35/36 the meaning of i_lock changed.

-- Ted

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Messages in current thread:

[patch 00/52] vfs scalability patches updated, npiggin, (Wed Jun 23, 8:02 pm)

[patch 01/52] kernel: add bl_list, npiggin, (Wed Jun 23, 8:02 pm)

[patch 02/52] fs: fix superblock iteration race, npiggin, (Wed Jun 23, 8:02 pm)

[patch 03/52] fs: fs_struct rwlock to spinlock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 04/52] fs: cleanup files_lock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 05/52] lglock: introduce special lglock and brlock ..., npiggin, (Wed Jun 23, 8:02 pm)

[patch 06/52] fs: scale files_lock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 07/52] fs: brlock vfsmount_lock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 08/52] fs: scale mntget/mntput, npiggin, (Wed Jun 23, 8:02 pm)

[patch 09/52] fs: dcache scale hash, npiggin, (Wed Jun 23, 8:02 pm)

[patch 10/52] fs: dcache scale lru, npiggin, (Wed Jun 23, 8:02 pm)

[patch 11/52] fs: dcache scale nr_dentry, npiggin, (Wed Jun 23, 8:02 pm)

[patch 12/52] fs: dcache scale dentry refcount, npiggin, (Wed Jun 23, 8:02 pm)

[patch 13/52] fs: dcache scale d_unhashed, npiggin, (Wed Jun 23, 8:02 pm)

[patch 14/52] fs: dcache scale subdirs, npiggin, (Wed Jun 23, 8:02 pm)

[patch 15/52] fs: dcache scale inode alias list, npiggin, (Wed Jun 23, 8:02 pm)

[patch 16/52] fs: dcache RCU for multi-step operaitons, npiggin, (Wed Jun 23, 8:02 pm)

[patch 17/52] fs: dcache remove dcache_lock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 18/52] fs: dcache reduce dput locking, npiggin, (Wed Jun 23, 8:02 pm)

[patch 19/52] fs: dcache per-bucket dcache hash locking, npiggin, (Wed Jun 23, 8:02 pm)

[patch 20/52] fs: dcache reduce dcache_inode_lock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 21/52] fs: dcache per-inode inode alias locking, npiggin, (Wed Jun 23, 8:02 pm)

[patch 22/52] fs: dcache rationalise dget variants, npiggin, (Wed Jun 23, 8:02 pm)

[patch 23/52] fs: dcache percpu nr_dentry, npiggin, (Wed Jun 23, 8:02 pm)

[patch 24/52] fs: dcache reduce d_parent locking, npiggin, (Wed Jun 23, 8:02 pm)

[patch 25/52] fs: dcache DCACHE_REFERENCED improve, npiggin, (Wed Jun 23, 8:02 pm)

[patch 26/52] fs: icache lock s_inodes list, npiggin, (Wed Jun 23, 8:02 pm)

[patch 27/52] fs: icache lock inode hash, npiggin, (Wed Jun 23, 8:02 pm)

[patch 28/52] fs: icache lock i_state, npiggin, (Wed Jun 23, 8:02 pm)

[patch 29/52] fs: icache lock i_count, npiggin, (Wed Jun 23, 8:02 pm)

[patch 30/52] fs: icache lock lru/writeback lists, npiggin, (Wed Jun 23, 8:02 pm)

[patch 31/52] fs: icache atomic inodes_stat, npiggin, (Wed Jun 23, 8:02 pm)

[patch 32/52] fs: icache protect inode state, npiggin, (Wed Jun 23, 8:02 pm)

[patch 33/52] fs: icache atomic last_ino, iunique lock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 34/52] fs: icache remove inode_lock, npiggin, (Wed Jun 23, 8:02 pm)

[patch 35/52] fs: icache factor hash lock into functions, npiggin, (Wed Jun 23, 8:02 pm)

[patch 36/52] fs: icache per-bucket inode hash locks, npiggin, (Wed Jun 23, 8:02 pm)

[patch 37/52] fs: icache lazy lru, npiggin, (Wed Jun 23, 8:02 pm)

[patch 38/52] fs: icache RCU free inodes, npiggin, (Wed Jun 23, 8:02 pm)

[patch 39/52] fs: icache rcu walk for i_sb_list, npiggin, (Wed Jun 23, 8:02 pm)

[patch 40/52] fs: dcache improve scalability of pseudo fil ..., npiggin, (Wed Jun 23, 8:02 pm)

[patch 41/52] fs: icache reduce atomics, npiggin, (Wed Jun 23, 8:02 pm)

[patch 42/52] fs: icache per-cpu last_ino allocator, npiggin, (Wed Jun 23, 8:02 pm)

[patch 43/52] fs: icache per-cpu nr_inodes counter, npiggin, (Wed Jun 23, 8:02 pm)

[patch 44/52] fs: icache per-CPU sb inode lists and locks, npiggin, (Wed Jun 23, 8:02 pm)

[patch 45/52] fs: icache RCU hash lookups, npiggin, (Wed Jun 23, 8:02 pm)

[patch 46/52] fs: icache reduce locking, npiggin, (Wed Jun 23, 8:02 pm)

[patch 47/52] fs: keep inode with backing-dev, npiggin, (Wed Jun 23, 8:02 pm)

[patch 48/52] fs: icache split IO and LRU lists, npiggin, (Wed Jun 23, 8:03 pm)

[patch 49/52] fs: icache scale writeback list locking, npiggin, (Wed Jun 23, 8:03 pm)

[patch 50/52] mm: implement per-zone shrinker, npiggin, (Wed Jun 23, 8:03 pm)

[patch 51/52] fs: per-zone dentry and inode LRU, npiggin, (Wed Jun 23, 8:03 pm)

[patch 52/52] fs: icache less I_FREEING time, npiggin, (Wed Jun 23, 8:03 pm)

Re: [patch 01/52] kernel: add bl_list, Eric Dumazet, (Wed Jun 23, 11:04 pm)

Re: [patch 06/52] fs: scale files_lock, Peter Zijlstra, (Thu Jun 24, 12:52 am)

Re: [patch 14/52] fs: dcache scale subdirs, Peter Zijlstra, (Thu Jun 24, 12:56 am)

Re: [patch 16/52] fs: dcache RCU for multi-step operaitons, Peter Zijlstra, (Thu Jun 24, 12:58 am)

Re: [patch 24/52] fs: dcache reduce d_parent locking, Peter Zijlstra, (Thu Jun 24, 1:44 am)

Re: [patch 30/52] fs: icache lock lru/writeback lists, Peter Zijlstra, (Thu Jun 24, 1:58 am)

Re: [patch 42/52] fs: icache per-cpu last_ino allocator, Andi Kleen, (Thu Jun 24, 2:48 am)

Re: [patch 14/52] fs: dcache scale subdirs, Andi Kleen, (Thu Jun 24, 2:50 am)

Re: [patch 37/52] fs: icache lazy lru, Andi Kleen, (Thu Jun 24, 2:52 am)

Re: [patch 50/52] mm: implement per-zone shrinker, Andi Kleen, (Thu Jun 24, 3:06 am)

Re: [patch 01/52] kernel: add bl_list, Nick Piggin, (Thu Jun 24, 7:42 am)

Re: [patch 06/52] fs: scale files_lock, Nick Piggin, (Thu Jun 24, 8:00 am)

Re: [patch 16/52] fs: dcache RCU for multi-step operaitons, Nick Piggin, (Thu Jun 24, 8:03 am)

Re: [patch 24/52] fs: dcache reduce d_parent locking, Nick Piggin, (Thu Jun 24, 8:07 am)

Re: [patch 30/52] fs: icache lock lru/writeback lists, Nick Piggin, (Thu Jun 24, 8:09 am)

Re: [patch 30/52] fs: icache lock lru/writeback lists, Peter Zijlstra, (Thu Jun 24, 8:13 am)

Re: [patch 24/52] fs: dcache reduce d_parent locking, Paul E. McKenney, (Thu Jun 24, 8:32 am)

Re: [patch 42/52] fs: icache per-cpu last_ino allocator, Nick Piggin, (Thu Jun 24, 8:52 am)

Re: [patch 14/52] fs: dcache scale subdirs, Nick Piggin, (Thu Jun 24, 8:53 am)

Re: [patch 37/52] fs: icache lazy lru, Nick Piggin, (Thu Jun 24, 8:59 am)

Re: [patch 50/52] mm: implement per-zone shrinker, Nick Piggin, (Thu Jun 24, 9:00 am)

Re: [patch 01/52] kernel: add bl_list, Eric Dumazet, (Thu Jun 24, 9:01 am)

Re: [patch 24/52] fs: dcache reduce d_parent locking, Nick Piggin, (Thu Jun 24, 9:05 am)

Re: [patch 42/52] fs: icache per-cpu last_ino allocator, Andi Kleen, (Thu Jun 24, 9:19 am)

Re: [patch 50/52] mm: implement per-zone shrinker, Andi Kleen, (Thu Jun 24, 9:27 am)

Re: [patch 50/52] mm: implement per-zone shrinker, Andi Kleen, (Thu Jun 24, 9:32 am)

Re: [patch 50/52] mm: implement per-zone shrinker, Andi Kleen, (Thu Jun 24, 9:37 am)

Re: [patch 42/52] fs: icache per-cpu last_ino allocator, Nick Piggin, (Thu Jun 24, 9:38 am)

Re: [patch 24/52] fs: dcache reduce d_parent locking, Paul E. McKenney, (Thu Jun 24, 9:41 am)

Re: [patch 16/52] fs: dcache RCU for multi-step operaitons, john stultz, (Thu Jun 24, 10:22 am)

Re: [patch 16/52] fs: dcache RCU for multi-step operaitons, john stultz, (Thu Jun 24, 10:26 am)

Re: [patch 05/52] lglock: introduce special lglock and brl ..., Thomas Gleixner, (Thu Jun 24, 11:15 am)

Re: [patch 05/52] lglock: introduce special lglock and brl ..., Nick Piggin, (Thu Jun 24, 11:22 pm)

Re: [patch 00/52] vfs scalability patches updated, Christoph Hellwig, (Fri Jun 25, 12:12 am)

Re: [patch 00/52] vfs scalability patches updated, Nick Piggin, (Fri Jun 25, 1:05 am)

Re: [patch 05/52] lglock: introduce special lglock and brl ..., Thomas Gleixner, (Fri Jun 25, 2:50 am)

Re: [patch 01/52] kernel: add bl_list, Paul E. McKenney, (Mon Jun 28, 2:37 pm)

Re: [patch 24/52] fs: dcache reduce d_parent locking, Paul E. McKenney, (Mon Jun 28, 2:50 pm)

Re: [patch 01/52] kernel: add bl_list, Nick Piggin, (Mon Jun 28, 11:30 pm)

Re: [patch 02/52] fs: fix superblock iteration race, Christoph Hellwig, (Tue Jun 29, 6:02 am)

Re: [patch 02/52] fs: fix superblock iteration race, Nick Piggin, (Tue Jun 29, 7:56 am)

Re: [patch 02/52] fs: fix superblock iteration race, Linus Torvalds, (Tue Jun 29, 10:35 am)

Re: [patch 02/52] fs: fix superblock iteration race, Nick Piggin, (Tue Jun 29, 10:41 am)

Re: [patch 02/52] fs: fix superblock iteration race, Linus Torvalds, (Tue Jun 29, 10:52 am)

Re: [patch 02/52] fs: fix superblock iteration race, Linus Torvalds, (Tue Jun 29, 10:58 am)

Re: [patch 02/52] fs: fix superblock iteration race, Nick Piggin, (Tue Jun 29, 1:14 pm)

Re: [patch 02/52] fs: fix superblock iteration race, Chris Clayton, (Tue Jun 29, 1:38 pm)

Re: [patch 50/52] mm: implement per-zone shrinker, Dave Chinner, (Tue Jun 29, 11:28 pm)

Re: [patch 02/52] fs: fix superblock iteration race, Chris Clayton, (Wed Jun 30, 12:13 am)

Re: [patch 29/52] fs: icache lock i_count, Dave Chinner, (Wed Jun 30, 12:27 am)

Re: [patch 37/52] fs: icache lazy lru, Dave Chinner, (Wed Jun 30, 1:38 am)

Re: [patch 38/52] fs: icache RCU free inodes, Dave Chinner, (Wed Jun 30, 1:57 am)

Re: [patch 44/52] fs: icache per-CPU sb inode lists and locks, Dave Chinner, (Wed Jun 30, 2:26 am)

Re: [patch 52/52] fs: icache less I_FREEING time, Dave Chinner, (Wed Jun 30, 3:13 am)

Re: [patch 00/52] vfs scalability patches updated, Dave Chinner, (Wed Jun 30, 4:30 am)

Re: [patch 50/52] mm: implement per-zone shrinker, Nick Piggin, (Wed Jun 30, 5:03 am)

Re: [patch 37/52] fs: icache lazy lru, Nick Piggin, (Wed Jun 30, 5:06 am)

Re: [patch 38/52] fs: icache RCU free inodes, Nick Piggin, (Wed Jun 30, 5:07 am)

Re: [patch 44/52] fs: icache per-CPU sb inode lists and locks, Nick Piggin, (Wed Jun 30, 5:08 am)

Re: [patch 51/52] fs: per-zone dentry and inode LRU, Nick Piggin, (Wed Jun 30, 5:13 am)

Re: [patch 52/52] fs: icache less I_FREEING time, Nick Piggin, (Wed Jun 30, 5:14 am)

Re: [patch 00/52] vfs scalability patches updated, Nick Piggin, (Wed Jun 30, 5:40 am)

Re: [patch 02/52] fs: fix superblock iteration race, Al Viro, (Wed Jun 30, 5:51 am)

Re: [patch 00/52] vfs scalability patches updated, Frank Mayhar, (Wed Jun 30, 10:08 am)

Re: [patch 29/52] fs: icache lock i_count, Dave Chinner, (Wed Jun 30, 7:36 pm)

Re: [patch 37/52] fs: icache lazy lru, Dave Chinner, (Wed Jun 30, 7:46 pm)

Re: [patch 44/52] fs: icache per-CPU sb inode lists and locks, Dave Chinner, (Wed Jun 30, 8:12 pm)

Re: [patch 52/52] fs: icache less I_FREEING time, Dave Chinner, (Wed Jun 30, 8:33 pm)

Re: [patch 00/52] vfs scalability patches updated, Dave Chinner, (Wed Jun 30, 8:56 pm)

Re: [patch 29/52] fs: icache lock i_count, Nick Piggin, (Thu Jul 1, 12:54 am)

Re: [patch 37/52] fs: icache lazy lru, Nick Piggin, (Thu Jul 1, 12:57 am)

Re: [patch 44/52] fs: icache per-CPU sb inode lists and locks, Nick Piggin, (Thu Jul 1, 1:00 am)

Re: [patch 52/52] fs: icache less I_FREEING time, Nick Piggin, (Thu Jul 1, 1:06 am)

Re: [patch 00/52] vfs scalability patches updated, Nick Piggin, (Thu Jul 1, 1:20 am)

Re: [patch 29/52] fs: icache lock i_count, Nick Piggin, (Thu Jul 1, 2:36 am)

Re: [patch 29/52] fs: icache lock i_count, Frank Mayhar, (Thu Jul 1, 9:21 am)

Re: [patch 00/52] vfs scalability patches updated, Nick Piggin, (Thu Jul 1, 10:23 am)

Re: [patch 00/52] vfs scalability patches updated, Andi Kleen, (Thu Jul 1, 10:28 am)

Re: [patch 00/52] vfs scalability patches updated, Linus Torvalds, (Thu Jul 1, 10:35 am)

Re: [patch 00/52] vfs scalability patches updated, Andi Kleen, (Thu Jul 1, 10:36 am)

Re: [patch 00/52] vfs scalability patches updated, Nick Piggin, (Thu Jul 1, 10:52 am)

Re: [patch 00/52] vfs scalability patches updated, Paul E. McKenney, (Thu Jul 1, 9:01 pm)

Re: [patch 29/52] fs: icache lock i_count, Andrew Morton, (Fri Jul 2, 7:03 pm)

Re: [patch 29/52] fs: icache lock i_count, Nick Piggin, (Fri Jul 2, 8:41 pm)

Re: [patch 29/52] fs: icache lock i_count, Andrew Morton, (Fri Jul 2, 9:31 pm)

Re: [patch 29/52] fs: icache lock i_count, Nick Piggin, (Fri Jul 2, 10:06 pm)

Re: [patch 29/52] fs: icache lock i_count, Nick Piggin, (Fri Jul 2, 10:18 pm)

Re: [patch 29/52] fs: icache lock i_count, Dave Chinner, (Mon Jul 5, 3:41 pm)

Re: [patch 29/52] fs: icache lock i_count, Theodore Tso, (Tue Jul 6, 3:38 am)

Re: [patch 29/52] fs: icache lock i_count, Nick Piggin, (Tue Jul 6, 6:04 am)

Re: [patch 00/52] vfs scalability patches updated, Nick Piggin, (Tue Jul 6, 10:49 am)

Re: [patch 24/52] fs: dcache reduce d_parent locking, Nick Piggin, (Wed Jul 7, 7:35 am)

Re: [patch 29/52] fs: icache lock i_count, Frank Mayhar, (Wed Jul 7, 10:00 am)

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