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2011-01-07fs: use RCU in shrink_dentry_list to reduce lock nestingNick Piggin
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: reduce dcache_inode_lock width in lru scanningNick Piggin
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache reduce prune_one_dentry lockingNick Piggin
prune_one_dentry can avoid quite a bit of locking in the common case where ancestors have an elevated refcount. Alternatively, we could have gone the other way and made fewer trylocks in the case where d_count goes to zero, but is probably less common. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache reduce d_parent lockingNick Piggin
Use RCU to simplify locking in dget_parent. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache rationalise dget variantsNick Piggin
dget_locked was a shortcut to avoid the lazy lru manipulation when we already held dcache_lock (lru manipulation was relatively cheap at that point). However, how that the lru lock is an innermost one, we never hold it at any caller, so the lock cost can now be avoided. We already have well working lazy dcache LRU, so it should be fine to defer LRU manipulations to scan time. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache reduce dcache_inode_lockNick Piggin
dcache_inode_lock can be avoided in d_delete() and d_materialise_unique() in cases where it is not required. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache reduce locking in d_allocNick Piggin
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache reduce dput lockingNick Piggin
It is possible to run dput without taking data structure locks up-front. In many cases where we don't kill the dentry anyway, these locks are not required. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache avoid starvation in dcache multi-step operationsNick Piggin
Long lived dcache "multi-step" operations which retry on rename seq can be starved with a lot of rename activity. If they fail after the 1st pass, take the rename_lock for writing to avoid further starvation. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache remove dcache_lockNick Piggin
dcache_lock no longer protects anything. remove it. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: Use rename lock and RCU for multi-step operationsNick Piggin
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>
2011-01-07fs: increase d_name lock coverageNick Piggin
Cover d_name with d_lock in more cases, where there may be concurrent modification to it. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: scale inode alias listNick Piggin
Add a new lock, dcache_inode_lock, to protect the inode's i_dentry list from concurrent modification. d_alias is also protected by d_lock. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache scale subdirsNick Piggin
Protect d_subdirs and d_child with d_lock, except in filesystems that aren't using dcache_lock for these anyway (eg. using i_mutex). Note: if we change the locking rule in future so that ->d_child protection is provided only with ->d_parent->d_lock, it may allow us to reduce some locking. But it would be an exception to an otherwise regular locking scheme, so we'd have to see some good results. Probably not worthwhile. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache scale d_unhashedNick Piggin
Protect d_unhashed(dentry) condition with d_lock. This means keeping DCACHE_UNHASHED bit in synch with hash manipulations. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache scale dentry refcountNick Piggin
Make d_count non-atomic and protect it with d_lock. This allows us to ensure a 0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when we start protecting many other dentry members with d_lock. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache scale lruNick Piggin
Add a new lock, dcache_lru_lock, to protect the dcache LRU list from concurrent modification. d_lru is also protected by d_lock, which allows LRU lists to be accessed without the lru lock, using RCU in future patches. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: dcache scale hashNick Piggin
Add a new lock, dcache_hash_lock, to protect the dcache hash table from concurrent modification. d_hash is also protected by d_lock. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07hostfs: simplify lockingNick Piggin
Remove dcache_lock locking from hostfs filesystem, and move it into dcache helpers. All that is required is a coherent path name. Protection from concurrent modification of the namespace after path name generation is not provided in current code, because dcache_lock is dropped before the path is used. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: change d_hash for rcu-walkNick Piggin
Change d_hash so it may be called from lock-free RCU lookups. See similar patch for d_compare for details. For in-tree filesystems, this is just a mechanical change. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: change d_compare for rcu-walkNick Piggin
Change d_compare so it may be called from lock-free RCU lookups. This does put significant restrictions on what may be done from the callback, however there don't seem to have been any problems with in-tree fses. If some strange use case pops up that _really_ cannot cope with the rcu-walk rules, we can just add new rcu-unaware callbacks, which would cause name lookup to drop out of rcu-walk mode. For in-tree filesystems, this is just a mechanical change. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: name case update methodNick Piggin
smpfs and ncpfs want to update a live dentry name in-place. Rather than have them open code the locking, provide a documented dcache API. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07jfs: dont overwrite dentry name in d_revalidateNick Piggin
Use vfat's method for dealing with negative dentries to preserve case, rather than overwrite dentry name in d_revalidate, which is a bit ugly and also gets in the way of doing lock-free path walking. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07cifs: dont overwrite dentry name in d_revalidateNick Piggin
Use vfat's method for dealing with negative dentries to preserve case, rather than overwrite dentry name in d_revalidate, which is a bit ugly and also gets in the way of doing lock-free path walking. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: change d_delete semanticsNick Piggin
Change d_delete from a dentry deletion notification to a dentry caching advise, more like ->drop_inode. Require it to be constant and idempotent, and not take d_lock. This is how all existing filesystems use the callback anyway. This makes fine grained dentry locking of dput and dentry lru scanning much simpler. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07config fs: avoid switching ->d_op on live dentryNick Piggin
Switching d_op on a live dentry is racy in general, so avoid it. In this case it is a negative dentry, which is safer, but there are still concurrent ops which may be called on d_op in that case (eg. d_revalidate). So in general a filesystem may not do this. Fix configfs so as not to do this. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: use fast counters for vfs cachesNick Piggin
percpu_counter library generates quite nasty code, so unless you need to dynamically allocate counters or take fast approximate value, a simple per cpu set of counters is much better. The percpu_counter can never be made to work as well, because it has an indirection from pointer to percpu memory, and it can't use direct this_cpu_inc interfaces because it doesn't use static PER_CPU data, so code will always be worse. In the fastpath, it is the difference between this: incl %gs:nr_dentry # nr_dentry and this: movl percpu_counter_batch(%rip), %edx # percpu_counter_batch, movl $1, %esi #, movq $nr_dentry, %rdi #, call __percpu_counter_add # (plus I clobber registers) __percpu_counter_add: pushq %rbp # movq %rsp, %rbp #, subq $32, %rsp #, movq %rbx, -24(%rbp) #, movq %r12, -16(%rbp) #, movq %r13, -8(%rbp) #, movq %rdi, %rbx # fbc, fbc #APP # 216 "/home/npiggin/usr/src/linux-2.6/arch/x86/include/asm/thread_info.h" 1 movq %gs:kernel_stack,%rax #, pfo_ret__ # 0 "" 2 #NO_APP incl -8124(%rax) # <variable>.preempt_count movq 32(%rdi), %r12 # <variable>.counters, tcp_ptr__ #APP # 78 "lib/percpu_counter.c" 1 add %gs:this_cpu_off, %r12 # this_cpu_off, tcp_ptr__ # 0 "" 2 #NO_APP movslq (%r12),%r13 #* tcp_ptr__, tmp73 movslq %edx,%rax # batch, batch addq %rsi, %r13 # amount, count cmpq %rax, %r13 # batch, count jge .L27 #, negl %edx # tmp76 movslq %edx,%rdx # tmp76, tmp77 cmpq %rdx, %r13 # tmp77, count jg .L28 #, .L27: movq %rbx, %rdi # fbc, call _raw_spin_lock # addq %r13, 8(%rbx) # count, <variable>.count movq %rbx, %rdi # fbc, movl $0, (%r12) #,* tcp_ptr__ call _raw_spin_unlock # .L29: #APP # 216 "/home/npiggin/usr/src/linux-2.6/arch/x86/include/asm/thread_info.h" 1 movq %gs:kernel_stack,%rax #, pfo_ret__ # 0 "" 2 #NO_APP decl -8124(%rax) # <variable>.preempt_count movq -8136(%rax), %rax #, D.14625 testb $8, %al #, D.14625 jne .L32 #, .L31: movq -24(%rbp), %rbx #, movq -16(%rbp), %r12 #, movq -8(%rbp), %r13 #, leave ret .p2align 4,,10 .p2align 3 .L28: movl %r13d, (%r12) # count,* jmp .L29 # .L32: call preempt_schedule # .p2align 4,,6 jmp .L31 # .size __percpu_counter_add, .-__percpu_counter_add .p2align 4,,15 Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07vfs: revert per-cpu nr_unused counters for dentry and inodesNick Piggin
The nr_unused counters count the number of objects on an LRU, and as such they are synchronized with LRU object insertion and removal and scanning, and protected under the LRU lock. Making it per-cpu does not actually get any concurrency improvements because of this lock, and summing the counter is much slower, and incrementing/decrementing it costs more code size and is slower too. These counters should stay per-LRU, which currently means global. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: d_validate fixesNick Piggin
d_validate has been broken for a long time. kmem_ptr_validate does not guarantee that a pointer can be dereferenced if it can go away at any time. Even rcu_read_lock doesn't help, because the pointer might be queued in RCU callbacks but not executed yet. So the parent cannot be checked, nor the name hashed. The dentry pointer can not be touched until it can be verified under lock. Hashing simply cannot be used. Instead, verify the parent/child relationship by traversing parent's d_child list. It's slow, but only ncpfs and the destaged smbfs care about it, at this point. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-06Merge branch 'v4l_for_linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 * 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6: (255 commits) [media] radio-aimslab.c: Fix gcc 4.5+ bug [media] cx25821: Fix compilation breakage due to BKL dependency [media] v4l2-compat-ioctl32: fix compile warning [media] zoran: fix compiler warning [media] tda18218: fix compile warning [media] ngene: fix compile warning [media] DVB: IR support for TechnoTrend CT-3650 [media] cx23885, cimax2.c: Fix case of two CAM insertion irq [media] ir-nec-decoder: fix repeat key issue [media] staging: se401 depends on USB [media] staging: usbvideo/vicam depends on USB [media] soc_camera: Add the ability to bind regulators to soc_camedra devices [media] V4L2: Add a v4l2-subdev (soc-camera) driver for OmniVision OV2640 sensor [media] v4l: soc-camera: switch to .unlocked_ioctl [media] v4l: ov772x: simplify pointer dereference [media] ov9640: fix OmniVision OV9640 sensor driver's priv data retrieving [media] ov9640: use macro to request OmniVision OV9640 sensor private data [media] ivtv-i2c: Fix two warnings [media] staging/lirc: Update lirc TODO files [media] cx88: Remove the obsolete i2c_adapter.id field ...
2011-01-06Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-armLinus Torvalds
* 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm: (416 commits) ARM: DMA: add support for DMA debugging ARM: PL011: add DMA burst threshold support for ST variants ARM: PL011: Add support for transmit DMA ARM: PL011: Ensure IRQs are disabled in UART interrupt handler ARM: PL011: Separate hardware FIFO size from TTY FIFO size ARM: PL011: Allow better handling of vendor data ARM: PL011: Ensure error flags are clear at startup ARM: PL011: include revision number in boot-time port printk ARM: vexpress: add sched_clock() for Versatile Express ARM i.MX53: Make MX53 EVK bootable ARM i.MX53: Some bug fix about MX53 MSL code ARM: 6607/1: sa1100: Update platform device registration ARM: 6606/1: sa1100: Fix platform device registration ARM i.MX51: rename IPU irqs ARM i.MX51: Add ipu clock support ARM: imx/mx27_3ds: Add PMIC support ARM: DMA: Replace page_to_dma()/dma_to_page() with pfn_to_dma()/dma_to_pfn() mx51: fix usb clock support MX51: Add support for usb host 2 arch/arm/plat-mxc/ehci.c: fix errors/typos ...
2011-01-06NFSv4: Ensure continued open and lockowner name uniquenessTrond Myklebust
In order to enable migration support, we will want to move some of the structures that are subject to migration into the struct nfs_server. In particular, if we are to move the state_owner and state_owner_id to being a per-filesystem structure, then we should label the resulting open/lock owners with a per-filesytem label to ensure global uniqueness. This patch does so by adding the super block s_dev to the open/lock owner name. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06NFS: Move cl_delegations to the nfs_server structChuck Lever
Delegations are per-inode, not per-nfs_client. When a server file system is migrated, delegations on the client must be moved from the source to the destination nfs_server. Make it easier to manage a mount point's delegation list across a migration event by moving the list to the nfs_server struct. Clean up: I added documenting comments to public functions I changed in this patch. For consistency I added comments to all the other public functions in fs/nfs/delegation.c. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06NFS: Introduce nfs_detach_delegations()Chuck Lever
Clean up: Refactor code that takes clp->cl_lock and calls nfs_detach_delegations_locked() into its own function. While we're changing the call sites, get rid of the second parameter and the logic in nfs_detach_delegations_locked() that uses it, since callers always set that parameter of nfs_detach_delegations_locked() to NULL. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06NFS: Move cl_state_owners and related fields to the nfs_server structChuck Lever
NFSv4 migration needs to reassociate state owners from the source to the destination nfs_server data structures. To make that easier, move the cl_state_owners field to the nfs_server struct. cl_openowner_id and cl_lockowner_id accompany this move, as they are used in conjunction with cl_state_owners. The cl_lock field in the parent nfs_client continues to protect all three of these fields. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06NFS: Allow walking nfs_client.cl_superblocks list outside client.cChuck Lever
We're about to move some fields from struct nfs_client to struct nfs_server. There is a many-to-one relationship between nfs_servers and nfs_clients. After these fields are moved to the nfs_server struct, to visit all of the data in these fields that is owned by one nfs_client, code will need to visit each nfs_server on the cl_superblocks list for that nfs_client. To serialize changes to the cl_superblocks list during these little expeditions, protect the list with RCU. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: layout roc codeFred Isaman
A layout can request return-on-close. How this interacts with the forgetful model of never sending LAYOUTRETURNS is a bit ambiguous. We forget any layouts marked roc, and wait for them to be completely forgotten before continuing with the close. In addition, to compensate for races with any inflight LAYOUTGETs, and the fact that we do not get any layout stateid back from the server, we set the barrier to the worst case scenario of current_seqid + number of outstanding LAYOUTGETS. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: update nfs4_callback_recallany to handle layoutsAlexandros Batsakis
While here, update the code a bit. Signed-off-by: Alexandros Batsakis <batsakis@netapp.com> Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: add CB_LAYOUTRECALL handlingFred Isaman
This is the heart of the wave 2 submission. Add the code to trigger drain and forget of any afected layouts. In addition, we set a "barrier", below which any LAYOUTGET reply is ignored. This is to compensate for the fact that we do not wait for outstanding LAYOUTGETs to complete as per section 12.5.5.2.1 of RFC 5661. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: CB_LAYOUTRECALL xdr codeFred Isaman
This is the xdr decoding for CB_LAYOUTRECALL. Signed-off-by: Alexandros Batsakis <batsakis@netapp.com> Signed-off-by: Dean Hildebrand <dhildeb@us.ibm.com> Signed-off-by: Marc Eshel <eshel@almaden.ibm.com> Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: change lo refcounting to atomic_tFred Isaman
This will be required to allow us to grab reference outside of i_lock. While we are at it, make put_layout_hdr take the same argument as all the related functions. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: check that partial LAYOUTGET return is ignoredFred Isaman
Either a bad server reply, or our ignoring of multiple array segments in a reply, can cause a reply to not meet our requirements. Ensure that we ignore such replies. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: add layout to client list before sending rpcFred Isaman
Since this list will be used to search for layouts to recall, this is necessary to avoid a race where the recall comes in, sees there is nothing in the client list, and prepares to return NOMATCHING, while the LAYOUTGET gets processed before the recall updates the stateid. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: serialize LAYOUTGET(openstateid)Fred Isaman
We shouldn't send a LAYOUTGET(openstateid) unless all outstanding RPCs using the previous stateid are completed. This requires choosing the stateid to encode earlier, so we can abort if one is not available (we want to use the open stateid, but a LAYOUTGET is already out using it), and adding a count of the number of outstanding rpc calls using layout state (which for now consist solely of LAYOUTGETs). Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: layoutget rpc code cleanupFred Isaman
No functional changes, just some code minor code rearrangement and comments. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: change how lsegs are removed from layout listFred Isaman
This is to prepare the way for sensible io draining. Instead of just removing the lseg from the list, we instead clear the VALID flag (preventing new io from grabbing references to the lseg) and remove the reference holding it in the list. Thus the lseg will be removed once any io in progress completes and any references still held are dropped. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: change layout state seqlock to a spinlockFred Isaman
This prepares for future changes, where the layout state needs to change atomically with several other variables. In particular, it will need to know if lo->segs is empty, as we test that instead of manipulating the NFS_LAYOUT_STATEID_SET bit. Moreover, the layoutstateid is not really a read-mostly structure, as it is written almost as often as it is read. The behavior of pnfs_get_layout_stateid is also slightly changed, so that it no longer changes the stateid. Its name is changed to +pnfs_choose_layoutget_stateid. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: add prefix to struct pnfs_layout_hdr fieldsFred Isaman
Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: add prefix to struct pnfs_layout_segment fieldsFred Isaman
While we are renaming all the fields, change lo->state to lo->plh_flags. Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-06pnfs: remove unnecessary field lgp->statusFred Isaman
Signed-off-by: Fred Isaman <iisaman@netapp.com> Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>