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OpenCloudOS-Kernel
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NeilBrown e04bbf6b1b NFS: Avoid quadratic search when freeing delegations. 
There are three places that walk all delegation for an nfs_client and
restart whenever they find something interesting - potentially
resulting in a quadratic search:  If there are 10,000 uninteresting
delegations followed by 10,000 interesting one, then the code
skips over 100,000,000 delegations, which can take a noticeable amount
of time.

Of these nfs_delegation_reap_unclaimed() and
nfs_reap_expired_delegations() are only called during unusual events:
a server reboots or reports expired delegations, probably due to a
network partition.  Optimizing these is not particularly important.

The third, nfs_client_return_marked_delegations(), is called
periodically via nfs_expire_unreferenced_delegations().  It could
cause periodic problems on a busy server.

New delegations are added to the end of the list, so if there are
10,000 open files with delegations, and 10,000 more recently opened files
that received delegations but are now closed, then
nfs_client_return_marked_delegations() can take seconds to skip over
the 10,000 open files 10,000 times.  That is a waste of time.

The avoid this waste a place-holder (an inode) is kept when locks are
dropped, so that the place can usually be found again after taking
rcu_readlock().  This place holder ensure that we find the right
starting point in the list of nfs_servers, and makes is probable that
we find the right starting point in the list of delegations.
We might need to occasionally restart at the head of that list.

It might be possible that the place_holder inode could lose its
delegation separately, and then get a new one using the same (freed
and then reallocated) 'struct nfs_delegation'.  Were this to happen,
the new delegation would be at the end of the list and we would miss
returning some other delegations.  This would have the effect of
unnecessarily delaying the return of some unused delegations until the
next time this function is called - typically 90 seconds later.  As
this is not a correctness issue and is vanishingly unlikely to happen,
it does not seem worth addressing.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
 		2018-05-31 15:02:14 -04:00
..
9p fscache development 2018-04-07 09:08:24 -07:00
adfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
affs affs_lookup: switch to d_splice_alias() 2018-05-21 14:29:12 -04:00
afs afs: Fix the non-encryption of calls 2018-05-14 15:15:19 +01:00
autofs4 autofs: mount point create should honour passed in mode 2018-04-20 17:18:35 -07:00
befs befs_lookup(): use d_splice_alias() 2018-05-21 14:30:07 -04:00
bfs
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btrfs for-4.17-rc6-tag 2018-05-24 11:47:43 -07:00
cachefiles cachefiles: vfs_mkdir() might succeed leaving dentry negative unhashed 2018-05-21 14:30:10 -04:00
ceph ceph: fix iov_iter issues in ceph_direct_read_write() 2018-05-10 10:15:12 +02:00
cifs Merge candidates for 4.17-rc 2018-05-24 14:12:05 -07:00
coda vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
configfs
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cramfs cramfs: Fix IS_ENABLED typo 2018-05-21 14:30:08 -04:00
crypto fscrypt: fix build with pre-4.6 gcc versions 2018-02-01 10:51:18 -05:00
debugfs debugfs_lookup(): switch to lookup_one_len_unlocked() 2018-03-29 15:07:47 -04:00
devpts devpts: comment devpts_mntget() 2018-03-14 13:31:23 +01:00
dlm net: make getname() functions return length rather than use int* parameter 2018-02-12 14:15:04 -05:00
ecryptfs Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-05-21 11:54:57 -07:00
efivarfs efivarfs: Limit the rate for non-root to read files 2018-02-22 10:21:02 -08:00
efs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
exofs iversion.h related cleanup for v4.16 2018-02-07 14:25:22 -08:00
exportfs ovl: do not try to reconnect a disconnected origin dentry 2018-04-12 12:04:49 +02:00
ext2 Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-05-21 11:54:57 -07:00
ext4 Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-05-21 11:54:57 -07:00
f2fs do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
fat iversion: Rename make inode_cmp_iversion{+raw} to inode_eq_iversion{+raw} 2018-02-01 08:15:25 -05:00
freevxfs vxfs: Define usercopy region in vxfs_inode slab cache 2018-01-15 12:07:57 -08:00
fscache fscache: use appropriate radix tree accessors 2018-04-11 10:28:39 -07:00
fuse fuse: define the filesystem as untrusted 2018-03-23 06:31:37 -04:00
gfs2 GFS2: Minor improvements to comments and documentation 2018-04-12 10:07:51 -07:00
hfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
hfsplus hfsplus: stop workqueue when fill_super() failed 2018-05-18 17:17:12 -07:00
hostfs hostfs: rename do_rmdir() to hostfs_do_rmdir() 2018-04-02 20:15:53 +02:00
hpfs hpfs: don't bother with the i_version counter or f_version 2017-12-10 12:58:18 -08:00
hugetlbfs hugetlbfs: fix bug in pgoff overflow checking 2018-04-05 21:36:21 -07:00
isofs isofs: fix potential memory leak in mount option parsing 2018-04-16 09:47:41 +02:00
jbd2 ext4: set h_journal if there is a failure starting a reserved handle 2018-04-18 11:49:31 -04:00
jffs2 do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
jfs do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
kernfs kernfs: deal with kernfs_fill_super() failures 2018-05-21 14:30:08 -04:00
lockd net: Drop pernet_operations::async 2018-03-27 13:18:09 -04:00
minix treewide: simplify Kconfig dependencies for removed archs 2018-03-26 15:55:57 +02:00
nfs NFS: Avoid quadratic search when freeing delegations. 2018-05-31 15:02:14 -04:00
nfs_common net: Drop pernet_operations::async 2018-03-27 13:18:09 -04:00
nfsd nfsd: vfs_mkdir() might succeed leaving dentry negative unhashed 2018-05-21 14:30:10 -04:00
nilfs2 do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
nls
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notify fsnotify: fix ignore mask logic in send_to_group() 2018-04-13 15:52:49 +02:00
ntfs ntfs: fix bogus __mark_inode_dirty(I_DIRTY_SYNC | I_DIRTY_DATASYNC) call 2018-03-28 01:39:02 -04:00
ocfs2 ocfs2: revert "ocfs2/o2hb: check len for bio_add_page() to avoid getting incorrect bio" 2018-05-25 18:12:10 -07:00
omfs
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openpromfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
orangefs do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
overlayfs ovl: add support for "xino" mount and config options 2018-04-12 12:04:50 +02:00
proc Merge branch 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-21 11:23:26 -07:00
pstore pstore: fix crypto dependencies without compression 2018-04-06 15:45:33 -07:00
qnx4 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
qnx6 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
quota fs: quota: Replace GFP_ATOMIC with GFP_KERNEL in dquot_init 2018-04-09 17:48:54 +02:00
ramfs
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reiserfs do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
romfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
squashfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
sysfs unfuck sysfs_mount() 2018-05-21 14:30:09 -04:00
sysv Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
tracefs
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ubifs This pull request contains updates for both UBI and UBIFS: 2018-04-11 16:39:34 -07:00
udf Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-05-21 11:54:57 -07:00
ufs do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
xfs xfs: cap the length of deduplication requests 2018-05-02 09:21:33 -07:00
Kconfig libnvdimm for 4.16 2018-02-06 10:41:33 -08:00
Kconfig.binfmt treewide: simplify Kconfig dependencies for removed archs 2018-03-26 15:55:57 +02:00
Makefile split d_path() and friends into a separate file 2018-03-29 15:07:46 -04:00
aio.c aio: fix io_destroy(2) vs. lookup_ioctx() race 2018-05-21 14:30:11 -04:00
anon_inodes.c
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attr.c
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bad_inode.c
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binfmt_aout.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_elf.c fs, elf: don't complain MAP_FIXED_NOREPLACE unless -EEXIST error 2018-04-20 17:18:36 -07:00
binfmt_elf_fdpic.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_em86.c
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binfmt_flat.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_misc.c fs: add ksys_close() wrapper; remove in-kernel calls to sys_close() 2018-04-02 20:16:00 +02:00
binfmt_script.c
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block_dev.c libnvdimm for 4.17 2018-04-10 10:25:57 -07:00
buffer.c Merge branch 'work.thaw' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-12 12:28:32 -07:00
char_dev.c block, char_dev: Use correct format specifier for unsigned ints 2018-03-15 17:59:24 +01:00
compat.c
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compat_binfmt_elf.c
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compat_ioctl.c fs: compat_ioctl: add new DVB demux ioctls 2017-12-28 11:17:29 -05:00
coredump.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 11:54:55 -08:00
d_path.c split d_path() and friends into a separate file 2018-03-29 15:07:46 -04:00
dax.c page cache: use xa_lock 2018-04-11 10:28:39 -07:00
dcache.c do d_instantiate/unlock_new_inode combinations safely 2018-05-11 15:36:37 -04:00
dcookies.c fs: add do_lookup_dcookie() helper; remove in-kernel call to syscall 2018-04-02 20:15:39 +02:00
direct-io.c Merge branch 'akpm' (patches from Andrew) 2018-04-06 14:19:26 -07:00
drop_caches.c
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eventfd.c fs: add do_eventfd() helper; remove internal call to sys_eventfd() 2018-04-02 20:15:39 +02:00
eventpoll.c fs: add do_epoll_*() helpers; remove internal calls to sys_epoll_*() 2018-04-02 20:15:37 +02:00
exec.c exec: pin stack limit during exec 2018-04-11 10:28:37 -07:00
fcntl.c fs: add do_compat_fcntl64() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:42 +02:00
fhandle.c vfs: Copy struct mount.mnt_id to userspace using put_user() 2018-01-15 12:07:51 -08:00
file.c fs: add ksys_close() wrapper; remove in-kernel calls to sys_close() 2018-04-02 20:16:00 +02:00
file_table.c vfs: remove unused hardirq.h 2017-12-07 14:23:30 -05:00
filesystems.c
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fs-writeback.c bdi: Fix oops in wb_workfn() 2018-05-03 16:11:37 -06:00
fs_pin.c
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fs_struct.c
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inode.c page cache: use xa_lock 2018-04-11 10:28:39 -07:00
internal.h Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-06 11:07:08 -07:00
ioctl.c fs: add ksys_ioctl() helper; remove in-kernel calls to sys_ioctl() 2018-04-02 20:16:03 +02:00
iomap.c iomap: warn on zero-length mappings 2018-01-29 07:27:24 -08:00
libfs.c fs, dax: prepare for dax-specific address_space_operations 2018-03-30 11:34:55 -07:00
locks.c treewide: Align function definition open/close braces 2018-03-26 11:13:09 +02:00
mbcache.c mbcache: make sure c_entry_count is not decremented past zero 2018-01-09 23:57:52 -05:00
mount.h
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mpage.c
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namei.c Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-09 12:48:05 -07:00
namespace.c vfs: Undo an overly zealous MS_RDONLY -> SB_RDONLY conversion 2018-04-20 09:59:33 -07:00
no-block.c
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nsfs.c net: Export open_related_ns() 2018-02-15 15:34:42 -05:00
open.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-06 11:07:08 -07:00
pipe.c fs: add do_pipe2() helper; remove internal call to sys_pipe2() 2018-04-02 20:15:35 +02:00
pnode.c
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pnode.h
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posix_acl.c posix_acl: convert posix_acl.a_refcount from atomic_t to refcount_t 2018-01-02 19:27:28 -08:00
proc_namespace.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
read_write.c fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscalls 2018-04-02 20:16:09 +02:00
readdir.c fs: add ksys_getdents64() helper; remove in-kernel calls to sys_getdents64() 2018-04-02 20:16:02 +02:00
select.c fs: add do_compat_select() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:42 +02:00
seq_file.c proc: fix smaps and meminfo alignment 2018-05-25 18:12:11 -07:00
signalfd.c fs: add do_compat_signalfd4() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:43 +02:00
splice.c fs: add do_vmsplice() helper; remove in-kernel call to syscall 2018-04-02 20:15:40 +02:00
stack.c
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stat.c fs: add do_readlinkat() helper; remove internal call to sys_readlinkat() 2018-04-02 20:15:34 +02:00
statfs.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
super.c fs: don't scan the inode cache before SB_BORN is set 2018-05-11 15:37:57 -04:00
sync.c Changes for this release: 2018-04-04 12:44:02 -07:00
timerfd.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
userfaultfd.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
utimes.c fs: add do_compat_futimesat() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:44 +02:00
xattr.c
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