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c1221321b7
linux-kernel-test/fs
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NeilBrown c1221321b7 sched: Allow wait_on_bit_action() functions to support a timeout 
It is currently not possible for various wait_on_bit functions
to implement a timeout.

While the "action" function that is called to do the waiting
could certainly use schedule_timeout(), there is no way to carry
forward the remaining timeout after a false wake-up.
As false-wakeups a clearly possible at least due to possible
hash collisions in bit_waitqueue(), this is a real problem.

The 'action' function is currently passed a pointer to the word
containing the bit being waited on.  No current action functions
use this pointer.  So changing it to something else will be a
little noisy but will have no immediate effect.

This patch changes the 'action' function to take a pointer to
the "struct wait_bit_key", which contains a pointer to the word
containing the bit so nothing is really lost.

It also adds a 'private' field to "struct wait_bit_key", which
is initialized to zero.

An action function can now implement a timeout with something
like

static int timed_out_waiter(struct wait_bit_key *key)
{
	unsigned long waited;
	if (key->private == 0) {
		key->private = jiffies;
		if (key->private == 0)
			key->private -= 1;
	}
	waited = jiffies - key->private;
	if (waited > 10 * HZ)
		return -EAGAIN;
	schedule_timeout(waited - 10 * HZ);
	return 0;
}

If any other need for context in a waiter were found it would be
easy to use ->private for some other purpose, or even extend
"struct wait_bit_key".

My particular need is to support timeouts in nfs_release_page()
to avoid deadlocks with loopback mounted NFS.

While wait_on_bit_timeout() would be a cleaner interface, it
will not meet my need.  I need the timeout to be sensitive to
the state of the connection with the server, which could change.
 So I need to use an 'action' interface.

Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steve French <sfrench@samba.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140707051604.28027.41257.stgit@notabene.brown
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-16 15:10:41 +02:00
..
9p Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
adfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
affs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
afs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
autofs4 autofs4: fix false positive compile error 2014-07-03 09:21:53 -07:00
befs fs/befs: kernel-doc fixes 2014-06-06 16:08:09 -07:00
bfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
btrfs sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
cachefiles fs/cachefiles: replace kerror by pr_err 2014-06-06 16:08:14 -07:00
ceph Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client 2014-06-12 23:06:23 -07:00
cifs sched: Allow wait_on_bit_action() functions to support a timeout 2014-07-16 15:10:41 +02:00
coda coda: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
configfs fs/configfs: use pr_fmt 2014-06-04 16:53:53 -07:00
cramfs Major changes for 3.14 include support for the newly added ZERO_RANGE 2014-04-04 15:39:39 -07:00
debugfs Major changes for 3.14 include support for the newly added ZERO_RANGE 2014-04-04 15:39:39 -07:00
devpts fs/devpts/inode.c: convert printk to pr_foo() 2014-06-06 16:08:14 -07:00
dlm dlm: keep listening connection alive with sctp mode 2014-06-12 10:26:14 -05:00
ecryptfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
efivarfs fs/efivarfs/super.c: use static const for dentry_operations 2014-06-04 16:54:14 -07:00
efs fs/efs: convert printk(KERN_DEBUG to pr_debug 2014-06-04 16:54:21 -07:00
exofs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
exportfs fs/exportfs/expfs.c: kernel-doc warning fixes 2014-06-04 16:54:14 -07:00
ext2 ->splice_write() via ->write_iter() 2014-06-12 00:18:51 -04:00
ext3 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
ext4 ext4: fix potential null pointer dereference in ext4_free_inode 2014-07-12 16:11:42 -04:00
f2fs f2fs: avoid to access NULL pointer in issue_flush_thread 2014-07-09 05:59:55 -07:00
fat Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
freevxfs Major changes for 3.14 include support for the newly added ZERO_RANGE 2014-04-04 15:39:39 -07:00
fscache sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
fuse Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
gfs2 sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
hfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
hfsplus Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
hostfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
hpfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
hppfs
hugetlbfs fs/hugetlbfs/inode.c: remove null test before kfree 2014-06-04 16:54:11 -07:00
isofs Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2014-04-07 17:59:17 -07:00
jbd fs/jbd/revoke.c: replace shift loop by ilog2 2014-05-21 10:26:13 +02:00
jbd2 sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
jffs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
jfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
kernfs Merge branch 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-07-10 11:38:23 -07:00
lockd Merge branch 'for-3.16' of git://linux-nfs.org/~bfields/linux 2014-06-10 11:50:57 -07:00
logfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
minix write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
ncpfs fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul 2014-06-04 16:54:21 -07:00
nfs sched: Allow wait_on_bit_action() functions to support a timeout 2014-07-16 15:10:41 +02:00
nfs_common
nfsd nfsd: Fix bad reserving space for encoding rdattr_error 2014-07-07 14:16:31 -04:00
nilfs2 write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
nls
notify inotify: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
ntfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
ocfs2 ocfs2/dlm: do not purge lockres that is queued for assert master 2014-06-23 16:47:45 -07:00
omfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
openpromfs fs: push sync_filesystem() down to the file system's remount_fs() 2014-03-13 10:14:33 -04:00
proc /proc/stat: convert to single_open_size() 2014-07-03 09:21:54 -07:00
pstore fs/pstore: logging clean-up 2014-06-06 16:08:13 -07:00
qnx4 fs: push sync_filesystem() down to the file system's remount_fs() 2014-03-13 10:14:33 -04:00
qnx6 fs: push sync_filesystem() down to the file system's remount_fs() 2014-03-13 10:14:33 -04:00
quota xfs: fix Q_XQUOTARM ioctl 2014-05-05 17:25:50 +10:00
ramfs ->splice_write() via ->write_iter() 2014-06-12 00:18:51 -04:00
reiserfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
romfs switch simple generic_file_aio_read() users to ->read_iter() 2014-05-06 17:37:55 -04:00
squashfs fs/squashfs/squashfs.h: replace pr_warning by pr_warn 2014-06-04 16:53:52 -07:00
sysfs kernfs: move the last knowledge of sysfs out from kernfs 2014-06-03 08:11:18 -07:00
sysv write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
ubifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
udf udf: switch to ->write_iter() 2014-05-06 17:39:36 -04:00
ufs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
xfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
aio.c aio: fix kernel memory disclosure in io_getevents() introduced in v3.10 2014-06-24 13:46:01 -04:00
anon_inodes.c vfs: Allocate anon_inode_inode in anon_inode_init() 2014-03-27 09:52:54 -07:00
attr.c fs,userns: Change inode_capable to capable_wrt_inode_uidgid 2014-06-10 13:57:22 -07:00
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c
binfmt_elf.c Merge branch 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next 2014-06-05 08:05:29 -07:00
binfmt_em86.c
binfmt_flat.c fs/binfmt_flat.c: make old_reloc() static 2014-06-04 16:54:21 -07:00
binfmt_misc.c binfmt_misc: add missing 'break' statement 2014-04-03 16:21:16 -07:00
binfmt_script.c
binfmt_som.c
block_dev.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
buffer.c sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c
compat.c locks: rename file-private locks to "open file description locks" 2014-04-22 08:23:58 -04:00
coredump.c coredump: fix va_list corruption 2014-04-19 13:23:31 -07:00
dcache.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
dcookies.c
direct-io.c new helper: iov_iter_npages() 2014-05-06 17:32:52 -04:00
drop_caches.c fs: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
eventfd.c
eventpoll.c epoll: fix use-after-free in eventpoll_release_file 2014-06-16 17:21:59 -10:00
exec.c perf: Differentiate exec() and non-exec() comm events 2014-06-06 07:56:22 +02:00
fcntl.c locks: rename file-private locks to "open file description locks" 2014-04-22 08:23:58 -04:00
fhandle.c
file_table.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
file.c fs/file.c: don't open-code kvfree() 2014-05-06 17:31:10 -04:00
filesystems.c sys_sysfs: Add CONFIG_SYSFS_SYSCALL 2014-04-03 16:21:05 -07:00
fs_struct.c
fs-writeback.c sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
inode.c sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
internal.h
ioctl.c
Kconfig
Kconfig.binfmt
libfs.c fs/libfs.c: add generic data flush to fsync 2014-06-04 16:53:55 -07:00
locks.c locks: set fl_owner for leases back to current->files 2014-06-10 12:29:05 -04:00
Makefile block: move ioprio.c from fs/ to block/ 2014-05-19 11:02:18 -06:00
mbcache.c fs/mbcache: replace __builtin_log2() with ilog2() 2014-06-25 22:08:29 -04:00
mount.h reduce m_start() cost... 2014-04-01 23:19:09 -04:00
mpage.c fs/block_dev.c: add bdev_read_page() and bdev_write_page() 2014-06-04 16:54:02 -07:00
namei.c fs,userns: Change inode_capable to capable_wrt_inode_uidgid 2014-06-10 13:57:22 -07:00
namespace.c VFS: Make delayed_free() call free_vfsmnt() 2014-04-01 23:19:18 -04:00
no-block.c
open.c new methods: ->read_iter() and ->write_iter() 2014-05-06 17:36:00 -04:00
pipe.c new helper: copy_page_from_iter() 2014-05-06 17:39:42 -04:00
pnode.c smarter propagate_mnt() 2014-04-01 23:19:08 -04:00
pnode.h smarter propagate_mnt() 2014-04-01 23:19:08 -04:00
posix_acl.c posix_acl: handle NULL ACL in posix_acl_equiv_mode 2014-05-06 13:58:42 -04:00
proc_namespace.c reduce m_start() cost... 2014-04-01 23:19:09 -04:00
read_write.c switch simple generic_file_aio_read() users to ->read_iter() 2014-05-06 17:37:55 -04:00
readdir.c fanotify: create FAN_ACCESS event for readdir 2014-06-04 16:53:52 -07:00
select.c
seq_file.c fs/seq_file: fallback to vmalloc allocation 2014-07-03 09:21:54 -07:00
signalfd.c
splice.c Merge commit '9f12600fe425bc28f0ccba034a77783c09c15af4' into for-linus 2014-06-12 00:28:09 -04:00
stack.c
stat.c
statfs.c
super.c fs/superblock: avoid locking counting inodes and dentries before reclaiming them 2014-06-04 16:54:11 -07:00
sync.c
timerfd.c
utimes.c
xattr.c