Theodore Ts'o 8b0f9e8f78 ext4: avoid unnecessary spinlock in critical POSIX ACL path ... If a filesystem supports POSIX ACL's, the VFS layer expects the filesystem to do POSIX ACL checks on any files not owned by the caller, and it does this for every single pathname component that it looks up. That obviously can be pretty expensive if the filesystem isn't careful about it, especially with locking. That's doubly sad, since the common case tends to be that there are no ACL's associated with the files in question. ext4 already caches the ACL data so that it doesn't have to look it up over and over again, but it does so by taking the inode->i_lock spinlock on every lookup. Which is a noticeable overhead even if it's a private lock, especially on CPU's where the serialization is expensive (eg Intel Netburst aka 'P4'). For the special case of not actually having any ACL's, all that locking is unnecessary. Even if somebody else were to be changing the ACL's on another CPU, we simply don't care - if we've seen a NULL ACL, we might as well use it. So just load the ACL speculatively without any locking, and if it was NULL, just use it. If it's non-NULL (either because we had a cached entry, or because the cache hasn't been filled in at all), it means that we'll need to get the lock and re-load it properly. (This commit was ported from a patch originally authored by Linus for ext3.) Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>		2009-04-27 17:33:23 -04:00
..
9p	Fix a leak in failure exit in 9p ->get_sb()	2009-05-09 10:49:40 -04:00
adfs	Fix adfs GET_FRAG_ID() on big-endian	2009-06-11 21:36:14 -04:00
affs	affs: add ->sync_fs	2009-06-11 21:36:14 -04:00
afs	AFS: Correctly translate auth error aborts and don't failover in such cases	2009-06-16 21:20:14 -07:00
autofs	switch follow_down()	2009-06-11 21:36:01 -04:00
autofs4	switch follow_down()	2009-06-11 21:36:01 -04:00
befs	NLS: update handling of Unicode	2009-06-15 21:44:43 -07:00
bfs	bfs: add ->sync_fs	2009-06-11 21:36:14 -04:00
btrfs	Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block	2009-06-16 11:46:45 -07:00
cachefiles	enforce ->sync_fs is only called for rw superblock	2009-06-11 21:36:06 -04:00
cifs	push BKL down into ->put_super	2009-06-11 21:36:07 -04:00
coda	splice: implement default splice_read method	2009-05-11 14:13:10 +02:00
configfs	configfs: Rework configfs_depend_item() locking and make lockdep happy	2009-04-30 10:48:26 -07:00
cramfs	fs/cramfs: return f_fsid for statfs(2)	2009-04-02 19:05:08 -07:00
debugfs	debugfs: use specified mode to possibly mark files read/write only	2009-06-15 21:30:28 -07:00
devpts	devpts: unregister the file system on error	2009-06-11 08:51:06 -07:00
dlm	dlm: use more NOFS allocation	2009-05-15 11:24:59 -05:00
ecryptfs	push BKL down into ->put_super	2009-06-11 21:36:07 -04:00
efs	fs/efs: return f_fsid for statfs(2)	2009-04-02 19:05:09 -07:00
exofs	[SCSI] Merge branch 'linus'	2009-06-12 10:02:03 -05:00
exportfs
ext2	trivial: ext2: fix a typo in comment in ext2.h	2009-06-12 18:01:44 +02:00
ext3	Push BKL down into ->remount_fs()	2009-06-11 21:36:11 -04:00
ext4	ext4: avoid unnecessary spinlock in critical POSIX ACL path	2009-04-27 17:33:23 -04:00
fat	Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6	2009-06-16 13:06:10 -07:00
freevxfs	push BKL down into ->put_super	2009-06-11 21:36:07 -04:00
fscache	FS-Cache: Fixup renamed filenames in comments in internal.h	2009-05-27 10:20:13 -07:00
fuse	Merge branch 'cuse' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse	2009-06-12 09:31:20 -07:00
gfs2	GFS2: Remove lock_kernel from gfs2_put_super()	2009-06-12 13:40:47 +01:00
hfs	hfs: add ->sync_fs	2009-06-11 21:36:15 -04:00
hfsplus	hfsplus: add ->sync_fs	2009-06-11 21:36:16 -04:00
hostfs	constify dentry_operations: misc filesystems	2009-03-27 14:44:00 -04:00
hpfs	Push BKL down into ->remount_fs()	2009-06-11 21:36:11 -04:00
hppfs	hppfs: hppfs_read_file() may return -ERROR	2009-04-02 19:04:53 -07:00
hugetlbfs	Merge branch 'master' into next	2009-05-22 18:40:59 +10:00
isofs	NLS: update handling of Unicode	2009-06-15 21:44:43 -07:00
jbd	jbd: fix race in buffer processing in commit code	2009-06-09 16:59:03 -07:00
jbd2	jbd2: convert instrumentation from markers to tracepoints	2009-06-17 11:47:48 -04:00
jffs2	jffs2: call jffs2_write_super from jffs2_sync_fs	2009-06-11 21:36:16 -04:00
jfs	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shaggy/jfs-2.6	2009-06-16 12:23:52 -07:00
lockd	lockd: fix list corruption on lockd restart	2009-05-06 17:19:36 -04:00
minix	switch minix to simple_fsync()	2009-06-11 21:36:12 -04:00
ncpfs	NLS: update handling of Unicode	2009-06-15 21:44:43 -07:00
nfs	remove put_cpu_no_resched()	2009-06-16 19:47:48 -07:00
nfs_common
nfsd	switch follow_down()	2009-06-11 21:36:01 -04:00
nilfs2	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2	2009-06-15 09:13:49 -07:00
nls	NLS: update handling of Unicode	2009-06-15 21:44:43 -07:00
notify	fsnotify: allow groups to set freeing_mark to null	2009-06-11 14:57:55 -04:00
ntfs	ntfs: use is_power_of_2() function for clarity.	2009-06-16 19:47:48 -07:00
ocfs2	Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2	2009-06-16 12:11:57 -07:00
omfs	switch omfs to simple_fsync()	2009-06-11 21:36:13 -04:00
openpromfs
partitions	Merge branch 'for-2.6.31' of git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6	2009-06-12 09:29:42 -07:00
proc	oom: move oom_adj value from task_struct to mm_struct	2009-06-16 19:47:43 -07:00
qnx4	fs/qnx4: sanitize includes	2009-06-11 21:36:12 -04:00
quota	quota: cleanup dquota sync functions (version 4)	2009-06-11 21:36:04 -04:00
ramfs	ramfs: ignore unknown mount options	2009-06-14 17:58:25 -07:00
reiserfs	Push BKL down into ->remount_fs()	2009-06-11 21:36:11 -04:00
romfs	ROMFS: romfs_dev_read() error ignored	2009-05-09 10:49:41 -04:00
smbfs	push BKL down into ->put_super	2009-06-11 21:36:07 -04:00
squashfs	push BKL down into ->put_super	2009-06-11 21:36:07 -04:00
sysfs	Sysfs: fix possible memleak in sysfs_follow_link	2009-06-15 21:30:23 -07:00
sysv	sysv: add ->sync_fs	2009-06-11 21:36:16 -04:00
ubifs	ubifs: register backing_dev_info	2009-06-16 08:21:04 +02:00
udf	switch udf to simple_fsync()	2009-06-11 21:36:13 -04:00
ufs	ufs: add ->sync_fs	2009-06-11 21:36:16 -04:00
xfs	Merge branch 'master' of git://oss.sgi.com/xfs/xfs into for-linus	2009-06-12 21:28:59 -05:00
aio.c	aio: lookup_ioctx can return the wrong value when looking up a bogus context	2009-03-19 15:57:18 -07:00
anon_inodes.c	constify dentry_operations: rest	2009-03-27 14:44:03 -04:00
attr.c	vfs: Use lowercase names of quota functions	2009-03-26 02:18:35 +01:00
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c	ptrace: s/parent/real_parent/ in binfmt_elf_fdpic.c	2009-05-02 15:36:10 -07:00
binfmt_elf.c	Trim includes in binfmt_elf	2009-03-31 23:00:27 -04:00
binfmt_em86.c
binfmt_flat.c	flat: fix data sections alignment	2009-05-29 08:40:02 -07:00
binfmt_misc.c
binfmt_script.c
binfmt_som.c	Don't crap into descriptor table in binfmt_som	2009-03-31 23:00:28 -04:00
bio-integrity.c	block: add private bio_set for bio integrity allocations	2009-03-24 12:35:17 +01:00
bio.c	block: remove some includings of blktrace_api.h	2009-06-16 11:19:36 +02:00
block_dev.c	vfs: Rename fsync_super() to sync_filesystem() (version 4)	2009-06-11 21:36:04 -04:00
buffer.c	Merge branch 'for-2.6.31' of git://git.kernel.dk/linux-2.6-block	2009-06-11 11:10:35 -07:00
char_dev.c	fs: Remove i_cindex from struct inode	2009-06-11 21:36:09 -04:00
compat_binfmt_elf.c
compat_ioctl.c	trivial: fix typo compatiable/compatiability has extra 'a'.	2009-06-12 18:01:46 +02:00
compat.c	trivial: fix comment typo in fs/compat.c	2009-06-12 18:01:44 +02:00
dcache.c	dcache: extrace and use d_unlinked()	2009-06-11 21:36:06 -04:00
dcookies.c	[CVE-2009-0029] System call wrapper special cases	2009-01-14 14:15:18 +01:00
direct-io.c	block: Do away with the notion of hardsect_size	2009-05-22 23:22:54 +02:00
drop_caches.c	mm: remove __invalidate_mapping_pages variant	2009-06-16 19:47:43 -07:00
eventfd.c	eventfd: export eventfd_signal and eventfd_fget for lguest	2009-06-12 22:27:09 +09:30
eventpoll.c	epoll: fix size check in epoll_create()	2009-05-12 14:11:35 -07:00
exec.c	Merge branch 'perfcounters-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-06-11 14:01:07 -07:00
fcntl.c	send_sigio_to_task: sanitize the usage of fown->signum	2009-06-16 15:36:17 -07:00
fifo.c
file_table.c	fs: move mark_files_ro into file_table.c	2009-06-11 21:36:02 -04:00
file.c
filesystems.c	fs: Mark get_filesystem_list() as __init function.	2009-04-20 23:02:52 -04:00
fs_struct.c	Get rid of indirect include of fs_struct.h	2009-03-31 23:00:27 -04:00
fs-writeback.c	writeback: skip new or to-be-freed inodes	2009-06-16 19:47:45 -07:00
generic_acl.c	New helper - current_umask()	2009-03-31 23:00:26 -04:00
inode.c	trivial: fs/inode: Fix typo in file_update_time nanodoc	2009-06-12 18:01:45 +02:00
internal.h	Trim a bit of crap from fs.h	2009-06-11 21:36:07 -04:00
ioctl.c	fiemap: fix problem with setting FIEMAP_EXTENT_LAST	2009-05-06 16:36:09 -07:00
ioprio.c	[CVE-2009-0029] System call wrappers part 28	2009-01-14 14:15:30 +01:00
Kconfig	CONFIG_FILE_LOCKING should not depend on CONFIG_BLOCK	2009-06-16 19:47:52 -07:00
Kconfig.binfmt	CORE_DUMP_DEFAULT_ELF_HEADERS depends on ELF_CORE	2009-01-09 16:54:41 -08:00
libfs.c	New helper - simple_fsync()	2009-06-11 21:36:11 -04:00
locks.c	[CVE-2009-0029] System call wrappers part 16	2009-01-14 14:15:25 +01:00
Makefile	nilfs2: update makefile and Kconfig	2009-04-07 08:31:16 -07:00
mbcache.c
mpage.c	ext4: Properly initialize the buffer_head state	2009-05-13 15:13:42 -04:00
namei.c	switch lookup_mnt()	2009-06-11 21:36:01 -04:00
namespace.c	Push BKL down into do_remount_sb()	2009-06-11 21:36:08 -04:00
nfsctl.c	[CVE-2009-0029] System call wrappers part 27	2009-01-14 14:15:29 +01:00
no-block.c
open.c	fs: introduce mnt_clone_write	2009-06-11 21:36:02 -04:00
pipe.c	splice: implement default splice_read method	2009-05-11 14:13:10 +02:00
pnode.c
pnode.h
posix_acl.c
read_write.c	splice: implement default splice_read method	2009-05-11 14:13:10 +02:00
read_write.h
readdir.c	[CVE-2009-0029] System call wrappers part 32	2009-01-14 14:15:31 +01:00
select.c	poll: avoid extra wakeups in select/poll	2009-06-16 19:47:48 -07:00
seq_file.c	cpumask: fix seq_bitmap_*() functions.	2009-03-30 22:05:11 +10:30
signalfd.c	[CVE-2009-0029] System call wrappers part 31	2009-01-14 14:15:31 +01:00
splice.c	splice: fix kmaps in default_file_splice_write()	2009-05-19 11:37:46 +02:00
stack.c
stat.c	kill vfs_stat_fd / vfs_lstat_fd	2009-04-20 23:02:52 -04:00
super.c	Push BKL down into ->remount_fs()	2009-06-11 21:36:11 -04:00
sync.c	remove the call to ->write_super in __sync_filesystem	2009-06-11 21:36:17 -04:00
timerfd.c	timerfd: add flags check	2009-02-18 15:37:53 -08:00
utimes.c	[CVE-2009-0029] System call wrappers part 30	2009-01-14 14:15:30 +01:00
xattr_acl.c
xattr.c	fs: introduce mnt_clone_write	2009-06-11 21:36:02 -04:00