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f03c65993b
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Al Viro f03c65993b sanitize vfsmount refcounting changes 
Instead of splitting refcount between (per-cpu) mnt_count
and (SMP-only) mnt_longrefs, make all references contribute
to mnt_count again and keep track of how many are longterm
ones.

Accounting rules for longterm count:
	* 1 for each fs_struct.root.mnt
	* 1 for each fs_struct.pwd.mnt
	* 1 for having non-NULL ->mnt_ns
	* decrement to 0 happens only under vfsmount lock exclusive

That allows nice common case for mntput() - since we can't drop the
final reference until after mnt_longterm has reached 0 due to the rules
above, mntput() can grab vfsmount lock shared and check mnt_longterm.
If it turns out to be non-zero (which is the common case), we know
that this is not the final mntput() and can just blindly decrement
percpu mnt_count.  Otherwise we grab vfsmount lock exclusive and
do usual decrement-and-check of percpu mnt_count.

For fs_struct.c we have mnt_make_longterm() and mnt_make_shortterm();
namespace.c uses the latter in places where we don't already hold
vfsmount lock exclusive and opencodes a few remaining spots where
we need to manipulate mnt_longterm.

Note that we mostly revert the code outside of fs/namespace.c back
to what we used to have; in particular, normal code doesn't need
to care about two kinds of references, etc.  And we get to keep
the optimization Nick's variant had bought us...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-16 13:47:07 -05:00
..
accessibility
acpi Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2011-01-14 09:29:05 -08:00
amba
ata Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
atm Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
auxdisplay
base thp: transparent hugepage sysfs meminfo 2011-01-13 17:32:46 -08:00
block Merge branch 'for-2.6.38/drivers' of git://git.kernel.dk/linux-2.6-block 2011-01-13 10:50:24 -08:00
bluetooth
cdrom Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block 2011-01-13 10:45:01 -08:00
char Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6 2011-01-13 20:15:35 -08:00
clk
clocksource clocksource: sh_cmt: Remove nested spinlock fix 2010-12-17 19:38:33 +09:00
connector connector: Use this_cpu operations 2010-12-17 15:18:05 +01:00
cpufreq perf: Clean up power events by introducing new, more generic ones 2011-01-04 08:16:54 +01:00
cpuidle Merge branch 'cpuidle-perf-events' into idle-test 2011-01-12 18:06:19 -05:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2011-01-13 10:25:58 -08:00
dca dca: remove unneeded NULL check 2011-01-13 08:03:09 -08:00
dio
dma Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
edac Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
eisa
firewire firewire: ohci: fix compilation on arches without PAGE_KERNEL_RO 2011-01-13 15:48:29 +01:00
firmware
gpio Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-2.6 2011-01-14 09:08:00 -08:00
gpu Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6 2011-01-13 20:15:35 -08:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2011-01-13 09:58:38 -08:00
hwmon hwmon: (dme1737) Minor cleanups 2011-01-12 21:55:13 +01:00
i2c i2c: Convert SCx200 driver from using raw PCI to platform device 2011-01-14 12:38:15 +01:00
ide
idle Merge branch 'cpuidle-perf-events' into idle-test 2011-01-12 18:06:19 -05:00
ieee802154
infiniband Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
input Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
isdn Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
leds leds: add output inversion option to backlight trigger 2011-01-13 08:03:06 -08:00
lguest
macintosh Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
mca
md Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm 2011-01-13 17:30:47 -08:00
media Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2011-01-14 09:29:05 -08:00
memstick memstick: factor out transfer initiating functionality in mspro_block.c 2011-01-13 08:03:22 -08:00
message Merge branch 'master' into for-next 2010-12-22 18:57:02 +01:00
mfd mfd: ab8500-core chip version cut 2.0 support 2011-01-14 12:38:18 +01:00
misc misc: Make AB8500_PWM driver depend on U8500 due to PWM breakage 2011-01-14 12:38:12 +01:00
mmc Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
mtd sanitize vfsmount refcounting changes 2011-01-16 13:47:07 -05:00
net Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2011-01-14 09:29:05 -08:00
nfc NFC: Driver for NXP Semiconductors PN544 NFC chip. 2011-01-13 08:03:19 -08:00
nubus
of Merge remote branch 'gcl/next' into next 2011-01-11 15:10:08 +11:00
oprofile
parisc
parport
pci Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2011-01-14 09:29:05 -08:00
pcmcia Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
platform Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6 2011-01-13 20:15:35 -08:00
pnp Merge branch 'pnp' into release 2011-01-12 04:59:44 -05:00
power Merge git://git.infradead.org/battery-2.6 2011-01-14 09:25:59 -08:00
pps pps: add parallel port PPS signal generator 2011-01-13 08:03:21 -08:00
ps3
rapidio rapidio: add new idt sRIO switches 2011-01-13 08:03:18 -08:00
regulator regulator: Support MAX8998/LP3974 DVS-GPIO 2011-01-14 12:38:16 +01:00
rtc mfd: Support LP3974 RTC 2011-01-14 12:38:16 +01:00
s390 Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6 2011-01-14 08:47:26 -08:00
sbus sparc: explicitly cast negative phandle checks to s32 2011-01-03 20:02:06 -07:00
scsi Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2011-01-14 09:29:05 -08:00
serial atmel_serial: fix RTS high after initialization in RS485 mode 2011-01-13 17:32:31 -08:00
sfi SFI: use ioremap_cache() instead of ioremap() 2011-01-11 23:27:25 -05:00
sh headers: kobject.h redux 2011-01-10 08:51:44 -08:00
sn
spi Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
ssb ssb: Use pci_is_pcie() 2010-12-22 15:43:26 -05:00
staging Add a dentry op to allow processes to be held during pathwalk transit 2011-01-15 20:07:31 -05:00
tc
telephony Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-01-13 10:05:56 -08:00
thermal Merge branch 'misc' into release 2011-01-12 05:14:15 -05:00
tty Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 2011-01-07 14:39:20 -08:00
uio
usb Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block 2011-01-13 10:45:01 -08:00
uwb
vhost
video Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/fbdev-2.6 2011-01-13 10:39:14 -08:00
virtio
vlynq
w1 w1: DS2423 counter driver and documentation 2011-01-13 08:03:22 -08:00
watchdog watchdog: Add MCF548x watchdog driver. 2011-01-12 13:51:35 +00:00
xen Merge branch 'stable/gntdev' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen 2011-01-13 18:46:48 -08:00
zorro
Kconfig NFC: Driver for NXP Semiconductors PN544 NFC chip. 2011-01-13 08:03:19 -08:00
Makefile NFC: Driver for NXP Semiconductors PN544 NFC chip. 2011-01-13 08:03:19 -08:00