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David Howells 1bccf513ac FS-Cache: Fix lock misorder in fscache_write_op() 
FS-Cache has two structs internally for keeping track of the internal state of
a cached file: the fscache_cookie struct, which represents the netfs's state,
and fscache_object struct, which represents the cache's state.  Each has a
pointer that points to the other (when both are in existence), and each has a
spinlock for pointer maintenance.

Since netfs operations approach these structures from the cookie side, they get
the cookie lock first, then the object lock.  Cache operations, on the other
hand, approach from the object side, and get the object lock first.  It is not
then permitted for a cache operation to get the cookie lock whilst it is
holding the object lock lest deadlock occur; instead, it must do one of two
things:

 (1) increment the cookie usage counter, drop the object lock and then get both
     locks in order, or

 (2) simply hold the object lock as certain parts of the cookie may not be
     altered whilst the object lock is held.

It is also not permitted to follow either pointer without holding the lock at
the end you start with.  To break the pointers between the cookie and the
object, both locks must be held.

fscache_write_op(), however, violates the locking rules: It attempts to get the
cookie lock without (a) checking that the cookie pointer is a valid pointer,
and (b) holding the object lock to protect the cookie pointer whilst it follows
it.  This is so that it can access the pending page store tree without
interference from __fscache_write_page().

This is fixed by splitting the cookie lock, such that the page store tracking
tree is protected by its own lock, and checking that the cookie pointer is
non-NULL before we attempt to follow it whilst holding the object lock.

The new lock is subordinate to both the cookie lock and the object lock, and so
should be taken after those.

Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 18:11:25 +00:00
..
ABI Documentation: ABI: /sys/devices/system/cpu/cpu#/node 2009-10-30 14:59:53 -07:00
accounting Documentation/: fix warnings from -Wmissing-prototypes in HOSTCFLAGS 2009-09-23 07:39:28 -07:00
acpi
aoe
arm ARM: 5738/1: Correct TCM documentation 2009-10-01 16:26:16 +01:00
auxdisplay includecheck fix: Documentation, cfag12864b-example.c 2009-09-24 07:20:57 -07:00
blackfin Blackfin arch: Add document about bfin-gpio 2009-01-07 23:14:38 +08:00
block Trivial typo fixes in Documentation/block/data-integrity.txt. 2009-07-01 10:56:25 +02:00
blockdev mflash: initial support 2009-04-07 08:12:38 +02:00
cdrom debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
cgroups cgroups: update documentation of cgroups tasks and procs files 2009-10-08 07:36:39 -07:00
connector connector: Provide the sender's credentials to the callback 2009-10-02 10:54:01 -07:00
console
cpu-freq [CPUFREQ] update Doc for cpuinfo_cur_freq and scaling_cur_freq 2009-09-01 12:45:09 -04:00
cpuidle
cris
crypto async_tx: add support for asynchronous RAID6 recovery operations 2009-08-29 19:09:27 -07:00
development-process docs: Encourage better changelogs in the development process document 2009-06-04 10:32:49 -06:00
device-mapper dm raid1: add userspace log 2009-06-22 10:12:35 +01:00
DocBook Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-09-22 07:51:45 -07:00
driver-model driver model: fix show/store prototypes in doc. 2009-07-12 13:02:10 -07:00
dvb V4L/DVB (12902): Documentation: synchronize documentation for Technisat cards 2009-09-19 00:14:32 -03:00
early-userspace
fault-injection debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
fb matroxfb: make CONFIG_FB_MATROX_MULTIHEAD=y mandatory 2009-09-23 07:39:56 -07:00
filesystems FS-Cache: Fix lock misorder in fscache_write_op() 2009-11-19 18:11:25 +00:00
firmware_class driver core: fix documentation of request_firmware_nowait 2009-06-15 21:30:24 -07:00
frv
hwmon hwmon: enhance the sysfs API for power meters 2009-10-29 07:39:30 -07:00
i2c i2c-piix4: Modify code name SB900 to Hudson-2 2009-11-07 13:10:46 +01:00
i2o
ia64 Documentation/: fix warnings from -Wmissing-prototypes in HOSTCFLAGS 2009-09-23 07:39:28 -07:00
ide ide: preserve Host Protected Area by default (v2) 2009-06-07 13:52:52 +02:00
infiniband IB: Fix typo in udev rule documentation 2009-10-07 15:35:55 -07:00
input Input: add new driver for Sentelic Finger Sensing Pad 2009-08-19 21:46:09 -07:00
ioctl drivers/char/uv_mmtimer.c: add memory mapped RTC driver for UV 2009-09-24 07:21:03 -07:00
isdn Documentation: expand isdn/INTERFACE.CAPI document 2009-10-06 22:20:51 -07:00
ja_JP block: rename CONFIG_LBD to CONFIG_LBDAF 2009-06-19 08:08:50 +02:00
kbuild kbuild: introduce ld-option 2009-09-20 12:27:42 +02:00
kdump trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
ko_KR
kvm KVM: Document KVM_CAP_IRQCHIP 2009-09-10 10:46:55 +03:00
laptops Merge branch 'thinkpad-2.6.32-part2' into release 2009-09-26 01:08:55 -04:00
lguest virtio: let header files include virtio_ids.h 2009-10-22 16:39:28 +10:30
m68k
make
mips ide: remove unused CONFIG_BLK_DEV_IDE_AU1XXX_SEQTS_PER_RQ 2009-01-14 19:19:03 +01:00
misc-devices max6875: Discard obsolete detect method 2009-10-04 22:53:41 +02:00
mn10300 trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
mtd trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
namespaces
netlabel
networking pktgen: Fix multiqueue handling 2009-10-04 21:08:54 -07:00
parisc
PCI PCI: document PCIe fundamental reset interfaces 2009-09-09 13:29:38 -07:00
pcmcia Documentation/: fix warnings from -Wmissing-prototypes in HOSTCFLAGS 2009-09-23 07:39:28 -07:00
power Merge git://git.infradead.org/battery-2.6 2009-09-23 10:11:08 -07:00
powerpc Merge git://git.infradead.org/mtd-2.6 2009-09-23 10:07:49 -07:00
pps LinuxPPS: core support 2009-06-18 13:04:04 -07:00
prctl
RCU rcu: Remove CONFIG_PREEMPT_RCU 2009-08-23 10:32:40 +02:00
s390 [S390] s390dbf: Add description for usage of "%s" in sprintf events 2009-09-11 10:29:53 +02:00
scheduler sched: Documentation/sched-rt-group: Fix style issues & bump version 2009-06-21 13:12:46 +02:00
scsi [SCSI] hptiop: Add RR44xx adapter support 2009-10-02 09:45:22 -05:00
serial
sh
sound ALSA: dummy - Fix descriptions of pcm_substreams parameter 2009-11-02 14:11:55 +01:00
sparc
spi spi: fix spelling of `automatically' in documentation 2009-09-23 07:39:44 -07:00
sysctl Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 2009-09-24 07:53:22 -07:00
telephony
thermal thermal: sysfs-api.txt - document passive attribute for thermal zones 2009-11-05 18:11:18 -05:00
timers trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
trace tracing: Fix comment typo and documentation example 2009-10-24 11:07:50 +02:00
uml
usb USB: Fix sysfs paths in documentation 2009-09-23 06:46:41 -07:00
video4linux Documentation/: fix warnings from -Wmissing-prototypes in HOSTCFLAGS 2009-09-23 07:39:28 -07:00
vm Merge branch 'hostprogs-wmissing-prototypes' of git://git.kernel.org/pub/scm/linux/kernel/git/josh/linux-misc 2009-11-17 09:14:49 -08:00
w1 ds2482: Discard obsolete detect method 2009-10-04 22:53:41 +02:00
watchdog Documentation/: fix warnings from -Wmissing-prototypes in HOSTCFLAGS 2009-09-23 07:39:28 -07:00
wimax i2400m: documentation and instructions for usage 2009-01-07 10:00:18 -08:00
x86 USB: ehci-dbgp,documentation: Documentation updates for ehci-dbgp 2009-09-23 06:46:39 -07:00
zh_CN
00-INDEX Bluetooth: Add documentation for Marvell Bluetooth driver 2009-08-22 14:25:32 -07:00
applying-patches.txt
atomic_ops.txt Documentation/atomic_ops.txt: fix sample code 2009-06-16 19:47:52 -07:00
bad_memory.txt
basic_profiling.txt
binfmt_misc.txt
braille-console.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
bt8xxgpio.txt
btmrvl.txt Bluetooth: Add documentation for Marvell Bluetooth driver 2009-08-22 14:25:32 -07:00
BUG-HUNTING
c2port.txt
cachetlb.txt
Changes Documentation/Changes: perl is needed to build the kernel 2009-06-18 13:03:46 -07:00
CodingStyle trivial: fix typo milisecond/millisecond for documentation and source comments. 2009-06-12 18:01:46 +02:00
cpu-hotplug.txt
cpu-load.txt
cputopology.txt Documentation: ABI: /sys/devices/system/cpu/cpu#/ topology files 2009-10-30 14:59:52 -07:00
credentials.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt ieee1394: update URLs in debugging-via-ohci1394.txt 2009-10-03 09:28:11 +02:00
dell_rbu.txt trivial: Documentation/dell_rbu.txt: fix typos 2009-06-12 18:01:50 +02:00
devices.txt lanana: assign a device name and numbering for MAX3100 2009-04-07 08:44:05 -07:00
DMA-API.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
DMA-attributes.txt
DMA-ISA-LPC.txt
DMA-mapping.txt dma-mapping: update the old macro DMA_nBIT_MASK related documentations 2009-04-07 08:31:12 -07:00
dmaengine.txt async_tx, dmaengine: document channel allocation and api rework 2009-01-05 18:10:19 -07:00
dontdiff sparc: Kill PROM console driver. 2009-09-15 17:04:38 -07:00
dynamic-debug-howto.txt Dynamic debug: allow simple quoting of words 2009-03-24 16:38:27 -07:00
edac.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
eisa.txt
email-clients.txt
feature-removal-schedule.txt inotify: deprecate the inotify kernel interface 2009-10-18 15:49:38 -04:00
flexible-arrays.txt Update flex_arrays.txt 2009-10-15 07:25:20 -06:00
futex-requeue-pi.txt futex: add requeue-pi documentation 2009-05-09 07:12:50 +02:00
gcov.txt trivial: fix typo in CONFIG_DEBUG_FS in gcov doc 2009-09-21 15:14:56 +02:00
gpio.txt gpiolib: allow poll() on value 2009-09-23 07:39:48 -07:00
highuid.txt
HOWTO
hw_random.txt
ics932s401
initrd.txt
Intel-IOMMU.txt intel-iommu: Kill DMAR_BROKEN_GFX_WA option. 2009-09-19 09:37:23 -07:00
intel_txt.txt x86, intel_txt: Intel TXT boot support 2009-07-21 11:49:06 -07:00
io-mapping.txt
IO-mapping.txt Documentation: move DMA-mapping.txt to Doc/PCI/ 2009-01-29 18:19:29 -08:00
io_ordering.txt
iostats.txt
IPMI.txt
IRQ-affinity.txt
IRQ.txt
irqflags-tracing.txt
isapnp.txt
java.txt
kernel-doc-nano-HOWTO.txt kernel-doc: allow multi-line declaration purpose descriptions 2009-09-18 09:48:52 -07:00
kernel-docs.txt
kernel-parameters.txt x86: earlyprintk: Fix regression to handle serial,ttySn as 1 arg 2009-10-01 10:34:16 +02:00
keys-request-key.txt
keys.txt KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] 2009-09-02 21:29:22 +10:00
kmemcheck.txt kmemcheck: update documentation 2009-07-01 22:36:22 +02:00
kmemleak.txt kmemleak: add clear command support 2009-09-08 16:36:08 +01:00
kobject.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
kprobes.txt debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
kref.txt kref: double kref_put() in my_data_handler() 2009-09-18 09:48:52 -07:00
ldm.txt
leds-class.txt led: document sysfs interface 2009-08-28 15:21:12 -04:00
leds-lp3944.txt leds: LED driver for National Semiconductor LP3944 Funlight Chip 2009-06-23 20:21:38 +01:00
local_ops.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
lockdep-design.txt lockdep: Fix typos in documentation 2009-08-07 12:03:46 +02:00
lockstat.txt
logo.gif Revert "linux.conf.au 2009: Tuz" 2009-04-27 12:00:27 -07:00
logo.txt Revert "linux.conf.au 2009: Tuz" 2009-04-27 12:00:27 -07:00
magic-number.txt documentation: update header file paths 2009-01-06 15:59:28 -08:00
Makefile
ManagementStyle
mca.txt
md.txt Documentation/md.txt update 2009-03-31 15:18:37 +11:00
memory-barriers.txt sched: Document memory barriers implied by sleep/wake-up primitives 2009-04-29 14:15:55 +02:00
memory-hotplug.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
memory.txt Documentation/memory.txt: remove some very outdated recommendations 2009-09-22 07:17:26 -07:00
mono.txt
mutex-design.txt
nmi_watchdog.txt
nommu-mmap.txt NOMMU: Make mmap allocation page trimming behaviour configurable. 2009-01-08 12:04:47 +00:00
numastat.txt mm: fix NUMA accounting in numastat.txt 2009-09-22 07:17:39 -07:00
oops-tracing.txt
parport-lowlevel.txt
parport.txt
pi-futex.txt
pnp.txt
preempt-locking.txt
printk-formats.txt
prio_tree.txt
rbtree.txt trivial: rbtree.txt: fix rb_entry() parameters in sample code 2009-06-12 18:01:47 +02:00
rfkill.txt rfkill: export persistent attribute in sysfs 2009-06-19 11:50:18 -04:00
robust-futex-ABI.txt futex: documentation: fix inconsistent description of futex list_op_pending 2009-06-18 13:03:56 -07:00
robust-futexes.txt
rt-mutex-design.txt
rt-mutex.txt
rtc.txt rtc: add boot_timesource sysfs attribute 2009-09-23 07:39:46 -07:00
SAK.txt
SecurityBugs
SELinux.txt
serial-console.txt
sgi-ioc4.txt
sgi-visws.txt
slow-work.txt SLOW_WORK: Allow a requeueable work item to sleep till the thread is needed 2009-11-19 18:10:57 +00:00
SM501.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
Smack.txt smack: implement logging V3 2009-04-14 09:00:23 +10:00
sparse.txt Documentation: explain the difference between __bitwise and __bitwise__ 2009-04-11 08:18:11 +02:00
spinlocks.txt
stable_api_nonsense.txt
stable_kernel_rules.txt
SubmitChecklist block: rename CONFIG_LBD to CONFIG_LBDAF 2009-06-19 08:08:50 +02:00
SubmittingDrivers
SubmittingPatches docs: update patch size in SubmittingPatches 2009-10-01 16:11:12 -07:00
svga.txt
sysfs-rules.txt Doc/sysfs-rules: Swap the order of the words so the sentence makes more sense 2009-05-08 19:22:20 -07:00
sysrq.txt sysrq, kdump: make sysrq-c consistent 2009-07-29 19:10:36 -07:00
tomoyo.txt tomoyo: add Documentation/tomoyo.txt 2009-04-14 09:14:58 +10:00
unaligned-memory-access.txt
unicode.txt
unshare.txt
VGA-softcursor.txt
vgaarbiter.txt PCI/VGA: add VGA arbitration documentation 2009-09-09 13:29:42 -07:00
video-output.txt
volatile-considered-harmful.txt
voyager.txt
zorro.txt