linux/drivers
Tejun Heo e525fd89d3 block: make blkdev_get/put() handle exclusive access
Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.

* blkdev_get/put() are the primary open and close functions.

* bd_claim/release() deal with exclusive open.

* open/close_bdev_exclusive() are combination of open and claim and
  the other way around, respectively.

* bd_link/unlink_disk_holder() to create and remove holder/slave
  symlinks.

* open_by_devnum() wraps bdget() + blkdev_get().

The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access.  Reorganize the interface such that,

* blkdev_get() is extended to include exclusive access management.
  @holder argument is added and, if is @FMODE_EXCL specified, it will
  gain exclusive access atomically w.r.t. other exclusive accesses.

* blkdev_put() is similarly extended.  It now takes @mode argument and
  if @FMODE_EXCL is set, it releases an exclusive access.  Also, when
  the last exclusive claim is released, the holder/slave symlinks are
  removed automatically.

* bd_claim/release() and close_bdev_exclusive() are no longer
  necessary and either made static or removed.

* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
  is no longer necessary and removed.

* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
  and blkdev_get().  It also has an unexpected extra bdev_read_only()
  test which probably should be moved into blkdev_get().

* open_by_devnum() is modified to take @holder argument and pass it to
  blkdev_get().

Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should).  This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.

open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features.  Well, let's leave them for another day.

Most conversions are straight-forward.  drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
2010-11-13 11:55:17 +01:00
..
accessibility
acpi
amba
ata ATA: pata_octeon_cf: Use I/O clock rate for timing calculations. 2010-10-29 19:08:41 +01:00
atm
auxdisplay
base Merge branch 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6 2010-10-29 15:09:56 -07:00
block block: make blkdev_get/put() handle exclusive access 2010-11-13 11:55:17 +01:00
bluetooth
cdrom
char block: make blkdev_get/put() handle exclusive access 2010-11-13 11:55:17 +01:00
clocksource ARM: shmobile: remove sh_timer_config clk member 2010-10-31 10:40:39 -04:00
connector
cpufreq
cpuidle
crypto
dca
dio
dma drivers/dma/Kconfig: add part number for Topcliff. 2010-10-29 14:14:02 -07:00
edac
eisa
firewire Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2010-11-05 14:17:22 -07:00
firmware
gpio gpio: Add VIA VX855 GPIO driver 2010-10-29 00:29:51 +02:00
gpu
hid
hwmon hwmon: (ltc4261) Fix error message format 2010-11-05 10:17:19 -07:00
i2c i2c-i801: Add PCI idents for Patsburg 'IDF' SMBus controllers 2010-10-31 21:07:00 +01:00
ide
idle
ieee802154
infiniband convert get_sb_single() users 2010-10-29 04:16:28 -04:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2010-10-31 21:02:39 -04:00
isdn Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2010-11-05 15:25:48 -07:00
leds leds-net5501: taints kernel, add license 2010-11-05 09:51:56 -07:00
lguest
macintosh Move ams driver to macintosh 2010-10-28 20:31:50 +02:00
mca
md block: make blkdev_get/put() handle exclusive access 2010-11-13 11:55:17 +01:00
media Input: ir-keytable - fix uninitialized variable warning 2010-10-31 21:05:43 -04:00
memstick
message
mfd mfd: Fix a memory leak when unload mc13xxx-core module 2010-10-29 00:30:43 +02:00
misc Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb 2010-10-29 11:49:38 -07:00
mmc mfd: Adding twl6030 mmc card detect support for MMC1 2010-10-29 00:29:59 +02:00
mtd block: make blkdev_get/put() handle exclusive access 2010-11-13 11:55:17 +01:00
net ipw2x00: remove the right /proc/net entry 2010-11-05 18:57:04 -07:00
nubus
of
oprofile Merge branches 'perf-fixes-for-linus' and 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-10-30 11:43:26 -07:00
parisc
parport
pci Merge branch 'stable/xen-pcifront-0.8.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen 2010-10-28 17:11:17 -07:00
pcmcia
platform
pnp
power power: Revert "power_supply: Mark twl4030_charger as broken" 2010-10-29 00:30:44 +02:00
pps
ps3
rapidio
regulator regulator: max8998 BUCK1/2 voltage change with use of GPIOs 2010-10-29 00:30:15 +02:00
rtc sh: mach-snapgear: Kill off machtype, consolidate board def. 2010-10-29 19:06:53 +09:00
s390 block: make blkdev_get/put() handle exclusive access 2010-11-13 11:55:17 +01:00
sbus
scsi [SCSI] pmcraid: add support for set timestamp command and other fixes 2010-10-29 12:03:01 -05:00
serial Merge branch 'for-linus' of git://www.jni.nu/cris 2010-11-01 07:53:19 -04:00
sfi
sh Merge branches 'sh/pio-death', 'sh/nommu', 'sh/clkfwk', 'sh/core' and 'sh/intc-extension' into sh-fixes-for-linus 2010-11-08 09:42:43 +09:00
sn
spi Merge branch 'next-spi' of git://git.secretlab.ca/git/linux-2.6 2010-11-01 07:50:43 -04:00
ssb
staging Staging: ath6kl: remove empty files that mess with 'distclean' 2010-11-06 11:27:04 -07:00
tc
telephony
thermal
tty TTY: move .gitignore from drivers/char/ to drivers/tty/vt/ 2010-11-05 22:18:23 -07:00
uio
usb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2010-11-05 15:25:48 -07:00
uwb
vhost
video Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm 2010-10-30 08:26:25 -07:00
virtio
vlynq
w1
watchdog WATCHDOG: octeon-wdt: Use I/O clock rate for timing calculations. 2010-10-29 19:08:42 +01:00
xen convert get_sb_single() users 2010-10-29 04:16:28 -04:00
zorro
Kconfig
Makefile TTY: create drivers/tty and move the tty core files there 2010-11-05 08:10:33 -07:00