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authorTejun Heo <tj@kernel.org>2010-11-13 05:55:17 -0500
committerTejun Heo <tj@kernel.org>2010-11-13 05:55:17 -0500
commite525fd89d380c4a94c0d63913a1dd1a593ed25e7 (patch)
treed226ef40d3f99e42fcf272ad432585cbd641ebec /kernel
parente09b457bdb7e8d23fc54dcef0930ac697d8de895 (diff)
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/power/swap.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index a0e4a86ccf94..513a77f1a0b3 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -223,7 +223,7 @@ static int swsusp_swap_check(void)
223 return res; 223 return res;
224 224
225 root_swap = res; 225 root_swap = res;
226 res = blkdev_get(hib_resume_bdev, FMODE_WRITE); 226 res = blkdev_get(hib_resume_bdev, FMODE_WRITE, NULL);
227 if (res) 227 if (res)
228 return res; 228 return res;
229 229
@@ -907,7 +907,8 @@ int swsusp_check(void)
907{ 907{
908 int error; 908 int error;
909 909
910 hib_resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ); 910 hib_resume_bdev = open_by_devnum(swsusp_resume_device,
911 FMODE_READ, NULL);
911 if (!IS_ERR(hib_resume_bdev)) { 912 if (!IS_ERR(hib_resume_bdev)) {
912 set_blocksize(hib_resume_bdev, PAGE_SIZE); 913 set_blocksize(hib_resume_bdev, PAGE_SIZE);
913 clear_page(swsusp_header); 914 clear_page(swsusp_header);