diff options
authorTejun Heo2010-11-13 04:55:17 -0600
committerTejun Heo2010-11-13 04:55:17 -0600
commite525fd89d380c4a94c0d63913a1dd1a593ed25e7 (patch)
treed226ef40d3f99e42fcf272ad432585cbd641ebec /block/ioctl.c
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 'block/ioctl.c')
1 files changed, 3 insertions, 2 deletions
diff --git a/block/ioctl.c b/block/ioctl.c
index d724ceb1d46..cc46d499fd2 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -294,11 +294,12 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
294 return -EINVAL; 294 return -EINVAL;
295 if (get_user(n, (int __user *) arg)) 295 if (get_user(n, (int __user *) arg))
296 return -EFAULT; 296 return -EFAULT;
297 if (!(mode & FMODE_EXCL) && bd_claim(bdev, &bdev) < 0) 297 if (!(mode & FMODE_EXCL) &&
298 blkdev_get(bdev, mode | FMODE_EXCL, &bdev) < 0)
298 return -EBUSY; 299 return -EBUSY;
299 ret = set_blocksize(bdev, n); 300 ret = set_blocksize(bdev, n);
300 if (!(mode & FMODE_EXCL)) 301 if (!(mode & FMODE_EXCL))
301 bd_release(bdev); 302 blkdev_put(bdev, mode | FMODE_EXCL);
302 return ret; 303 return ret;
303 case BLKPG: 304 case BLKPG:
304 ret = blkpg_ioctl(bdev, (struct blkpg_ioctl_arg __user *) arg); 305 ret = blkpg_ioctl(bdev, (struct blkpg_ioctl_arg __user *) arg);