Commit e525fd89 authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarNeil Brown <neilb@suse.de>
Acked-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
Acked-by: default avatarPhilipp 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>
parent e09b457b
......@@ -294,11 +294,12 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
return -EINVAL;
if (get_user(n, (int __user *) arg))
return -EFAULT;
if (!(mode & FMODE_EXCL) && bd_claim(bdev, &bdev) < 0)
if (!(mode & FMODE_EXCL) &&
blkdev_get(bdev, mode | FMODE_EXCL, &bdev) < 0)
return -EBUSY;
ret = set_blocksize(bdev, n);
if (!(mode & FMODE_EXCL))
bd_release(bdev);
blkdev_put(bdev, mode | FMODE_EXCL);
return ret;
case BLKPG:
ret = blkpg_ioctl(bdev, (struct blkpg_ioctl_arg __user *) arg);
......
......@@ -923,8 +923,6 @@ struct drbd_md {
struct drbd_backing_dev {
struct block_device *backing_bdev;
struct block_device *md_bdev;
struct file *lo_file;
struct file *md_file;
struct drbd_md md;
struct disk_conf dc; /* The user provided config... */
sector_t known_size; /* last known size of that backing device */
......
......@@ -3361,11 +3361,8 @@ void drbd_free_bc(struct drbd_backing_dev *ldev)
if (ldev == NULL)
return;
bd_release(ldev->backing_bdev);
bd_release(ldev->md_bdev);
fput(ldev->lo_file);
fput(ldev->md_file);
blkdev_put(ldev->backing_bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
blkdev_put(ldev->md_bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
kfree(ldev);
}
......
......@@ -855,7 +855,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
sector_t max_possible_sectors;
sector_t min_md_device_sectors;
struct drbd_backing_dev *nbc = NULL; /* new_backing_conf */
struct inode *inode, *inode2;
struct block_device *bdev;
struct lru_cache *resync_lru = NULL;
union drbd_state ns, os;
unsigned int max_seg_s;
......@@ -902,46 +902,40 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
}
}
nbc->lo_file = filp_open(nbc->dc.backing_dev, O_RDWR, 0);
if (IS_ERR(nbc->lo_file)) {
bdev = open_bdev_exclusive(nbc->dc.backing_dev,
FMODE_READ | FMODE_WRITE, mdev);
if (IS_ERR(bdev)) {
dev_err(DEV, "open(\"%s\") failed with %ld\n", nbc->dc.backing_dev,
PTR_ERR(nbc->lo_file));
nbc->lo_file = NULL;
PTR_ERR(bdev));
retcode = ERR_OPEN_DISK;
goto fail;
}
nbc->backing_bdev = bdev;
inode = nbc->lo_file->f_dentry->d_inode;
if (!S_ISBLK(inode->i_mode)) {
retcode = ERR_DISK_NOT_BDEV;
goto fail;
}
nbc->md_file = filp_open(nbc->dc.meta_dev, O_RDWR, 0);
if (IS_ERR(nbc->md_file)) {
/*
* meta_dev_idx >= 0: external fixed size, possibly multiple
* drbd sharing one meta device. TODO in that case, paranoia
* check that [md_bdev, meta_dev_idx] is not yet used by some
* other drbd minor! (if you use drbd.conf + drbdadm, that
* should check it for you already; but if you don't, or
* someone fooled it, we need to double check here)
*/
bdev = open_bdev_exclusive(nbc->dc.meta_dev,
FMODE_READ | FMODE_WRITE,
(nbc->dc.meta_dev_idx < 0) ?
(void *)mdev : (void *)drbd_m_holder);
if (IS_ERR(bdev)) {
dev_err(DEV, "open(\"%s\") failed with %ld\n", nbc->dc.meta_dev,
PTR_ERR(nbc->md_file));
nbc->md_file = NULL;
PTR_ERR(bdev));
retcode = ERR_OPEN_MD_DISK;
goto fail;
}
nbc->md_bdev = bdev;
inode2 = nbc->md_file->f_dentry->d_inode;
if (!S_ISBLK(inode2->i_mode)) {
retcode = ERR_MD_NOT_BDEV;
goto fail;
}
nbc->backing_bdev = inode->i_bdev;
if (bd_claim(nbc->backing_bdev, mdev)) {
printk(KERN_ERR "drbd: bd_claim(%p,%p); failed [%p;%p;%u]\n",
nbc->backing_bdev, mdev,
nbc->backing_bdev->bd_holder,
nbc->backing_bdev->bd_contains->bd_holder,
nbc->backing_bdev->bd_holders);
retcode = ERR_BDCLAIM_DISK;
if ((nbc->backing_bdev == nbc->md_bdev) !=
(nbc->dc.meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
nbc->dc.meta_dev_idx == DRBD_MD_INDEX_FLEX_INT)) {
retcode = ERR_MD_IDX_INVALID;
goto fail;
}
......@@ -950,28 +944,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
offsetof(struct bm_extent, lce));
if (!resync_lru) {
retcode = ERR_NOMEM;
goto release_bdev_fail;
}
/* meta_dev_idx >= 0: external fixed size,
* possibly multiple drbd sharing one meta device.
* TODO in that case, paranoia check that [md_bdev, meta_dev_idx] is
* not yet used by some other drbd minor!
* (if you use drbd.conf + drbdadm,
* that should check it for you already; but if you don't, or someone
* fooled it, we need to double check here) */
nbc->md_bdev = inode2->i_bdev;
if (bd_claim(nbc->md_bdev, (nbc->dc.meta_dev_idx < 0) ? (void *)mdev
: (void *) drbd_m_holder)) {
retcode = ERR_BDCLAIM_MD_DISK;
goto release_bdev_fail;
}
if ((nbc->backing_bdev == nbc->md_bdev) !=
(nbc->dc.meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
nbc->dc.meta_dev_idx == DRBD_MD_INDEX_FLEX_INT)) {
retcode = ERR_MD_IDX_INVALID;
goto release_bdev2_fail;
goto fail;
}
/* RT - for drbd_get_max_capacity() DRBD_MD_INDEX_FLEX_INT */
......@@ -982,7 +955,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
(unsigned long long) drbd_get_max_capacity(nbc),
(unsigned long long) nbc->dc.disk_size);
retcode = ERR_DISK_TO_SMALL;
goto release_bdev2_fail;
goto fail;
}
if (nbc->dc.meta_dev_idx < 0) {
......@@ -999,7 +972,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
dev_warn(DEV, "refusing attach: md-device too small, "
"at least %llu sectors needed for this meta-disk type\n",
(unsigned long long) min_md_device_sectors);
goto release_bdev2_fail;
goto fail;
}
/* Make sure the new disk is big enough
......@@ -1007,7 +980,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
if (drbd_get_max_capacity(nbc) <
drbd_get_capacity(mdev->this_bdev)) {
retcode = ERR_DISK_TO_SMALL;
goto release_bdev2_fail;
goto fail;
}
nbc->known_size = drbd_get_capacity(nbc->backing_bdev);
......@@ -1030,7 +1003,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
retcode = _drbd_request_state(mdev, NS(disk, D_ATTACHING), CS_VERBOSE);
drbd_resume_io(mdev);
if (retcode < SS_SUCCESS)
goto release_bdev2_fail;
goto fail;
if (!get_ldev_if_state(mdev, D_ATTACHING))
goto force_diskless;
......@@ -1264,18 +1237,14 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
force_diskless:
drbd_force_state(mdev, NS(disk, D_DISKLESS));
drbd_md_sync(mdev);
release_bdev2_fail:
if (nbc)
bd_release(nbc->md_bdev);
release_bdev_fail:
if (nbc)
bd_release(nbc->backing_bdev);
fail:
if (nbc) {
if (nbc->lo_file)
fput(nbc->lo_file);
if (nbc->md_file)
fput(nbc->md_file);
if (nbc->backing_bdev)
blkdev_put(nbc->backing_bdev,
FMODE_READ | FMODE_WRITE | FMODE_EXCL);
if (nbc->md_bdev)
blkdev_put(nbc->md_bdev,
FMODE_READ | FMODE_WRITE | FMODE_EXCL);
kfree(nbc);
}
lc_destroy(resync_lru);
......
......@@ -2296,15 +2296,12 @@ static int pkt_open_dev(struct pktcdvd_device *pd, fmode_t write)
* so bdget() can't fail.
*/
bdget(pd->bdev->bd_dev);
if ((ret = blkdev_get(pd->bdev, FMODE_READ)))
if ((ret = blkdev_get(pd->bdev, FMODE_READ | FMODE_EXCL, pd)))
goto out;
if ((ret = bd_claim(pd->bdev, pd)))
goto out_putdev;
if ((ret = pkt_get_last_written(pd, &lba))) {
printk(DRIVER_NAME": pkt_get_last_written failed\n");
goto out_unclaim;
goto out_putdev;
}
set_capacity(pd->disk, lba << 2);
......@@ -2314,7 +2311,7 @@ static int pkt_open_dev(struct pktcdvd_device *pd, fmode_t write)
q = bdev_get_queue(pd->bdev);
if (write) {
if ((ret = pkt_open_write(pd)))
goto out_unclaim;
goto out_putdev;
/*
* Some CDRW drives can not handle writes larger than one packet,
* even if the size is a multiple of the packet size.
......@@ -2329,23 +2326,21 @@ static int pkt_open_dev(struct pktcdvd_device *pd, fmode_t write)
}
if ((ret = pkt_set_segment_merging(pd, q)))
goto out_unclaim;
goto out_putdev;
if (write) {
if (!pkt_grow_pktlist(pd, CONFIG_CDROM_PKTCDVD_BUFFERS)) {
printk(DRIVER_NAME": not enough memory for buffers\n");
ret = -ENOMEM;
goto out_unclaim;
goto out_putdev;
}
printk(DRIVER_NAME": %lukB available on disc\n", lba << 1);
}
return 0;
out_unclaim:
bd_release(pd->bdev);
out_putdev:
blkdev_put(pd->bdev, FMODE_READ);
blkdev_put(pd->bdev, FMODE_READ | FMODE_EXCL);
out:
return ret;
}
......@@ -2362,8 +2357,7 @@ static void pkt_release_dev(struct pktcdvd_device *pd, int flush)
pkt_lock_door(pd, 0);
pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);
bd_release(pd->bdev);
blkdev_put(pd->bdev, FMODE_READ);
blkdev_put(pd->bdev, FMODE_READ | FMODE_EXCL);
pkt_shrink_pktlist(pd);
}
......@@ -2733,7 +2727,7 @@ static int pkt_new_dev(struct pktcdvd_device *pd, dev_t dev)
bdev = bdget(dev);
if (!bdev)
return -ENOMEM;
ret = blkdev_get(bdev, FMODE_READ | FMODE_NDELAY);
ret = blkdev_get(bdev, FMODE_READ | FMODE_NDELAY, NULL);
if (ret)
return ret;
......
......@@ -65,15 +65,12 @@ static int raw_open(struct inode *inode, struct file *filp)
if (!bdev)
goto out;
igrab(bdev->bd_inode);
err = blkdev_get(bdev, filp->f_mode);
err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);
if (err)
goto out;
err = bd_claim(bdev, raw_open);
if (err)
goto out1;
err = set_blocksize(bdev, bdev_logical_block_size(bdev));
if (err)
goto out2;
goto out1;
filp->f_flags |= O_DIRECT;
filp->f_mapping = bdev->bd_inode->i_mapping;
if (++raw_devices[minor].inuse == 1)
......@@ -83,10 +80,8 @@ static int raw_open(struct inode *inode, struct file *filp)
mutex_unlock(&raw_mutex);
return 0;
out2:
bd_release(bdev);
out1:
blkdev_put(bdev, filp->f_mode);
blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
out:
mutex_unlock(&raw_mutex);
return err;
......@@ -110,8 +105,7 @@ static int raw_release(struct inode *inode, struct file *filp)
}
mutex_unlock(&raw_mutex);
bd_release(bdev);
blkdev_put(bdev, filp->f_mode);
blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
return 0;
}
......
......@@ -325,20 +325,13 @@ static int open_dev(struct dm_dev_internal *d, dev_t dev,
BUG_ON(d->dm_dev.bdev);
bdev = open_by_devnum(dev, d->dm_dev.mode);
bdev = open_by_devnum(dev, d->dm_dev.mode | FMODE_EXCL, _claim_ptr);
if (IS_ERR(bdev))
return PTR_ERR(bdev);
r = bd_claim(bdev, _claim_ptr);
if (r) {
blkdev_put(bdev, d->dm_dev.mode);
return r;
}
r = bd_link_disk_holder(bdev, dm_disk(md));
if (r) {
bd_release(bdev);
blkdev_put(bdev, d->dm_dev.mode);
blkdev_put(bdev, d->dm_dev.mode | FMODE_EXCL);
return r;
}
......@@ -354,9 +347,7 @@ static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
if (!d->dm_dev.bdev)
return;
bd_unlink_disk_holder(d->dm_dev.bdev);
bd_release(d->dm_dev.bdev);
blkdev_put(d->dm_dev.bdev, d->dm_dev.mode);
blkdev_put(d->dm_dev.bdev, d->dm_dev.mode | FMODE_EXCL);
d->dm_dev.bdev = NULL;
}
......
......@@ -1907,7 +1907,6 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
MD_BUG();
return;
}
bd_unlink_disk_holder(rdev->bdev);
list_del_rcu(&rdev->same_set);
printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
rdev->mddev = NULL;
......@@ -1935,19 +1934,13 @@ static int lock_rdev(mdk_rdev_t *rdev, dev_t dev, int shared)
struct block_device *bdev;
char b[BDEVNAME_SIZE];
bdev = open_by_devnum(dev, FMODE_READ|FMODE_WRITE);
bdev = open_by_devnum(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
shared ? (mdk_rdev_t *)lock_rdev : rdev);
if (IS_ERR(bdev)) {
printk(KERN_ERR "md: could not open %s.\n",
__bdevname(dev, b));
return PTR_ERR(bdev);
}
err = bd_claim(bdev, shared ? (mdk_rdev_t *)lock_rdev : rdev);
if (err) {
printk(KERN_ERR "md: could not bd_claim %s.\n",
bdevname(bdev, b));
blkdev_put(bdev, FMODE_READ|FMODE_WRITE);
return err;
}
if (!shared)
set_bit(AllReserved, &rdev->flags);
rdev->bdev = bdev;
......@@ -1960,8 +1953,7 @@ static void unlock_rdev(mdk_rdev_t *rdev)
rdev->bdev = NULL;
if (!bdev)
MD_BUG();
bd_release(bdev);
blkdev_put(bdev, FMODE_READ|FMODE_WRITE);
blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
}
void md_autodetect_dev(dev_t dev);
......
......@@ -224,7 +224,7 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
if (dev->blkdev) {
invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
0, -1);
close_bdev_exclusive(dev->blkdev, FMODE_READ|FMODE_WRITE);
blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
}
kfree(dev);
......@@ -234,7 +234,7 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
/* FIXME: ensure that mtd->size % erase_size == 0 */
static struct block2mtd_dev *add_device(char *devname, int erase_size)
{
const fmode_t mode = FMODE_READ | FMODE_WRITE;
const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
struct block_device *bdev;
struct block2mtd_dev *dev;
char *name;
......@@ -255,17 +255,8 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
to resolve the device name by other means. */
dev_t devt = name_to_dev_t(devname);
if (devt) {
bdev = open_by_devnum(devt, mode);
if (!IS_ERR(bdev)) {
int ret;
ret = bd_claim(bdev, dev);
if (ret) {
blkdev_put(bdev, mode);
bdev = ERR_PTR(ret);
}
}
}
if (devt)
bdev = open_by_devnum(devt, mode, dev);
}
#endif
......
......@@ -103,7 +103,7 @@ int dasd_scan_partitions(struct dasd_block *block)
struct block_device *bdev;
bdev = bdget_disk(block->gdp, 0);
if (!bdev || blkdev_get(bdev, FMODE_READ) < 0)
if (!bdev || blkdev_get(bdev, FMODE_READ, NULL) < 0)
return -ENODEV;
/*
* See fs/partition/check.c:register_disk,rescan_partitions
......
......@@ -660,7 +660,7 @@ static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
else if (bdev->bd_contains == bdev)
return true; /* is a whole device which isn't held */
else if (whole->bd_holder == bd_claim)
else if (whole->bd_holder == bd_may_claim)
return true; /* is a partition of a device that is being partitioned */
else if (whole->bd_holder != NULL)
return false; /* is a partition of a held device */
......@@ -807,10 +807,10 @@ static void __bd_claim(struct block_device *bdev, struct block_device *whole,
{
/* note that for a whole device bd_holders
* will be incremented twice, and bd_holder will
* be set to bd_claim before being set to holder
* be set to bd_may_claim before being set to holder
*/
whole->bd_holders++;
whole->bd_holder = bd_claim;
whole->bd_holder = bd_may_claim;
bdev->bd_holders++;
bdev->bd_holder = holder;
}
......@@ -835,37 +835,7 @@ static void bd_finish_claiming(struct block_device *bdev,
__bd_abort_claiming(whole, holder); /* not actually an abort */
}
/**
* bd_claim - claim a block device
* @bdev: block device to claim
* @holder: holder trying to claim @bdev
*
* Try to claim @bdev which must have been opened successfully.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* 0 if successful, -EBUSY if @bdev is already claimed.
*/
int bd_claim(struct block_device *bdev, void *holder)
{
struct block_device *whole = bdev->bd_contains;
int res;
might_sleep();
spin_lock(&bdev_lock);
res = bd_prepare_to_claim(bdev, whole, holder);
if (res == 0)
__bd_claim(bdev, whole, holder);
spin_unlock(&bdev_lock);
return res;
}
EXPORT_SYMBOL(bd_claim);
void bd_release(struct block_device *bdev)
static void bd_release(struct block_device *bdev)
{
spin_lock(&bdev_lock);
if (!--bdev->bd_contains->bd_holders)
......@@ -875,8 +845,6 @@ void bd_release(struct block_device *bdev)
spin_unlock(&bdev_lock);
}
EXPORT_SYMBOL(bd_release);
#ifdef CONFIG_SYSFS
static int add_symlink(struct kobject *from, struct kobject *to)
{
......@@ -943,7 +911,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
void bd_unlink_disk_holder(struct block_device *bdev)
static void bd_unlink_disk_holder(struct block_device *bdev)
{
struct gendisk *disk = bdev->bd_holder_disk;
......@@ -954,7 +922,9 @@ void bd_unlink_disk_holder(struct block_device *bdev)
del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
del_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
}
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
#else
static inline void bd_unlink_disk_holder(struct block_device *bdev)
{ }
#endif
/*
......@@ -964,12 +934,12 @@ EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
* to be used for internal purposes. If you ever need it - reconsider
* your API.
*/
struct block_device *open_by_devnum(dev_t dev, fmode_t mode)
struct block_device *open_by_devnum(dev_t dev, fmode_t mode, void *holder)
{
struct block_device *bdev = bdget(dev);
int err = -ENOMEM;
if (bdev)
err = blkdev_get(bdev, mode);
err = blkdev_get(bdev, mode, holder);
return err ? ERR_PTR(err) : bdev;
}
......@@ -1235,17 +1205,37 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
return ret;
}
int blkdev_get(struct block_device *bdev, fmode_t mode)
int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
{
return __blkdev_get(bdev, mode, 0);
struct block_device *whole = NULL;
int res;
WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
if ((mode & FMODE_EXCL) && holder) {
whole = bd_start_claiming(bdev, holder);
if (IS_ERR(whole)) {
bdput(bdev);
return PTR_ERR(whole);
}
}
res = __blkdev_get(bdev, mode, 0);
if (whole) {
if (res == 0)
bd_finish_claiming(bdev, whole, holder);
else
bd_abort_claiming(whole, holder);
}
return res;
}
EXPORT_SYMBOL(blkdev_get);
static int blkdev_open(struct inode * inode, struct file * filp)
{
struct block_device *whole = NULL;
struct block_device *bdev;
int res;
/*
* Preserve backwards compatibility and allow large file access
......@@ -1266,26 +1256,9 @@ static int blkdev_open(struct inode * inode, struct file * filp)
if (bdev == NULL)
return -ENOMEM;
if (filp->f_mode & FMODE_EXCL) {
whole = bd_start_claiming(bdev, filp);
if (IS_ERR(whole)) {
bdput(bdev);
return PTR_ERR(whole);
}
}
filp->f_mapping = bdev->bd_inode->i_mapping;
res = blkdev_get(bdev, filp->f_mode);
if (whole) {
if (res == 0)
bd_finish_claiming(bdev, whole, filp);
else
bd_abort_claiming(whole, filp);
}
return res;
return blkdev_get(bdev, filp->f_mode, filp);
}
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
......@@ -1329,6 +1302,13 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
int blkdev_put(struct block_device *bdev, fmode_t mode)
{
if (mode & FMODE_EXCL) {
mutex_lock(&bdev->bd_mutex);
bd_release(bdev);
if (!bdev->bd_holders)