diff options
| author | David Woodhouse <dwmw2@infradead.org> | 2008-02-06 01:36:27 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-06 10:41:01 -0800 |
| commit | 96c5865559cee0f9cbc5173f3c949f6ce3525581 (patch) | |
| tree | bbcfa89faeae5e5b1334a8f537b6bdb7caa992d8 | |
| parent | a3b81113fb6658629f4ebaabf8dd3067cd341020 (diff) | |
Allow auto-destruction of loop devices
This allows a flag to be set on loop devices so that when they are
closed for the last time, they'll self-destruct.
In general, so that we can automatically allocate loop devices (as with
losetup -f) and have them disappear when we're done with them.
In particular, right now, so that we can stop relying on the hackish
special-case in umount(8) which kills off loop devices which were set up by
'mount -oloop'. That means we can stop putting crap in /etc/mtab which
doesn't belong there, which means it can be a symlink to /proc/mounts, which
means yet another writable file on the root filesystem is eliminated and the
'stateless' folks get happier... and OLPC trac #356 can be closed.
The mount(8) side of that is at
http://marc.info/?l=util-linux-ng&m=119362955431694&w=2
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Cc: Bernardo Innocenti <bernie@codewiz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | drivers/block/loop.c | 8 | ||||
| -rw-r--r-- | include/linux/loop.h | 1 |
2 files changed, 9 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index b8af22e610d..91ebb007416 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -973,6 +973,10 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) lo->transfer = xfer->transfer; lo->ioctl = xfer->ioctl; + if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) != + (info->lo_flags & LO_FLAGS_AUTOCLEAR)) + lo->lo_flags ^= LO_FLAGS_AUTOCLEAR; + lo->lo_encrypt_key_size = info->lo_encrypt_key_size; lo->lo_init[0] = info->lo_init[0]; lo->lo_init[1] = info->lo_init[1]; @@ -1331,6 +1335,10 @@ static int lo_release(struct inode *inode, struct file *file) mutex_lock(&lo->lo_ctl_mutex); --lo->lo_refcnt; + + if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) && !lo->lo_refcnt) + loop_clr_fd(lo, inode->i_bdev); + mutex_unlock(&lo->lo_ctl_mutex); return 0; diff --git a/include/linux/loop.h b/include/linux/loop.h index 26a0a103898..46169a7b559 100644 --- a/include/linux/loop.h +++ b/include/linux/loop.h @@ -76,6 +76,7 @@ struct loop_device { enum { LO_FLAGS_READ_ONLY = 1, LO_FLAGS_USE_AOPS = 2, + LO_FLAGS_AUTOCLEAR = 4, }; #include <asm/posix_types.h> /* for __kernel_old_dev_t */ |