Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 96c58655 authored by David Woodhouse's avatar David Woodhouse Committed by Linus Torvalds
Browse files

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: default avatarDavid Woodhouse <dwmw2@infradead.org>
Cc: Bernardo Innocenti <bernie@codewiz.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a3b81113

drivers/block/loop.c

+8 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/loop.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */