On Wed, Nov 08, 2006 at 03:43:26PM +0100, Rafael J. Wysocki wrote:
> Will it be enough to cover the interactions with dm?
There are cases where you *cannot* freeze the filesystem (unless
you wait for userspace processes to finish what they are doing) -
and only dm can tell you that.
The freeze_filesystems() code ought to do it's best in any given
circumstances within the constraints.
So:
Get the filesystem's block device.
Check the full tree of devices that that block device depends upon
and for any device that belongs to device-mapper check if it is suspended.
If it is, skip the original device.
struct mapped_device *dm_get_md(dev_t dev);
int dm_suspended(struct mapped_device *md);
void dm_put(struct mapped_device *md);
Handling the tree is the difficult bit, but sysfs could help.
[You can get the device-mapper dependencies with:
struct mapped_device *dm_get_md(dev_t dev);
struct dm_table *dm_get_table(struct mapped_device *md);
struct list_head *dm_table_get_devices(struct dm_table *t);
void dm_table_put(struct dm_table *t);
void dm_put(struct mapped_device *md);
]
Consider that you could have an already-frozen filesystem containing a loop
device containing a device-mapper device containing a not-frozen filesystem.
You won't be able to freeze that top filesystem because the I/O would
queue lower down the stack. (Similar problem if the device-mapper device
in the stack was suspended.)
Alasdair
--
[email protected]
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
