| Message ID | 1397681253-5203-1-git-send-email-ezequiel.garcia@free-electrons.com |
|---|---|
| State | Accepted |
| Headers | show |
On Wed, 2014-04-16 at 17:47 -0300, Ezequiel Garcia wrote: > The UBI volume rename ioctl (UBI_IOCRNVOL) open the volumes in exclusive > mode. The volumes are opened for two reasons: to build a volume rename list, > and a volume remove list. > > However, the first open constraint is excessive and can be replaced by > a 'read-write' open mode. The second open constraint is properly set as > 'exclusive' given the volume is opened for removal and we don't want any > users around. Pushed to l2-mtd.git, thanks!
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c index f54562a..7646220 100644 --- a/drivers/mtd/ubi/cdev.c +++ b/drivers/mtd/ubi/cdev.c @@ -731,7 +731,7 @@ static int rename_volumes(struct ubi_device *ubi, goto out_free; } - re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_EXCLUSIVE); + re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_READWRITE); if (IS_ERR(re->desc)) { err = PTR_ERR(re->desc); ubi_err("cannot open volume %d, error %d", vol_id, err);
The UBI volume rename ioctl (UBI_IOCRNVOL) open the volumes in exclusive mode. The volumes are opened for two reasons: to build a volume rename list, and a volume remove list. However, the first open constraint is excessive and can be replaced by a 'read-write' open mode. The second open constraint is properly set as 'exclusive' given the volume is opened for removal and we don't want any users around. By weakening the former 'exclusive' mode, we allow 'read-only' users to keep the volume open, while a rename is taking place. This is useful to perform an atomic rename, in a firmware upgrade scenario, while keeping the volume in read-only use (for instance, if a ubiblock is mounted as rootfs). It's worth mention this is not the case of UBIFS, which keeps the volume opened as 'read-write' despite mounted as read-write or read-only mode. This change was suggested at least twice by Artem: http://lists.infradead.org/pipermail/linux-mtd/2012-September/044175.html http://permalink.gmane.org/gmane.linux.drivers.mtd/39866 Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> --- drivers/mtd/ubi/cdev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)