diff options
| author | Vivek Goyal <vgoyal@redhat.com> | 2012-08-01 12:24:18 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-08-01 12:24:18 +0200 |
| commit | c83f6bf98dc1f1a194118b3830706cebbebda8c4 (patch) | |
| tree | ea8fbd925584f784164617964a9f025bda16ed15 /include/linux/blkpg.h | |
| parent | 4638a83e8615de9c16c39dfed234951d0f468cf1 (diff) | |
block: add partition resize function to blkpg ioctl
Add a new operation code (BLKPG_RESIZE_PARTITION) to the BLKPG ioctl that
allows altering the size of an existing partition, even if it is currently
in use.
This patch converts hd_struct->nr_sects into sequence counter because
One might extend a partition while IO is happening to it and update of
nr_sects can be non-atomic on 32bit machines with 64bit sector_t. This
can lead to issues like reading inconsistent size of a partition. Sequence
counter have been used so that readers don't have to take bdev mutex lock
as we call sector_in_part() very frequently.
Now all the access to hd_struct->nr_sects should happen using sequence
counter read/update helper functions part_nr_sects_read/part_nr_sects_write.
There is one exception though, set_capacity()/get_capacity(). I think
theoritically race should exist there too but this patch does not
modify set_capacity()/get_capacity() due to sheer number of call sites
and I am afraid that change might break something. I have left that as a
TODO item. We can handle it later if need be. This patch does not introduce
any new races as such w.r.t set_capacity()/get_capacity().
v2: Add CONFIG_LBDAF test to UP preempt case as suggested by Phillip.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Phillip Susi <psusi@ubuntu.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blkpg.h')
| -rw-r--r-- | include/linux/blkpg.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/blkpg.h b/include/linux/blkpg.h index faf8a45af210..a8519446c111 100644 --- a/include/linux/blkpg.h +++ b/include/linux/blkpg.h @@ -40,6 +40,7 @@ struct blkpg_ioctl_arg { /* The subfunctions (for the op field) */ #define BLKPG_ADD_PARTITION 1 #define BLKPG_DEL_PARTITION 2 +#define BLKPG_RESIZE_PARTITION 3 /* Sizes of name fields. Unused at present. */ #define BLKPG_DEVNAMELTH 64 |