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author | Vivek Goyal <vgoyal@redhat.com> | 2012-08-01 12:24:18 +0200 |
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committer | Jens Axboe <axboe@kernel.dk> | 2012-08-01 12:24:18 +0200 |
commit | c83f6bf98dc1f1a194118b3830706cebbebda8c4 (patch) | |
tree | ea8fbd925584f784164617964a9f025bda16ed15 /drivers/Makefile | |
parent | 4638a83e8615de9c16c39dfed234951d0f468cf1 (diff) | |
download | linux-rt-c83f6bf98dc1f1a194118b3830706cebbebda8c4.tar.gz |
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 'drivers/Makefile')
0 files changed, 0 insertions, 0 deletions