On Tue, Oct 25 2016 at 9:07P -0400,
Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> I think the right fix is to kill off the BLKFLSBUF special case in
> brd. Yes, it break compatibility - but in this case the compatibility
> breaks more than it helps.
Jens, please pick up this patch:
From: Mike Snitzer <snitzer@xxxxxxxxxx>
Date: Tue, 25 Oct 2016 10:25:07 -0400
Subject: [PATCH] brd: remove support for BLKFLSBUF
Discontinue having the brd driver destructively free all pages in the
ramdisk in response to the BLKFLSBUF ioctl. Doing so allows a BLKFLSBUF
ioctl issued to a logical partition to destroy pages of the parent brd
device (and all other partitions of that brd device).
This change breaks compatibility - but in this case the compatibility
breaks more than it helps.
Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Suggested-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/block/brd.c | 35 -----------------------------------
1 file changed, 35 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 0c76d40..45c998a 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -395,44 +395,9 @@ static long brd_direct_access(struct block_device *bdev, sector_t sector,
#define brd_direct_access NULL
#endif
-static int brd_ioctl(struct block_device *bdev, fmode_t mode,
- unsigned int cmd, unsigned long arg)
-{
- int error;
- struct brd_device *brd = bdev->bd_disk->private_data;
-
- if (cmd != BLKFLSBUF)
- return -ENOTTY;
-
- /*
- * ram device BLKFLSBUF has special semantics, we want to actually
- * release and destroy the ramdisk data.
- */
- mutex_lock(&brd_mutex);
- mutex_lock(&bdev->bd_mutex);
- error = -EBUSY;
- if (bdev->bd_openers <= 1) {
- /*
- * Kill the cache first, so it isn't written back to the
- * device.
- *
- * Another thread might instantiate more buffercache here,
- * but there is not much we can do to close that race.
- */
- kill_bdev(bdev);
- brd_free_pages(brd);
- error = 0;
- }
- mutex_unlock(&bdev->bd_mutex);
- mutex_unlock(&brd_mutex);
-
- return error;
-}
-
static const struct block_device_operations brd_fops = {
.owner = THIS_MODULE,
.rw_page = brd_rw_page,
- .ioctl = brd_ioctl,
.direct_access = brd_direct_access,
};
--
2.8.4 (Apple Git-73)
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