Discarding can take very long time for some device mapper targets, this
patch makes it possible to kill a process that issues the BLKDISCARD
ioctl.
Note that some filesystems call blkdev_issue_discard or
__blkdev_issue_discard directly, they may not be prepared to handle the
failure, so this patch introduces a flag BLKDEV_DISCARD_KILLABLE that is
only set when the discard is initiated by an ioctl.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
block/blk-lib.c | 13 +++++++++++--
block/ioctl.c | 4 ++--
include/linux/blkdev.h | 1 +
3 files changed, 14 insertions(+), 4 deletions(-)
Index: linux-2.6/block/blk-lib.c
===================================================================
--- linux-2.6.orig/block/blk-lib.c 2018-06-29 20:10:55.540000000 +0200
+++ linux-2.6/block/blk-lib.c 2018-06-29 23:12:24.520000000 +0200
@@ -7,6 +7,7 @@
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/scatterlist.h>
+#include <linux/sched/signal.h>
#include "blk.h"
@@ -33,6 +34,7 @@ int __blkdev_issue_discard(struct block_
unsigned int op;
int alignment;
sector_t bs_mask;
+ int r;
if (!q)
return -ENXIO;
@@ -68,8 +70,10 @@ int __blkdev_issue_discard(struct block_
*/
req_sects = min_t(sector_t, nr_sects,
q->limits.max_discard_sectors);
- if (!req_sects)
+ if (!req_sects) {
+ r = -EOPNOTSUPP;
goto fail;
+ }
if (req_sects > UINT_MAX >> 9)
req_sects = UINT_MAX >> 9;
@@ -96,6 +100,11 @@ int __blkdev_issue_discard(struct block_
nr_sects -= req_sects;
sector = end_sect;
+ if (flags & BLKDEV_DISCARD_KILLABLE && fatal_signal_pending(current)) {
+ r = -EINTR;
+ goto fail;
+ }
+
/*
* We can loop for a long time in here, if someone does
* full device discards (like mkfs). Be nice and allow
@@ -114,7 +123,7 @@ fail:
bio_put(bio);
}
*biop = NULL;
- return -EOPNOTSUPP;
+ return r;
}
EXPORT_SYMBOL(__blkdev_issue_discard);
Index: linux-2.6/block/ioctl.c
===================================================================
--- linux-2.6.orig/block/ioctl.c 2018-05-31 18:04:38.068000000 +0200
+++ linux-2.6/block/ioctl.c 2018-06-29 23:06:07.180000000 +0200
@@ -522,10 +522,10 @@ int blkdev_ioctl(struct block_device *bd
case BLKROSET:
return blkdev_roset(bdev, mode, cmd, arg);
case BLKDISCARD:
- return blk_ioctl_discard(bdev, mode, arg, 0);
+ return blk_ioctl_discard(bdev, mode, arg, BLKDEV_DISCARD_KILLABLE);
case BLKSECDISCARD:
return blk_ioctl_discard(bdev, mode, arg,
- BLKDEV_DISCARD_SECURE);
+ BLKDEV_DISCARD_SECURE | BLKDEV_DISCARD_KILLABLE);
case BLKZEROOUT:
return blk_ioctl_zeroout(bdev, mode, arg);
case BLKREPORTZONE:
Index: linux-2.6/include/linux/blkdev.h
===================================================================
--- linux-2.6.orig/include/linux/blkdev.h 2018-06-18 01:09:22.040000000 +0200
+++ linux-2.6/include/linux/blkdev.h 2018-06-29 23:09:50.010000000 +0200
@@ -1390,6 +1390,7 @@ extern int blkdev_issue_write_same(struc
sector_t nr_sects, gfp_t gfp_mask, struct page *page);
#define BLKDEV_DISCARD_SECURE (1 << 0) /* issue a secure erase */
+#define BLKDEV_DISCARD_KILLABLE (1 << 1) /* allow killing the process */
extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
--
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