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authorMartin K. Petersen <martin.petersen@oracle.com>2009-12-03 09:24:48 +0100
committerJens Axboe <jens.axboe@oracle.com>2009-12-03 09:24:48 +0100
commit98262f2762f0067375f83824d81ea929e37e6bfe (patch)
treea26618d5c305eed975501c80cb02bc0f1b6e4524
parent464191c65b85a8ec68a6e1a6293af625287c807e (diff)
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block: Allow devices to indicate whether discarded blocks are zeroed
The discard ioctl is used by mkfs utilities to clear a block device prior to putting metadata down. However, not all devices return zeroed blocks after a discard. Some drives return stale data, potentially containing old superblocks. It is therefore important to know whether discarded blocks are properly zeroed. Both ATA and SCSI drives have configuration bits that indicate whether zeroes are returned after a discard operation. Implement a block level interface that allows this information to be bubbled up the stack and queried via a new block device ioctl. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
-rw-r--r--block/blk-settings.c2
-rw-r--r--block/blk-sysfs.c11
-rw-r--r--block/compat_ioctl.c2
-rw-r--r--block/ioctl.c2
-rw-r--r--include/linux/blkdev.h14
-rw-r--r--include/linux/fs.h1
6 files changed, 32 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 1ebc1fdb914..dd1f1e0e196 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -101,6 +101,7 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->discard_granularity = 0;
lim->discard_alignment = 0;
lim->discard_misaligned = 0;
+ lim->discard_zeroes_data = -1;
lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
lim->alignment_offset = 0;
@@ -544,6 +545,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
t->io_min = max(t->io_min, b->io_min);
t->no_cluster |= b->no_cluster;
+ t->discard_zeroes_data &= b->discard_zeroes_data;
/* Bottom device offset aligned? */
if (offset &&
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 3147145edc1..8606c9543fd 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -136,6 +136,11 @@ static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
return queue_var_show(q->limits.max_discard_sectors << 9, page);
}
+static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
+{
+ return queue_var_show(queue_discard_zeroes_data(q), page);
+}
+
static ssize_t
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
@@ -313,6 +318,11 @@ static struct queue_sysfs_entry queue_discard_max_entry = {
.show = queue_discard_max_show,
};
+static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
+ .attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
+ .show = queue_discard_zeroes_data_show,
+};
+
static struct queue_sysfs_entry queue_nonrot_entry = {
.attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
.show = queue_nonrot_show,
@@ -350,6 +360,7 @@ static struct attribute *default_attrs[] = {
&queue_io_opt_entry.attr,
&queue_discard_granularity_entry.attr,
&queue_discard_max_entry.attr,
+ &queue_discard_zeroes_data_entry.attr,
&queue_nonrot_entry.attr,
&queue_nomerges_entry.attr,
&queue_rq_affinity_entry.attr,
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 9bd086c1a4d..4eb8e9ea4af 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -747,6 +747,8 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
return compat_put_uint(arg, bdev_io_opt(bdev));
case BLKALIGNOFF:
return compat_put_int(arg, bdev_alignment_offset(bdev));
+ case BLKDISCARDZEROES:
+ return compat_put_uint(arg, bdev_discard_zeroes_data(bdev));
case BLKFLSBUF:
case BLKROSET:
case BLKDISCARD:
diff --git a/block/ioctl.c b/block/ioctl.c
index 1f4d1de12b0..be48ea51fae 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -280,6 +280,8 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
return put_uint(arg, bdev_io_opt(bdev));
case BLKALIGNOFF:
return put_int(arg, bdev_alignment_offset(bdev));
+ case BLKDISCARDZEROES:
+ return put_uint(arg, bdev_discard_zeroes_data(bdev));
case BLKSECTGET:
return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev)));
case BLKRASET:
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e727f6c44c4..784a919aa0d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -322,6 +322,7 @@ struct queue_limits {
unsigned char misaligned;
unsigned char discard_misaligned;
unsigned char no_cluster;
+ signed char discard_zeroes_data;
};
struct request_queue
@@ -1150,6 +1151,19 @@ static inline int queue_sector_discard_alignment(struct request_queue *q,
& (q->limits.discard_granularity - 1);
}
+static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
+{
+ if (q->limits.discard_zeroes_data == 1)
+ return 1;
+
+ return 0;
+}
+
+static inline unsigned int bdev_discard_zeroes_data(struct block_device *bdev)
+{
+ return queue_discard_zeroes_data(bdev_get_queue(bdev));
+}
+
static inline int queue_dma_alignment(struct request_queue *q)
{
return q ? q->dma_alignment : 511;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 79cea805173..891f7d642e5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -304,6 +304,7 @@ struct inodes_stat_t {
#define BLKIOOPT _IO(0x12,121)
#define BLKALIGNOFF _IO(0x12,122)
#define BLKPBSZGET _IO(0x12,123)
+#define BLKDISCARDZEROES _IO(0x12,124)
#define BMAP_IOCTL 1 /* obsolete - kept for compatibility */
#define FIBMAP _IO(0x00,1) /* bmap access */