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authorMartin K. Petersen2009-12-03 02:24:48 -0600
committerJens Axboe2009-12-03 02:24:48 -0600
commit98262f2762f0067375f83824d81ea929e37e6bfe (patch)
treea26618d5c305eed975501c80cb02bc0f1b6e4524 /block
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>
Diffstat (limited to 'block')
-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
4 files changed, 17 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)
101 lim->discard_granularity = 0; 101 lim->discard_granularity = 0;
102 lim->discard_alignment = 0; 102 lim->discard_alignment = 0;
103 lim->discard_misaligned = 0; 103 lim->discard_misaligned = 0;
104 lim->discard_zeroes_data = -1;
104 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; 105 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
105 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); 106 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
106 lim->alignment_offset = 0; 107 lim->alignment_offset = 0;
@@ -544,6 +545,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
544 545
545 t->io_min = max(t->io_min, b->io_min); 546 t->io_min = max(t->io_min, b->io_min);
546 t->no_cluster |= b->no_cluster; 547 t->no_cluster |= b->no_cluster;
548 t->discard_zeroes_data &= b->discard_zeroes_data;
547 549
548 /* Bottom device offset aligned? */ 550 /* Bottom device offset aligned? */
549 if (offset && 551 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)
136 return queue_var_show(q->limits.max_discard_sectors << 9, page); 136 return queue_var_show(q->limits.max_discard_sectors << 9, page);
137} 137}
138 138
139static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
140{
141 return queue_var_show(queue_discard_zeroes_data(q), page);
142}
143
139static ssize_t 144static ssize_t
140queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) 145queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
141{ 146{
@@ -313,6 +318,11 @@ static struct queue_sysfs_entry queue_discard_max_entry = {
313 .show = queue_discard_max_show, 318 .show = queue_discard_max_show,
314}; 319};
315 320
321static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
322 .attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
323 .show = queue_discard_zeroes_data_show,
324};
325
316static struct queue_sysfs_entry queue_nonrot_entry = { 326static struct queue_sysfs_entry queue_nonrot_entry = {
317 .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR }, 327 .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
318 .show = queue_nonrot_show, 328 .show = queue_nonrot_show,
@@ -350,6 +360,7 @@ static struct attribute *default_attrs[] = {
350 &queue_io_opt_entry.attr, 360 &queue_io_opt_entry.attr,
351 &queue_discard_granularity_entry.attr, 361 &queue_discard_granularity_entry.attr,
352 &queue_discard_max_entry.attr, 362 &queue_discard_max_entry.attr,
363 &queue_discard_zeroes_data_entry.attr,
353 &queue_nonrot_entry.attr, 364 &queue_nonrot_entry.attr,
354 &queue_nomerges_entry.attr, 365 &queue_nomerges_entry.attr,
355 &queue_rq_affinity_entry.attr, 366 &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)
747 return compat_put_uint(arg, bdev_io_opt(bdev)); 747 return compat_put_uint(arg, bdev_io_opt(bdev));
748 case BLKALIGNOFF: 748 case BLKALIGNOFF:
749 return compat_put_int(arg, bdev_alignment_offset(bdev)); 749 return compat_put_int(arg, bdev_alignment_offset(bdev));
750 case BLKDISCARDZEROES:
751 return compat_put_uint(arg, bdev_discard_zeroes_data(bdev));
750 case BLKFLSBUF: 752 case BLKFLSBUF:
751 case BLKROSET: 753 case BLKROSET:
752 case BLKDISCARD: 754 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,
280 return put_uint(arg, bdev_io_opt(bdev)); 280 return put_uint(arg, bdev_io_opt(bdev));
281 case BLKALIGNOFF: 281 case BLKALIGNOFF:
282 return put_int(arg, bdev_alignment_offset(bdev)); 282 return put_int(arg, bdev_alignment_offset(bdev));
283 case BLKDISCARDZEROES:
284 return put_uint(arg, bdev_discard_zeroes_data(bdev));
283 case BLKSECTGET: 285 case BLKSECTGET:
284 return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev))); 286 return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev)));
285 case BLKRASET: 287 case BLKRASET: