* [PATCH v2 0/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
@ 2017-10-04 15:03 Ilya Dryomov
2017-10-04 15:03 ` [PATCH v2 1/2] block: factor out __blkdev_issue_zero_pages() Ilya Dryomov
2017-10-04 15:03 ` [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() Ilya Dryomov
0 siblings, 2 replies; 11+ messages in thread
From: Ilya Dryomov @ 2017-10-04 15:03 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Hannes Reinecke, Jens Axboe, linux-block
Hi Christoph, Martin,
blkdev_issue_zeroout() now checks for any error. This required a minor
refactor, so I dropped the stable tag, Jens can add it back if needed.
v1 -> v2:
- changed code flow in blkdev_issue_zeroout() according to Christoph's
suggestion
- this required adding additional checks to blkdev_issue_zeroout() and
__blkdev_issue_zero_pages(), the latter is no longer void
Previous patch(es) and discussion at
https://marc.info/?l=linux-block&m=150471953327942&w=2
https://marc.info/?l=linux-block&m=150601399031909&w=2
Thanks,
Ilya
Ilya Dryomov (2):
block: factor out __blkdev_issue_zero_pages()
block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
block/blk-lib.c | 104 ++++++++++++++++++++++++++++++++++++--------------------
1 file changed, 68 insertions(+), 36 deletions(-)
--
2.4.3
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v2 1/2] block: factor out __blkdev_issue_zero_pages()
2017-10-04 15:03 [PATCH v2 0/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() Ilya Dryomov
@ 2017-10-04 15:03 ` Ilya Dryomov
2017-10-05 17:05 ` Christoph Hellwig
2017-10-04 15:03 ` [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() Ilya Dryomov
1 sibling, 1 reply; 11+ messages in thread
From: Ilya Dryomov @ 2017-10-04 15:03 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Hannes Reinecke, Jens Axboe, linux-block
blkdev_issue_zeroout() will use this in !BLKDEV_ZERO_NOFALLBACK case.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
block/blk-lib.c | 63 +++++++++++++++++++++++++++++++++------------------------
1 file changed, 37 insertions(+), 26 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 62240f8832ca..9d2ab8bba52a 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -274,6 +274,40 @@ static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
return min(pages, (sector_t)BIO_MAX_PAGES);
}
+static int __blkdev_issue_zero_pages(struct block_device *bdev,
+ sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
+ struct bio **biop)
+{
+ struct request_queue *q = bdev_get_queue(bdev);
+ struct bio *bio = *biop;
+ int bi_size = 0;
+ unsigned int sz;
+
+ if (!q)
+ return -ENXIO;
+
+ while (nr_sects != 0) {
+ bio = next_bio(bio, __blkdev_sectors_to_bio_pages(nr_sects),
+ gfp_mask);
+ bio->bi_iter.bi_sector = sector;
+ bio_set_dev(bio, bdev);
+ bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
+
+ while (nr_sects != 0) {
+ sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
+ bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
+ nr_sects -= bi_size >> 9;
+ sector += bi_size >> 9;
+ if (bi_size < sz)
+ break;
+ }
+ cond_resched();
+ }
+
+ *biop = bio;
+ return 0;
+}
+
/**
* __blkdev_issue_zeroout - generate number of zero filed write bios
* @bdev: blockdev to issue
@@ -304,9 +338,6 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
unsigned flags)
{
int ret;
- int bi_size = 0;
- struct bio *bio = *biop;
- unsigned int sz;
sector_t bs_mask;
bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
@@ -316,30 +347,10 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
biop, flags);
if (ret != -EOPNOTSUPP || (flags & BLKDEV_ZERO_NOFALLBACK))
- goto out;
-
- ret = 0;
- while (nr_sects != 0) {
- bio = next_bio(bio, __blkdev_sectors_to_bio_pages(nr_sects),
- gfp_mask);
- bio->bi_iter.bi_sector = sector;
- bio_set_dev(bio, bdev);
- bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
-
- while (nr_sects != 0) {
- sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
- bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
- nr_sects -= bi_size >> 9;
- sector += bi_size >> 9;
- if (bi_size < sz)
- break;
- }
- cond_resched();
- }
+ return ret;
- *biop = bio;
-out:
- return ret;
+ return __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
+ biop);
}
EXPORT_SYMBOL(__blkdev_issue_zeroout);
--
2.4.3
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-04 15:03 [PATCH v2 0/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() Ilya Dryomov
2017-10-04 15:03 ` [PATCH v2 1/2] block: factor out __blkdev_issue_zero_pages() Ilya Dryomov
@ 2017-10-04 15:03 ` Ilya Dryomov
2017-10-05 17:13 ` Christoph Hellwig
1 sibling, 1 reply; 11+ messages in thread
From: Ilya Dryomov @ 2017-10-04 15:03 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Hannes Reinecke, Jens Axboe, linux-block
sd_config_write_same() ignores ->max_ws_blocks == 0 and resets it to
permit trying WRITE SAME on older SCSI devices, unless ->no_write_same
is set. Because REQ_OP_WRITE_ZEROES is implemented in terms of WRITE
SAME, blkdev_issue_zeroout() may fail with -EREMOTEIO:
$ fallocate -zn -l 1k /dev/sdg
fallocate: fallocate failed: Remote I/O error
$ fallocate -zn -l 1k /dev/sdg # OK
$ fallocate -zn -l 1k /dev/sdg # OK
The following calls succeed because sd_done() sets ->no_write_same in
response to a sense that would become BLK_STS_TARGET/-EREMOTEIO, causing
__blkdev_issue_zeroout() to fall back to generating ZERO_PAGE bios.
This means blkdev_issue_zeroout() must cope with WRITE ZEROES failing
and fall back to manually zeroing, unless BLKDEV_ZERO_NOFALLBACK is
specified. For BLKDEV_ZERO_NOFALLBACK case, return -EOPNOTSUPP if
sd_done() has just set ->no_write_same thus indicating lack of offload
support.
Fixes: c20cfc27a473 ("block: stop using blkdev_issue_write_same for zeroing")
Cc: Christoph Hellwig <hch@lst.de>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
block/blk-lib.c | 41 +++++++++++++++++++++++++++++++----------
1 file changed, 31 insertions(+), 10 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 9d2ab8bba52a..17494275673e 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -321,12 +321,6 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev,
* Zero-fill a block range, either using hardware offload or by explicitly
* writing zeroes to the device.
*
- * Note that this function may fail with -EOPNOTSUPP if the driver signals
- * zeroing offload support, but the device fails to process the command (for
- * some devices there is no non-destructive way to verify whether this
- * operation is actually supported). In this case the caller should call
- * retry the call to blkdev_issue_zeroout() and the fallback path will be used.
- *
* If a device is using logical block provisioning, the underlying space will
* not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
*
@@ -370,18 +364,45 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout);
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
{
- int ret;
- struct bio *bio = NULL;
+ int ret = 0;
+ sector_t bs_mask;
+ struct bio *bio;
struct blk_plug plug;
+ bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
+
+ bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
+ if ((sector | nr_sects) & bs_mask)
+ return -EINVAL;
+retry:
+ bio = NULL;
blk_start_plug(&plug);
- ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
- &bio, flags);
+ if (try_write_zeroes) {
+ ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
+ gfp_mask, &bio, flags);
+ } else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
+ ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
+ gfp_mask, &bio);
+ } else if (!bdev_write_zeroes_sectors(bdev)) {
+ /*
+ * Manual zeroout is not allowed and either:
+ * - no zeroing offload support
+ * - zeroing offload support was indicated, but the device
+ * reported ILLEGAL REQUEST (for some devices there is no
+ * non-destructive way to verify whether WRITE ZEROES is
+ * actually supported)
+ */
+ ret = -EOPNOTSUPP;
+ }
if (ret == 0 && bio) {
ret = submit_bio_wait(bio);
bio_put(bio);
}
blk_finish_plug(&plug);
+ if (ret && try_write_zeroes) {
+ try_write_zeroes = false;
+ goto retry;
+ }
return ret;
}
--
2.4.3
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH v2 1/2] block: factor out __blkdev_issue_zero_pages()
2017-10-04 15:03 ` [PATCH v2 1/2] block: factor out __blkdev_issue_zero_pages() Ilya Dryomov
@ 2017-10-05 17:05 ` Christoph Hellwig
0 siblings, 0 replies; 11+ messages in thread
From: Christoph Hellwig @ 2017-10-05 17:05 UTC (permalink / raw)
To: Ilya Dryomov
Cc: Christoph Hellwig, Martin K. Petersen, Hannes Reinecke,
Jens Axboe, linux-block
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-04 15:03 ` [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() Ilya Dryomov
@ 2017-10-05 17:13 ` Christoph Hellwig
2017-10-05 19:32 ` Ilya Dryomov
0 siblings, 1 reply; 11+ messages in thread
From: Christoph Hellwig @ 2017-10-05 17:13 UTC (permalink / raw)
To: Ilya Dryomov
Cc: Christoph Hellwig, Martin K. Petersen, Hannes Reinecke,
Jens Axboe, linux-block
On Wed, Oct 04, 2017 at 05:03:16PM +0200, Ilya Dryomov wrote:
> sd_config_write_same() ignores ->max_ws_blocks == 0 and resets it to
> permit trying WRITE SAME on older SCSI devices, unless ->no_write_same
> is set. Because REQ_OP_WRITE_ZEROES is implemented in terms of WRITE
> SAME, blkdev_issue_zeroout() may fail with -EREMOTEIO:
>
> $ fallocate -zn -l 1k /dev/sdg
> fallocate: fallocate failed: Remote I/O error
> $ fallocate -zn -l 1k /dev/sdg # OK
> $ fallocate -zn -l 1k /dev/sdg # OK
Can we wire this up for blktests somehow?
>
> The following calls succeed because sd_done() sets ->no_write_same in
> response to a sense that would become BLK_STS_TARGET/-EREMOTEIO, causing
> __blkdev_issue_zeroout() to fall back to generating ZERO_PAGE bios.
>
> This means blkdev_issue_zeroout() must cope with WRITE ZEROES failing
> and fall back to manually zeroing, unless BLKDEV_ZERO_NOFALLBACK is
> specified. For BLKDEV_ZERO_NOFALLBACK case, return -EOPNOTSUPP if
> sd_done() has just set ->no_write_same thus indicating lack of offload
> support.
>
> Fixes: c20cfc27a473 ("block: stop using blkdev_issue_write_same for zeroing")
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> Cc: Hannes Reinecke <hare@suse.com>
> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
> ---
> block/blk-lib.c | 41 +++++++++++++++++++++++++++++++----------
> 1 file changed, 31 insertions(+), 10 deletions(-)
>
> diff --git a/block/blk-lib.c b/block/blk-lib.c
> index 9d2ab8bba52a..17494275673e 100644
> --- a/block/blk-lib.c
> +++ b/block/blk-lib.c
> @@ -321,12 +321,6 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev,
> * Zero-fill a block range, either using hardware offload or by explicitly
> * writing zeroes to the device.
> *
> - * Note that this function may fail with -EOPNOTSUPP if the driver signals
> - * zeroing offload support, but the device fails to process the command (for
> - * some devices there is no non-destructive way to verify whether this
> - * operation is actually supported). In this case the caller should call
> - * retry the call to blkdev_issue_zeroout() and the fallback path will be used.
> - *
> * If a device is using logical block provisioning, the underlying space will
> * not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
> *
> @@ -370,18 +364,45 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout);
> int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
> sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
> {
> - int ret;
> - struct bio *bio = NULL;
> + int ret = 0;
> + sector_t bs_mask;
> + struct bio *bio;
> struct blk_plug plug;
> + bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
> +
> + bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
> + if ((sector | nr_sects) & bs_mask)
> + return -EINVAL;
>
> +retry:
> + bio = NULL;
> blk_start_plug(&plug);
> - ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
> - &bio, flags);
> + if (try_write_zeroes) {
> + ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
> + gfp_mask, &bio, flags);
> + } else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
> + ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
> + gfp_mask, &bio);
> + } else if (!bdev_write_zeroes_sectors(bdev)) {
> + /*
> + * Manual zeroout is not allowed and either:
> + * - no zeroing offload support
> + * - zeroing offload support was indicated, but the device
> + * reported ILLEGAL REQUEST (for some devices there is no
> + * non-destructive way to verify whether WRITE ZEROES is
> + * actually supported)
> + */
> + ret = -EOPNOTSUPP;
I don't understand the conditional above this error return - if
we can't zero using either method we should always return an error.
Except for that the patch looks fine.
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-05 17:13 ` Christoph Hellwig
@ 2017-10-05 19:32 ` Ilya Dryomov
2017-10-06 12:05 ` Christoph Hellwig
0 siblings, 1 reply; 11+ messages in thread
From: Ilya Dryomov @ 2017-10-05 19:32 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Hannes Reinecke, Jens Axboe, linux-block
On Thu, Oct 5, 2017 at 7:13 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Wed, Oct 04, 2017 at 05:03:16PM +0200, Ilya Dryomov wrote:
>> sd_config_write_same() ignores ->max_ws_blocks == 0 and resets it to
>> permit trying WRITE SAME on older SCSI devices, unless ->no_write_same
>> is set. Because REQ_OP_WRITE_ZEROES is implemented in terms of WRITE
>> SAME, blkdev_issue_zeroout() may fail with -EREMOTEIO:
>>
>> $ fallocate -zn -l 1k /dev/sdg
>> fallocate: fallocate failed: Remote I/O error
>> $ fallocate -zn -l 1k /dev/sdg # OK
>> $ fallocate -zn -l 1k /dev/sdg # OK
>
> Can we wire this up for blktests somehow?
This is covered by Darrick's generic/351, part of fstests blockdev
group.
>
>>
>> The following calls succeed because sd_done() sets ->no_write_same in
>> response to a sense that would become BLK_STS_TARGET/-EREMOTEIO, causing
>> __blkdev_issue_zeroout() to fall back to generating ZERO_PAGE bios.
>>
>> This means blkdev_issue_zeroout() must cope with WRITE ZEROES failing
>> and fall back to manually zeroing, unless BLKDEV_ZERO_NOFALLBACK is
>> specified. For BLKDEV_ZERO_NOFALLBACK case, return -EOPNOTSUPP if
>> sd_done() has just set ->no_write_same thus indicating lack of offload
>> support.
>>
>> Fixes: c20cfc27a473 ("block: stop using blkdev_issue_write_same for zeroing")
>> Cc: Christoph Hellwig <hch@lst.de>
>> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
>> Cc: Hannes Reinecke <hare@suse.com>
>> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
>> ---
>> block/blk-lib.c | 41 +++++++++++++++++++++++++++++++----------
>> 1 file changed, 31 insertions(+), 10 deletions(-)
>>
>> diff --git a/block/blk-lib.c b/block/blk-lib.c
>> index 9d2ab8bba52a..17494275673e 100644
>> --- a/block/blk-lib.c
>> +++ b/block/blk-lib.c
>> @@ -321,12 +321,6 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev,
>> * Zero-fill a block range, either using hardware offload or by explicitly
>> * writing zeroes to the device.
>> *
>> - * Note that this function may fail with -EOPNOTSUPP if the driver signals
>> - * zeroing offload support, but the device fails to process the command (for
>> - * some devices there is no non-destructive way to verify whether this
>> - * operation is actually supported). In this case the caller should call
>> - * retry the call to blkdev_issue_zeroout() and the fallback path will be used.
>> - *
>> * If a device is using logical block provisioning, the underlying space will
>> * not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
>> *
>> @@ -370,18 +364,45 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout);
>> int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
>> sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
>> {
>> - int ret;
>> - struct bio *bio = NULL;
>> + int ret = 0;
>> + sector_t bs_mask;
>> + struct bio *bio;
>> struct blk_plug plug;
>> + bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
>> +
>> + bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
>> + if ((sector | nr_sects) & bs_mask)
>> + return -EINVAL;
>>
>> +retry:
>> + bio = NULL;
>> blk_start_plug(&plug);
>> - ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
>> - &bio, flags);
>> + if (try_write_zeroes) {
>> + ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
>> + gfp_mask, &bio, flags);
>> + } else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
>> + ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
>> + gfp_mask, &bio);
>> + } else if (!bdev_write_zeroes_sectors(bdev)) {
>> + /*
>> + * Manual zeroout is not allowed and either:
>> + * - no zeroing offload support
>> + * - zeroing offload support was indicated, but the device
>> + * reported ILLEGAL REQUEST (for some devices there is no
>> + * non-destructive way to verify whether WRITE ZEROES is
>> + * actually supported)
>> + */
>> + ret = -EOPNOTSUPP;
>
> I don't understand the conditional above this error return - if
> we can't zero using either method we should always return an error.
This is to avoid returning -EREMOTEIO in the following case: device
doesn't support WRITE SAME but scsi_disk::max_ws_blocks != 0, zeroout
is called with BLKDEV_ZERO_NOFALLBACK. Enter blkdev_issue_zeroout(),
bdev_write_zeroes_sectors() != 0, so we issue WRITE ZEROES. The
request fails with ILLEGAL REQUEST, sd_done() sets ->no_write_same and
updates queue_limits, ILLEGAL REQUEST is translated into -EREMOTEIO,
which is returned from submit_bio_wait(). Manual zeroing is not
allowed, so we must return an error, but it shouldn't be -EREMOTEIO if
queue_limits just got updated because of ILLEGAL REQUEST. Without this
conditional, we'd get
$ fallocate -pn -l 1k /dev/sdg
fallocate: fallocate failed: Remote I/O error
$ fallocate -pn -l 1k /dev/sdg # -EOPNOTSUPP
fallocate: keep size mode (-n option) unsupported
$ fallocate -pn -l 1k /dev/sdg # -EOPNOTSUPP
fallocate: keep size mode (-n option) unsupported
I tried to explain this between the comment and the commit message.
Basically, just mopping up after sd_config_write_same().
Thanks,
Ilya
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-05 19:32 ` Ilya Dryomov
@ 2017-10-06 12:05 ` Christoph Hellwig
2017-10-06 12:31 ` Ilya Dryomov
0 siblings, 1 reply; 11+ messages in thread
From: Christoph Hellwig @ 2017-10-06 12:05 UTC (permalink / raw)
To: Ilya Dryomov
Cc: Christoph Hellwig, Martin K. Petersen, Hannes Reinecke,
Jens Axboe, linux-block
On Thu, Oct 05, 2017 at 09:32:33PM +0200, Ilya Dryomov wrote:
> This is to avoid returning -EREMOTEIO in the following case: device
> doesn't support WRITE SAME but scsi_disk::max_ws_blocks != 0, zeroout
> is called with BLKDEV_ZERO_NOFALLBACK. Enter blkdev_issue_zeroout(),
> bdev_write_zeroes_sectors() != 0, so we issue WRITE ZEROES. The
> request fails with ILLEGAL REQUEST, sd_done() sets ->no_write_same and
> updates queue_limits, ILLEGAL REQUEST is translated into -EREMOTEIO,
> which is returned from submit_bio_wait(). Manual zeroing is not
> allowed, so we must return an error, but it shouldn't be -EREMOTEIO if
> queue_limits just got updated because of ILLEGAL REQUEST. Without this
> conditional, we'd get
Hmm. I think we'd better off to just do the before the retry loop:
if (ret && try_write_zeroes) {
if (!(flags & BLKDEV_ZERO_NOFALLBACK))
try_write_zeroes = false;
goto retry;
}
ret = -EOPNOTSUPP;
}
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-06 12:05 ` Christoph Hellwig
@ 2017-10-06 12:31 ` Ilya Dryomov
2017-10-16 8:17 ` Ilya Dryomov
2017-10-16 11:44 ` Christoph Hellwig
0 siblings, 2 replies; 11+ messages in thread
From: Ilya Dryomov @ 2017-10-06 12:31 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Hannes Reinecke, Jens Axboe, linux-block
On Fri, Oct 6, 2017 at 2:05 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Thu, Oct 05, 2017 at 09:32:33PM +0200, Ilya Dryomov wrote:
>> This is to avoid returning -EREMOTEIO in the following case: device
>> doesn't support WRITE SAME but scsi_disk::max_ws_blocks != 0, zeroout
>> is called with BLKDEV_ZERO_NOFALLBACK. Enter blkdev_issue_zeroout(),
>> bdev_write_zeroes_sectors() != 0, so we issue WRITE ZEROES. The
>> request fails with ILLEGAL REQUEST, sd_done() sets ->no_write_same and
>> updates queue_limits, ILLEGAL REQUEST is translated into -EREMOTEIO,
>> which is returned from submit_bio_wait(). Manual zeroing is not
>> allowed, so we must return an error, but it shouldn't be -EREMOTEIO if
>> queue_limits just got updated because of ILLEGAL REQUEST. Without this
>> conditional, we'd get
>
> Hmm. I think we'd better off to just do the before the retry loop:
>
> if (ret && try_write_zeroes) {
> if (!(flags & BLKDEV_ZERO_NOFALLBACK))
> try_write_zeroes = false;
> goto retry;
> }
> ret = -EOPNOTSUPP;
> }
This would unconditionally overwrite any WRITE ZEROS error. If we get
e.g. -EIO, and manual zeroing is not allowed, I don't think we want to
return -EOPNOTSUPP?
Returning -EOPNOTSUPP to mean "can't zero using either method" doesn't
make sense to me, because manual zeroing is always supported, just not
always allowed.
Thanks,
Ilya
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-06 12:31 ` Ilya Dryomov
@ 2017-10-16 8:17 ` Ilya Dryomov
2017-10-16 11:44 ` Christoph Hellwig
1 sibling, 0 replies; 11+ messages in thread
From: Ilya Dryomov @ 2017-10-16 8:17 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Hannes Reinecke, Jens Axboe, linux-block
On Fri, Oct 6, 2017 at 2:31 PM, Ilya Dryomov <idryomov@gmail.com> wrote:
> On Fri, Oct 6, 2017 at 2:05 PM, Christoph Hellwig <hch@infradead.org> wrote:
>> On Thu, Oct 05, 2017 at 09:32:33PM +0200, Ilya Dryomov wrote:
>>> This is to avoid returning -EREMOTEIO in the following case: device
>>> doesn't support WRITE SAME but scsi_disk::max_ws_blocks != 0, zeroout
>>> is called with BLKDEV_ZERO_NOFALLBACK. Enter blkdev_issue_zeroout(),
>>> bdev_write_zeroes_sectors() != 0, so we issue WRITE ZEROES. The
>>> request fails with ILLEGAL REQUEST, sd_done() sets ->no_write_same and
>>> updates queue_limits, ILLEGAL REQUEST is translated into -EREMOTEIO,
>>> which is returned from submit_bio_wait(). Manual zeroing is not
>>> allowed, so we must return an error, but it shouldn't be -EREMOTEIO if
>>> queue_limits just got updated because of ILLEGAL REQUEST. Without this
>>> conditional, we'd get
>>
>> Hmm. I think we'd better off to just do the before the retry loop:
>>
>> if (ret && try_write_zeroes) {
>> if (!(flags & BLKDEV_ZERO_NOFALLBACK))
>> try_write_zeroes = false;
>> goto retry;
>> }
>> ret = -EOPNOTSUPP;
>> }
>
> This would unconditionally overwrite any WRITE ZEROS error. If we get
> e.g. -EIO, and manual zeroing is not allowed, I don't think we want to
> return -EOPNOTSUPP?
>
> Returning -EOPNOTSUPP to mean "can't zero using either method" doesn't
> make sense to me, because manual zeroing is always supported, just not
> always allowed.
Ping...
Thanks,
Ilya
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-06 12:31 ` Ilya Dryomov
2017-10-16 8:17 ` Ilya Dryomov
@ 2017-10-16 11:44 ` Christoph Hellwig
2017-10-16 14:03 ` Ilya Dryomov
1 sibling, 1 reply; 11+ messages in thread
From: Christoph Hellwig @ 2017-10-16 11:44 UTC (permalink / raw)
To: Ilya Dryomov
Cc: Christoph Hellwig, Martin K. Petersen, Hannes Reinecke,
Jens Axboe, linux-block
On Fri, Oct 06, 2017 at 02:31:20PM +0200, Ilya Dryomov wrote:
> This would unconditionally overwrite any WRITE ZEROS error. If we get
> e.g. -EIO, and manual zeroing is not allowed, I don't think we want to
> return -EOPNOTSUPP?
>
> Returning -EOPNOTSUPP to mean "can't zero using either method" doesn't
> make sense to me, because manual zeroing is always supported, just not
> always allowed.
Then thow the throw bdev_write_zeroes_sectors check back in:
if (ret && try_write_zeroes) {
if (!(flags & BLKDEV_ZERO_NOFALLBACK))
try_write_zeroes = false;
goto retry;
}
if (!bdev_write_zeroes_sectors(bdev))
ret = -EOPNOTSUPP;
}
The important bit is that the structure in the current patch where the
bdev_write_zeroes_sectors check is on the same level as the method
selection is extremely confusing.
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
2017-10-16 11:44 ` Christoph Hellwig
@ 2017-10-16 14:03 ` Ilya Dryomov
0 siblings, 0 replies; 11+ messages in thread
From: Ilya Dryomov @ 2017-10-16 14:03 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Hannes Reinecke, Jens Axboe, linux-block
On Mon, Oct 16, 2017 at 1:44 PM, Christoph Hellwig <hch@infradead.org> wrote:
> On Fri, Oct 06, 2017 at 02:31:20PM +0200, Ilya Dryomov wrote:
>> This would unconditionally overwrite any WRITE ZEROS error. If we get
>> e.g. -EIO, and manual zeroing is not allowed, I don't think we want to
>> return -EOPNOTSUPP?
>>
>> Returning -EOPNOTSUPP to mean "can't zero using either method" doesn't
>> make sense to me, because manual zeroing is always supported, just not
>> always allowed.
>
> Then thow the throw bdev_write_zeroes_sectors check back in:
>
> if (ret && try_write_zeroes) {
> if (!(flags & BLKDEV_ZERO_NOFALLBACK))
> try_write_zeroes = false;
> goto retry;
> }
> if (!bdev_write_zeroes_sectors(bdev))
> ret = -EOPNOTSUPP;
> }
>
> The important bit is that the structure in the current patch where the
> bdev_write_zeroes_sectors check is on the same level as the method
> selection is extremely confusing.
I see. An updated version should be in your inbox.
Thanks,
Ilya
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2017-10-16 14:03 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-10-04 15:03 [PATCH v2 0/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() Ilya Dryomov
2017-10-04 15:03 ` [PATCH v2 1/2] block: factor out __blkdev_issue_zero_pages() Ilya Dryomov
2017-10-05 17:05 ` Christoph Hellwig
2017-10-04 15:03 ` [PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() Ilya Dryomov
2017-10-05 17:13 ` Christoph Hellwig
2017-10-05 19:32 ` Ilya Dryomov
2017-10-06 12:05 ` Christoph Hellwig
2017-10-06 12:31 ` Ilya Dryomov
2017-10-16 8:17 ` Ilya Dryomov
2017-10-16 11:44 ` Christoph Hellwig
2017-10-16 14:03 ` Ilya Dryomov
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