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Groups > linux.kernel > #1617911 > unrolled thread

[PATCH 5/5] block: truncate page cache only when necessary on fallocate

Started byDmitry Monakhov <dmonakhov@openvz.org>
First post2017-04-06 14:10 +0200
Last post2017-04-06 18:00 +0200
Articles 3 — 2 participants

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  [PATCH 5/5] block: truncate page cache only when necessary on fallocate Dmitry Monakhov <dmonakhov@openvz.org> - 2017-04-06 14:10 +0200
    Re: [PATCH 5/5] block: truncate page cache only when necessary on  fallocate Christoph Hellwig <hch@infradead.org> - 2017-04-06 17:50 +0200
      Re: [PATCH 5/5] block: truncate page cache only when necessary on fallocate Dmitry Monakhov <dmonakhov@openvz.org> - 2017-04-06 18:00 +0200

#1617911 — [PATCH 5/5] block: truncate page cache only when necessary on fallocate

FromDmitry Monakhov <dmonakhov@openvz.org>
Date2017-04-06 14:10 +0200
Subject[PATCH 5/5] block: truncate page cache only when necessary on fallocate
Message-ID<tteoG-8jD-19@gated-at.bofh.it>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/block_dev.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 2eca00e..f4b13e1 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -2075,7 +2075,7 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 {
 	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
 	struct request_queue *q = bdev_get_queue(bdev);
-	struct address_space *mapping;
+	struct address_space *mapping = bdev->bd_inode->i_mapping;
 	loff_t end = start + len - 1;
 	loff_t isize;
 	int error;
@@ -2102,13 +2102,10 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 	if ((start | len) & (bdev_logical_block_size(bdev) - 1))
 		return -EINVAL;
 
-	/* Invalidate the page cache, including dirty pages. */
-	mapping = bdev->bd_inode->i_mapping;
-	truncate_inode_pages_range(mapping, start, end);
-
 	switch (mode) {
 	case FALLOC_FL_ZERO_RANGE:
 	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
+		truncate_inode_pages_range(mapping, start, end);
 		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
 					    GFP_KERNEL, false);
 		break;
@@ -2116,12 +2113,14 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 		/* Only punch if the device can do zeroing discard. */
 		if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data)
 			return -EOPNOTSUPP;
+		truncate_inode_pages_range(mapping, start, end);
 		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
 					     GFP_KERNEL, 0);
 		break;
 	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
 		if (!blk_queue_discard(q))
 			return -EOPNOTSUPP;
+		truncate_inode_pages_range(mapping, start, end);
 		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
 					     GFP_KERNEL, 0);
 		break;
-- 
2.9.3

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#1618119 — Re: [PATCH 5/5] block: truncate page cache only when necessary on fallocate

FromChristoph Hellwig <hch@infradead.org>
Date2017-04-06 17:50 +0200
SubjectRe: [PATCH 5/5] block: truncate page cache only when necessary on fallocate
Message-ID<tthPz-2yp-1@gated-at.bofh.it>
In reply to#1617911
why?

On Thu, Apr 06, 2017 at 04:02:49PM +0400, Dmitry Monakhov wrote:
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> ---
>  fs/block_dev.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 2eca00e..f4b13e1 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -2075,7 +2075,7 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
>  {
>  	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
>  	struct request_queue *q = bdev_get_queue(bdev);
> -	struct address_space *mapping;
> +	struct address_space *mapping = bdev->bd_inode->i_mapping;
>  	loff_t end = start + len - 1;
>  	loff_t isize;
>  	int error;
> @@ -2102,13 +2102,10 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
>  	if ((start | len) & (bdev_logical_block_size(bdev) - 1))
>  		return -EINVAL;
>  
> -	/* Invalidate the page cache, including dirty pages. */
> -	mapping = bdev->bd_inode->i_mapping;
> -	truncate_inode_pages_range(mapping, start, end);
> -
>  	switch (mode) {
>  	case FALLOC_FL_ZERO_RANGE:
>  	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
> +		truncate_inode_pages_range(mapping, start, end);
>  		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
>  					    GFP_KERNEL, false);
>  		break;
> @@ -2116,12 +2113,14 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
>  		/* Only punch if the device can do zeroing discard. */
>  		if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data)
>  			return -EOPNOTSUPP;
> +		truncate_inode_pages_range(mapping, start, end);
>  		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
>  					     GFP_KERNEL, 0);
>  		break;
>  	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
>  		if (!blk_queue_discard(q))
>  			return -EOPNOTSUPP;
> +		truncate_inode_pages_range(mapping, start, end);
>  		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
>  					     GFP_KERNEL, 0);
>  		break;
> -- 
> 2.9.3
> 
---end quoted text---

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#1618134

FromDmitry Monakhov <dmonakhov@openvz.org>
Date2017-04-06 18:00 +0200
Message-ID<tthZh-2Gn-27@gated-at.bofh.it>
In reply to#1618119
Christoph Hellwig <hch@infradead.org> writes:

> why?
because it is not good thing to truncate page cache and fiew lines later
realize that feature is not supported !blk_queue_discard(q) and return ENOTSUPP.

Event more:  if mode ==  FALLOC_FL_KEEP_SIZE then we do nothing and
return ENOTSUPP unconditionally.

IMHO (mode ==  FALLOC_FL_KEEP_SIZE) is sane API for thin-provision blkdevs
to preallocate space in advance. Nobody use it at the moment, but it may
be usefull in future.
>
> On Thu, Apr 06, 2017 at 04:02:49PM +0400, Dmitry Monakhov wrote:
>> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
>> ---
>>  fs/block_dev.c | 9 ++++-----
>>  1 file changed, 4 insertions(+), 5 deletions(-)
>> 
>> diff --git a/fs/block_dev.c b/fs/block_dev.c
>> index 2eca00e..f4b13e1 100644
>> --- a/fs/block_dev.c
>> +++ b/fs/block_dev.c
>> @@ -2075,7 +2075,7 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
>>  {
>>  	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
>>  	struct request_queue *q = bdev_get_queue(bdev);
>> -	struct address_space *mapping;
>> +	struct address_space *mapping = bdev->bd_inode->i_mapping;
>>  	loff_t end = start + len - 1;
>>  	loff_t isize;
>>  	int error;
>> @@ -2102,13 +2102,10 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
>>  	if ((start | len) & (bdev_logical_block_size(bdev) - 1))
>>  		return -EINVAL;
>>  
>> -	/* Invalidate the page cache, including dirty pages. */
>> -	mapping = bdev->bd_inode->i_mapping;
>> -	truncate_inode_pages_range(mapping, start, end);
>> -
>>  	switch (mode) {
>>  	case FALLOC_FL_ZERO_RANGE:
>>  	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
>> +		truncate_inode_pages_range(mapping, start, end);
>>  		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
>>  					    GFP_KERNEL, false);
>>  		break;
>> @@ -2116,12 +2113,14 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
>>  		/* Only punch if the device can do zeroing discard. */
>>  		if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data)
>>  			return -EOPNOTSUPP;
>> +		truncate_inode_pages_range(mapping, start, end);
>>  		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
>>  					     GFP_KERNEL, 0);
>>  		break;
>>  	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
>>  		if (!blk_queue_discard(q))
>>  			return -EOPNOTSUPP;
>> +		truncate_inode_pages_range(mapping, start, end);
>>  		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
>>  					     GFP_KERNEL, 0);
>>  		break;
>> -- 
>> 2.9.3
>> 
> ---end quoted text---

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