Christoph Hellwig <h...@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 <dmonak...@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---
