On 02/26/2013 10:40 AM, Nicholas A. Bellinger wrote:
> On Mon, 2013-02-25 at 14:03 +0800, Asias He wrote:
>> This patch adds support for emulation of WRITE_SAME w/ UNMAP=1 within
>> fd_execute_write_same_unmap() backend code.
>>
>> If the FILEIO backend is normal file, the emulation uses fallocate to
>> punch hole to reclaim the free space used by the file. If the FILEIO
>> backend is block device, the emulation uses blkdev_issue_discard().
>>
>> Tested with 512, 1k, 2k, and 4k block_sizes.
>>
>> Changes in v2:
>> - Set the various dev->dev_attrib.*unmap* values (nab)
>>
>> Cc: Christoph Hellwig <hch@xxxxxx>
>> Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
>> Cc: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>> Signed-off-by: Asias He <asias@xxxxxxxxxx>
>> ---
>> drivers/target/target_core_file.c | 94 ++++++++++++++++++++++++++++++++++++---
>> 1 file changed, 89 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
>> index ca36a38..eafa1bf 100644
>> --- a/drivers/target/target_core_file.c
>> +++ b/drivers/target/target_core_file.c
>> @@ -30,6 +30,7 @@
>> #include <linux/slab.h>
>> #include <linux/spinlock.h>
>> #include <linux/module.h>
>> +#include <linux/falloc.h>
>> #include <scsi/scsi.h>
>> #include <scsi/scsi_host.h>
>>
>> @@ -166,6 +167,30 @@ static int fd_configure_device(struct se_device *dev)
>> " block_device blocks: %llu logical_block_size: %d\n",
>> dev_size, div_u64(dev_size, fd_dev->fd_block_size),
>> fd_dev->fd_block_size);
>> + /*
>> + * Check if the underlying struct block_device request_queue supports
>> + * the QUEUE_FLAG_DISCARD bit for UNMAP/WRITE_SAME in SCSI + TRIM
>> + * in ATA and we need to set TPE=1
>> + */
>> + if (blk_queue_discard(q)) {
>> + dev->dev_attrib.max_unmap_lba_count =
>> + q->limits.max_discard_sectors;
>> + /*
>> + * Currently hardcoded to 1 in Linux/SCSI code..
>> + */
>> + dev->dev_attrib.max_unmap_block_desc_count = 1;
>> + dev->dev_attrib.unmap_granularity =
>> + q->limits.discard_granularity >> 9;
>> + dev->dev_attrib.unmap_granularity_alignment =
>> + q->limits.discard_alignment;
>> + pr_debug("IFILE: BLOCK Discard support available,"
>> + " disabled by default\n");
>> + }
>> + /*
>> + * Enable write same emulation for IBLOCK and use 0xFFFF as
>> + * the smaller WRITE_SAME(10) only has a two-byte block count.
>> + */
>> + dev->dev_attrib.max_write_same_len = 0xFFFF;
>
> Ok, this should still be limited to 0x1000 (same as below) due to the
> vfs_writev() limitiation on number of struct iovecs.
Good catch. Thanks.
>> } else {
>> if (!(fd_dev->fbd_flags & FBDF_HAS_SIZE)) {
>> pr_err("FILEIO: Missing fd_dev_size="
>> @@ -176,6 +201,23 @@ static int fd_configure_device(struct se_device *dev)
>>
>> dev->dev_attrib.hw_block_size = FD_BLOCKSIZE;
>> dev->dev_attrib.hw_max_sectors = FD_MAX_SECTORS;
>> +
>> + /*
>> + * Limit UNMAP emulation to 8k Number of LBAs (NoLB)
>> + */
>> + dev->dev_attrib.max_unmap_lba_count = 0x2000;
>> + /*
>> + * Currently hardcoded to 1 in Linux/SCSI code..
>> + */
>> + dev->dev_attrib.max_unmap_block_desc_count = 1;
>> + dev->dev_attrib.unmap_granularity = 1;
>> + dev->dev_attrib.unmap_granularity_alignment = 0;
>> +
>> + /*
>> + * Limit WRITE_SAME w/ UNMAP=0 emulation to 8k Number of LBAs (NoLB)
>> + * based upon struct iovec limit for vfs_writev()
>> + */
>> + dev->dev_attrib.max_write_same_len = 0x1000;
>> }
>>
>
> Squashing the following into patch #1 in target-pending/queue.
>
> --nab
>
> diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
> index eafa1bf..eb6f16b 100644
> --- a/drivers/target/target_core_file.c
> +++ b/drivers/target/target_core_file.c
> @@ -186,11 +186,6 @@ static int fd_configure_device(struct se_device *dev)
> pr_debug("IFILE: BLOCK Discard support available,"
> " disabled by default\n");
> }
> - /*
> - * Enable write same emulation for IBLOCK and use 0xFFFF as
> - * the smaller WRITE_SAME(10) only has a two-byte block count.
> - */
> - dev->dev_attrib.max_write_same_len = 0xFFFF;
> } else {
> if (!(fd_dev->fbd_flags & FBDF_HAS_SIZE)) {
> pr_err("FILEIO: Missing fd_dev_size="
> @@ -212,13 +207,12 @@ static int fd_configure_device(struct se_device *dev)
> dev->dev_attrib.max_unmap_block_desc_count = 1;
> dev->dev_attrib.unmap_granularity = 1;
> dev->dev_attrib.unmap_granularity_alignment = 0;
> -
> - /*
> - * Limit WRITE_SAME w/ UNMAP=0 emulation to 8k Number of LBAs (NoLB)
> - * based upon struct iovec limit for vfs_writev()
> - */
> - dev->dev_attrib.max_write_same_len = 0x1000;
> }
> + /*
> + * Limit WRITE_SAME w/ UNMAP=0 emulation to 8k Number of LBAs (NoLB)
> + * based upon struct iovec limit for vfs_writev()
> + */
> + dev->dev_attrib.max_write_same_len = 0x1000;
>
> fd_dev->fd_block_size = dev->dev_attrib.hw_block_size;
>
>
>
--
Asias
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