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.
> } 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;
--
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