target/file: Add WRITE_SAME w/ UNMAP=0 emulation support

This patch adds support for emulation of WRITE_SAME w/ UNMAP=0 within
fd_execute_write_same() backend code.

The emulation uses vfs_writev() to submit a locally populated buffer
from the received WRITE_SAME scatterlist block for duplication, and by
default enforces a limit of max_write_same_len=0x1000 (8192) sectors up
to the limit of 1024 iovec entries for the single call to vfs_writev().

It also sets max_write_same_len to the operational default at setup ->
fd_configure_device() time.

Tested with 512, 1k, 2k, and 4k block_sizes.

(asias: convert to vzalloc)

Cc: Martin K. Petersen <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Asias He <[email protected]>
Signed-off-by: Nicholas Bellinger <[email protected]>

0 files changed, 0 insertions, 0 deletions