018c14911d
When running command pipelining for WRITE direction commands (e.g. tape device write), userspace sends cmd completion to cmd ring before processing write data. In that case userspace has to copy data before sending completion, because cmd completion also implicitly releases the data buffer in data area. The new feature KEEP_BUF allows userspace to optionally keep the buffer after completion by setting new bit TCMU_UFLAG_KEEP_BUF in tcmu_cmd_entry_hdr->uflags. In that case buffer has to be released explicitly by writing the cmd_id to new action item free_kept_buf. All kept buffers are released during reset_ring and if userspace closes uio device (tcmu_release). Link: https://lore.kernel.org/r/20210713175021.20103-1-bostroesser@gmail.com Reviewed-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Bodo Stroesser <bostroesser@gmail.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> |
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| Kbuild | ||