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Subject: [PATCH 4/4] virtio-blk: replace "unmap" with "discard"
Use consistently the same word throughout the description of the discard and write zeroes commands. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- content.tex | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/content.tex b/content.tex index b7d0bea..4240aa1 100644 --- a/content.tex +++ b/content.tex @@ -3598,7 +3598,7 @@ struct virtio_blk_config { le32 discard_sector_alignment; le32 max_write_zeroes_sectors; le32 max_write_zeroes_seg; - u8 write_zeroes_may_unmap; + u8 write_zeroes_may_discard; u8 unused1[3]; }; \end{lstlisting} @@ -3719,7 +3719,7 @@ struct virtio_blk_discard_write_zeroes { le64 sector; le32 num_sectors; struct { - le32 unmap:1; + le32 discard:1; le32 reserved:31; } flags; }; @@ -3745,7 +3745,7 @@ The \field{data} used for discard or write zeroes command is described by one or more virtio_blk_discard_write_zeroes structs. \field{sector} indicates the starting offset (in 512-byte units) of the segment, while \field{num_sectors} indicates the number of sectors in each discarded -range. \field{unmap} is only used for write zeroes command. +range. \field{discard} is only used for write zeroes command. The final \field{status} byte is written by the device: either VIRTIO_BLK_S_OK for success, VIRTIO_BLK_S_IOERR for device or driver @@ -3783,7 +3783,7 @@ switch to writethrough or writeback mode by writing respectively 0 and the driver MUST NOT assume that any volatile writes have been committed to persistent device backend storage. -The \field{unmap} bit MUST be zero for discard commands. The driver +The \field{discard} bit MUST be zero for discard commands. The driver MUST NOT assume anything about the data returned by read requests after a range of sectors has been discarded. @@ -3804,18 +3804,18 @@ write any data. The device MUST set the \field{status} byte to VIRTIO_BLK_S_UNSUPP for discard and write zeroes commands if any unknown flag is set. Furthermore, the device MUST set the \field{status} byte to -VIRTIO_BLK_S_UNSUPP for discard commands if the \field{unmap} flag is set. +VIRTIO_BLK_S_UNSUPP for discard commands if the \field{discard} flag is set. For discard commands, the device MAY deallocate the specified range of sectors in the device backend storage. -For write zeroes commands, if the \field{unmap} is set, the device MAY +For write zeroes commands, if the \field{discard} is set, the device MAY deallocate the specified range of sectors in the device backend storage, as if the DISCARD command had been sent. After a write zeroes command is completed, reads of the specified ranges of sectors MUST return -zeroes. This is true independent of whether \field{unmap} was set or clear. +zeroes. This is true independent of whether \field{discard} was set or clear. -The device SHOULD clear the \field{write_zeroes_may_unmap} field of the +The device SHOULD clear the \field{write_zeroes_may_discard} field of the virtio configuration space if and only if a write zeroes request cannot result in deallocating one or more sectors. The device MAY change the content of the field during operation of the device; when this happens, -- 2.17.1
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