block: BLK_PERM_WRITE includes ..._UNCHANGED
Currently we never actually check whether the WRITE_UNCHANGED permission has been taken for unchanging writes. But the one check that is commented out checks both WRITE and WRITE_UNCHANGED; and considering that WRITE_UNCHANGED is already documented as being weaker than WRITE, we should probably explicitly document WRITE to include WRITE_UNCHANGED. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Message-id: 20180421132929.21610-3-mreitz@redhat.com Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
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@ -205,6 +205,9 @@ enum {
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* This permission (which is weaker than BLK_PERM_WRITE) is both enough and
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* This permission (which is weaker than BLK_PERM_WRITE) is both enough and
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* required for writes to the block node when the caller promises that
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* required for writes to the block node when the caller promises that
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* the visible disk content doesn't change.
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* the visible disk content doesn't change.
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*
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* As the BLK_PERM_WRITE permission is strictly stronger, either is
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* sufficient to perform an unchanging write.
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*/
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*/
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BLK_PERM_WRITE_UNCHANGED = 0x04,
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BLK_PERM_WRITE_UNCHANGED = 0x04,
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