diff options
Diffstat (limited to 'include/xen/interface/io/blkif.h')
| -rw-r--r-- | include/xen/interface/io/blkif.h | 72 |
1 files changed, 67 insertions, 5 deletions
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h index 3d5d6db864f..ee338bfde18 100644 --- a/include/xen/interface/io/blkif.h +++ b/include/xen/interface/io/blkif.h @@ -57,6 +57,51 @@ typedef uint64_t blkif_sector_t; * "feature-flush-cache" node! */ #define BLKIF_OP_FLUSH_DISKCACHE 3 + +/* + * Recognised only if "feature-discard" is present in backend xenbus info. + * The "feature-discard" node contains a boolean indicating whether trim + * (ATA) or unmap (SCSI) - conviently called discard requests are likely + * to succeed or fail. Either way, a discard request + * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by + * the underlying block-device hardware. The boolean simply indicates whether + * or not it is worthwhile for the frontend to attempt discard requests. + * If a backend does not recognise BLKIF_OP_DISCARD, it should *not* + * create the "feature-discard" node! + * + * Discard operation is a request for the underlying block device to mark + * extents to be erased. However, discard does not guarantee that the blocks + * will be erased from the device - it is just a hint to the device + * controller that these blocks are no longer in use. What the device + * controller does with that information is left to the controller. + * Discard operations are passed with sector_number as the + * sector index to begin discard operations at and nr_sectors as the number of + * sectors to be discarded. The specified sectors should be discarded if the + * underlying block device supports trim (ATA) or unmap (SCSI) operations, + * or a BLKIF_RSP_EOPNOTSUPP should be returned. + * More information about trim/unmap operations at: + * http://t13.org/Documents/UploadedDocuments/docs2008/ + * e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc + * http://www.seagate.com/staticfiles/support/disc/manuals/ + * Interface%20manuals/100293068c.pdf + * The backend can optionally provide three extra XenBus attributes to + * further optimize the discard functionality: + * 'discard-aligment' - Devices that support discard functionality may + * internally allocate space in units that are bigger than the exported + * logical block size. The discard-alignment parameter indicates how many bytes + * the beginning of the partition is offset from the internal allocation unit's + * natural alignment. + * 'discard-granularity' - Devices that support discard functionality may + * internally allocate space using units that are bigger than the logical block + * size. The discard-granularity parameter indicates the size of the internal + * allocation unit in bytes if reported by the device. Otherwise the + * discard-granularity will be set to match the device's physical block size. + * 'discard-secure' - All copies of the discarded sectors (potentially created + * by garbage collection) must also be erased. To use this feature, the flag + * BLKIF_DISCARD_SECURE must be set in the blkif_request_trim. + */ +#define BLKIF_OP_DISCARD 5 + /* * Maximum scatter/gather segments per request. * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE. @@ -65,6 +110,12 @@ typedef uint64_t blkif_sector_t; #define BLKIF_MAX_SEGMENTS_PER_REQUEST 11 struct blkif_request_rw { + uint8_t nr_segments; /* number of segments */ + blkif_vdev_t handle; /* only for read/write requests */ +#ifdef CONFIG_X86_64 + uint32_t _pad1; /* offsetof(blkif_request,u.rw.id) == 8 */ +#endif + uint64_t id; /* private guest value, echoed in resp */ blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ struct blkif_request_segment { grant_ref_t gref; /* reference to I/O buffer frame */ @@ -72,17 +123,28 @@ struct blkif_request_rw { /* @last_sect: last sector in frame to transfer (inclusive). */ uint8_t first_sect, last_sect; } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; -}; +} __attribute__((__packed__)); + +struct blkif_request_discard { + uint8_t flag; /* BLKIF_DISCARD_SECURE or zero. */ +#define BLKIF_DISCARD_SECURE (1<<0) /* ignored if discard-secure=0 */ + blkif_vdev_t _pad1; /* only for read/write requests */ +#ifdef CONFIG_X86_64 + uint32_t _pad2; /* offsetof(blkif_req..,u.discard.id)==8*/ +#endif + uint64_t id; /* private guest value, echoed in resp */ + blkif_sector_t sector_number; + uint64_t nr_sectors; + uint8_t _pad3; +} __attribute__((__packed__)); struct blkif_request { uint8_t operation; /* BLKIF_OP_??? */ - uint8_t nr_segments; /* number of segments */ - blkif_vdev_t handle; /* only for read/write requests */ - uint64_t id; /* private guest value, echoed in resp */ union { struct blkif_request_rw rw; + struct blkif_request_discard discard; } u; -}; +} __attribute__((__packed__)); struct blkif_response { uint64_t id; /* copied from request */ |