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-rw-r--r--include/xen/interface/io/blkif.h34
1 files changed, 14 insertions, 20 deletions
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index ae665ac59c36..32ec05a6572f 100644
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -113,13 +113,13 @@ typedef uint64_t blkif_sector_t;
113 * it's less than the number provided by the backend. The indirect_grefs field 113 * it's less than the number provided by the backend. The indirect_grefs field
114 * in blkif_request_indirect should be filled by the frontend with the 114 * in blkif_request_indirect should be filled by the frontend with the
115 * grant references of the pages that are holding the indirect segments. 115 * grant references of the pages that are holding the indirect segments.
116 * This pages are filled with an array of blkif_request_segment_aligned 116 * These pages are filled with an array of blkif_request_segment that hold the
117 * that hold the information about the segments. The number of indirect 117 * information about the segments. The number of indirect pages to use is
118 * pages to use is determined by the maximum number of segments 118 * determined by the number of segments an indirect request contains. Every
119 * a indirect request contains. Every indirect page can contain a maximum 119 * indirect page can contain a maximum of
120 * of 512 segments (PAGE_SIZE/sizeof(blkif_request_segment_aligned)), 120 * (PAGE_SIZE / sizeof(struct blkif_request_segment)) segments, so to
121 * so to calculate the number of indirect pages to use we have to do 121 * calculate the number of indirect pages to use we have to do
122 * ceil(indirect_segments/512). 122 * ceil(indirect_segments / (PAGE_SIZE / sizeof(struct blkif_request_segment))).
123 * 123 *
124 * If a backend does not recognize BLKIF_OP_INDIRECT, it should *not* 124 * If a backend does not recognize BLKIF_OP_INDIRECT, it should *not*
125 * create the "feature-max-indirect-segments" node! 125 * create the "feature-max-indirect-segments" node!
@@ -135,13 +135,12 @@ typedef uint64_t blkif_sector_t;
135 135
136#define BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST 8 136#define BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST 8
137 137
138struct blkif_request_segment_aligned { 138struct blkif_request_segment {
139 grant_ref_t gref; /* reference to I/O buffer frame */ 139 grant_ref_t gref; /* reference to I/O buffer frame */
140 /* @first_sect: first sector in frame to transfer (inclusive). */ 140 /* @first_sect: first sector in frame to transfer (inclusive). */
141 /* @last_sect: last sector in frame to transfer (inclusive). */ 141 /* @last_sect: last sector in frame to transfer (inclusive). */
142 uint8_t first_sect, last_sect; 142 uint8_t first_sect, last_sect;
143 uint16_t _pad; /* padding to make it 8 bytes, so it's cache-aligned */ 143};
144} __attribute__((__packed__));
145 144
146struct blkif_request_rw { 145struct blkif_request_rw {
147 uint8_t nr_segments; /* number of segments */ 146 uint8_t nr_segments; /* number of segments */
@@ -151,12 +150,7 @@ struct blkif_request_rw {
151#endif 150#endif
152 uint64_t id; /* private guest value, echoed in resp */ 151 uint64_t id; /* private guest value, echoed in resp */
153 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ 152 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
154 struct blkif_request_segment { 153 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
155 grant_ref_t gref; /* reference to I/O buffer frame */
156 /* @first_sect: first sector in frame to transfer (inclusive). */
157 /* @last_sect: last sector in frame to transfer (inclusive). */
158 uint8_t first_sect, last_sect;
159 } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
160} __attribute__((__packed__)); 154} __attribute__((__packed__));
161 155
162struct blkif_request_discard { 156struct blkif_request_discard {