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xen-blkif: drop struct blkif_request_segment_aligned

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This was wrongly introduced in commit 402b27f9, the only difference
between blkif_request_segment_aligned and blkif_request_segment is
that the former has a named padding, while both share the same
memory layout.

Also correct a few minor glitches in the description, including for it
to no longer assume PAGE_SIZE == 4096.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
[Description fix by Jan Beulich]
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reported-by: Jan Beulich <jbeulich@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Matt Rushton <mrushton@amazon.com>
Cc: Matt Wilson <msw@amazon.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Roger Pau Monne 2014-02-04 11:26:15 +01:00 • committed by Konrad Rzeszutek Wilk
parent c05f3e3c85
commit 80bfa2f6e2
4 changed files with 19 additions and 25 deletions
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34
include/xen/interface/io/blkif.h
View file

@ -113,13 +113,13 @@ typedef uint64_t blkif_sector_t;
* it's less than the number provided by the backend. The indirect_grefs field
* in blkif_request_indirect should be filled by the frontend with the
* grant references of the pages that are holding the indirect segments.
* This pages are filled with an array of blkif_request_segment_aligned
* that hold the information about the segments. The number of indirect
* pages to use is determined by the maximum number of segments
* a indirect request contains. Every indirect page can contain a maximum
* of 512 segments (PAGE_SIZE/sizeof(blkif_request_segment_aligned)),
* so to calculate the number of indirect pages to use we have to do
* ceil(indirect_segments/512).
* These pages are filled with an array of blkif_request_segment that hold the
* information about the segments. The number of indirect pages to use is
* determined by the number of segments an indirect request contains. Every
* indirect page can contain a maximum of
* (PAGE_SIZE / sizeof(struct blkif_request_segment)) segments, so to
* calculate the number of indirect pages to use we have to do
* ceil(indirect_segments / (PAGE_SIZE / sizeof(struct blkif_request_segment))).
*
* If a backend does not recognize BLKIF_OP_INDIRECT, it should *not*
* create the "feature-max-indirect-segments" node!
@ -135,13 +135,12 @@ typedef uint64_t blkif_sector_t;
#define BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST 8
struct blkif_request_segment_aligned {
grant_ref_t gref; /* reference to I/O buffer frame */
/* @first_sect: first sector in frame to transfer (inclusive). */
/* @last_sect: last sector in frame to transfer (inclusive). */
uint8_t first_sect, last_sect;
uint16_t _pad; /* padding to make it 8 bytes, so it's cache-aligned */
} __attribute__((__packed__));
struct blkif_request_segment {
grant_ref_t gref; /* reference to I/O buffer frame */
/* @first_sect: first sector in frame to transfer (inclusive). */
/* @last_sect: last sector in frame to transfer (inclusive). */
uint8_t first_sect, last_sect;
};
struct blkif_request_rw {
uint8_t nr_segments; /* number of segments */
@ -151,12 +150,7 @@ struct blkif_request_rw {
#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 */
/* @first_sect: first sector in frame to transfer (inclusive). */
/* @last_sect: last sector in frame to transfer (inclusive). */
uint8_t first_sect, last_sect;
} seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
} __attribute__((__packed__));
struct blkif_request_discard {