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authorJens Axboe <axboe@fb.com>2014-06-24 16:22:24 -0600
committerJens Axboe <axboe@fb.com>2014-06-24 16:22:24 -0600
commit66cb45aa41315d1d9972cada354fbdf7870d7714 (patch)
tree5ca5ef3c31f24a7a11989d8a6a163eed9aaf9528 /include
parent3a4b0eda8e4b27e6aca86f9f4d327c1070815e30 (diff)
block: add support for limiting gaps in SG lists
Another restriction inherited for NVMe - those devices don't support SG lists that have "gaps" in them. Gaps refers to cases where the previous SG entry doesn't end on a page boundary. For NVMe, all SG entries must start at offset 0 (except the first) and end on a page boundary (except the last). Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/bio.h9
-rw-r--r--include/linux/blkdev.h1
2 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h
index f91decbca96b..d2633ee099d9 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -186,6 +186,15 @@ static inline void *bio_data(struct bio *bio)
#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
+/*
+ * Check if adding a bio_vec after bprv with offset would create a gap in
+ * the SG list. Most drivers don't care about this, but some do.
+ */
+static inline bool bvec_gap_to_prev(struct bio_vec *bprv, unsigned int offset)
+{
+ return offset || ((bprv->bv_offset + bprv->bv_len) & (PAGE_SIZE - 1));
+}
+
#define bio_io_error(bio) bio_endio((bio), -EIO)
/*
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 713f8b62b435..8699bcf5f099 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -512,6 +512,7 @@ struct request_queue {
#define QUEUE_FLAG_DEAD 19 /* queue tear-down finished */
#define QUEUE_FLAG_INIT_DONE 20 /* queue is initialized */
#define QUEUE_FLAG_NO_SG_MERGE 21 /* don't attempt to merge SG segments*/
+#define QUEUE_FLAG_SG_GAPS 22 /* queue doesn't support SG gaps */
#define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_STACKABLE) | \

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