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authorKent Overstreet2013-11-24 03:19:27 +0100
committerKent Overstreet2013-11-24 07:33:54 +0100
commit59d276fe02d7e887a4825ef05c80b8f8c54ba60a (patch)
treedbb8c78a922d47652c08d9f5e46d77708ac95543 /fs/bio.c
parentblock: Refactor bio_clone_bioset() for immutable biovecs (diff)
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block: Add bio_clone_fast()
bio_clone() just got more expensive - however, most users of bio_clone() don't actually need to modify the biovec. If they aren't modifying the biovec, and they can guarantee that the original bio isn't freed before the clone (also true in most cases), we can just point the clone at the original bio's biovec. Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Diffstat (limited to 'fs/bio.c')
-rw-r--r--fs/bio.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/fs/bio.c b/fs/bio.c
index 1628917e262a..00dc1893c6ee 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -549,6 +549,66 @@ void __bio_clone(struct bio *bio, struct bio *bio_src)
EXPORT_SYMBOL(__bio_clone);
/**
+ * __bio_clone_fast - clone a bio that shares the original bio's biovec
+ * @bio: destination bio
+ * @bio_src: bio to clone
+ *
+ * Clone a &bio. Caller will own the returned bio, but not
+ * the actual data it points to. Reference count of returned
+ * bio will be one.
+ *
+ * Caller must ensure that @bio_src is not freed before @bio.
+ */
+void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
+{
+ BUG_ON(bio->bi_pool && BIO_POOL_IDX(bio) != BIO_POOL_NONE);
+
+ /*
+ * most users will be overriding ->bi_bdev with a new target,
+ * so we don't set nor calculate new physical/hw segment counts here
+ */
+ bio->bi_bdev = bio_src->bi_bdev;
+ bio->bi_flags |= 1 << BIO_CLONED;
+ bio->bi_rw = bio_src->bi_rw;
+ bio->bi_iter = bio_src->bi_iter;
+ bio->bi_io_vec = bio_src->bi_io_vec;
+}
+EXPORT_SYMBOL(__bio_clone_fast);
+
+/**
+ * bio_clone_fast - clone a bio that shares the original bio's biovec
+ * @bio: bio to clone
+ * @gfp_mask: allocation priority
+ * @bs: bio_set to allocate from
+ *
+ * Like __bio_clone_fast, only also allocates the returned bio
+ */
+struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
+{
+ struct bio *b;
+
+ b = bio_alloc_bioset(gfp_mask, 0, bs);
+ if (!b)
+ return NULL;
+
+ __bio_clone_fast(b, bio);
+
+ if (bio_integrity(bio)) {
+ int ret;
+
+ ret = bio_integrity_clone(b, bio, gfp_mask);
+
+ if (ret < 0) {
+ bio_put(b);
+ return NULL;
+ }
+ }
+
+ return b;
+}
+EXPORT_SYMBOL(bio_clone_fast);
+
+/**
* bio_clone_bioset - clone a bio
* @bio_src: bio to clone
* @gfp_mask: allocation priority