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authorKent Overstreet <koverstreet@google.com>2012-09-06 15:34:58 -0700
committerJens Axboe <axboe@kernel.dk>2012-09-09 10:35:39 +0200
commitf44b48c7691be7643877d1f881b5eeace654d05d (patch)
treea862b4844b99abfa1bfb6fd437cf1ee4f055c438
parent94818742316e27d01506240cf8b07d69844d31af (diff)
block: Add bio_reset()
Reusing bios is something that's been highly frowned upon in the past, but driver code keeps doing it anyways. If it's going to happen anyways, we should provide a generic method. This'll help with getting rid of bi_destructor - drivers/block/pktcdvd.c was open coding it, by doing a bio_init() and resetting bi_destructor. This required reordering struct bio, but the block layer is not yet nearly fast enough for any cacheline effects to matter here. v5: Add a define BIO_RESET_BITS, to be very explicit about what parts of bio->bi_flags are saved. v6: Further commenting verbosity, per Tejun v9: Add a function comment Signed-off-by: Kent Overstreet <koverstreet@google.com> CC: Jens Axboe <axboe@kernel.dk> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/bio.c24
-rw-r--r--include/linux/bio.h1
-rw-r--r--include/linux/blk_types.h25
3 files changed, 44 insertions, 6 deletions
diff --git a/fs/bio.c b/fs/bio.c
index b14f71adff4a..919ee9aa5c57 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -263,6 +263,30 @@ void bio_init(struct bio *bio)
EXPORT_SYMBOL(bio_init);
/**
+ * bio_reset - reinitialize a bio
+ * @bio: bio to reset
+ *
+ * Description:
+ * After calling bio_reset(), @bio will be in the same state as a freshly
+ * allocated bio returned bio bio_alloc_bioset() - the only fields that are
+ * preserved are the ones that are initialized by bio_alloc_bioset(). See
+ * comment in struct bio.
+ */
+void bio_reset(struct bio *bio)
+{
+ unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
+
+ if (bio_integrity(bio))
+ bio_integrity_free(bio);
+
+ bio_disassociate_task(bio);
+
+ memset(bio, 0, BIO_RESET_BYTES);
+ bio->bi_flags = flags|(1 << BIO_UPTODATE);
+}
+EXPORT_SYMBOL(bio_reset);
+
+/**
* bio_alloc_bioset - allocate a bio for I/O
* @gfp_mask: the GFP_ mask given to the slab allocator
* @nr_iovecs: number of iovecs to pre-allocate
diff --git a/include/linux/bio.h b/include/linux/bio.h
index a11f74bc82d2..76f6c252baff 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -226,6 +226,7 @@ extern void __bio_clone(struct bio *, struct bio *);
extern struct bio *bio_clone(struct bio *, gfp_t);
extern void bio_init(struct bio *);
+extern void bio_reset(struct bio *);
extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index af9dd9d2efc4..1b607c247d72 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -59,12 +59,6 @@ struct bio {
unsigned int bi_seg_front_size;
unsigned int bi_seg_back_size;
- unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
-
- atomic_t bi_cnt; /* pin count */
-
- struct bio_vec *bi_io_vec; /* the actual vec list */
-
bio_end_io_t *bi_end_io;
void *bi_private;
@@ -80,6 +74,16 @@ struct bio {
struct bio_integrity_payload *bi_integrity; /* data integrity */
#endif
+ /*
+ * Everything starting with bi_max_vecs will be preserved by bio_reset()
+ */
+
+ unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
+
+ atomic_t bi_cnt; /* pin count */
+
+ struct bio_vec *bi_io_vec; /* the actual vec list */
+
/* If bi_pool is non NULL, bi_destructor is not called */
struct bio_set *bi_pool;
@@ -93,6 +97,8 @@ struct bio {
struct bio_vec bi_inline_vecs[0];
};
+#define BIO_RESET_BYTES offsetof(struct bio, bi_max_vecs)
+
/*
* bio flags
*/
@@ -108,6 +114,13 @@ struct bio {
#define BIO_FS_INTEGRITY 9 /* fs owns integrity data, not block layer */
#define BIO_QUIET 10 /* Make BIO Quiet */
#define BIO_MAPPED_INTEGRITY 11/* integrity metadata has been remapped */
+
+/*
+ * Flags starting here get preserved by bio_reset() - this includes
+ * BIO_POOL_IDX()
+ */
+#define BIO_RESET_BITS 12
+
#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
/*