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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 /fs/bio.c
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>
Diffstat (limited to 'fs/bio.c')
-rw-r--r--fs/bio.c24
1 files changed, 24 insertions, 0 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