Btrfs: use a btrfs bioset instead of abusing bio internals
Btrfs has been pointer tagging bi_private and using bi_bdev
to store the stripe index and mirror number of failed IOs.
As bios bubble back up through the call chain, we use these
to decide if and how to retry our IOs. They are also used
to count IO failures on a per device basis.
Recently a bio tracepoint was added lead to crashes because
we were abusing bi_bdev.
This commit adds a btrfs bioset, and creates explicit fields
for the mirror number and stripe index. The plan is to
extend this structure for all of the fields currently in
struct btrfs_bio, which will mean one less kmalloc in
our IO path.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Reported-by: Tejun Heo <tj@kernel.org>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d2ac518..fe1d6c3 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -23,6 +23,7 @@
static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
+static struct bio_set *btrfs_bioset;
#ifdef CONFIG_BTRFS_DEBUG
static LIST_HEAD(buffers);
@@ -125,10 +126,20 @@
SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
if (!extent_buffer_cache)
goto free_state_cache;
+
+ btrfs_bioset = bioset_create(BIO_POOL_SIZE,
+ offsetof(struct btrfs_io_bio, bio));
+ if (!btrfs_bioset)
+ goto free_buffer_cache;
return 0;
+free_buffer_cache:
+ kmem_cache_destroy(extent_buffer_cache);
+ extent_buffer_cache = NULL;
+
free_state_cache:
kmem_cache_destroy(extent_state_cache);
+ extent_state_cache = NULL;
return -ENOMEM;
}
@@ -145,6 +156,8 @@
kmem_cache_destroy(extent_state_cache);
if (extent_buffer_cache)
kmem_cache_destroy(extent_buffer_cache);
+ if (btrfs_bioset)
+ bioset_free(btrfs_bioset);
}
void extent_io_tree_init(struct extent_io_tree *tree,
@@ -2046,7 +2059,7 @@
if (btrfs_is_parity_mirror(map_tree, logical, length, mirror_num))
return 0;
- bio = bio_alloc(GFP_NOFS, 1);
+ bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
if (!bio)
return -EIO;
bio->bi_private = &compl;
@@ -2336,7 +2349,7 @@
return -EIO;
}
- bio = bio_alloc(GFP_NOFS, 1);
+ bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
if (!bio) {
free_io_failure(inode, failrec, 0);
return -EIO;
@@ -2457,10 +2470,11 @@
struct page *page = bvec->bv_page;
struct extent_state *cached = NULL;
struct extent_state *state;
+ struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
pr_debug("end_bio_extent_readpage: bi_sector=%llu, err=%d, "
- "mirror=%ld\n", (u64)bio->bi_sector, err,
- (long int)bio->bi_bdev);
+ "mirror=%lu\n", (u64)bio->bi_sector, err,
+ io_bio->mirror_num);
tree = &BTRFS_I(page->mapping->host)->io_tree;
start = page_offset(page) + bvec->bv_offset;
@@ -2485,7 +2499,7 @@
}
spin_unlock(&tree->lock);
- mirror = (int)(unsigned long)bio->bi_bdev;
+ mirror = io_bio->mirror_num;
if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
ret = tree->ops->readpage_end_io_hook(page, start, end,
state, mirror);
@@ -2550,17 +2564,23 @@
bio_put(bio);
}
+/*
+ * this allocates from the btrfs_bioset. We're returning a bio right now
+ * but you can call btrfs_io_bio for the appropriate container_of magic
+ */
struct bio *
btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
gfp_t gfp_flags)
{
struct bio *bio;
- bio = bio_alloc(gfp_flags, nr_vecs);
+ bio = bio_alloc_bioset(gfp_flags, nr_vecs, btrfs_bioset);
if (bio == NULL && (current->flags & PF_MEMALLOC)) {
- while (!bio && (nr_vecs /= 2))
- bio = bio_alloc(gfp_flags, nr_vecs);
+ while (!bio && (nr_vecs /= 2)) {
+ bio = bio_alloc_bioset(gfp_flags,
+ nr_vecs, btrfs_bioset);
+ }
}
if (bio) {
@@ -2571,6 +2591,19 @@
return bio;
}
+struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
+{
+ return bio_clone_bioset(bio, gfp_mask, btrfs_bioset);
+}
+
+
+/* this also allocates from the btrfs_bioset */
+struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
+{
+ return bio_alloc_bioset(gfp_mask, nr_iovecs, btrfs_bioset);
+}
+
+
static int __must_check submit_one_bio(int rw, struct bio *bio,
int mirror_num, unsigned long bio_flags)
{
