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>

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index f489e24659a4..79bd479317cb 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1296,7 +1296,7 @@ static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
                 }
 
                 WARN_ON(!page->page);
-                bio = bio_alloc(GFP_NOFS, 1);
+                bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
                 if (!bio) {
                         page->io_error = 1;
                         sblock->no_io_error_seen = 0;
@@ -1431,7 +1431,7 @@ static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
                         return -EIO;
                 }
 
-                bio = bio_alloc(GFP_NOFS, 1);
+                bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
                 if (!bio)
                         return -EIO;
                 bio->bi_bdev = page_bad->dev->bdev;
@@ -1522,7 +1522,7 @@ again:
                 sbio->dev = wr_ctx->tgtdev;
                 bio = sbio->bio;
                 if (!bio) {
-                        bio = bio_alloc(GFP_NOFS, wr_ctx->pages_per_wr_bio);
+                        bio = btrfs_io_bio_alloc(GFP_NOFS, wr_ctx->pages_per_wr_bio);
                         if (!bio) {
                                 mutex_unlock(&wr_ctx->wr_lock);
                                 return -ENOMEM;
@@ -1930,7 +1930,7 @@ again:
                 sbio->dev = spage->dev;
                 bio = sbio->bio;
                 if (!bio) {
-                        bio = bio_alloc(GFP_NOFS, sctx->pages_per_rd_bio);
+                        bio = btrfs_io_bio_alloc(GFP_NOFS, sctx->pages_per_rd_bio);
                         if (!bio)
                                 return -ENOMEM;
                         sbio->bio = bio;
@@ -3307,7 +3307,7 @@ static int write_page_nocow(struct scrub_ctx *sctx,
                         "btrfs: scrub write_page_nocow(bdev == NULL) is unexpected!\n");
                 return -EIO;
         }
-        bio = bio_alloc(GFP_NOFS, 1);
+        bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
         if (!bio) {
                 spin_lock(&sctx->stat_lock);
                 sctx->stat.malloc_errors++;