Btrfs: add ref_count and free function for btrfs_bio

1: ref_count is simple than current RBIO_HOLD_BBIO_MAP_BIT flag
   to keep btrfs_bio's memory in raid56 recovery implement.
2: free function for bbio will make code clean and flexible, plus
   forced data type checking in compile.

Changelog v1->v2:
 Rename following by David Sterba's suggestion:
 put_btrfs_bio() -> btrfs_put_bio()
 get_btrfs_bio() -> btrfs_get_bio()
 bbio->ref_count -> bbio->refs

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

7 files changed, 57 insertions, 54 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3af53f8313af..1d361ac9abc9 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1926,7 +1926,7 @@ int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
                          */
                         ret = 0;
                 }
-                kfree(bbio);
+                btrfs_put_bbio(bbio);
         }
 
         if (actual_bytes)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 65bd285ef361..dab8af4450e1 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2058,7 +2058,7 @@ int repair_io_failure(struct inode *inode, u64 start, u64 length, u64 logical,
         sector = bbio->stripes[mirror_num-1].physical >> 9;
         bio->bi_iter.bi_sector = sector;
         dev = bbio->stripes[mirror_num-1].dev;
-        kfree(bbio);
+        btrfs_put_bbio(bbio);
         if (!dev || !dev->bdev || !dev->writeable) {
                 bio_put(bio);
                 return -EIO;
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index e301d3302edf..cbc416204452 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -58,15 +58,6 @@
  */
 #define RBIO_CACHE_READY_BIT    3
 
-/*
- * bbio and raid_map is managed by the caller, so we shouldn't free
- * them here. And besides that, all rbios with this flag should not
- * be cached, because we need raid_map to check the rbios' stripe
- * is the same or not, but it is very likely that the caller has
- * free raid_map, so don't cache those rbios.
- */
-#define RBIO_HOLD_BBIO_MAP_BIT  4
-
 #define RBIO_CACHE_SIZE 1024
 
 enum btrfs_rbio_ops {
@@ -834,19 +825,6 @@ done_nolock:
                 remove_rbio_from_cache(rbio);
 }
 
-static inline void
-__free_bbio(struct btrfs_bio *bbio, int need)
-{
-        if (need)
-                kfree(bbio);
-}
-
-static inline void free_bbio(struct btrfs_raid_bio *rbio)
-{
-        __free_bbio(rbio->bbio,
-                    !test_bit(RBIO_HOLD_BBIO_MAP_BIT, &rbio->flags));
-}
-
 static void __free_raid_bio(struct btrfs_raid_bio *rbio)
 {
         int i;
@@ -866,8 +844,7 @@ static void __free_raid_bio(struct btrfs_raid_bio *rbio)
                 }
         }
 
-        free_bbio(rbio);
-
+        btrfs_put_bbio(rbio->bbio);
         kfree(rbio);
 }
 
@@ -1774,7 +1751,7 @@ int raid56_parity_write(struct btrfs_root *root, struct bio *bio,
 
         rbio = alloc_rbio(root, bbio, stripe_len);
         if (IS_ERR(rbio)) {
-                __free_bbio(bbio, 1);
+                btrfs_put_bbio(bbio);
                 return PTR_ERR(rbio);
         }
         bio_list_add(&rbio->bio_list, bio);
@@ -1990,8 +1967,7 @@ cleanup:
 
 cleanup_io:
         if (rbio->operation == BTRFS_RBIO_READ_REBUILD) {
-                if (err == 0 &&
-                    !test_bit(RBIO_HOLD_BBIO_MAP_BIT, &rbio->flags))
+                if (err == 0)
                         cache_rbio_pages(rbio);
                 else
                         clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags);
@@ -2153,7 +2129,8 @@ int raid56_parity_recover(struct btrfs_root *root, struct bio *bio,
 
         rbio = alloc_rbio(root, bbio, stripe_len);
         if (IS_ERR(rbio)) {
-                __free_bbio(bbio, generic_io);
+                if (generic_io)
+                        btrfs_put_bbio(bbio);
                 return PTR_ERR(rbio);
         }
 
@@ -2164,7 +2141,8 @@ int raid56_parity_recover(struct btrfs_root *root, struct bio *bio,
         rbio->faila = find_logical_bio_stripe(rbio, bio);
         if (rbio->faila == -1) {
                 BUG();
-                __free_bbio(bbio, generic_io);
+                if (generic_io)
+                        btrfs_put_bbio(bbio);
                 kfree(rbio);
                 return -EIO;
         }
@@ -2173,7 +2151,7 @@ int raid56_parity_recover(struct btrfs_root *root, struct bio *bio,
                 btrfs_bio_counter_inc_noblocked(root->fs_info);
                 rbio->generic_bio_cnt = 1;
         } else {
-                set_bit(RBIO_HOLD_BBIO_MAP_BIT, &rbio->flags);
+                btrfs_get_bbio(bbio);
         }
 
         /*
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 4d3d4e5287c5..0e7beea92b4c 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -461,7 +461,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
         spin_unlock(&fs_info->reada_lock);
         btrfs_dev_replace_unlock(&fs_info->dev_replace);
 
-        kfree(bbio);
+        btrfs_put_bbio(bbio);
         return re;
 
 error:
@@ -486,7 +486,7 @@ error:
                 kref_put(&zone->refcnt, reada_zone_release);
                 spin_unlock(&fs_info->reada_lock);
         }
-        kfree(bbio);
+        btrfs_put_bbio(bbio);
         kfree(re);
         return re_exist;
 }
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 9d07c981ec82..1388e7127eea 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -855,7 +855,7 @@ static inline void scrub_get_recover(struct scrub_recover *recover)
 static inline void scrub_put_recover(struct scrub_recover *recover)
 {
         if (atomic_dec_and_test(&recover->refs)) {
-                kfree(recover->bbio);
+                btrfs_put_bbio(recover->bbio);
                 kfree(recover);
         }
 }
@@ -1373,13 +1373,13 @@ static int scrub_setup_recheck_block(struct scrub_ctx *sctx,
                 ret = btrfs_map_sblock(fs_info, REQ_GET_READ_MIRRORS, logical,
                                        &mapped_length, &bbio, 0, 1);
                 if (ret || !bbio || mapped_length < sublen) {
-                        kfree(bbio);
+                        btrfs_put_bbio(bbio);
                         return -EIO;
                 }
 
                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
                 if (!recover) {
-                        kfree(bbio);
+                        btrfs_put_bbio(bbio);
                         return -ENOMEM;
                 }
 
@@ -2748,7 +2748,7 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
 rbio_out:
         bio_put(bio);
 bbio_out:
-        kfree(bbio);
+        btrfs_put_bbio(bbio);
         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
                   sparity->nsectors);
         spin_lock(&sctx->stat_lock);
@@ -3879,14 +3879,14 @@ static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
                               &mapped_length, &bbio, 0);
         if (ret || !bbio || mapped_length < extent_len ||
             !bbio->stripes[0].dev->bdev) {
-                kfree(bbio);
+                btrfs_put_bbio(bbio);
                 return;
         }
 
         *extent_physical = bbio->stripes[0].physical;
         *extent_mirror_num = bbio->mirror_num;
         *extent_dev = bbio->stripes[0].dev;
-        kfree(bbio);
+        btrfs_put_bbio(bbio);
 }
 
 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c0f1d524c371..0843bcd6304c 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4901,6 +4901,37 @@ static void sort_parity_stripes(struct btrfs_bio *bbio, int num_stripes)
         }
 }
 
+static struct btrfs_bio *alloc_btrfs_bio(int total_stripes, int real_stripes)
+{
+        struct btrfs_bio *bbio = kzalloc(
+                sizeof(struct btrfs_bio) +
+                sizeof(struct btrfs_bio_stripe) * (total_stripes) +
+                sizeof(int) * (real_stripes) +
+                sizeof(u64) * (real_stripes),
+                GFP_NOFS);
+        if (!bbio)
+                return NULL;
+
+        atomic_set(&bbio->error, 0);
+        atomic_set(&bbio->refs, 1);
+
+        return bbio;
+}
+
+void btrfs_get_bbio(struct btrfs_bio *bbio)
+{
+        WARN_ON(!atomic_read(&bbio->refs));
+        atomic_inc(&bbio->refs);
+}
+
+void btrfs_put_bbio(struct btrfs_bio *bbio)
+{
+        if (!bbio)
+                return;
+        if (atomic_dec_and_test(&bbio->refs))
+                kfree(bbio);
+}
+
 static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                              u64 logical, u64 *length,
                              struct btrfs_bio **bbio_ret,
@@ -5052,7 +5083,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                          * is not left of the left cursor
                          */
                         ret = -EIO;
-                        kfree(tmp_bbio);
+                        btrfs_put_bbio(tmp_bbio);
                         goto out;
                 }
 
@@ -5087,11 +5118,11 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                 } else {
                         WARN_ON(1);
                         ret = -EIO;
-                        kfree(tmp_bbio);
+                        btrfs_put_bbio(tmp_bbio);
                         goto out;
                 }
 
-                kfree(tmp_bbio);
+                btrfs_put_bbio(tmp_bbio);
         } else if (mirror_num > map->num_stripes) {
                 mirror_num = 0;
         }
@@ -5213,13 +5244,11 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                 tgtdev_indexes = num_stripes;
         }
 
-        bbio = kzalloc(btrfs_bio_size(num_alloc_stripes, tgtdev_indexes),
-                       GFP_NOFS);
+        bbio = alloc_btrfs_bio(num_alloc_stripes, tgtdev_indexes);
         if (!bbio) {
                 ret = -ENOMEM;
                 goto out;
         }
-        atomic_set(&bbio->error, 0);
         if (dev_replace_is_ongoing)
                 bbio->tgtdev_map = (int *)(bbio->stripes + num_alloc_stripes);
 
@@ -5558,7 +5587,7 @@ static inline void btrfs_end_bbio(struct btrfs_bio *bbio, struct bio *bio, int e
                 bio_endio_nodec(bio, err);
         else
                 bio_endio(bio, err);
-        kfree(bbio);
+        btrfs_put_bbio(bbio);
 }
 
 static void btrfs_end_bio(struct bio *bio, int err)
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index fb0e8c3f296e..4313e8ff91e5 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -295,6 +295,7 @@ typedef void (btrfs_bio_end_io_t) (struct btrfs_bio *bio, int err);
 #define BTRFS_BIO_ORIG_BIO_SUBMITTED    (1 << 0)
 
 struct btrfs_bio {
+        atomic_t refs;
         atomic_t stripes_pending;
         struct btrfs_fs_info *fs_info;
         bio_end_io_t *end_io;
@@ -394,13 +395,8 @@ struct btrfs_balance_control {
 
 int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
                                    u64 end, u64 *length);
-
-#define btrfs_bio_size(total_stripes, real_stripes)             \
-        (sizeof(struct btrfs_bio) +                             \
-         (sizeof(struct btrfs_bio_stripe) * (total_stripes)) +  \
-         (sizeof(int) * (real_stripes)) +                       \
-         (sizeof(u64) * (real_stripes)))
-
+void btrfs_get_bbio(struct btrfs_bio *bbio);
+void btrfs_put_bbio(struct btrfs_bio *bbio);
 int btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                     u64 logical, u64 *length,
                     struct btrfs_bio **bbio_ret, int mirror_num);