[RFC v3 2/8] ext4: Refactor code related to freeing PAs

Ojaswin Mujoo
2022-09-27T09:20:38Z

This patch makes the following changes:

* Rename ext4_mb_pa_free to ext4_mb_pa_put_free
to better reflect its purpose

* Add new ext4_mb_pa_free() which only handles freeing

* Refactor ext4_mb_pa_callback() to use ext4_mb_pa_free()

There are no functional changes in this patch

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
fs/ext4/mballoc.c | 29 ++++++++++++++++++++---------
1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 2e3eb632a216..8be6f8765a6f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4531,16 +4531,21 @@ static void ext4_mb_mark_pa_deleted(struct super_block *sb,
}
}

-static void ext4_mb_pa_callback(struct rcu_head *head)
+static void inline ext4_mb_pa_free(struct ext4_prealloc_space *pa)
{
- struct ext4_prealloc_space *pa;
- pa = container_of(head, struct ext4_prealloc_space, u.pa_rcu);
-
+ BUG_ON(!pa);
BUG_ON(atomic_read(&pa->pa_count));
BUG_ON(pa->pa_deleted == 0);
kmem_cache_free(ext4_pspace_cachep, pa);
}

+static void ext4_mb_pa_callback(struct rcu_head *head)
+{
+ struct ext4_prealloc_space *pa;
+ pa = container_of(head, struct ext4_prealloc_space, u.pa_rcu);
+ ext4_mb_pa_free(pa);
+}
+
/*
* drops a reference to preallocated space descriptor
* if this was the last reference and the space is consumed
@@ -5067,14 +5072,20 @@ static int ext4_mb_pa_alloc(struct ext4_allocation_context *ac)
return 0;
}

-static void ext4_mb_pa_free(struct ext4_allocation_context *ac)
+static void ext4_mb_pa_put_free(struct ext4_allocation_context *ac)
{
struct ext4_prealloc_space *pa = ac->ac_pa;

BUG_ON(!pa);
ac->ac_pa = NULL;
WARN_ON(!atomic_dec_and_test(&pa->pa_count));
- kmem_cache_free(ext4_pspace_cachep, pa);
+ /*
+ * current function is only called due to an error or due to
+ * len of found blocks < len of requested blocks hence the PA has not
+ * been added to grp->bb_prealloc_list. So we don't need to lock it
+ */
+ pa->pa_deleted = 1;
+ ext4_mb_pa_free(pa);
}

#ifdef CONFIG_EXT4_DEBUG
@@ -5623,13 +5634,13 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
* So we have to free this pa here itself.
*/
if (*errp) {
- ext4_mb_pa_free(ac);
+ ext4_mb_pa_put_free(ac);
ext4_discard_allocated_blocks(ac);
goto errout;
}
if (ac->ac_status == AC_STATUS_FOUND &&
ac->ac_o_ex.fe_len >= ac->ac_f_ex.fe_len)
- ext4_mb_pa_free(ac);
+ ext4_mb_pa_put_free(ac);
}
if (likely(ac->ac_status == AC_STATUS_FOUND)) {
*errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs);
@@ -5648,7 +5659,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
* If block allocation fails then the pa allocated above
* needs to be freed here itself.
*/
- ext4_mb_pa_free(ac);
+ ext4_mb_pa_put_free(ac);
*errp = -ENOSPC;
}

--
2.31.1