ext4: Refactor code related to freeing PAs

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>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/b273bc9cbf5bd278f641fa5bc6c0cc9e6cb3330c.1679731817.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 2d4dc30..58f1600 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4528,16 +4528,22 @@ static void ext4_mb_mark_pa_deleted(struct super_block *sb,
        }
 }
 
-static void ext4_mb_pa_callback(struct rcu_head *head)
+static inline void 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
@@ -5055,14 +5061,20 @@ 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
@@ -5605,13 +5617,13 @@ repeat:
                 * 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);
@@ -5630,7 +5642,7 @@ repeat:
                 * 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;
        }