@@ -351,6 +351,8 @@ static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
ext4_group_t group);
static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac);
+static inline void ext4_mb_show_pa(struct super_block *sb);
+
/*
* The algorithm using this percpu seq counter goes below:
* 1. We sample the percpu discard_pa_seq counter before trying for block
@@ -4217,9 +4219,9 @@ static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
struct ext4_prealloc_space *pa, *tmp;
struct list_head list;
struct ext4_buddy e4b;
+ int free_total = 0;
+ int busy, free;
int err;
- int busy = 0;
- int free, free_total = 0;
mb_debug(sb, "discard preallocation for group %u\n", group);
if (list_empty(&grp->bb_prealloc_list))
@@ -4247,6 +4249,7 @@ static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
INIT_LIST_HEAD(&list);
repeat:
+ busy = 0;
free = 0;
ext4_lock_group(sb, group);
list_for_each_entry_safe(pa, tmp,
@@ -4255,6 +4258,8 @@ static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
if (atomic_read(&pa->pa_count)) {
spin_unlock(&pa->pa_lock);
busy = 1;
+ mb_debug(sb, "used pa while discarding for group %u\n", group);
+ ext4_mb_show_pa(sb);
continue;
}
if (pa->pa_deleted) {
@@ -4300,7 +4305,6 @@ static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
if (free_total < needed && busy) {
ext4_unlock_group(sb, group);
cond_resched();
- busy = 0;
goto repeat;
}
ext4_unlock_group(sb, group);
The variable status is being initialized with a value that is never read and it is being updated later with a new value. The initialization is redundant and could be removed. Also put the variable declarations into reverse christmas tree order. Finally, we add the log printing and ext4_mb_show_pa() for troubleshooting, they are enabled only when CONFIG_EXT4_DEBUG is set. Signed-off-by: Wen Yang <wenyang@linux.alibaba.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Baoyou Xie <baoyou.xie@alibaba-inc.com> Cc: linux-ext4@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- fs/ext4/mballoc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)