erofs: fix possible memory leak in z_erofs_gbuf_exit()

Because we incorrectly reused of variable `i` in `z_erofs_gbuf_exit()`
for inner loop, we may exit early from outer loop resulting in memory
leak. Fix this by using separate variable for iterating through inner loop.

Fixes: f36f301 ("erofs: rename per-CPU buffers to global buffer pool and make it configurable")
Signed-off-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20240624220206.3373197-1-dhavale@google.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Author: dhavale

fs/erofs/zutil.c

@@ -148,7 +148,7 @@ int __init z_erofs_gbuf_init(void)
 
 void z_erofs_gbuf_exit(void)
 {
-	int i;
+	int i, j;
 
 	for (i = 0; i < z_erofs_gbuf_count + (!!z_erofs_rsvbuf); ++i) {
 		struct z_erofs_gbuf *gbuf = &z_erofs_gbufpool[i];
@@ -161,9 +161,9 @@ void z_erofs_gbuf_exit(void)
 		if (!gbuf->pages)
 			continue;
 
-		for (i = 0; i < gbuf->nrpages; ++i)
-			if (gbuf->pages[i])
-				put_page(gbuf->pages[i]);
+		for (j = 0; j < gbuf->nrpages; ++j)
+			if (gbuf->pages[j])
+				put_page(gbuf->pages[j]);
 		kfree(gbuf->pages);
 		gbuf->pages = NULL;
 	}