md/r5cache: Check array size in r5l_init_log

Currently, r5l_write_stripe checks meta size for each stripe write,
which is not necessary.

With this patch, r5l_init_log checks maximal meta size of the array,
which is (r5l_meta_block + raid_disks x r5l_payload_data_parity).
If this is too big to fit in one page, r5l_init_log aborts.

With current meta data, r5l_log support raid_disks up to 203.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index f73672b..33fc850 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -441,7 +441,6 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
 {
        int write_disks = 0;
        int data_pages, parity_pages;
-       int meta_size;
        int reserve;
        int i;
        int ret = 0;
@@ -473,15 +472,6 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
        parity_pages = 1 + !!(sh->qd_idx >= 0);
        data_pages = write_disks - parity_pages;
 
-       meta_size =
-               ((sizeof(struct r5l_payload_data_parity) + sizeof(__le32))
-                * data_pages) +
-               sizeof(struct r5l_payload_data_parity) +
-               sizeof(__le32) * parity_pages;
-       /* Doesn't work with very big raid array */
-       if (meta_size + sizeof(struct r5l_meta_block) > PAGE_SIZE)
-               return -EINVAL;
-
        set_bit(STRIPE_LOG_TRAPPED, &sh->state);
        /*
         * The stripe must enter state machine again to finish the write, so
@@ -1197,6 +1187,22 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
 
        if (PAGE_SIZE != 4096)
                return -EINVAL;
+
+       /*
+        * The PAGE_SIZE must be big enough to hold 1 r5l_meta_block and
+        * raid_disks r5l_payload_data_parity.
+        *
+        * Write journal and cache does not work for very big array
+        * (raid_disks > 203)
+        */
+       if (sizeof(struct r5l_meta_block) +
+           ((sizeof(struct r5l_payload_data_parity) + sizeof(__le32)) *
+            conf->raid_disks) > PAGE_SIZE) {
+               pr_err("md/raid:%s: write journal/cache doesn't work for array with %d disks\n",
+                      mdname(conf->mddev), conf->raid_disks);
+               return -EINVAL;
+       }
+
        log = kzalloc(sizeof(*log), GFP_KERNEL);
        if (!log)
                return -ENOMEM;