Commit c757ec95 authored by Song Liu's avatar Song Liu Committed by Shaohua Li
Browse files

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: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 504634f6

drivers/md/raid5-cache.c

+16 −10
Original line number Diff line number Diff line
@@ -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;

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