Commit c5a41562 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: raid56: prepare data checksums for later RMW verification 



This is for later data checksum verification at RMW time.

This patch will try to allocate the needed memory for a locked rbio if
the rbio is for data exclusively (we don't want to handle mixed bg yet).
The memory will be released when the rbio is finished.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 97e38239

fs/btrfs/raid56.c

+74 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include "volumes.h"

#include "raid56.h"

#include "async-thread.h"

#include "file-item.h"



/* set when additional merges to this rbio are not allowed */

#define RBIO_RMW_LOCKED_BIT	1
@@ -835,6 +836,11 @@ static void rbio_orig_end_io(struct btrfs_raid_bio *rbio, blk_status_t err) 
	struct bio *cur = bio_list_get(&rbio->bio_list);

	struct bio *extra;



	kfree(rbio->csum_buf);

	bitmap_free(rbio->csum_bitmap);

	rbio->csum_buf = NULL;

	rbio->csum_bitmap = NULL;



	/*

	 * Clear the data bitmap, as the rbio may be cached for later usage.

	 * do this before before unlock_stripe() so there will be no new bio
@@ -2048,6 +2054,67 @@ void raid56_parity_recover(struct bio *bio, struct btrfs_io_context *bioc, 
	start_async_work(rbio, recover_rbio_work);

}



static void fill_data_csums(struct btrfs_raid_bio *rbio)

{

	struct btrfs_fs_info *fs_info = rbio->bioc->fs_info;

	struct btrfs_root *csum_root = btrfs_csum_root(fs_info,

						       rbio->bioc->raid_map[0]);

	const u64 start = rbio->bioc->raid_map[0];

	const u32 len = (rbio->nr_data * rbio->stripe_nsectors) <<

			fs_info->sectorsize_bits;

	int ret;



	/* The rbio should not have its csum buffer initialized. */

	ASSERT(!rbio->csum_buf && !rbio->csum_bitmap);



	/*

	 * Skip the csum search if:

	 *

	 * - The rbio doesn't belong to data block groups

	 *   Then we are doing IO for tree blocks, no need to search csums.

	 *

	 * - The rbio belongs to mixed block groups

	 *   This is to avoid deadlock, as we're already holding the full

	 *   stripe lock, if we trigger a metadata read, and it needs to do

	 *   raid56 recovery, we will deadlock.

	 */

	if (!(rbio->bioc->map_type & BTRFS_BLOCK_GROUP_DATA) ||

	    rbio->bioc->map_type & BTRFS_BLOCK_GROUP_METADATA)

		return;



	rbio->csum_buf = kzalloc(rbio->nr_data * rbio->stripe_nsectors *

				 fs_info->csum_size, GFP_NOFS);

	rbio->csum_bitmap = bitmap_zalloc(rbio->nr_data * rbio->stripe_nsectors,

					  GFP_NOFS);

	if (!rbio->csum_buf || !rbio->csum_bitmap) {

		ret = -ENOMEM;

		goto error;

	}



	ret = btrfs_lookup_csums_bitmap(csum_root, start, start + len - 1,

					rbio->csum_buf, rbio->csum_bitmap);

	if (ret < 0)

		goto error;

	if (bitmap_empty(rbio->csum_bitmap, len >> fs_info->sectorsize_bits))

		goto no_csum;

	return;



error:

	/*

	 * We failed to allocate memory or grab the csum, but it's not fatal,

	 * we can still continue.  But better to warn users that RMW is no

	 * longer safe for this particular sub-stripe write.

	 */

	btrfs_warn_rl(fs_info,

"sub-stripe write for full stripe %llu is not safe, failed to get csum: %d",

			rbio->bioc->raid_map[0], ret);

no_csum:

	kfree(rbio->csum_buf);

	bitmap_free(rbio->csum_bitmap);

	rbio->csum_buf = NULL;

	rbio->csum_bitmap = NULL;

}



static int rmw_read_and_wait(struct btrfs_raid_bio *rbio)

{

	struct bio_list bio_list;
@@ -2056,6 +2123,13 @@ static int rmw_read_and_wait(struct btrfs_raid_bio *rbio) 


	bio_list_init(&bio_list);



	/*

	 * Fill the data csums we need for data verification.  We need to fill

	 * the csum_bitmap/csum_buf first, as our endio function will try to

	 * verify the data sectors.

	 */

	fill_data_csums(rbio);



	ret = rmw_assemble_read_bios(rbio, &bio_list);

	if (ret < 0)

		goto out;

fs/btrfs/raid56.h

+12 −0
Original line number Diff line number Diff line
@@ -129,6 +129,18 @@ struct btrfs_raid_bio { 
	 * Thus making it much harder to iterate.

	 */

	unsigned long *error_bitmap;



	/*

	 * Checksum buffer if the rbio is for data.  The buffer should cover

	 * all data sectors (exlcuding P/Q sectors).

	 */

	u8 *csum_buf;



	/*

	 * Each bit represents if the corresponding sector has data csum found.

	 * Should only cover data sectors (excluding P/Q sectors).

	 */

	unsigned long *csum_bitmap;

};



/*