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Btrfs: fix device replace of a missing RAID 5/6 device
The original implementation of device replace on RAID 5/6 seems to have missed support for replacing a missing device. When this is attempted, we end up calling bio_add_page() on a bio with a NULL ->bi_bdev, which crashes when we try to dereference it. This happens because btrfs_map_block() has no choice but to return us the missing device because RAID 5/6 don't have any alternate mirrors to read from, and a missing device has a NULL bdev. The idea implemented here is to handle the missing device case separately, which better only happen when we're replacing a missing RAID 5/6 device. We use the new BTRFS_RBIO_REBUILD_MISSING operation to reconstruct the data from parity, check it with scrub_recheck_block_checksum(), and write it out with scrub_write_block_to_dev_replace(). Reported-by: Philip <bugzilla@philip-seeger.de> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=96141 Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
parent
b4ee178268
commit
73ff61dbe5
1 changed files with 147 additions and 10 deletions
157
fs/btrfs/scrub.c
157
fs/btrfs/scrub.c
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@ -125,6 +125,7 @@ struct scrub_block {
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/* It is for the data with checksum */
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unsigned int data_corrected:1;
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};
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struct btrfs_work work;
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};
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/* Used for the chunks with parity stripe such RAID5/6 */
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@ -2173,6 +2174,134 @@ static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
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return 0;
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}
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static void scrub_missing_raid56_end_io(struct bio *bio, int error)
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{
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struct scrub_block *sblock = bio->bi_private;
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struct btrfs_fs_info *fs_info = sblock->sctx->dev_root->fs_info;
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if (error)
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sblock->no_io_error_seen = 0;
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btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
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}
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static void scrub_missing_raid56_worker(struct btrfs_work *work)
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{
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struct scrub_block *sblock = container_of(work, struct scrub_block, work);
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struct scrub_ctx *sctx = sblock->sctx;
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struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
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unsigned int is_metadata;
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unsigned int have_csum;
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u8 *csum;
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u64 generation;
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u64 logical;
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struct btrfs_device *dev;
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is_metadata = !(sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA);
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have_csum = sblock->pagev[0]->have_csum;
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csum = sblock->pagev[0]->csum;
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generation = sblock->pagev[0]->generation;
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logical = sblock->pagev[0]->logical;
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dev = sblock->pagev[0]->dev;
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if (sblock->no_io_error_seen) {
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scrub_recheck_block_checksum(fs_info, sblock, is_metadata,
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have_csum, csum, generation,
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sctx->csum_size);
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}
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if (!sblock->no_io_error_seen) {
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spin_lock(&sctx->stat_lock);
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sctx->stat.read_errors++;
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spin_unlock(&sctx->stat_lock);
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printk_ratelimited_in_rcu(KERN_ERR
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"BTRFS: I/O error rebulding logical %llu for dev %s\n",
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logical, rcu_str_deref(dev->name));
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} else if (sblock->header_error || sblock->checksum_error) {
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spin_lock(&sctx->stat_lock);
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sctx->stat.uncorrectable_errors++;
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spin_unlock(&sctx->stat_lock);
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printk_ratelimited_in_rcu(KERN_ERR
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"BTRFS: failed to rebuild valid logical %llu for dev %s\n",
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logical, rcu_str_deref(dev->name));
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} else {
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scrub_write_block_to_dev_replace(sblock);
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}
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scrub_block_put(sblock);
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if (sctx->is_dev_replace &&
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atomic_read(&sctx->wr_ctx.flush_all_writes)) {
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mutex_lock(&sctx->wr_ctx.wr_lock);
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scrub_wr_submit(sctx);
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mutex_unlock(&sctx->wr_ctx.wr_lock);
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}
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scrub_pending_bio_dec(sctx);
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}
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static void scrub_missing_raid56_pages(struct scrub_block *sblock)
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{
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struct scrub_ctx *sctx = sblock->sctx;
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struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
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u64 length = sblock->page_count * PAGE_SIZE;
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u64 logical = sblock->pagev[0]->logical;
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struct btrfs_bio *bbio;
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struct bio *bio;
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struct btrfs_raid_bio *rbio;
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int ret;
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int i;
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ret = btrfs_map_sblock(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
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&bbio, 0, 1);
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if (ret || !bbio || !bbio->raid_map)
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goto bbio_out;
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if (WARN_ON(!sctx->is_dev_replace ||
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!(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
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/*
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* We shouldn't be scrubbing a missing device. Even for dev
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* replace, we should only get here for RAID 5/6. We either
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* managed to mount something with no mirrors remaining or
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* there's a bug in scrub_remap_extent()/btrfs_map_block().
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*/
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goto bbio_out;
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}
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bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
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if (!bio)
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goto bbio_out;
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bio->bi_iter.bi_sector = logical >> 9;
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bio->bi_private = sblock;
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bio->bi_end_io = scrub_missing_raid56_end_io;
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rbio = raid56_alloc_missing_rbio(sctx->dev_root, bio, bbio, length);
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if (!rbio)
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goto rbio_out;
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for (i = 0; i < sblock->page_count; i++) {
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struct scrub_page *spage = sblock->pagev[i];
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raid56_add_scrub_pages(rbio, spage->page, spage->logical);
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}
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btrfs_init_work(&sblock->work, btrfs_scrub_helper,
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scrub_missing_raid56_worker, NULL, NULL);
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scrub_block_get(sblock);
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scrub_pending_bio_inc(sctx);
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raid56_submit_missing_rbio(rbio);
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return;
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rbio_out:
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bio_put(bio);
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bbio_out:
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btrfs_put_bbio(bbio);
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spin_lock(&sctx->stat_lock);
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sctx->stat.malloc_errors++;
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spin_unlock(&sctx->stat_lock);
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}
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static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
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u64 physical, struct btrfs_device *dev, u64 flags,
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u64 gen, int mirror_num, u8 *csum, int force,
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@ -2236,19 +2365,27 @@ static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
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}
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WARN_ON(sblock->page_count == 0);
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for (index = 0; index < sblock->page_count; index++) {
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struct scrub_page *spage = sblock->pagev[index];
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int ret;
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if (dev->missing) {
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/*
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* This case should only be hit for RAID 5/6 device replace. See
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* the comment in scrub_missing_raid56_pages() for details.
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*/
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scrub_missing_raid56_pages(sblock);
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} else {
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for (index = 0; index < sblock->page_count; index++) {
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struct scrub_page *spage = sblock->pagev[index];
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int ret;
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ret = scrub_add_page_to_rd_bio(sctx, spage);
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if (ret) {
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scrub_block_put(sblock);
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return ret;
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ret = scrub_add_page_to_rd_bio(sctx, spage);
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if (ret) {
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scrub_block_put(sblock);
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return ret;
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}
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}
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}
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if (force)
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scrub_submit(sctx);
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if (force)
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scrub_submit(sctx);
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}
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/* last one frees, either here or in bio completion for last page */
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scrub_block_put(sblock);
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