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authorOmar Sandoval <osandov@fb.com>2015-06-19 21:52:51 +0300
committerChris Mason <clm@fb.com>2015-08-09 17:34:26 +0300
commit73ff61dbe5edeb1799d7e91c8b0641f87feb75fa (patch)
treecb58fb5cbe9a3c6c0077babd130ee54135e35e8a /fs/btrfs
parentb4ee1782686d5b7a97826d67fdeaefaedbca23ce (diff)
downloadlinux-73ff61dbe5edeb1799d7e91c8b0641f87feb75fa.tar.xz
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>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/scrub.c157
1 files changed, 147 insertions, 10 deletions
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 038162456cfa..6bce7f2ff805 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -125,6 +125,7 @@ struct scrub_block {
/* It is for the data with checksum */
unsigned int data_corrected:1;
};
+ struct btrfs_work work;
};
/* Used for the chunks with parity stripe such RAID5/6 */
@@ -2173,6 +2174,134 @@ again:
return 0;
}
+static void scrub_missing_raid56_end_io(struct bio *bio, int error)
+{
+ struct scrub_block *sblock = bio->bi_private;
+ struct btrfs_fs_info *fs_info = sblock->sctx->dev_root->fs_info;
+
+ if (error)
+ sblock->no_io_error_seen = 0;
+
+ btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
+}
+
+static void scrub_missing_raid56_worker(struct btrfs_work *work)
+{
+ struct scrub_block *sblock = container_of(work, struct scrub_block, work);
+ struct scrub_ctx *sctx = sblock->sctx;
+ struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+ unsigned int is_metadata;
+ unsigned int have_csum;
+ u8 *csum;
+ u64 generation;
+ u64 logical;
+ struct btrfs_device *dev;
+
+ is_metadata = !(sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA);
+ have_csum = sblock->pagev[0]->have_csum;
+ csum = sblock->pagev[0]->csum;
+ generation = sblock->pagev[0]->generation;
+ logical = sblock->pagev[0]->logical;
+ dev = sblock->pagev[0]->dev;
+
+ if (sblock->no_io_error_seen) {
+ scrub_recheck_block_checksum(fs_info, sblock, is_metadata,
+ have_csum, csum, generation,
+ sctx->csum_size);
+ }
+
+ if (!sblock->no_io_error_seen) {
+ spin_lock(&sctx->stat_lock);
+ sctx->stat.read_errors++;
+ spin_unlock(&sctx->stat_lock);
+ printk_ratelimited_in_rcu(KERN_ERR
+ "BTRFS: I/O error rebulding logical %llu for dev %s\n",
+ logical, rcu_str_deref(dev->name));
+ } else if (sblock->header_error || sblock->checksum_error) {
+ spin_lock(&sctx->stat_lock);
+ sctx->stat.uncorrectable_errors++;
+ spin_unlock(&sctx->stat_lock);
+ printk_ratelimited_in_rcu(KERN_ERR
+ "BTRFS: failed to rebuild valid logical %llu for dev %s\n",
+ logical, rcu_str_deref(dev->name));
+ } else {
+ scrub_write_block_to_dev_replace(sblock);
+ }
+
+ scrub_block_put(sblock);
+
+ if (sctx->is_dev_replace &&
+ atomic_read(&sctx->wr_ctx.flush_all_writes)) {
+ mutex_lock(&sctx->wr_ctx.wr_lock);
+ scrub_wr_submit(sctx);
+ mutex_unlock(&sctx->wr_ctx.wr_lock);
+ }
+
+ scrub_pending_bio_dec(sctx);
+}
+
+static void scrub_missing_raid56_pages(struct scrub_block *sblock)
+{
+ struct scrub_ctx *sctx = sblock->sctx;
+ struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+ u64 length = sblock->page_count * PAGE_SIZE;
+ u64 logical = sblock->pagev[0]->logical;
+ struct btrfs_bio *bbio;
+ struct bio *bio;
+ struct btrfs_raid_bio *rbio;
+ int ret;
+ int i;
+
+ ret = btrfs_map_sblock(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
+ &bbio, 0, 1);
+ if (ret || !bbio || !bbio->raid_map)
+ goto bbio_out;
+
+ if (WARN_ON(!sctx->is_dev_replace ||
+ !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
+ /*
+ * We shouldn't be scrubbing a missing device. Even for dev
+ * replace, we should only get here for RAID 5/6. We either
+ * managed to mount something with no mirrors remaining or
+ * there's a bug in scrub_remap_extent()/btrfs_map_block().
+ */
+ goto bbio_out;
+ }
+
+ bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
+ if (!bio)
+ goto bbio_out;
+
+ bio->bi_iter.bi_sector = logical >> 9;
+ bio->bi_private = sblock;
+ bio->bi_end_io = scrub_missing_raid56_end_io;
+
+ rbio = raid56_alloc_missing_rbio(sctx->dev_root, bio, bbio, length);
+ if (!rbio)
+ goto rbio_out;
+
+ for (i = 0; i < sblock->page_count; i++) {
+ struct scrub_page *spage = sblock->pagev[i];
+
+ raid56_add_scrub_pages(rbio, spage->page, spage->logical);
+ }
+
+ btrfs_init_work(&sblock->work, btrfs_scrub_helper,
+ scrub_missing_raid56_worker, NULL, NULL);
+ scrub_block_get(sblock);
+ scrub_pending_bio_inc(sctx);
+ raid56_submit_missing_rbio(rbio);
+ return;
+
+rbio_out:
+ bio_put(bio);
+bbio_out:
+ btrfs_put_bbio(bbio);
+ spin_lock(&sctx->stat_lock);
+ sctx->stat.malloc_errors++;
+ spin_unlock(&sctx->stat_lock);
+}
+
static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
u64 physical, struct btrfs_device *dev, u64 flags,
u64 gen, int mirror_num, u8 *csum, int force,
@@ -2236,19 +2365,27 @@ leave_nomem:
}
WARN_ON(sblock->page_count == 0);
- for (index = 0; index < sblock->page_count; index++) {
- struct scrub_page *spage = sblock->pagev[index];
- int ret;
+ if (dev->missing) {
+ /*
+ * This case should only be hit for RAID 5/6 device replace. See
+ * the comment in scrub_missing_raid56_pages() for details.
+ */
+ scrub_missing_raid56_pages(sblock);
+ } else {
+ for (index = 0; index < sblock->page_count; index++) {
+ struct scrub_page *spage = sblock->pagev[index];
+ int ret;
- ret = scrub_add_page_to_rd_bio(sctx, spage);
- if (ret) {
- scrub_block_put(sblock);
- return ret;
+ ret = scrub_add_page_to_rd_bio(sctx, spage);
+ if (ret) {
+ scrub_block_put(sblock);
+ return ret;
+ }
}
- }
- if (force)
- scrub_submit(sctx);
+ if (force)
+ scrub_submit(sctx);
+ }
/* last one frees, either here or in bio completion for last page */
scrub_block_put(sblock);