btrfs: scrub: implement raid stripe tree support

A filesystem that uses the raid stripe tree for logical to physical
address translation can't use the regular scrub path, that reads all
stripes and then checks if a sector is unused afterwards.

When using the raid stripe tree, this will result in lookup errors, as
the stripe tree doesn't know the requested logical addresses.

In case we're scrubbing a filesystem which uses the RAID stripe tree for
multi-device logical to physical address translation, perform an extra
block mapping step to get the real on-disk stripe length from the stripe
tree when scrubbing the sectors.

This prevents a double completion of the btrfs_bio caused by splitting the
underlying bio and ultimately a use-after-free.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index ac6bc4f43ffb7c9318ef547845d58c77452b595c..ab7ee090b6067955405fa4e447a788b06202bd88 100644 (file)
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -663,6 +663,8 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
        blk_status_t ret;
        int error;
 
+       smap.is_scrub = !bbio->inode;
+
        btrfs_bio_counter_inc_blocked(fs_info);
        error = btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,
                                &bioc, &smap, &mirror_num);

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index c7e18a85f72336006f89e7f4544f2cd7fe46ddc5..a4451452ab680c7f479e2be22181ad33eb648c4f 100644 (file)
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -171,6 +171,11 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
        if (!path)
                return -ENOMEM;
 
+       if (stripe->is_scrub) {
+               path->skip_locking = 1;
+               path->search_commit_root = 1;
+       }
+
        ret = btrfs_search_slot(NULL, stripe_root, &stripe_key, path, 0, 0);
        if (ret < 0)
                goto free_path;
@@ -246,7 +251,7 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
 out:
        if (ret > 0)
                ret = -ENOENT;
-       if (ret && ret != -EIO) {
+       if (ret && ret != -EIO && !stripe->is_scrub) {
                if (IS_ENABLED(CONFIG_BTRFS_DEBUG))
                        btrfs_print_tree(leaf, 1);
                btrfs_err(fs_info,

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 7bcab3899ae627ba6a0ece7956b6b714fb92cb20..2ac574bde350c9a26c9babefc3ca5f9b264182d4 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -23,6 +23,7 @@
 #include "accessors.h"
 #include "file-item.h"
 #include "scrub.h"
+#include "raid-stripe-tree.h"
 
 /*
  * This is only the first step towards a full-features scrub. It reads all
@@ -1634,6 +1635,71 @@ static void scrub_reset_stripe(struct scrub_stripe *stripe)
        }
 }
 
+static void scrub_submit_extent_sector_read(struct scrub_ctx *sctx,
+                                           struct scrub_stripe *stripe)
+{
+       struct btrfs_fs_info *fs_info = stripe->bg->fs_info;
+       struct btrfs_bio *bbio = NULL;
+       u64 stripe_len = BTRFS_STRIPE_LEN;
+       int mirror = stripe->mirror_num;
+       int i;
+
+       atomic_inc(&stripe->pending_io);
+
+       for_each_set_bit(i, &stripe->extent_sector_bitmap, stripe->nr_sectors) {
+               struct page *page = scrub_stripe_get_page(stripe, i);
+               unsigned int pgoff = scrub_stripe_get_page_offset(stripe, i);
+
+               /* The current sector cannot be merged, submit the bio. */
+               if (bbio &&
+                   ((i > 0 &&
+                     !test_bit(i - 1, &stripe->extent_sector_bitmap)) ||
+                    bbio->bio.bi_iter.bi_size >= stripe_len)) {
+                       ASSERT(bbio->bio.bi_iter.bi_size);
+                       atomic_inc(&stripe->pending_io);
+                       btrfs_submit_bio(bbio, mirror);
+                       bbio = NULL;
+               }
+
+               if (!bbio) {
+                       struct btrfs_io_stripe io_stripe = {};
+                       struct btrfs_io_context *bioc = NULL;
+                       const u64 logical = stripe->logical +
+                                           (i << fs_info->sectorsize_bits);
+                       int err;
+
+                       bbio = btrfs_bio_alloc(stripe->nr_sectors, REQ_OP_READ,
+                                              fs_info, scrub_read_endio, stripe);
+                       bbio->bio.bi_iter.bi_sector = logical >> SECTOR_SHIFT;
+
+                       io_stripe.is_scrub = true;
+                       err = btrfs_map_block(fs_info, BTRFS_MAP_READ, logical,
+                                             &stripe_len, &bioc, &io_stripe,
+                                             &mirror);
+                       btrfs_put_bioc(bioc);
+                       if (err) {
+                               btrfs_bio_end_io(bbio,
+                                                errno_to_blk_status(err));
+                               return;
+                       }
+               }
+
+               __bio_add_page(&bbio->bio, page, fs_info->sectorsize, pgoff);
+       }
+
+       if (bbio) {
+               ASSERT(bbio->bio.bi_iter.bi_size);
+               atomic_inc(&stripe->pending_io);
+               btrfs_submit_bio(bbio, mirror);
+       }
+
+       if (atomic_dec_and_test(&stripe->pending_io)) {
+               wake_up(&stripe->io_wait);
+               INIT_WORK(&stripe->work, scrub_stripe_read_repair_worker);
+               queue_work(stripe->bg->fs_info->scrub_workers, &stripe->work);
+       }
+}
+
 static void scrub_submit_initial_read(struct scrub_ctx *sctx,
                                      struct scrub_stripe *stripe)
 {
@@ -1645,6 +1711,11 @@ static void scrub_submit_initial_read(struct scrub_ctx *sctx,
        ASSERT(stripe->mirror_num > 0);
        ASSERT(test_bit(SCRUB_STRIPE_FLAG_INITIALIZED, &stripe->state));
 
+       if (btrfs_need_stripe_tree_update(fs_info, stripe->bg->flags)) {
+               scrub_submit_extent_sector_read(sctx, stripe);
+               return;
+       }
+
        bbio = btrfs_bio_alloc(SCRUB_STRIPE_PAGES, REQ_OP_READ, fs_info,
                               scrub_read_endio, stripe);
 

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 000c56a3d2a2ebecb403ad1c3f8b601e79783fbc..a0e76bb201407d09d23d23bc585fb89164aaf9c7 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -393,6 +393,7 @@ struct btrfs_io_stripe {
        /* Block mapping. */
        u64 physical;
        u64 length;
+       bool is_scrub;
        /* For the endio handler. */
        struct btrfs_io_context *bioc;
 };