Merge tag 'for-5.6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull more btrfs updates from David Sterba:
"Fixes that arrived after the merge window freeze, mostly stable
material.
- fix race in tree-mod-log element tracking
- fix bio flushing inside extent writepages
- fix assertion when in-memory tracking of discarded extents finds an
empty tree (eg. after adding a new device)
- update logic of temporary read-only block groups to take into
account overcommit
- fix some fixup worker corner cases:
- page could not go through proper COW cycle and the dirty status
is lost due to page migration
- deadlock if delayed allocation is performed under page lock
- fix send emitting invalid clones within the same file
- fix statfs reporting 0 free space when global block reserve size is
larger than remaining free space but there is still space for new
chunks"
* tag 'for-5.6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: do not zero f_bavail if we have available space
Btrfs: send, fix emission of invalid clone operations within the same file
btrfs: do not do delalloc reservation under page lock
btrfs: drop the -EBUSY case in __extent_writepage_io
Btrfs: keep pages dirty when using btrfs_writepage_fixup_worker
btrfs: take overcommit into account in inc_block_group_ro
btrfs: fix force usage in inc_block_group_ro
btrfs: Correctly handle empty trees in find_first_clear_extent_bit
btrfs: flush write bio if we loop in extent_write_cache_pages
Btrfs: fix race between adding and putting tree mod seq elements and nodes
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 1485158..404e050 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1191,7 +1191,6 @@ static int inc_block_group_ro(struct btrfs_block_group *cache, int force)
{
struct btrfs_space_info *sinfo = cache->space_info;
u64 num_bytes;
- u64 sinfo_used;
int ret = -ENOSPC;
spin_lock(&sinfo->lock);
@@ -1205,19 +1204,38 @@ static int inc_block_group_ro(struct btrfs_block_group *cache, int force)
num_bytes = cache->length - cache->reserved - cache->pinned -
cache->bytes_super - cache->used;
- sinfo_used = btrfs_space_info_used(sinfo, true);
/*
- * sinfo_used + num_bytes should always <= sinfo->total_bytes.
- *
- * Here we make sure if we mark this bg RO, we still have enough
- * free space as buffer.
+ * Data never overcommits, even in mixed mode, so do just the straight
+ * check of left over space in how much we have allocated.
*/
- if (sinfo_used + num_bytes <= sinfo->total_bytes) {
+ if (force) {
+ ret = 0;
+ } else if (sinfo->flags & BTRFS_BLOCK_GROUP_DATA) {
+ u64 sinfo_used = btrfs_space_info_used(sinfo, true);
+
+ /*
+ * Here we make sure if we mark this bg RO, we still have enough
+ * free space as buffer.
+ */
+ if (sinfo_used + num_bytes <= sinfo->total_bytes)
+ ret = 0;
+ } else {
+ /*
+ * We overcommit metadata, so we need to do the
+ * btrfs_can_overcommit check here, and we need to pass in
+ * BTRFS_RESERVE_NO_FLUSH to give ourselves the most amount of
+ * leeway to allow us to mark this block group as read only.
+ */
+ if (btrfs_can_overcommit(cache->fs_info, sinfo, num_bytes,
+ BTRFS_RESERVE_NO_FLUSH))
+ ret = 0;
+ }
+
+ if (!ret) {
sinfo->bytes_readonly += num_bytes;
cache->ro++;
list_add_tail(&cache->ro_list, &sinfo->ro_bgs);
- ret = 0;
}
out:
spin_unlock(&cache->lock);
@@ -1225,9 +1243,6 @@ static int inc_block_group_ro(struct btrfs_block_group *cache, int force)
if (ret == -ENOSPC && btrfs_test_opt(cache->fs_info, ENOSPC_DEBUG)) {
btrfs_info(cache->fs_info,
"unable to make block group %llu ro", cache->start);
- btrfs_info(cache->fs_info,
- "sinfo_used=%llu bg_num_bytes=%llu",
- sinfo_used, num_bytes);
btrfs_dump_space_info(cache->fs_info, cache->space_info, 0, 0);
}
return ret;
@@ -2225,7 +2240,7 @@ int btrfs_inc_block_group_ro(struct btrfs_block_group *cache,
}
}
- ret = inc_block_group_ro(cache, !do_chunk_alloc);
+ ret = inc_block_group_ro(cache, 0);
if (!do_chunk_alloc)
goto unlock_out;
if (!ret)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 24658b5..f2ec1a9 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -326,12 +326,10 @@ u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
struct seq_list *elem)
{
write_lock(&fs_info->tree_mod_log_lock);
- spin_lock(&fs_info->tree_mod_seq_lock);
if (!elem->seq) {
elem->seq = btrfs_inc_tree_mod_seq(fs_info);
list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
}
- spin_unlock(&fs_info->tree_mod_seq_lock);
write_unlock(&fs_info->tree_mod_log_lock);
return elem->seq;
@@ -351,7 +349,7 @@ void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
if (!seq_putting)
return;
- spin_lock(&fs_info->tree_mod_seq_lock);
+ write_lock(&fs_info->tree_mod_log_lock);
list_del(&elem->list);
elem->seq = 0;
@@ -362,19 +360,17 @@ void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
* blocker with lower sequence number exists, we
* cannot remove anything from the log
*/
- spin_unlock(&fs_info->tree_mod_seq_lock);
+ write_unlock(&fs_info->tree_mod_log_lock);
return;
}
min_seq = cur_elem->seq;
}
}
- spin_unlock(&fs_info->tree_mod_seq_lock);
/*
* anything that's lower than the lowest existing (read: blocked)
* sequence number can be removed from the tree.
*/
- write_lock(&fs_info->tree_mod_log_lock);
tm_root = &fs_info->tree_mod_log;
for (node = rb_first(tm_root); node; node = next) {
next = rb_next(node);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f90b820..36df977 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -714,14 +714,12 @@ struct btrfs_fs_info {
atomic_t nr_delayed_iputs;
wait_queue_head_t delayed_iputs_wait;
- /* this protects tree_mod_seq_list */
- spinlock_t tree_mod_seq_lock;
atomic64_t tree_mod_seq;
- struct list_head tree_mod_seq_list;
- /* this protects tree_mod_log */
+ /* this protects tree_mod_log and tree_mod_seq_list */
rwlock_t tree_mod_log_lock;
struct rb_root tree_mod_log;
+ struct list_head tree_mod_seq_list;
atomic_t async_delalloc_pages;
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index df3bd88..dfdb7d4 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -492,7 +492,7 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
if (head->is_data)
return;
- spin_lock(&fs_info->tree_mod_seq_lock);
+ read_lock(&fs_info->tree_mod_log_lock);
if (!list_empty(&fs_info->tree_mod_seq_list)) {
struct seq_list *elem;
@@ -500,7 +500,7 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
struct seq_list, list);
seq = elem->seq;
}
- spin_unlock(&fs_info->tree_mod_seq_lock);
+ read_unlock(&fs_info->tree_mod_log_lock);
again:
for (node = rb_first_cached(&head->ref_tree); node;
@@ -518,7 +518,7 @@ int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
struct seq_list *elem;
int ret = 0;
- spin_lock(&fs_info->tree_mod_seq_lock);
+ read_lock(&fs_info->tree_mod_log_lock);
if (!list_empty(&fs_info->tree_mod_seq_list)) {
elem = list_first_entry(&fs_info->tree_mod_seq_list,
struct seq_list, list);
@@ -531,7 +531,7 @@ int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
}
}
- spin_unlock(&fs_info->tree_mod_seq_lock);
+ read_unlock(&fs_info->tree_mod_log_lock);
return ret;
}
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index aea48d6..7fa9bb7 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2697,7 +2697,6 @@ int __cold open_ctree(struct super_block *sb,
spin_lock_init(&fs_info->fs_roots_radix_lock);
spin_lock_init(&fs_info->delayed_iput_lock);
spin_lock_init(&fs_info->defrag_inodes_lock);
- spin_lock_init(&fs_info->tree_mod_seq_lock);
spin_lock_init(&fs_info->super_lock);
spin_lock_init(&fs_info->buffer_lock);
spin_lock_init(&fs_info->unused_bgs_lock);
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index e2d3028..c0f2027 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1593,21 +1593,25 @@ void find_first_clear_extent_bit(struct extent_io_tree *tree, u64 start,
/* Find first extent with bits cleared */
while (1) {
node = __etree_search(tree, start, &next, &prev, NULL, NULL);
- if (!node) {
+ if (!node && !next && !prev) {
+ /*
+ * Tree is completely empty, send full range and let
+ * caller deal with it
+ */
+ *start_ret = 0;
+ *end_ret = -1;
+ goto out;
+ } else if (!node && !next) {
+ /*
+ * We are past the last allocated chunk, set start at
+ * the end of the last extent.
+ */
+ state = rb_entry(prev, struct extent_state, rb_node);
+ *start_ret = state->end + 1;
+ *end_ret = -1;
+ goto out;
+ } else if (!node) {
node = next;
- if (!node) {
- /*
- * We are past the last allocated chunk,
- * set start at the end of the last extent. The
- * device alloc tree should never be empty so
- * prev is always set.
- */
- ASSERT(prev);
- state = rb_entry(prev, struct extent_state, rb_node);
- *start_ret = state->end + 1;
- *end_ret = -1;
- goto out;
- }
}
/*
* At this point 'node' either contains 'start' or start is
@@ -3438,11 +3442,7 @@ static noinline_for_stack int __extent_writepage_io(struct inode *inode,
ret = btrfs_writepage_cow_fixup(page, start, page_end);
if (ret) {
/* Fixup worker will requeue */
- if (ret == -EBUSY)
- wbc->pages_skipped++;
- else
- redirty_page_for_writepage(wbc, page);
-
+ redirty_page_for_writepage(wbc, page);
update_nr_written(wbc, nr_written);
unlock_page(page);
return 1;
@@ -4166,7 +4166,16 @@ static int extent_write_cache_pages(struct address_space *mapping,
*/
scanned = 1;
index = 0;
- goto retry;
+
+ /*
+ * If we're looping we could run into a page that is locked by a
+ * writer and that writer could be waiting on writeback for a
+ * page in our current bio, and thus deadlock, so flush the
+ * write bio here.
+ */
+ ret = flush_write_bio(epd);
+ if (!ret)
+ goto retry;
}
if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole))
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 6d2bb58..5b3ec93 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2189,6 +2189,7 @@ int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end,
/* see btrfs_writepage_start_hook for details on why this is required */
struct btrfs_writepage_fixup {
struct page *page;
+ struct inode *inode;
struct btrfs_work work;
};
@@ -2202,27 +2203,71 @@ static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
struct inode *inode;
u64 page_start;
u64 page_end;
- int ret;
+ int ret = 0;
+ bool free_delalloc_space = true;
fixup = container_of(work, struct btrfs_writepage_fixup, work);
page = fixup->page;
+ inode = fixup->inode;
+ page_start = page_offset(page);
+ page_end = page_offset(page) + PAGE_SIZE - 1;
+
+ /*
+ * This is similar to page_mkwrite, we need to reserve the space before
+ * we take the page lock.
+ */
+ ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
+ PAGE_SIZE);
again:
lock_page(page);
+
+ /*
+ * Before we queued this fixup, we took a reference on the page.
+ * page->mapping may go NULL, but it shouldn't be moved to a different
+ * address space.
+ */
if (!page->mapping || !PageDirty(page) || !PageChecked(page)) {
- ClearPageChecked(page);
+ /*
+ * Unfortunately this is a little tricky, either
+ *
+ * 1) We got here and our page had already been dealt with and
+ * we reserved our space, thus ret == 0, so we need to just
+ * drop our space reservation and bail. This can happen the
+ * first time we come into the fixup worker, or could happen
+ * while waiting for the ordered extent.
+ * 2) Our page was already dealt with, but we happened to get an
+ * ENOSPC above from the btrfs_delalloc_reserve_space. In
+ * this case we obviously don't have anything to release, but
+ * because the page was already dealt with we don't want to
+ * mark the page with an error, so make sure we're resetting
+ * ret to 0. This is why we have this check _before_ the ret
+ * check, because we do not want to have a surprise ENOSPC
+ * when the page was already properly dealt with.
+ */
+ if (!ret) {
+ btrfs_delalloc_release_extents(BTRFS_I(inode),
+ PAGE_SIZE);
+ btrfs_delalloc_release_space(inode, data_reserved,
+ page_start, PAGE_SIZE,
+ true);
+ }
+ ret = 0;
goto out_page;
}
- inode = page->mapping->host;
- page_start = page_offset(page);
- page_end = page_offset(page) + PAGE_SIZE - 1;
+ /*
+ * We can't mess with the page state unless it is locked, so now that
+ * it is locked bail if we failed to make our space reservation.
+ */
+ if (ret)
+ goto out_page;
lock_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end,
&cached_state);
/* already ordered? We're done */
if (PagePrivate2(page))
- goto out;
+ goto out_reserved;
ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start,
PAGE_SIZE);
@@ -2235,39 +2280,49 @@ static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
goto again;
}
- ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
- PAGE_SIZE);
- if (ret) {
- mapping_set_error(page->mapping, ret);
- end_extent_writepage(page, ret, page_start, page_end);
- ClearPageChecked(page);
- goto out;
- }
-
ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
&cached_state);
- if (ret) {
- mapping_set_error(page->mapping, ret);
- end_extent_writepage(page, ret, page_start, page_end);
- ClearPageChecked(page);
+ if (ret)
goto out_reserved;
- }
- ClearPageChecked(page);
- set_page_dirty(page);
+ /*
+ * Everything went as planned, we're now the owner of a dirty page with
+ * delayed allocation bits set and space reserved for our COW
+ * destination.
+ *
+ * The page was dirty when we started, nothing should have cleaned it.
+ */
+ BUG_ON(!PageDirty(page));
+ free_delalloc_space = false;
out_reserved:
btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
- if (ret)
+ if (free_delalloc_space)
btrfs_delalloc_release_space(inode, data_reserved, page_start,
PAGE_SIZE, true);
-out:
unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start, page_end,
&cached_state);
out_page:
+ if (ret) {
+ /*
+ * We hit ENOSPC or other errors. Update the mapping and page
+ * to reflect the errors and clean the page.
+ */
+ mapping_set_error(page->mapping, ret);
+ end_extent_writepage(page, ret, page_start, page_end);
+ clear_page_dirty_for_io(page);
+ SetPageError(page);
+ }
+ ClearPageChecked(page);
unlock_page(page);
put_page(page);
kfree(fixup);
extent_changeset_free(data_reserved);
+ /*
+ * As a precaution, do a delayed iput in case it would be the last iput
+ * that could need flushing space. Recursing back to fixup worker would
+ * deadlock.
+ */
+ btrfs_add_delayed_iput(inode);
}
/*
@@ -2291,6 +2346,13 @@ int btrfs_writepage_cow_fixup(struct page *page, u64 start, u64 end)
if (TestClearPagePrivate2(page))
return 0;
+ /*
+ * PageChecked is set below when we create a fixup worker for this page,
+ * don't try to create another one if we're already PageChecked()
+ *
+ * The extent_io writepage code will redirty the page if we send back
+ * EAGAIN.
+ */
if (PageChecked(page))
return -EAGAIN;
@@ -2298,12 +2360,21 @@ int btrfs_writepage_cow_fixup(struct page *page, u64 start, u64 end)
if (!fixup)
return -EAGAIN;
+ /*
+ * We are already holding a reference to this inode from
+ * write_cache_pages. We need to hold it because the space reservation
+ * takes place outside of the page lock, and we can't trust
+ * page->mapping outside of the page lock.
+ */
+ ihold(inode);
SetPageChecked(page);
get_page(page);
btrfs_init_work(&fixup->work, btrfs_writepage_fixup_worker, NULL, NULL);
fixup->page = page;
+ fixup->inode = inode;
btrfs_queue_work(fs_info->fixup_workers, &fixup->work);
- return -EBUSY;
+
+ return -EAGAIN;
}
static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 091e5bc..a055b65 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -1269,7 +1269,8 @@ static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_)
* destination of the stream.
*/
if (ino == bctx->cur_objectid &&
- offset >= bctx->sctx->cur_inode_next_write_offset)
+ offset + bctx->extent_len >
+ bctx->sctx->cur_inode_next_write_offset)
return 0;
}
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 537bc31..01297c5 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -159,9 +159,9 @@ static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
return (global->size << 1);
}
-static int can_overcommit(struct btrfs_fs_info *fs_info,
- struct btrfs_space_info *space_info, u64 bytes,
- enum btrfs_reserve_flush_enum flush)
+int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
+ struct btrfs_space_info *space_info, u64 bytes,
+ enum btrfs_reserve_flush_enum flush)
{
u64 profile;
u64 avail;
@@ -226,7 +226,8 @@ void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
/* Check and see if our ticket can be satisified now. */
if ((used + ticket->bytes <= space_info->total_bytes) ||
- can_overcommit(fs_info, space_info, ticket->bytes, flush)) {
+ btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
+ flush)) {
btrfs_space_info_update_bytes_may_use(fs_info,
space_info,
ticket->bytes);
@@ -639,13 +640,14 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
return to_reclaim;
to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
- if (can_overcommit(fs_info, space_info, to_reclaim,
- BTRFS_RESERVE_FLUSH_ALL))
+ if (btrfs_can_overcommit(fs_info, space_info, to_reclaim,
+ BTRFS_RESERVE_FLUSH_ALL))
return 0;
used = btrfs_space_info_used(space_info, true);
- if (can_overcommit(fs_info, space_info, SZ_1M, BTRFS_RESERVE_FLUSH_ALL))
+ if (btrfs_can_overcommit(fs_info, space_info, SZ_1M,
+ BTRFS_RESERVE_FLUSH_ALL))
expected = div_factor_fine(space_info->total_bytes, 95);
else
expected = div_factor_fine(space_info->total_bytes, 90);
@@ -1004,7 +1006,7 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
*/
if (!pending_tickets &&
((used + orig_bytes <= space_info->total_bytes) ||
- can_overcommit(fs_info, space_info, orig_bytes, flush))) {
+ btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
btrfs_space_info_update_bytes_may_use(fs_info, space_info,
orig_bytes);
ret = 0;
diff --git a/fs/btrfs/space-info.h b/fs/btrfs/space-info.h
index 1a349e3..24514cd 100644
--- a/fs/btrfs/space-info.h
+++ b/fs/btrfs/space-info.h
@@ -127,6 +127,9 @@ int btrfs_reserve_metadata_bytes(struct btrfs_root *root,
enum btrfs_reserve_flush_enum flush);
void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info);
+int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
+ struct btrfs_space_info *space_info, u64 bytes,
+ enum btrfs_reserve_flush_enum flush);
static inline void btrfs_space_info_free_bytes_may_use(
struct btrfs_fs_info *fs_info,
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index a906315..0616a54 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2135,7 +2135,15 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
*/
thresh = SZ_4M;
- if (!mixed && total_free_meta - thresh < block_rsv->size)
+ /*
+ * We only want to claim there's no available space if we can no longer
+ * allocate chunks for our metadata profile and our global reserve will
+ * not fit in the free metadata space. If we aren't ->full then we
+ * still can allocate chunks and thus are fine using the currently
+ * calculated f_bavail.
+ */
+ if (!mixed && block_rsv->space_info->full &&
+ total_free_meta - thresh < block_rsv->size)
buf->f_bavail = 0;
buf->f_type = BTRFS_SUPER_MAGIC;
diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index c12b91f..84fb3fa9 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -142,7 +142,6 @@ struct btrfs_fs_info *btrfs_alloc_dummy_fs_info(u32 nodesize, u32 sectorsize)
spin_lock_init(&fs_info->qgroup_lock);
spin_lock_init(&fs_info->super_lock);
spin_lock_init(&fs_info->fs_roots_radix_lock);
- spin_lock_init(&fs_info->tree_mod_seq_lock);
mutex_init(&fs_info->qgroup_ioctl_lock);
mutex_init(&fs_info->qgroup_rescan_lock);
rwlock_init(&fs_info->tree_mod_log_lock);
diff --git a/fs/btrfs/tests/extent-io-tests.c b/fs/btrfs/tests/extent-io-tests.c
index 123d9a6..df7ce87 100644
--- a/fs/btrfs/tests/extent-io-tests.c
+++ b/fs/btrfs/tests/extent-io-tests.c
@@ -441,8 +441,17 @@ static int test_find_first_clear_extent_bit(void)
int ret = -EINVAL;
test_msg("running find_first_clear_extent_bit test");
+
extent_io_tree_init(NULL, &tree, IO_TREE_SELFTEST, NULL);
+ /* Test correct handling of empty tree */
+ find_first_clear_extent_bit(&tree, 0, &start, &end, CHUNK_TRIMMED);
+ if (start != 0 || end != -1) {
+ test_err(
+ "error getting a range from completely empty tree: start %llu end %llu",
+ start, end);
+ goto out;
+ }
/*
* Set 1M-4M alloc/discard and 32M-64M thus leaving a hole between
* 4M-32M
