btrfs: rework chunk allocation to avoid exhaustion of the system chunk array
Commit eafa4fd0ad0607 ("btrfs: fix exhaustion of the system chunk array
due to concurrent allocations") fixed a problem that resulted in
exhausting the system chunk array in the superblock when there are many
tasks allocating chunks in parallel. Basically too many tasks enter the
first phase of chunk allocation without previous tasks having finished
their second phase of allocation, resulting in too many system chunks
being allocated. That was originally observed when running the fallocate
tests of stress-ng on a PowerPC machine, using a node size of 64K.
However that commit also introduced a deadlock where a task in phase 1 of
the chunk allocation waited for another task that had allocated a system
chunk to finish its phase 2, but that other task was waiting on an extent
buffer lock held by the first task, therefore resulting in both tasks not
making any progress. That change was later reverted by a patch with the
subject "btrfs: fix deadlock with concurrent chunk allocations involving
system chunks", since there is no simple and short solution to address it
and the deadlock is relatively easy to trigger on zoned filesystems, while
the system chunk array exhaustion is not so common.
This change reworks the chunk allocation to avoid the system chunk array
exhaustion. It accomplishes that by making the first phase of chunk
allocation do the updates of the device items in the chunk btree and the
insertion of the new chunk item in the chunk btree. This is done while
under the protection of the chunk mutex (fs_info->chunk_mutex), in the
same critical section that checks for available system space, allocates
a new system chunk if needed and reserves system chunk space. This way
we do not have chunk space reserved until the second phase completes.
The same logic is applied to chunk removal as well, since it keeps
reserved system space long after it is done updating the chunk btree.
For direct allocation of system chunks, the previous behaviour remains,
because otherwise we would deadlock on extent buffers of the chunk btree.
Changes to the chunk btree are by large done by chunk allocation and chunk
removal, which first reserve chunk system space and then later do changes
to the chunk btree. The other remaining cases are uncommon and correspond
to adding a device, removing a device and resizing a device. All these
other cases do not pre-reserve system space, they modify the chunk btree
right away, so they don't hold reserved space for a long period like chunk
allocation and chunk removal do.
The diff of this change is huge, but more than half of it is just addition
of comments describing both how things work regarding chunk allocation and
removal, including both the new behavior and the parts of the old behavior
that did not change.
CC: stable@vger.kernel.org # 5.12+
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Tested-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 782e167..c6c1431 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1745,19 +1745,14 @@ static int btrfs_free_dev_extent(struct btrfs_trans_handle *trans,
extent = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_dev_extent);
} else {
- btrfs_handle_fs_error(fs_info, ret, "Slot search failed");
goto out;
}
*dev_extent_len = btrfs_dev_extent_length(leaf, extent);
ret = btrfs_del_item(trans, root, path);
- if (ret) {
- btrfs_handle_fs_error(fs_info, ret,
- "Failed to remove dev extent item");
- } else {
+ if (ret == 0)
set_bit(BTRFS_TRANS_HAVE_FREE_BGS, &trans->transaction->flags);
- }
out:
btrfs_free_path(path);
return ret;
@@ -2942,7 +2937,7 @@ static int btrfs_del_sys_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset)
u32 cur;
struct btrfs_key key;
- mutex_lock(&fs_info->chunk_mutex);
+ lockdep_assert_held(&fs_info->chunk_mutex);
array_size = btrfs_super_sys_array_size(super_copy);
ptr = super_copy->sys_chunk_array;
@@ -2972,7 +2967,6 @@ static int btrfs_del_sys_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset)
cur += len;
}
}
- mutex_unlock(&fs_info->chunk_mutex);
return ret;
}
@@ -3012,6 +3006,29 @@ struct extent_map *btrfs_get_chunk_map(struct btrfs_fs_info *fs_info,
return em;
}
+static int remove_chunk_item(struct btrfs_trans_handle *trans,
+ struct map_lookup *map, u64 chunk_offset)
+{
+ int i;
+
+ /*
+ * Removing chunk items and updating the device items in the chunks btree
+ * requires holding the chunk_mutex.
+ * See the comment at btrfs_chunk_alloc() for the details.
+ */
+ lockdep_assert_held(&trans->fs_info->chunk_mutex);
+
+ for (i = 0; i < map->num_stripes; i++) {
+ int ret;
+
+ ret = btrfs_update_device(trans, map->stripes[i].dev);
+ if (ret)
+ return ret;
+ }
+
+ return btrfs_free_chunk(trans, chunk_offset);
+}
+
int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
@@ -3032,14 +3049,16 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
return PTR_ERR(em);
}
map = em->map_lookup;
- mutex_lock(&fs_info->chunk_mutex);
- check_system_chunk(trans, map->type);
- mutex_unlock(&fs_info->chunk_mutex);
/*
- * Take the device list mutex to prevent races with the final phase of
- * a device replace operation that replaces the device object associated
- * with map stripes (dev-replace.c:btrfs_dev_replace_finishing()).
+ * First delete the device extent items from the devices btree.
+ * We take the device_list_mutex to avoid racing with the finishing phase
+ * of a device replace operation. See the comment below before acquiring
+ * fs_info->chunk_mutex. Note that here we do not acquire the chunk_mutex
+ * because that can result in a deadlock when deleting the device extent
+ * items from the devices btree - COWing an extent buffer from the btree
+ * may result in allocating a new metadata chunk, which would attempt to
+ * lock again fs_info->chunk_mutex.
*/
mutex_lock(&fs_devices->device_list_mutex);
for (i = 0; i < map->num_stripes; i++) {
@@ -3061,18 +3080,73 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
btrfs_clear_space_info_full(fs_info);
mutex_unlock(&fs_info->chunk_mutex);
}
-
- ret = btrfs_update_device(trans, device);
- if (ret) {
- mutex_unlock(&fs_devices->device_list_mutex);
- btrfs_abort_transaction(trans, ret);
- goto out;
- }
}
mutex_unlock(&fs_devices->device_list_mutex);
- ret = btrfs_free_chunk(trans, chunk_offset);
- if (ret) {
+ /*
+ * We acquire fs_info->chunk_mutex for 2 reasons:
+ *
+ * 1) Just like with the first phase of the chunk allocation, we must
+ * reserve system space, do all chunk btree updates and deletions, and
+ * update the system chunk array in the superblock while holding this
+ * mutex. This is for similar reasons as explained on the comment at
+ * the top of btrfs_chunk_alloc();
+ *
+ * 2) Prevent races with the final phase of a device replace operation
+ * that replaces the device object associated with the map's stripes,
+ * because the device object's id can change at any time during that
+ * final phase of the device replace operation
+ * (dev-replace.c:btrfs_dev_replace_finishing()), so we could grab the
+ * replaced device and then see it with an ID of
+ * BTRFS_DEV_REPLACE_DEVID, which would cause a failure when updating
+ * the device item, which does not exists on the chunk btree.
+ * The finishing phase of device replace acquires both the
+ * device_list_mutex and the chunk_mutex, in that order, so we are
+ * safe by just acquiring the chunk_mutex.
+ */
+ trans->removing_chunk = true;
+ mutex_lock(&fs_info->chunk_mutex);
+
+ check_system_chunk(trans, map->type);
+
+ ret = remove_chunk_item(trans, map, chunk_offset);
+ /*
+ * Normally we should not get -ENOSPC since we reserved space before
+ * through the call to check_system_chunk().
+ *
+ * Despite our system space_info having enough free space, we may not
+ * be able to allocate extents from its block groups, because all have
+ * an incompatible profile, which will force us to allocate a new system
+ * block group with the right profile, or right after we called
+ * check_system_space() above, a scrub turned the only system block group
+ * with enough free space into RO mode.
+ * This is explained with more detail at do_chunk_alloc().
+ *
+ * So if we get -ENOSPC, allocate a new system chunk and retry once.
+ */
+ if (ret == -ENOSPC) {
+ const u64 sys_flags = btrfs_system_alloc_profile(fs_info);
+ struct btrfs_block_group *sys_bg;
+
+ sys_bg = btrfs_alloc_chunk(trans, sys_flags);
+ if (IS_ERR(sys_bg)) {
+ ret = PTR_ERR(sys_bg);
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+
+ ret = btrfs_chunk_alloc_add_chunk_item(trans, sys_bg);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+
+ ret = remove_chunk_item(trans, map, chunk_offset);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ goto out;
+ }
+ } else if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
@@ -3087,6 +3161,15 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
}
}
+ mutex_unlock(&fs_info->chunk_mutex);
+ trans->removing_chunk = false;
+
+ /*
+ * We are done with chunk btree updates and deletions, so release the
+ * system space we previously reserved (with check_system_chunk()).
+ */
+ btrfs_trans_release_chunk_metadata(trans);
+
ret = btrfs_remove_block_group(trans, chunk_offset, em);
if (ret) {
btrfs_abort_transaction(trans, ret);
@@ -3094,6 +3177,10 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
}
out:
+ if (trans->removing_chunk) {
+ mutex_unlock(&fs_info->chunk_mutex);
+ trans->removing_chunk = false;
+ }
/* once for us */
free_extent_map(em);
return ret;
@@ -4860,13 +4947,12 @@ static int btrfs_add_system_chunk(struct btrfs_fs_info *fs_info,
u32 array_size;
u8 *ptr;
- mutex_lock(&fs_info->chunk_mutex);
+ lockdep_assert_held(&fs_info->chunk_mutex);
+
array_size = btrfs_super_sys_array_size(super_copy);
if (array_size + item_size + sizeof(disk_key)
- > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE) {
- mutex_unlock(&fs_info->chunk_mutex);
+ > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE)
return -EFBIG;
- }
ptr = super_copy->sys_chunk_array + array_size;
btrfs_cpu_key_to_disk(&disk_key, key);
@@ -4875,7 +4961,6 @@ static int btrfs_add_system_chunk(struct btrfs_fs_info *fs_info,
memcpy(ptr, chunk, item_size);
item_size += sizeof(disk_key);
btrfs_set_super_sys_array_size(super_copy, array_size + item_size);
- mutex_unlock(&fs_info->chunk_mutex);
return 0;
}
@@ -5225,13 +5310,14 @@ static int decide_stripe_size(struct btrfs_fs_devices *fs_devices,
}
}
-static int create_chunk(struct btrfs_trans_handle *trans,
+static struct btrfs_block_group *create_chunk(struct btrfs_trans_handle *trans,
struct alloc_chunk_ctl *ctl,
struct btrfs_device_info *devices_info)
{
struct btrfs_fs_info *info = trans->fs_info;
struct map_lookup *map = NULL;
struct extent_map_tree *em_tree;
+ struct btrfs_block_group *block_group;
struct extent_map *em;
u64 start = ctl->start;
u64 type = ctl->type;
@@ -5241,7 +5327,7 @@ static int create_chunk(struct btrfs_trans_handle *trans,
map = kmalloc(map_lookup_size(ctl->num_stripes), GFP_NOFS);
if (!map)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
map->num_stripes = ctl->num_stripes;
for (i = 0; i < ctl->ndevs; ++i) {
@@ -5263,7 +5349,7 @@ static int create_chunk(struct btrfs_trans_handle *trans,
em = alloc_extent_map();
if (!em) {
kfree(map);
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
}
set_bit(EXTENT_FLAG_FS_MAPPING, &em->flags);
em->map_lookup = map;
@@ -5279,12 +5365,12 @@ static int create_chunk(struct btrfs_trans_handle *trans,
if (ret) {
write_unlock(&em_tree->lock);
free_extent_map(em);
- return ret;
+ return ERR_PTR(ret);
}
write_unlock(&em_tree->lock);
- ret = btrfs_make_block_group(trans, 0, type, start, ctl->chunk_size);
- if (ret)
+ block_group = btrfs_make_block_group(trans, 0, type, start, ctl->chunk_size);
+ if (IS_ERR(block_group))
goto error_del_extent;
for (i = 0; i < map->num_stripes; i++) {
@@ -5304,7 +5390,7 @@ static int create_chunk(struct btrfs_trans_handle *trans,
check_raid56_incompat_flag(info, type);
check_raid1c34_incompat_flag(info, type);
- return 0;
+ return block_group;
error_del_extent:
write_lock(&em_tree->lock);
@@ -5316,34 +5402,36 @@ static int create_chunk(struct btrfs_trans_handle *trans,
/* One for the tree reference */
free_extent_map(em);
- return ret;
+ return block_group;
}
-int btrfs_alloc_chunk(struct btrfs_trans_handle *trans, u64 type)
+struct btrfs_block_group *btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
+ u64 type)
{
struct btrfs_fs_info *info = trans->fs_info;
struct btrfs_fs_devices *fs_devices = info->fs_devices;
struct btrfs_device_info *devices_info = NULL;
struct alloc_chunk_ctl ctl;
+ struct btrfs_block_group *block_group;
int ret;
lockdep_assert_held(&info->chunk_mutex);
if (!alloc_profile_is_valid(type, 0)) {
ASSERT(0);
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}
if (list_empty(&fs_devices->alloc_list)) {
if (btrfs_test_opt(info, ENOSPC_DEBUG))
btrfs_debug(info, "%s: no writable device", __func__);
- return -ENOSPC;
+ return ERR_PTR(-ENOSPC);
}
if (!(type & BTRFS_BLOCK_GROUP_TYPE_MASK)) {
btrfs_err(info, "invalid chunk type 0x%llx requested", type);
ASSERT(0);
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}
ctl.start = find_next_chunk(info);
@@ -5353,46 +5441,43 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans, u64 type)
devices_info = kcalloc(fs_devices->rw_devices, sizeof(*devices_info),
GFP_NOFS);
if (!devices_info)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
ret = gather_device_info(fs_devices, &ctl, devices_info);
- if (ret < 0)
+ if (ret < 0) {
+ block_group = ERR_PTR(ret);
goto out;
+ }
ret = decide_stripe_size(fs_devices, &ctl, devices_info);
- if (ret < 0)
+ if (ret < 0) {
+ block_group = ERR_PTR(ret);
goto out;
+ }
- ret = create_chunk(trans, &ctl, devices_info);
+ block_group = create_chunk(trans, &ctl, devices_info);
out:
kfree(devices_info);
- return ret;
+ return block_group;
}
/*
- * Chunk allocation falls into two parts. The first part does work
- * that makes the new allocated chunk usable, but does not do any operation
- * that modifies the chunk tree. The second part does the work that
- * requires modifying the chunk tree. This division is important for the
- * bootstrap process of adding storage to a seed btrfs.
+ * This function, btrfs_finish_chunk_alloc(), belongs to phase 2.
+ *
+ * See the comment at btrfs_chunk_alloc() for details about the chunk allocation
+ * phases.
*/
int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
u64 chunk_offset, u64 chunk_size)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
- struct btrfs_root *extent_root = fs_info->extent_root;
- struct btrfs_root *chunk_root = fs_info->chunk_root;
- struct btrfs_key key;
struct btrfs_device *device;
- struct btrfs_chunk *chunk;
- struct btrfs_stripe *stripe;
struct extent_map *em;
struct map_lookup *map;
- size_t item_size;
u64 dev_offset;
u64 stripe_size;
- int i = 0;
+ int i;
int ret = 0;
em = btrfs_get_chunk_map(fs_info, chunk_offset, chunk_size);
@@ -5400,53 +5485,117 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
return PTR_ERR(em);
map = em->map_lookup;
- item_size = btrfs_chunk_item_size(map->num_stripes);
stripe_size = em->orig_block_len;
- chunk = kzalloc(item_size, GFP_NOFS);
- if (!chunk) {
- ret = -ENOMEM;
- goto out;
- }
-
/*
* Take the device list mutex to prevent races with the final phase of
* a device replace operation that replaces the device object associated
* with the map's stripes, because the device object's id can change
* at any time during that final phase of the device replace operation
- * (dev-replace.c:btrfs_dev_replace_finishing()).
+ * (dev-replace.c:btrfs_dev_replace_finishing()), so we could grab the
+ * replaced device and then see it with an ID of BTRFS_DEV_REPLACE_DEVID,
+ * resulting in persisting a device extent item with such ID.
*/
mutex_lock(&fs_info->fs_devices->device_list_mutex);
for (i = 0; i < map->num_stripes; i++) {
device = map->stripes[i].dev;
dev_offset = map->stripes[i].physical;
- ret = btrfs_update_device(trans, device);
- if (ret)
- break;
ret = btrfs_alloc_dev_extent(trans, device, chunk_offset,
dev_offset, stripe_size);
if (ret)
break;
}
- if (ret) {
- mutex_unlock(&fs_info->fs_devices->device_list_mutex);
+ mutex_unlock(&fs_info->fs_devices->device_list_mutex);
+
+ free_extent_map(em);
+ return ret;
+}
+
+/*
+ * This function, btrfs_chunk_alloc_add_chunk_item(), typically belongs to the
+ * phase 1 of chunk allocation. It belongs to phase 2 only when allocating system
+ * chunks.
+ *
+ * See the comment at btrfs_chunk_alloc() for details about the chunk allocation
+ * phases.
+ */
+int btrfs_chunk_alloc_add_chunk_item(struct btrfs_trans_handle *trans,
+ struct btrfs_block_group *bg)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_root *extent_root = fs_info->extent_root;
+ struct btrfs_root *chunk_root = fs_info->chunk_root;
+ struct btrfs_key key;
+ struct btrfs_chunk *chunk;
+ struct btrfs_stripe *stripe;
+ struct extent_map *em;
+ struct map_lookup *map;
+ size_t item_size;
+ int i;
+ int ret;
+
+ /*
+ * We take the chunk_mutex for 2 reasons:
+ *
+ * 1) Updates and insertions in the chunk btree must be done while holding
+ * the chunk_mutex, as well as updating the system chunk array in the
+ * superblock. See the comment on top of btrfs_chunk_alloc() for the
+ * details;
+ *
+ * 2) To prevent races with the final phase of a device replace operation
+ * that replaces the device object associated with the map's stripes,
+ * because the device object's id can change at any time during that
+ * final phase of the device replace operation
+ * (dev-replace.c:btrfs_dev_replace_finishing()), so we could grab the
+ * replaced device and then see it with an ID of BTRFS_DEV_REPLACE_DEVID,
+ * which would cause a failure when updating the device item, which does
+ * not exists, or persisting a stripe of the chunk item with such ID.
+ * Here we can't use the device_list_mutex because our caller already
+ * has locked the chunk_mutex, and the final phase of device replace
+ * acquires both mutexes - first the device_list_mutex and then the
+ * chunk_mutex. Using any of those two mutexes protects us from a
+ * concurrent device replace.
+ */
+ lockdep_assert_held(&fs_info->chunk_mutex);
+
+ em = btrfs_get_chunk_map(fs_info, bg->start, bg->length);
+ if (IS_ERR(em)) {
+ ret = PTR_ERR(em);
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+
+ map = em->map_lookup;
+ item_size = btrfs_chunk_item_size(map->num_stripes);
+
+ chunk = kzalloc(item_size, GFP_NOFS);
+ if (!chunk) {
+ ret = -ENOMEM;
+ btrfs_abort_transaction(trans, ret);
goto out;
}
+ for (i = 0; i < map->num_stripes; i++) {
+ struct btrfs_device *device = map->stripes[i].dev;
+
+ ret = btrfs_update_device(trans, device);
+ if (ret)
+ goto out;
+ }
+
stripe = &chunk->stripe;
for (i = 0; i < map->num_stripes; i++) {
- device = map->stripes[i].dev;
- dev_offset = map->stripes[i].physical;
+ struct btrfs_device *device = map->stripes[i].dev;
+ const u64 dev_offset = map->stripes[i].physical;
btrfs_set_stack_stripe_devid(stripe, device->devid);
btrfs_set_stack_stripe_offset(stripe, dev_offset);
memcpy(stripe->dev_uuid, device->uuid, BTRFS_UUID_SIZE);
stripe++;
}
- mutex_unlock(&fs_info->fs_devices->device_list_mutex);
- btrfs_set_stack_chunk_length(chunk, chunk_size);
+ btrfs_set_stack_chunk_length(chunk, bg->length);
btrfs_set_stack_chunk_owner(chunk, extent_root->root_key.objectid);
btrfs_set_stack_chunk_stripe_len(chunk, map->stripe_len);
btrfs_set_stack_chunk_type(chunk, map->type);
@@ -5458,15 +5607,18 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
key.type = BTRFS_CHUNK_ITEM_KEY;
- key.offset = chunk_offset;
+ key.offset = bg->start;
ret = btrfs_insert_item(trans, chunk_root, &key, chunk, item_size);
- if (ret == 0 && map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
- /*
- * TODO: Cleanup of inserted chunk root in case of
- * failure.
- */
+ if (ret)
+ goto out;
+
+ bg->chunk_item_inserted = 1;
+
+ if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
ret = btrfs_add_system_chunk(fs_info, &key, chunk, item_size);
+ if (ret)
+ goto out;
}
out:
@@ -5479,16 +5631,41 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
u64 alloc_profile;
- int ret;
+ struct btrfs_block_group *meta_bg;
+ struct btrfs_block_group *sys_bg;
+
+ /*
+ * When adding a new device for sprouting, the seed device is read-only
+ * so we must first allocate a metadata and a system chunk. But before
+ * adding the block group items to the extent, device and chunk btrees,
+ * we must first:
+ *
+ * 1) Create both chunks without doing any changes to the btrees, as
+ * otherwise we would get -ENOSPC since the block groups from the
+ * seed device are read-only;
+ *
+ * 2) Add the device item for the new sprout device - finishing the setup
+ * of a new block group requires updating the device item in the chunk
+ * btree, so it must exist when we attempt to do it. The previous step
+ * ensures this does not fail with -ENOSPC.
+ *
+ * After that we can add the block group items to their btrees:
+ * update existing device item in the chunk btree, add a new block group
+ * item to the extent btree, add a new chunk item to the chunk btree and
+ * finally add the new device extent items to the devices btree.
+ */
alloc_profile = btrfs_metadata_alloc_profile(fs_info);
- ret = btrfs_alloc_chunk(trans, alloc_profile);
- if (ret)
- return ret;
+ meta_bg = btrfs_alloc_chunk(trans, alloc_profile);
+ if (IS_ERR(meta_bg))
+ return PTR_ERR(meta_bg);
alloc_profile = btrfs_system_alloc_profile(fs_info);
- ret = btrfs_alloc_chunk(trans, alloc_profile);
- return ret;
+ sys_bg = btrfs_alloc_chunk(trans, alloc_profile);
+ if (IS_ERR(sys_bg))
+ return PTR_ERR(sys_bg);
+
+ return 0;
}
static inline int btrfs_chunk_max_errors(struct map_lookup *map)
@@ -7415,10 +7592,18 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
total_dev++;
} else if (found_key.type == BTRFS_CHUNK_ITEM_KEY) {
struct btrfs_chunk *chunk;
+
+ /*
+ * We are only called at mount time, so no need to take
+ * fs_info->chunk_mutex. Plus, to avoid lockdep warnings,
+ * we always lock first fs_info->chunk_mutex before
+ * acquiring any locks on the chunk tree. This is a
+ * requirement for chunk allocation, see the comment on
+ * top of btrfs_chunk_alloc() for details.
+ */
+ ASSERT(!test_bit(BTRFS_FS_OPEN, &fs_info->flags));
chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
- mutex_lock(&fs_info->chunk_mutex);
ret = read_one_chunk(&found_key, leaf, chunk);
- mutex_unlock(&fs_info->chunk_mutex);
if (ret)
goto error;
}