From: Jeff Mahoney <je...@suse.com>
Any time the first block group of a new type is created, we add a new
kobject to sysfs to hold the attributes for that type. Kobject-internal
allocations always use GFP_KERNEL, making them prone to fs-reclaim races.
While it appears as if this can occur any time a block group is created,
the only times the first block group of a new type can be created in
memory is at mount and when we create the first new block group during
raid conversion.
This patch adds a new list to track pending kobject additions and then
handles them after we do chunk relocation. Between relocating the
target chunk (or forcing allocation of a new chunk in the case of data)
and removing the old chunk, we're in a safe place for fs-reclaim to
occur. We're holding the volume mutex, which is already held across
page faults, and the delete_unused_bgs_mutex, which will only stall
the cleaner thread.
Signed-off-by: Jeff Mahoney <je...@suse.com>
---
fs/btrfs/ctree.h | 6 ++++-
fs/btrfs/disk-io.c | 2 ++
fs/btrfs/extent-tree.c | 59 +++++++++++++++++++++++++++++++++++---------------
fs/btrfs/sysfs.c | 2 +-
fs/btrfs/volumes.c | 12 ++++++++++
5 files changed, 61 insertions(+), 20 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ffbb05aa66fa..75dbdf1bbead 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -381,8 +381,9 @@ struct btrfs_dev_replace {
/* For raid type sysfs entries */
struct raid_kobject {
- int raid_type;
+ u64 flags;
struct kobject kobj;
+ struct list_head list;
};
struct btrfs_space_info {
@@ -938,6 +939,8 @@ struct btrfs_fs_info {
int thread_pool_size;
struct kobject *space_info_kobj;
+ struct list_head pending_raid_kobjs;
+ spinlock_t pending_raid_kobjs_lock; /* uncontended */
u64 total_pinned;
@@ -2688,6 +2691,7 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64
bytenr);
int btrfs_make_block_group(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info, u64 bytes_used,
u64 type, u64 chunk_offset, u64 size);
+void btrfs_add_raid_kobjects(struct btrfs_fs_info *fs_info);
struct btrfs_trans_handle *btrfs_start_trans_remove_block_group(
struct btrfs_fs_info *fs_info,
const u64 chunk_offset);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index eb6bb3169a9e..d5e1c2ff71ff 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2447,6 +2447,8 @@ int open_ctree(struct super_block *sb,
INIT_LIST_HEAD(&fs_info->delayed_iputs);
INIT_LIST_HEAD(&fs_info->delalloc_roots);
INIT_LIST_HEAD(&fs_info->caching_block_groups);
+ INIT_LIST_HEAD(&fs_info->pending_raid_kobjs);
+ spin_lock_init(&fs_info->pending_raid_kobjs_lock);
spin_lock_init(&fs_info->delalloc_root_lock);
spin_lock_init(&fs_info->trans_lock);
spin_lock_init(&fs_info->fs_roots_radix_lock);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0e9a21230217..bb5368faa937 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -9908,9 +9908,39 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
return 0;
}
+/* link_block_group will queue up kobjects to add when we're reclaim-safe */
+void btrfs_add_raid_kobjects(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_space_info *space_info;
+ struct raid_kobject *rkobj;
+ LIST_HEAD(list);
+ int index;
+ int ret = 0;
+
+ spin_lock(&fs_info->pending_raid_kobjs_lock);
+ list_splice_init(&fs_info->pending_raid_kobjs, &list);
+ spin_unlock(&fs_info->pending_raid_kobjs_lock);
+
+ list_for_each_entry(rkobj, &list, list) {
+ space_info = __find_space_info(fs_info, rkobj->flags);
+ index = __get_raid_index(rkobj->flags);
+
+ ret = kobject_add(&rkobj->kobj, &space_info->kobj,
+ "%s", get_raid_name(index));
+ if (ret) {
+ kobject_put(&rkobj->kobj);
+ break;
+ }
+ }
+ if (ret)
+ btrfs_warn(fs_info,
+ "failed to add kobject for block cache, ignoring");
+}
+
static void link_block_group(struct btrfs_block_group_cache *cache)
{
struct btrfs_space_info *space_info = cache->space_info;
+ struct btrfs_fs_info *fs_info = cache->fs_info;
int index = get_block_group_index(cache);
bool first = false;
@@ -9921,27 +9951,19 @@ static void link_block_group(struct
btrfs_block_group_cache *cache)
up_write(&space_info->groups_sem);
if (first) {
- struct raid_kobject *rkobj;
- int ret;
-
- rkobj = kzalloc(sizeof(*rkobj), GFP_NOFS);
- if (!rkobj)
- goto out_err;
- rkobj->raid_type = index;
- kobject_init(&rkobj->kobj, &btrfs_raid_ktype);
- ret = kobject_add(&rkobj->kobj, &space_info->kobj,
- "%s", get_raid_name(index));
- if (ret) {
- kobject_put(&rkobj->kobj);
- goto out_err;
+ struct raid_kobject *rkobj = kzalloc(sizeof(*rkobj), GFP_NOFS);
+ if (!rkobj) {
+ btrfs_warn(cache->fs_info, "couldn't alloc memory for
raid level kobject");
+ return;
}
+ rkobj->flags = cache->flags;
+ kobject_init(&rkobj->kobj, &btrfs_raid_ktype);
+
+ spin_lock(&fs_info->pending_raid_kobjs_lock);
+ list_add_tail(&rkobj->list, &fs_info->pending_raid_kobjs);
+ spin_unlock(&fs_info->pending_raid_kobjs_lock);
space_info->block_group_kobjs[index] = &rkobj->kobj;
}
-
- return;
-out_err:
- btrfs_warn(cache->fs_info,
- "failed to add kobject for block cache, ignoring");
}
static struct btrfs_block_group_cache *
@@ -10157,6 +10179,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
inc_block_group_ro(cache, 1);
}
+ btrfs_add_raid_kobjects(info);
init_global_block_rsv(info);
ret = 0;
error:
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index a8bafed931f4..b975fda719e7 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -272,7 +272,7 @@ static ssize_t raid_bytes_show(struct kobject *kobj,
{
struct btrfs_space_info *sinfo = to_space_info(kobj->parent);
struct btrfs_block_group_cache *block_group;
- int index = to_raid_kobj(kobj)->raid_type;
+ int index = __get_raid_index(to_raid_kobj(kobj)->flags);
u64 val = 0;
down_read(&sinfo->groups_sem);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b2d05c6b1c56..b0cffce168cf 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2997,6 +2997,16 @@ static int btrfs_relocate_chunk(struct btrfs_fs_info
*fs_info, u64 chunk_offset)
if (ret)
return ret;
+ /*
+ * We add the kobjects here (and after forcing data chunk creation)
+ * since relocation is the only place we'll create chunks of a new
+ * type at runtime. The only place where we'll remove the last
+ * chunk of a type is the call immediately below this one. Even
+ * so, we're protected against races with the cleaner thread since
+ * we're covered by the delete_unused_bgs_mutex.
+ */
+ btrfs_add_raid_kobjects(fs_info);
+
trans = btrfs_start_trans_remove_block_group(root->fs_info,
chunk_offset);
if (IS_ERR(trans)) {
@@ -3124,6 +3134,8 @@ static int btrfs_may_alloc_data_chunk(struct
btrfs_fs_info *fs_info,
if (ret < 0)
return ret;
+ btrfs_add_raid_kobjects(fs_info);
+
return 1;
}
}
--
2.15.1
--
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