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authorKent Overstreet <kent.overstreet@linux.dev>2024-10-12 14:36:38 -0400
committerKent Overstreet <kent.overstreet@linux.dev>2024-10-14 05:43:01 -0400
commit5e3b72324d32629fa013f86657308f3dbc1115e1 (patch)
tree66d1d167a942aef22a89cfa0df092d1a593f663d /fs
parentcb6055e66faa0d4c15587ef67be18bc199aef085 (diff)
bcachefs: Fix sysfs warning in fstests generic/730,731
sysfs warns if we're removing a symlink from a directory that's no longer in sysfs; this is triggered by fstests generic/730, which simulates hot removal of a block device. This patch is however not a correct fix, since checking kobj->state_in_sysfs on a kobj owned by another subsystem is racy. A better fix would be to add the appropriate check to sysfs_remove_link() - and sysfs_create_link() as well. But kobject_add_internal()/kobject_del() do not as of today have locking that would support that. Note that the block/holder.c code appears to be subject to this race as well. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs')
-rw-r--r--fs/bcachefs/super.c34
1 files changed, 24 insertions, 10 deletions
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 873e4be7e1dc..77d811a539af 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -184,6 +184,7 @@ static DEFINE_MUTEX(bch_fs_list_lock);
DECLARE_WAIT_QUEUE_HEAD(bch2_read_only_wait);
+static void bch2_dev_unlink(struct bch_dev *);
static void bch2_dev_free(struct bch_dev *);
static int bch2_dev_alloc(struct bch_fs *, unsigned);
static int bch2_dev_sysfs_online(struct bch_fs *, struct bch_dev *);
@@ -620,9 +621,7 @@ void __bch2_fs_stop(struct bch_fs *c)
up_write(&c->state_lock);
for_each_member_device(c, ca)
- if (ca->kobj.state_in_sysfs &&
- ca->disk_sb.bdev)
- sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
+ bch2_dev_unlink(ca);
if (c->kobj.state_in_sysfs)
kobject_del(&c->kobj);
@@ -1187,9 +1186,7 @@ static void bch2_dev_free(struct bch_dev *ca)
{
cancel_work_sync(&ca->io_error_work);
- if (ca->kobj.state_in_sysfs &&
- ca->disk_sb.bdev)
- sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
+ bch2_dev_unlink(ca);
if (ca->kobj.state_in_sysfs)
kobject_del(&ca->kobj);
@@ -1226,10 +1223,7 @@ static void __bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca)
percpu_ref_kill(&ca->io_ref);
wait_for_completion(&ca->io_ref_completion);
- if (ca->kobj.state_in_sysfs) {
- sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
- sysfs_remove_link(&ca->kobj, "block");
- }
+ bch2_dev_unlink(ca);
bch2_free_super(&ca->disk_sb);
bch2_dev_journal_exit(ca);
@@ -1251,6 +1245,26 @@ static void bch2_dev_io_ref_complete(struct percpu_ref *ref)
complete(&ca->io_ref_completion);
}
+static void bch2_dev_unlink(struct bch_dev *ca)
+{
+ struct kobject *b;
+
+ /*
+ * This is racy w.r.t. the underlying block device being hot-removed,
+ * which removes it from sysfs.
+ *
+ * It'd be lovely if we had a way to handle this race, but the sysfs
+ * code doesn't appear to provide a good method and block/holder.c is
+ * susceptible as well:
+ */
+ if (ca->kobj.state_in_sysfs &&
+ ca->disk_sb.bdev &&
+ (b = bdev_kobj(ca->disk_sb.bdev))->state_in_sysfs) {
+ sysfs_remove_link(b, "bcachefs");
+ sysfs_remove_link(&ca->kobj, "block");
+ }
+}
+
static int bch2_dev_sysfs_online(struct bch_fs *c, struct bch_dev *ca)
{
int ret;