Recently i found that, the original code with out this patch has a bug during kobject clean up, which is prominent with this patch, i am digging more. Just an early headsup. Thxs. Anand.
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---- Anand Jain wrote ----
>This patch will provide a framework and help to create attributes
>from the structure btrfs_fs_devices which are available even before
>fs_info is created. So by moving the parent kobject super_kobj from
>fs_info to btrfs_fs_devices, it will help to create attributes
>from the btrfs_fs_devices as well.
>
>Patches on top of this patch now will be able to create the
>sys/fs/btrfs/fsid kobject and attributes from btrfs_fs_devices
>when devices are scanned and registered to the kernel.
>
>Just to note, this does not change any of the existing btrfs sysfs
>external kobject names and its attributes and not even the life
>cycle of them. Changes are internal only. And to ensure the same,
>this path has been tested with various device operations and,
>checking and comparing the sysfs kobjects and attributes with
>sysfs kobject and attributes with out this patch, and they remain
>same.
>
>Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
>---
> fs/btrfs/ctree.h | 3 --
> fs/btrfs/dev-replace.c | 4 +-
> fs/btrfs/disk-io.c | 1 -
> fs/btrfs/super.c | 1 +
> fs/btrfs/sysfs.c | 116 ++++++++++++++++++++++++++++++++++---------------
> fs/btrfs/sysfs.h | 6 ++-
> fs/btrfs/volumes.c | 13 ++++--
> fs/btrfs/volumes.h | 7 +++
> 8 files changed, 105 insertions(+), 46 deletions(-)
>
>diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
>index abf0c7b..d9604e5 100644
>--- a/fs/btrfs/ctree.h
>+++ b/fs/btrfs/ctree.h
>@@ -1580,10 +1580,7 @@ struct btrfs_fs_info {
> struct task_struct *cleaner_kthread;
> int thread_pool_size;
>
>- struct kobject super_kobj;
> struct kobject *space_info_kobj;
>- struct kobject *device_dir_kobj;
>- struct completion kobj_unregister;
> int do_barriers;
> int closing;
> int log_root_recovering;
>diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
>index ca6a3a3..124b60f 100644
>--- a/fs/btrfs/dev-replace.c
>+++ b/fs/btrfs/dev-replace.c
>@@ -592,8 +592,8 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
> mutex_unlock(&uuid_mutex);
>
> /* replace the sysfs entry */
>- btrfs_kobj_rm_device(fs_info, src_device);
>- btrfs_kobj_add_device(fs_info, tgt_device);
>+ btrfs_kobj_rm_device(fs_info->fs_devices, src_device);
>+ btrfs_kobj_add_device(fs_info->fs_devices, tgt_device);
> btrfs_rm_dev_replace_free_srcdev(fs_info, src_device);
>
> /* write back the superblocks */
>diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>index 86ff8c2..f15d2d9 100644
>--- a/fs/btrfs/disk-io.c
>+++ b/fs/btrfs/disk-io.c
>@@ -2236,7 +2236,6 @@ int open_ctree(struct super_block *sb,
> mutex_init(&fs_info->delalloc_root_mutex);
> seqlock_init(&fs_info->profiles_lock);
>
>- init_completion(&fs_info->kobj_unregister);
> INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
> INIT_LIST_HEAD(&fs_info->space_info);
> INIT_LIST_HEAD(&fs_info->tree_mod_seq_list);
>diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
>index 60f7cbe..a1d0a12 100644
>--- a/fs/btrfs/super.c
>+++ b/fs/btrfs/super.c
>@@ -1334,6 +1334,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
> }
>
> fs_info->fs_devices = fs_devices;
>+ fs_devices->fs_info = fs_info;
>
> fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
> fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
>diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
>index 92db3f6..775fdb9 100644
>--- a/fs/btrfs/sysfs.c
>+++ b/fs/btrfs/sysfs.c
>@@ -33,6 +33,7 @@
> #include "volumes.h"
>
> static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
>+static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj);
>
> static u64 get_features(struct btrfs_fs_info *fs_info,
> enum btrfs_feature_set set)
>@@ -428,7 +429,7 @@ static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
>
> BTRFS_ATTR(clone_alignment, btrfs_clone_alignment_show);
>
>-static struct attribute *btrfs_attrs[] = {
>+static const struct attribute *btrfs_attrs[] = {
> BTRFS_ATTR_PTR(label),
> BTRFS_ATTR_PTR(nodesize),
> BTRFS_ATTR_PTR(sectorsize),
>@@ -438,21 +439,27 @@ static struct attribute *btrfs_attrs[] = {
>
> static void btrfs_release_super_kobj(struct kobject *kobj)
> {
>- struct btrfs_fs_info *fs_info = to_fs_info(kobj);
>- complete(&fs_info->kobj_unregister);
>+ struct btrfs_fs_devices *fs_devs = to_fs_devs(kobj);
>+ complete(&fs_devs->kobj_unregister);
> }
>
> static struct kobj_type btrfs_ktype = {
> .sysfs_ops = &kobj_sysfs_ops,
> .release = btrfs_release_super_kobj,
>- .default_attrs = btrfs_attrs,
> };
>
>+static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj)
>+{
>+ if (kobj->ktype != &btrfs_ktype)
>+ return NULL;
>+ return container_of(kobj, struct btrfs_fs_devices, super_kobj);
>+}
>+
> static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
> {
> if (kobj->ktype != &btrfs_ktype)
> return NULL;
>- return container_of(kobj, struct btrfs_fs_info, super_kobj);
>+ return to_fs_devs(kobj)->fs_info;
> }
>
> #define NUM_FEATURE_BITS 64
>@@ -493,12 +500,12 @@ static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
> attrs[0] = &fa->kobj_attr.attr;
> if (add) {
> int ret;
>- ret = sysfs_merge_group(&fs_info->super_kobj,
>+ ret = sysfs_merge_group(&fs_info->fs_devices->super_kobj,
> &agroup);
> if (ret)
> return ret;
> } else
>- sysfs_unmerge_group(&fs_info->super_kobj,
>+ sysfs_unmerge_group(&fs_info->fs_devices->super_kobj,
> &agroup);
> }
>
>@@ -506,25 +513,44 @@ static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
> return 0;
> }
>
>-static void __btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
>+/*
>+ * Can be called when a volume is removed from the system
>+ * as of now only during modunload
>+*/
>+static void btrfs_kobject_remove_fsid(struct btrfs_fs_devices *fs_devs)
> {
>- kobject_del(&fs_info->super_kobj);
>- kobject_put(&fs_info->super_kobj);
>- wait_for_completion(&fs_info->kobj_unregister);
>+ struct list_head *fs_uuids = btrfs_get_fs_uuids();
>+
>+ if (fs_devs) {
>+ kobject_del(&fs_devs->super_kobj);
>+ kobject_put(&fs_devs->super_kobj);
>+ wait_for_completion(&fs_devs->kobj_unregister);
>+ return;
>+ }
>+
>+ list_for_each_entry(fs_devs, fs_uuids, list) {
>+ kobject_del(&fs_devs->super_kobj);
>+ kobject_put(&fs_devs->super_kobj);
>+ wait_for_completion(&fs_devs->kobj_unregister);
>+ }
> }
>
>+/* Called by the unmount thread */
> void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
> {
>+ struct kobject *super_kobj = &fs_info->fs_devices->super_kobj;
>+
> if (fs_info->space_info_kobj) {
> sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
> kobject_del(fs_info->space_info_kobj);
> kobject_put(fs_info->space_info_kobj);
> }
>- kobject_del(fs_info->device_dir_kobj);
>- kobject_put(fs_info->device_dir_kobj);
>+
>+ btrfs_kobj_rm_device(fs_info->fs_devices, NULL);
> addrm_unknown_feature_attrs(fs_info, false);
>- sysfs_remove_group(&fs_info->super_kobj, &btrfs_feature_attr_group);
>- __btrfs_sysfs_remove_one(fs_info);
>+ sysfs_remove_group(super_kobj, &btrfs_feature_attr_group);
>+ sysfs_remove_files(super_kobj, btrfs_attrs);
>+ btrfs_kobject_remove_fsid(fs_info->fs_devices);
> }
>
> const char * const btrfs_feature_set_names[3] = {
>@@ -602,38 +628,43 @@ static void init_feature_attrs(void)
> }
> }
>
>-int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
>+/* Called by the volume manager operations */
>+int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devs,
> struct btrfs_device *one_device)
> {
> struct hd_struct *disk;
> struct kobject *disk_kobj;
>
>- if (!fs_info->device_dir_kobj)
>+ if (!fs_devs->device_dir_kobj)
> return -EINVAL;
>
> if (one_device && one_device->bdev) {
> disk = one_device->bdev->bd_part;
> disk_kobj = &part_to_dev(disk)->kobj;
>
>- sysfs_remove_link(fs_info->device_dir_kobj,
>+ sysfs_remove_link(fs_devs->device_dir_kobj,
> disk_kobj->name);
>+ return 0;
> }
>
>+ kobject_del(fs_devs->device_dir_kobj);
>+ kobject_put(fs_devs->device_dir_kobj);
>+
> return 0;
> }
>
>-int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
>+/* Called by the volume manager operations */
>+int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devices,
> struct btrfs_device *one_device)
> {
> int error = 0;
>- struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
> struct btrfs_device *dev;
>
>- if (!fs_info->device_dir_kobj)
>- fs_info->device_dir_kobj = kobject_create_and_add("devices",
>- &fs_info->super_kobj);
>+ if (!fs_devices->device_dir_kobj)
>+ fs_devices->device_dir_kobj = kobject_create_and_add("devices",
>+ &fs_devices->super_kobj);
>
>- if (!fs_info->device_dir_kobj)
>+ if (!fs_devices->device_dir_kobj)
> return -ENOMEM;
>
> list_for_each_entry(dev, &fs_devices->devices, dev_list) {
>@@ -649,7 +680,7 @@ int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
> disk = dev->bdev->bd_part;
> disk_kobj = &part_to_dev(disk)->kobj;
>
>- error = sysfs_create_link(fs_info->device_dir_kobj,
>+ error = sysfs_create_link(fs_devices->device_dir_kobj,
> disk_kobj, disk_kobj->name);
> if (error)
> break;
>@@ -667,21 +698,37 @@ static struct dentry *btrfs_debugfs_root_dentry;
> /* Debugging tunables and exported data */
> u64 btrfs_debugfs_test;
>
>+/* Can be called by the device discovery thread */
>+int btrfs_kobj_add_fsid(struct btrfs_fs_devices *fs_devs,
>+ struct kobject *parent)
>+{
>+ int error;
>+
>+ init_completion(&fs_devs->kobj_unregister);
>+ fs_devs->super_kobj.kset = btrfs_kset;
>+ error = kobject_init_and_add(&fs_devs->super_kobj, &btrfs_ktype, NULL,
>+ "%pU", fs_devs->fsid);
>+ return error;
>+}
>+
>+/* Called when fs_info is created. That would be the mount thread */
> int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
> {
> int error;
>+ struct kobject *super_kobj = &fs_info->fs_devices->super_kobj;
>+
>+ /* This to be called from the volume.c */
>+ error = btrfs_kobj_add_fsid(fs_info->fs_devices, NULL);
>+ if (error)
>+ return error;
>
>- init_completion(&fs_info->kobj_unregister);
>- fs_info->super_kobj.kset = btrfs_kset;
>- error = kobject_init_and_add(&fs_info->super_kobj, &btrfs_ktype, NULL,
>- "%pU", fs_info->fsid);
>+ error = sysfs_create_files(super_kobj, btrfs_attrs);
> if (error)
> return error;
>
>- error = sysfs_create_group(&fs_info->super_kobj,
>- &btrfs_feature_attr_group);
>+ error = sysfs_create_group(super_kobj, &btrfs_feature_attr_group);
> if (error) {
>- __btrfs_sysfs_remove_one(fs_info);
>+ sysfs_remove_files(super_kobj, btrfs_attrs);
> return error;
> }
>
>@@ -689,12 +736,13 @@ int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
> if (error)
> goto failure;
>
>- error = btrfs_kobj_add_device(fs_info, NULL);
>+ /* This to be called from the volume.c */
>+ error = btrfs_kobj_add_device(fs_info->fs_devices, NULL);
> if (error)
> goto failure;
>
> fs_info->space_info_kobj = kobject_create_and_add("allocation",
>- &fs_info->super_kobj);
>+ super_kobj);
> if (!fs_info->space_info_kobj) {
> error = -ENOMEM;
> goto failure;
>diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
>index f7dd298..737cfd6 100644
>--- a/fs/btrfs/sysfs.h
>+++ b/fs/btrfs/sysfs.h
>@@ -70,8 +70,10 @@ char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags);
> extern const char * const btrfs_feature_set_names[3];
> extern struct kobj_type space_info_ktype;
> extern struct kobj_type btrfs_raid_ktype;
>-int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
>+int btrfs_kobj_add_device(struct btrfs_fs_devices *fs_devs,
> struct btrfs_device *one_device);
>-int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
>+int btrfs_kobj_rm_device(struct btrfs_fs_devices *fs_devs,
> struct btrfs_device *one_device);
>+int btrfs_kobj_add_fsid(struct btrfs_fs_devices *fs_devs,
>+ struct kobject *parent);
> #endif /* _BTRFS_SYSFS_H_ */
>diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>index 0144790..b87a576 100644
>--- a/fs/btrfs/volumes.c
>+++ b/fs/btrfs/volumes.c
>@@ -52,6 +52,10 @@ static void btrfs_dev_stat_print_on_load(struct btrfs_device *device);
>
> DEFINE_MUTEX(uuid_mutex);
> static LIST_HEAD(fs_uuids);
>+struct list_head *btrfs_get_fs_uuids(void)
>+{
>+ return &fs_uuids;
>+}
>
> static struct btrfs_fs_devices *__alloc_fs_devices(void)
> {
>@@ -1697,7 +1701,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
> if (device->bdev) {
> device->fs_devices->open_devices--;
> /* remove sysfs entry */
>- btrfs_kobj_rm_device(root->fs_info, device);
>+ btrfs_kobj_rm_device(root->fs_info->fs_devices, device);
> }
>
> call_rcu(&device->rcu, free_device);
>@@ -2095,6 +2099,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
> u64 tmp;
> int seeding_dev = 0;
> int ret = 0;
>+ struct kobject *super_kobj = &root->fs_info->fs_devices->super_kobj;
>
> if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
> return -EROFS;
>@@ -2202,7 +2207,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
> tmp + 1);
>
> /* add sysfs device entry */
>- btrfs_kobj_add_device(root->fs_info, device);
>+ btrfs_kobj_add_device(root->fs_info->fs_devices, device);
>
> /*
> * we've got more storage, clear any full flags on the space
>@@ -2243,7 +2248,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
> */
> snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU",
> root->fs_info->fsid);
>- if (kobject_rename(&root->fs_info->super_kobj, fsid_buf))
>+ if (kobject_rename(super_kobj, fsid_buf))
> goto error_trans;
> }
>
>@@ -2280,7 +2285,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
> error_trans:
> btrfs_end_transaction(trans, root);
> rcu_string_free(device->name);
>- btrfs_kobj_rm_device(root->fs_info, device);
>+ btrfs_kobj_rm_device(root->fs_info->fs_devices, device);
> kfree(device);
> error:
> blkdev_put(bdev, FMODE_EXCL);
>diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>index d6fe73c..06fde15 100644
>--- a/fs/btrfs/volumes.h
>+++ b/fs/btrfs/volumes.h
>@@ -253,6 +253,12 @@ struct btrfs_fs_devices {
> * nonrot flag set
> */
> int rotating;
>+
>+ struct btrfs_fs_info *fs_info;
>+
>+ struct kobject super_kobj;
>+ struct kobject *device_dir_kobj;
>+ struct completion kobj_unregister;
> };
>
> #define BTRFS_BIO_INLINE_CSUM_SIZE 64
>@@ -534,5 +540,6 @@ static inline void unlock_chunks(struct btrfs_root *root)
> mutex_unlock(&root->fs_info->chunk_mutex);
> }
>
>+struct list_head *btrfs_get_fs_uuids(void);
>
> #endif
>--
>2.1.0
>
>--
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