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Date: Mon, 10 Jan 2011 17:08:01 -0600
From: Eric Sandeen <sandeen@...hat.com>
To: Lukas Czerner <lczerner@...hat.com>
CC: linux-ext4@...r.kernel.org, tytso@....edu, rwheeler@...hat.com,
adilger@...ger.ca
Subject: Re: [PATCH 6/6] Add interface to advertise ext4 features in sysfs
On 09/15/2010 11:36 AM, Lukas Czerner wrote:
> User-space should have the opportunity to check what features doest ext4
> support in each particular copy. This adds easy interface by creating new
> "features" directory in sys/fs/ext4/. In that directory files
> advertising feature names can be created.
>
> Add lazy_itable_init to the feature list.
This seems to break unloading/reloading in .37; near as I can
tell /sys/fs/ext4 never gets unregistered on module unload.
-Eric
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> ---
> fs/ext4/ext4.h | 5 +++++
> fs/ext4/super.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 54 insertions(+), 1 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 0df3977..9ecac2e 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1502,6 +1502,11 @@ struct ext4_li_request {
> unsigned long lr_next_sched;
> };
>
> +struct ext4_features {
> + struct kobject f_kobj;
> + struct completion f_kobj_unregister;
> +};
> +
> /*
> * Function prototypes
> */
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 3e285eb..b817eba 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -57,6 +57,7 @@ struct proc_dir_entry *ext4_proc_root;
> static struct kset *ext4_kset;
> struct ext4_lazy_init *ext4_li_info;
> struct mutex ext4_li_mtx;
> +struct ext4_features *ext4_feat;
>
> static int ext4_load_journal(struct super_block *, struct ext4_super_block *,
> unsigned long journal_devnum);
> @@ -2349,6 +2350,7 @@ static struct ext4_attr ext4_attr_##_name = { \
> #define EXT4_ATTR(name, mode, show, store) \
> static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)
>
> +#define EXT4_INFO_ATTR(name) EXT4_ATTR(name, 0444, NULL, NULL)
> #define EXT4_RO_ATTR(name) EXT4_ATTR(name, 0444, name##_show, NULL)
> #define EXT4_RW_ATTR(name) EXT4_ATTR(name, 0644, name##_show, name##_store)
> #define EXT4_RW_ATTR_SBI_UI(name, elname) \
> @@ -2385,6 +2387,14 @@ static struct attribute *ext4_attrs[] = {
> NULL,
> };
>
> +/* Features this copy of ext4 supports */
> +EXT4_INFO_ATTR(lazy_itable_init);
> +
> +static struct attribute *ext4_feat_attrs[] = {
> + ATTR_LIST(lazy_itable_init),
> + NULL,
> +};
> +
> static ssize_t ext4_attr_show(struct kobject *kobj,
> struct attribute *attr, char *buf)
> {
> @@ -2413,7 +2423,6 @@ static void ext4_sb_release(struct kobject *kobj)
> complete(&sbi->s_kobj_unregister);
> }
>
> -
> static const struct sysfs_ops ext4_attr_ops = {
> .show = ext4_attr_show,
> .store = ext4_attr_store,
> @@ -2425,6 +2434,17 @@ static struct kobj_type ext4_ktype = {
> .release = ext4_sb_release,
> };
>
> +static void ext4_feat_release(struct kobject *kobj)
> +{
> + complete(&ext4_feat->f_kobj_unregister);
> +}
> +
> +static struct kobj_type ext4_feat_ktype = {
> + .default_attrs = ext4_feat_attrs,
> + .sysfs_ops = &ext4_attr_ops,
> + .release = ext4_feat_release,
> +};
> +
> /*
> * Check whether this filesystem can be mounted based on
> * the features present and the RDONLY/RDWR mount requested.
> @@ -4581,6 +4601,30 @@ static struct file_system_type ext4_fs_type = {
> .fs_flags = FS_REQUIRES_DEV,
> };
>
> +int __init ext4_init_feat_adverts(void)
> +{
> + struct ext4_features *ef;
> + int ret = -ENOMEM;
> +
> + ef = kzalloc(sizeof(struct ext4_features), GFP_KERNEL);
> + if (!ef)
> + goto out;
> +
> + ef->f_kobj.kset = ext4_kset;
> + init_completion(&ef->f_kobj_unregister);
> + ret = kobject_init_and_add(&ef->f_kobj, &ext4_feat_ktype, NULL,
> + "features");
> + if (ret) {
> + kfree(ef);
> + goto out;
> + }
> +
> + ext4_feat = ef;
> + ret = 0;
> +out:
> + return ret;
> +}
> +
> static int __init init_ext4_fs(void)
> {
> int err;
> @@ -4593,6 +4637,9 @@ static int __init init_ext4_fs(void)
> if (!ext4_kset)
> goto out4;
> ext4_proc_root = proc_mkdir("fs/ext4", NULL);
> +
> + err = ext4_init_feat_adverts();
> +
> err = init_ext4_mballoc();
> if (err)
> goto out3;
> @@ -4621,6 +4668,7 @@ out1:
> out2:
> exit_ext4_mballoc();
> out3:
> + kfree(ext4_feat);
> remove_proc_entry("fs/ext4", NULL);
> kset_unregister(ext4_kset);
> out4:
--
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