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Date: Tue, 11 Jan 2011 13:55:40 +0100 (CET)
From: Lukas Czerner <lczerner@...hat.com>
To: Eric Sandeen <sandeen@...hat.com>
cc: Lukas Czerner <lczerner@...hat.com>, 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 Mon, 10 Jan 2011, Eric Sandeen wrote:
> 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.
That's not good, I'll look at it.
Thanks!
-Lukas
>
> -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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