From: Kinglong Mee <kinglongmee@gmail.com>
To: Beata Michalska <b.michalska@samsung.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-api@vger.kernel.org
Cc: greg@kroah.com, jack@suse.cz, tytso@mit.edu,
adilger.kernel@dilger.ca, hughd@google.com, lczerner@redhat.com,
hch@infradead.org, linux-ext4@vger.kernel.org,
linux-mm@kvack.org, kyungmin.park@samsung.com,
kmpark@infradead.org, kinglongmee@gmail.com
Subject: Re: [RFC v3 1/4] fs: Add generic file system event notifications
Date: Thu, 18 Jun 2015 19:17:21 +0800 [thread overview]
Message-ID: <5582A8C1.3000002@gmail.com> (raw)
In-Reply-To: <1434460173-18427-2-git-send-email-b.michalska@samsung.com>
On 6/16/2015 9:09 PM, Beata Michalska wrote:
> Introduce configurable generic interface for file
> system-wide event notifications, to provide file
> systems with a common way of reporting any potential
> issues as they emerge.
... snip ...
> +
> +Sample request could look like the following:
> +
> + echo /sample/mount/point G T 710000 500000 > /sys/fs/events/config
> +
> +Multiple request might be specified provided they are separated with semicolon.
> +
> +The configuration itself might be modified at any time. One can add/remove
> +particular event types for given fielsystem, modify the threshold levels,
> +and remove single or all entries from the 'config' file.
> +
> + - Adding new event type:
> +
> + $ echo MOUNT EVENT_TYPE > /sys/fs/events/config
> +
> +(Note that is is enough to provide the event type to be enabled without
Should be "Note that it is ... " here ?
> +the already set ones.)
> +
> + - Removing event type:
> +
> + $ echo '!MOUNT EVENT_TYPE' > /sys/fs/events/config
> +
> + - Updating threshold limits:
> +
> + $ echo MOUNT T L1 L2 > /sys/fs/events/config
> +
> + - Removing single entry:
> +
> + $ echo '!MOUNT' > /sys/fs/events/config
> +
> + - Removing all entries:
> +
> + $ echo > /sys/fs/events/config
> +
> +Reading the file will list all registered entries with their current set-up
> +along with some additional info like the filesystem type and the backing device
> +name if available.
> +
> +Final, though a very important note on the configuration: when and if the
> +actual events are being triggered falls way beyond the scope of the generic
> +filesystem events interface. It is up to a particular filesystem
> +implementation which events are to be supported - if any at all. So if
> +given filesystem does not support the event notifications, an attempt to
> +enable those through 'config' file will fail.
> +
> +
> +3. The generic netlink interface support:
> +=========================================
> +
> +Whenever an event notification is triggered (by given filesystem) the current
> +configuration is being validated to decide whether a userpsace notification
> +should be launched. If there has been no request (in a mean of 'config' file
> +entry) for given event, one will be silently disregarded. If, on the other
> +hand, someone is 'watching' given filesystem for specific events, a generic
> +netlink message will be sent. A dedicated multicast group has been provided
> +solely for this purpose so in order to receive such notifications, one should
> +subscribe to this new multicast group. As for now only the init network
> +namespace is being supported.
> +
> +3.1 Message format
> +
> +The FS_NL_C_EVENT shall be stored within the generic netlink message header
> +as the command field. The message payload will provide more detailed info:
> +the backing device major and minor numbers, the event code and the id of
> +the process which action led to the event occurrence. In case of threshold
> +notifications, the current number of available blocks will be included
> +in the payload as well.
> +
> +
> + 0 1 2 3
> + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | NETLINK MESSAGE HEADER |
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | GENERIC NETLINK MESSAGE HEADER |
> + | (with FS_NL_C_EVENT as genlmsghdr cdm field) |
cmd, not cdm.
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | Optional user specific message header |
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | GENERIC MESSAGE PAYLOAD: |
> + +---------------------------------------------------------------+
> + | FS_NL_A_EVENT_ID (NLA_U32) |
> + +---------------------------------------------------------------+
> + | FS_NL_A_DEV_MAJOR (NLA_U32) |
> + +---------------------------------------------------------------+
> + | FS_NL_A_DEV_MINOR (NLA_U32) |
> + +---------------------------------------------------------------+
> + | FS_NL_A_CAUSED_ID (NLA_U32) |
Should be NLA_U64 ? The following uses as,
+ if (nla_put_u64(skb, FS_NL_A_CAUSED_ID, pid_vnr(task_pid(current))))
+ return -EINVAL;
Also, I'd like FS_NL_A_CAUSED_PID than FS_NL_A_CAUSED_ID.
> + +---------------------------------------------------------------+
> + | FS_NL_A_DATA (NLA_U64) |
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +
> +
> +The above figure is based on:
> + http://www.linuxfoundation.org/collaborate/workgroups/networking/generic_netlink_howto#Message_Format
> +
> +
... snip...
> + seq_putc(m, ' ');
> + if (sb->s_op->show_devname) {
> + sb->s_op->show_devname(m, en->mnt_path.mnt->mnt_root);
> + } else {
> + seq_escape(m, r_mnt->mnt_devname ? r_mnt->mnt_devname : "none",
> + " \t\n\\");
> + }
> + seq_puts(m, " (");
> +
> + nmask = en->notify;
> + for (match = fs_etypes; match->pattern; ++match) {
> + if (match->token & nmask) {
> + seq_puts(m, match->pattern);
Print here is better.
if (match->pattern & FS_EVENT_THRESH)
seq_printf(m, " %llu %llu", en->th.lrange, en->th.urange);
> + nmask &= ~match->token;
> + if (nmask)
> + seq_putc(m, ',');
> + }
> + }
> + seq_printf(m, " %llu %llu", en->th.lrange, en->th.urange);
Don't print the lrange/urange (always be zero) when without FS_EVENT_THRESH.
> + seq_puts(m, ")\n");
> + return 0;
> +}
> +
> +static const struct seq_operations fs_trace_seq_ops = {
> + .start = fs_trace_seq_start,
> + .next = fs_trace_seq_next,
> + .stop = fs_trace_seq_stop,
> + .show = fs_trace_seq_show,
> +};
> +
> +static int fs_trace_open(struct inode *inode, struct file *file)
> +{
> + return seq_open(file, &fs_trace_seq_ops);
> +}
> +
> +static const struct file_operations fs_trace_fops = {
> + .owner = THIS_MODULE,
> + .open = fs_trace_open,
> + .write = fs_trace_write,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = seq_release,
> +};
> +
> +static int fs_trace_init(void)
> +{
> + fs_trace_cachep = KMEM_CACHE(fs_trace_entry, 0);
> + if (!fs_trace_cachep)
> + return -EINVAL;
> + init_waitqueue_head(&trace_wq);
> + return 0;
> +}
> +
> +/* VFS support */
> +static int fs_trace_fill_super(struct super_block *sb, void *data, int silen)
> +{
> + int ret;
> + static struct tree_descr desc[] = {
> + [2] = {
> + .name = "config",
> + .ops = &fs_trace_fops,
> + .mode = S_IWUSR | S_IRUGO,
> + },
> + {""},
> + };
> +
> + ret = simple_fill_super(sb, 0x7246332, desc);
> + return !ret ? fs_trace_init() : ret;
> +}
> +
> +static struct dentry *fs_trace_do_mount(struct file_system_type *fs_type,
> + int ntype, const char *dev_name, void *data)
> +{
> + return mount_single(fs_type, ntype, data, fs_trace_fill_super);
> +}
> +
> +static void fs_trace_kill_super(struct super_block *sb)
> +{
> + /*
> + * The rcu_barrier here will/should make sure all call_rcu
> + * callbacks are completed - still there might be some active
> + * trace objects in use which can make calling the
> + * kmem_cache_destroy unsafe. So we wait until all traces
> + * are finally released.
> + */
> + fs_remove_all_traces();
> + rcu_barrier();
> + wait_event(trace_wq, !atomic_read(&stray_traces));
> +
> + kmem_cache_destroy(fs_trace_cachep);
> + kill_litter_super(sb);
> +}
> +
> +static struct kset *fs_trace_kset;
> +
> +static struct file_system_type fs_trace_fstype = {
> + .name = "fstrace",
> + .mount = fs_trace_do_mount,
> + .kill_sb = fs_trace_kill_super,
> +};
> +
> +static void __init fs_trace_vfs_init(void)
> +{
> + fs_trace_kset = kset_create_and_add("events", NULL, fs_kobj);
> +
> + if (!fs_trace_kset)
> + return;
> +
> + if (!register_filesystem(&fs_trace_fstype)) {
> + if (!fs_event_netlink_register())
> + return;
> + unregister_filesystem(&fs_trace_fstype);
> + }
> + kset_unregister(fs_trace_kset);
> +}
> +
> +static int __init fs_trace_evens_init(void)
> +{
> + fs_trace_vfs_init();
> + return 0;
> +};
> +module_init(fs_trace_evens_init);
> +
> diff --git a/fs/events/fs_event.h b/fs/events/fs_event.h
> new file mode 100644
> index 0000000..23f24c8
> --- /dev/null
> +++ b/fs/events/fs_event.h
> @@ -0,0 +1,22 @@
> +/*
> + * Copyright(c) 2015 Samsung Electronics. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2.
> + *
> + * The full GNU General Public License is included in this distribution in the
> + * file called COPYING.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +
> +#ifndef __GENERIC_FS_EVENTS_H
> +#define __GENERIC_FS_EVENTS_H
> +
> +int fs_event_netlink_register(void);
> +void fs_event_netlink_unregister(void);
> +
> +#endif /* __GENERIC_FS_EVENTS_H */
> diff --git a/fs/events/fs_event_netlink.c b/fs/events/fs_event_netlink.c
> new file mode 100644
> index 0000000..0c97eb7
> --- /dev/null
> +++ b/fs/events/fs_event_netlink.c
> @@ -0,0 +1,104 @@
> +/*
> + * Copyright(c) 2015 Samsung Electronics. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2.
> + *
> + * The full GNU General Public License is included in this distribution in the
> + * file called COPYING.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +#include <linux/fs.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <net/netlink.h>
> +#include <net/genetlink.h>
> +#include "fs_event.h"
> +
> +static const struct genl_multicast_group fs_event_mcgroups[] = {
> + { .name = FS_EVENTS_MCAST_GRP_NAME, },
> +};
> +
> +static struct genl_family fs_event_family = {
> + .id = GENL_ID_GENERATE,
> + .name = FS_EVENTS_FAMILY_NAME,
> + .version = 1,
> + .maxattr = FS_NL_A_MAX,
> + .mcgrps = fs_event_mcgroups,
> + .n_mcgrps = ARRAY_SIZE(fs_event_mcgroups),
> +};
> +
> +int fs_netlink_send_event(size_t size, unsigned int event_id,
> + int (*compose_msg)(struct sk_buff *skb, void *data),
> + void *cbdata)
> +{
> + static atomic_t seq;
> + struct sk_buff *skb;
> + void *msg_head;
> + int ret = 0;
> +
> + if (!size || !compose_msg)
> + return -EINVAL;
> +
> + /* Skip if there are no listeners */
> + if (!genl_has_listeners(&fs_event_family, &init_net, 0))
> + return 0;
> +
> + if (event_id != FS_EVENT_NONE)
> + size += nla_total_size(sizeof(u32));
> + size += nla_total_size(sizeof(u64));
What is this for ?
thanks
Kinglong Mee
WARNING: multiple messages have this Message-ID (diff)
From: Kinglong Mee <kinglongmee@gmail.com>
To: Beata Michalska <b.michalska@samsung.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-api@vger.kernel.org
Cc: greg@kroah.com, jack@suse.cz, tytso@mit.edu,
adilger.kernel@dilger.ca, hughd@google.com, lczerner@redhat.com,
hch@infradead.org, linux-ext4@vger.kernel.org,
linux-mm@kvack.org, kyungmin.park@samsung.com,
kmpark@infradead.org, kinglongmee@gmail.com
Subject: Re: [RFC v3 1/4] fs: Add generic file system event notifications
Date: Thu, 18 Jun 2015 19:17:21 +0800 [thread overview]
Message-ID: <5582A8C1.3000002@gmail.com> (raw)
In-Reply-To: <1434460173-18427-2-git-send-email-b.michalska@samsung.com>
On 6/16/2015 9:09 PM, Beata Michalska wrote:
> Introduce configurable generic interface for file
> system-wide event notifications, to provide file
> systems with a common way of reporting any potential
> issues as they emerge.
... snip ...
> +
> +Sample request could look like the following:
> +
> + echo /sample/mount/point G T 710000 500000 > /sys/fs/events/config
> +
> +Multiple request might be specified provided they are separated with semicolon.
> +
> +The configuration itself might be modified at any time. One can add/remove
> +particular event types for given fielsystem, modify the threshold levels,
> +and remove single or all entries from the 'config' file.
> +
> + - Adding new event type:
> +
> + $ echo MOUNT EVENT_TYPE > /sys/fs/events/config
> +
> +(Note that is is enough to provide the event type to be enabled without
Should be "Note that it is ... " here ?
> +the already set ones.)
> +
> + - Removing event type:
> +
> + $ echo '!MOUNT EVENT_TYPE' > /sys/fs/events/config
> +
> + - Updating threshold limits:
> +
> + $ echo MOUNT T L1 L2 > /sys/fs/events/config
> +
> + - Removing single entry:
> +
> + $ echo '!MOUNT' > /sys/fs/events/config
> +
> + - Removing all entries:
> +
> + $ echo > /sys/fs/events/config
> +
> +Reading the file will list all registered entries with their current set-up
> +along with some additional info like the filesystem type and the backing device
> +name if available.
> +
> +Final, though a very important note on the configuration: when and if the
> +actual events are being triggered falls way beyond the scope of the generic
> +filesystem events interface. It is up to a particular filesystem
> +implementation which events are to be supported - if any at all. So if
> +given filesystem does not support the event notifications, an attempt to
> +enable those through 'config' file will fail.
> +
> +
> +3. The generic netlink interface support:
> +=========================================
> +
> +Whenever an event notification is triggered (by given filesystem) the current
> +configuration is being validated to decide whether a userpsace notification
> +should be launched. If there has been no request (in a mean of 'config' file
> +entry) for given event, one will be silently disregarded. If, on the other
> +hand, someone is 'watching' given filesystem for specific events, a generic
> +netlink message will be sent. A dedicated multicast group has been provided
> +solely for this purpose so in order to receive such notifications, one should
> +subscribe to this new multicast group. As for now only the init network
> +namespace is being supported.
> +
> +3.1 Message format
> +
> +The FS_NL_C_EVENT shall be stored within the generic netlink message header
> +as the command field. The message payload will provide more detailed info:
> +the backing device major and minor numbers, the event code and the id of
> +the process which action led to the event occurrence. In case of threshold
> +notifications, the current number of available blocks will be included
> +in the payload as well.
> +
> +
> + 0 1 2 3
> + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | NETLINK MESSAGE HEADER |
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | GENERIC NETLINK MESSAGE HEADER |
> + | (with FS_NL_C_EVENT as genlmsghdr cdm field) |
cmd, not cdm.
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | Optional user specific message header |
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + | GENERIC MESSAGE PAYLOAD: |
> + +---------------------------------------------------------------+
> + | FS_NL_A_EVENT_ID (NLA_U32) |
> + +---------------------------------------------------------------+
> + | FS_NL_A_DEV_MAJOR (NLA_U32) |
> + +---------------------------------------------------------------+
> + | FS_NL_A_DEV_MINOR (NLA_U32) |
> + +---------------------------------------------------------------+
> + | FS_NL_A_CAUSED_ID (NLA_U32) |
Should be NLA_U64 ? The following uses as,
+ if (nla_put_u64(skb, FS_NL_A_CAUSED_ID, pid_vnr(task_pid(current))))
+ return -EINVAL;
Also, I'd like FS_NL_A_CAUSED_PID than FS_NL_A_CAUSED_ID.
> + +---------------------------------------------------------------+
> + | FS_NL_A_DATA (NLA_U64) |
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +
> +
> +The above figure is based on:
> + http://www.linuxfoundation.org/collaborate/workgroups/networking/generic_netlink_howto#Message_Format
> +
> +
... snip...
> + seq_putc(m, ' ');
> + if (sb->s_op->show_devname) {
> + sb->s_op->show_devname(m, en->mnt_path.mnt->mnt_root);
> + } else {
> + seq_escape(m, r_mnt->mnt_devname ? r_mnt->mnt_devname : "none",
> + " \t\n\\");
> + }
> + seq_puts(m, " (");
> +
> + nmask = en->notify;
> + for (match = fs_etypes; match->pattern; ++match) {
> + if (match->token & nmask) {
> + seq_puts(m, match->pattern);
Print here is better.
if (match->pattern & FS_EVENT_THRESH)
seq_printf(m, " %llu %llu", en->th.lrange, en->th.urange);
> + nmask &= ~match->token;
> + if (nmask)
> + seq_putc(m, ',');
> + }
> + }
> + seq_printf(m, " %llu %llu", en->th.lrange, en->th.urange);
Don't print the lrange/urange (always be zero) when without FS_EVENT_THRESH.
> + seq_puts(m, ")\n");
> + return 0;
> +}
> +
> +static const struct seq_operations fs_trace_seq_ops = {
> + .start = fs_trace_seq_start,
> + .next = fs_trace_seq_next,
> + .stop = fs_trace_seq_stop,
> + .show = fs_trace_seq_show,
> +};
> +
> +static int fs_trace_open(struct inode *inode, struct file *file)
> +{
> + return seq_open(file, &fs_trace_seq_ops);
> +}
> +
> +static const struct file_operations fs_trace_fops = {
> + .owner = THIS_MODULE,
> + .open = fs_trace_open,
> + .write = fs_trace_write,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = seq_release,
> +};
> +
> +static int fs_trace_init(void)
> +{
> + fs_trace_cachep = KMEM_CACHE(fs_trace_entry, 0);
> + if (!fs_trace_cachep)
> + return -EINVAL;
> + init_waitqueue_head(&trace_wq);
> + return 0;
> +}
> +
> +/* VFS support */
> +static int fs_trace_fill_super(struct super_block *sb, void *data, int silen)
> +{
> + int ret;
> + static struct tree_descr desc[] = {
> + [2] = {
> + .name = "config",
> + .ops = &fs_trace_fops,
> + .mode = S_IWUSR | S_IRUGO,
> + },
> + {""},
> + };
> +
> + ret = simple_fill_super(sb, 0x7246332, desc);
> + return !ret ? fs_trace_init() : ret;
> +}
> +
> +static struct dentry *fs_trace_do_mount(struct file_system_type *fs_type,
> + int ntype, const char *dev_name, void *data)
> +{
> + return mount_single(fs_type, ntype, data, fs_trace_fill_super);
> +}
> +
> +static void fs_trace_kill_super(struct super_block *sb)
> +{
> + /*
> + * The rcu_barrier here will/should make sure all call_rcu
> + * callbacks are completed - still there might be some active
> + * trace objects in use which can make calling the
> + * kmem_cache_destroy unsafe. So we wait until all traces
> + * are finally released.
> + */
> + fs_remove_all_traces();
> + rcu_barrier();
> + wait_event(trace_wq, !atomic_read(&stray_traces));
> +
> + kmem_cache_destroy(fs_trace_cachep);
> + kill_litter_super(sb);
> +}
> +
> +static struct kset *fs_trace_kset;
> +
> +static struct file_system_type fs_trace_fstype = {
> + .name = "fstrace",
> + .mount = fs_trace_do_mount,
> + .kill_sb = fs_trace_kill_super,
> +};
> +
> +static void __init fs_trace_vfs_init(void)
> +{
> + fs_trace_kset = kset_create_and_add("events", NULL, fs_kobj);
> +
> + if (!fs_trace_kset)
> + return;
> +
> + if (!register_filesystem(&fs_trace_fstype)) {
> + if (!fs_event_netlink_register())
> + return;
> + unregister_filesystem(&fs_trace_fstype);
> + }
> + kset_unregister(fs_trace_kset);
> +}
> +
> +static int __init fs_trace_evens_init(void)
> +{
> + fs_trace_vfs_init();
> + return 0;
> +};
> +module_init(fs_trace_evens_init);
> +
> diff --git a/fs/events/fs_event.h b/fs/events/fs_event.h
> new file mode 100644
> index 0000000..23f24c8
> --- /dev/null
> +++ b/fs/events/fs_event.h
> @@ -0,0 +1,22 @@
> +/*
> + * Copyright(c) 2015 Samsung Electronics. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2.
> + *
> + * The full GNU General Public License is included in this distribution in the
> + * file called COPYING.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +
> +#ifndef __GENERIC_FS_EVENTS_H
> +#define __GENERIC_FS_EVENTS_H
> +
> +int fs_event_netlink_register(void);
> +void fs_event_netlink_unregister(void);
> +
> +#endif /* __GENERIC_FS_EVENTS_H */
> diff --git a/fs/events/fs_event_netlink.c b/fs/events/fs_event_netlink.c
> new file mode 100644
> index 0000000..0c97eb7
> --- /dev/null
> +++ b/fs/events/fs_event_netlink.c
> @@ -0,0 +1,104 @@
> +/*
> + * Copyright(c) 2015 Samsung Electronics. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2.
> + *
> + * The full GNU General Public License is included in this distribution in the
> + * file called COPYING.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +#include <linux/fs.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <net/netlink.h>
> +#include <net/genetlink.h>
> +#include "fs_event.h"
> +
> +static const struct genl_multicast_group fs_event_mcgroups[] = {
> + { .name = FS_EVENTS_MCAST_GRP_NAME, },
> +};
> +
> +static struct genl_family fs_event_family = {
> + .id = GENL_ID_GENERATE,
> + .name = FS_EVENTS_FAMILY_NAME,
> + .version = 1,
> + .maxattr = FS_NL_A_MAX,
> + .mcgrps = fs_event_mcgroups,
> + .n_mcgrps = ARRAY_SIZE(fs_event_mcgroups),
> +};
> +
> +int fs_netlink_send_event(size_t size, unsigned int event_id,
> + int (*compose_msg)(struct sk_buff *skb, void *data),
> + void *cbdata)
> +{
> + static atomic_t seq;
> + struct sk_buff *skb;
> + void *msg_head;
> + int ret = 0;
> +
> + if (!size || !compose_msg)
> + return -EINVAL;
> +
> + /* Skip if there are no listeners */
> + if (!genl_has_listeners(&fs_event_family, &init_net, 0))
> + return 0;
> +
> + if (event_id != FS_EVENT_NONE)
> + size += nla_total_size(sizeof(u32));
> + size += nla_total_size(sizeof(u64));
What is this for ?
thanks
Kinglong Mee
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next prev parent reply other threads:[~2015-06-18 11:17 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 13:09 [RFC v3 0/4] fs: Add generic file system event notifications Beata Michalska
2015-06-16 13:09 ` Beata Michalska
2015-06-16 13:09 ` [RFC v3 1/4] " Beata Michalska
2015-06-16 13:09 ` Beata Michalska
2015-06-16 16:21 ` Al Viro
2015-06-16 16:21 ` Al Viro
2015-06-16 16:21 ` Al Viro
2015-06-17 9:22 ` Beata Michalska
2015-06-17 9:22 ` Beata Michalska
2015-06-17 23:06 ` Dave Chinner
2015-06-17 23:06 ` Dave Chinner
2015-06-18 8:25 ` Beata Michalska
2015-06-18 8:25 ` Beata Michalska
2015-06-19 0:03 ` Dave Chinner
2015-06-19 0:03 ` Dave Chinner
2015-06-19 17:28 ` Beata Michalska
2015-06-19 17:28 ` Beata Michalska
2015-06-19 17:28 ` Beata Michalska
2015-06-19 23:21 ` Dave Chinner
2015-06-19 23:21 ` Dave Chinner
2015-06-22 15:46 ` Beata Michalska
2015-06-22 15:46 ` Beata Michalska
2015-06-18 11:17 ` Kinglong Mee [this message]
2015-06-18 11:17 ` Kinglong Mee
2015-06-18 14:50 ` Beata Michalska
2015-06-18 14:50 ` Beata Michalska
2015-06-24 8:47 ` Dmitry Monakhov
2015-06-24 8:47 ` Dmitry Monakhov
2015-06-24 15:31 ` Beata Michalska
2015-06-24 15:31 ` Beata Michalska
2015-06-24 16:26 ` Steve French
2015-06-24 16:26 ` Steve French
2015-06-26 7:30 ` Beata Michalska
2015-06-26 7:30 ` Beata Michalska
2015-07-22 15:55 ` Bartlomiej Zolnierkiewicz
2015-07-22 15:55 ` Bartlomiej Zolnierkiewicz
2015-07-30 8:22 ` Beata Michalska
2015-07-30 8:22 ` Beata Michalska
2015-06-16 13:09 ` [RFC v3 2/4] ext4: Add helper function to mark group as corrupted Beata Michalska
2015-06-16 13:09 ` Beata Michalska
2015-07-22 10:40 ` Bartlomiej Zolnierkiewicz
2015-07-22 10:40 ` Bartlomiej Zolnierkiewicz
2015-06-16 13:09 ` [RFC v3 3/4] ext4: Add support for generic FS events Beata Michalska
2015-06-16 13:09 ` Beata Michalska
2015-06-16 13:09 ` Beata Michalska
2015-06-17 6:15 ` Leon Romanovsky
2015-06-17 6:15 ` Leon Romanovsky
2015-06-17 9:25 ` Beata Michalska
2015-06-17 9:25 ` Beata Michalska
2015-06-16 13:09 ` [RFC v3 4/4] shmem: " Beata Michalska
2015-06-16 13:09 ` Beata Michalska
2015-06-17 6:08 ` Leon Romanovsky
2015-06-17 6:08 ` Leon Romanovsky
2015-06-17 9:23 ` Beata Michalska
2015-06-17 9:23 ` Beata Michalska
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