Hi, On 06/18/2015 01:17 PM, Kinglong Mee wrote: > 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 ?
Right > >> +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. ditto > >> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >> + | 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; > Yes, or nla_put_u32 - either way my bad > Also, I'd like FS_NL_A_CAUSED_PID than FS_NL_A_CAUSED_ID. Alright > >> + +---------------------------------------------------------------+ >> + | 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. > ditto >> + 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 ? > This should actually get removed :) > thanks > Kinglong Mee > Thank You, Best Regards Beata -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
