lkml.org 
[lkml]   [2006]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [2.6.16 PATCH] Filesystem Events Connector v4
On Mon, Mar 27, 2006 at 11:05:38PM +0800, Yi Yang (yang.y.yi@gmail.com) wrote:
> This release is v4, compared with v3, it adds and improve some functions:
> * The user can set event filter in order to just get
> those events who concerns, filter may be based on
> event mask, pid, uid and gid.
> * it removes the atomic_t variable cn_fs_listener and
> adopt a smart way to decide whether it should send a
> event.
> * Add several filter operation commands and acknowleges
> , add a new struct fsevent_filter as command struct.
>
> basically, these functions enable it to meet the user's requirements better,
> but, it can't do better because of connector broadcast property, I plan to
> use netlink to let different user see different events, filter is based on
> userspace appplication using it, every application can set its own filters
> and see different events.
>
> drivers/connector/Kconfig | 12 +
> drivers/connector/Makefile | 1
> drivers/connector/cn_fs.c | 298 +++++++++++++++++++++++++++++++++++++++++
> drivers/connector/connector.c | 4
> fs/namespace.c | 12 +
> include/linux/connector.h | 8 -
> include/linux/fsevent.h | 122 +++++++++++++++++
> include/linux/fsnotify.h | 37 +++++
> 8 files changed, 490 insertions(+), 4 deletions(-)
>
> Signed-off-by: Yi Yang <yang.y.yi@gmail.com>

> +
> +#ifdef CONFIG_FS_EVENTS
> + {
> + u32 fsevent_mask = 0;
> + if (ia_valid & (ATTR_UID | ATTR_GID | ATTR_MODE))
> + fsevent_mask |= FSEVENT_MODIFY_ATTRIB;
> + if ((ia_valid & ATTR_ATIME) && (ia_valid & ATTR_MTIME))
> + fsevent_mask |= FSEVENT_MODIFY_ATTRIB;
> + else if (ia_valid & ATTR_ATIME)
> + fsevent_mask |= FSEVENT_ACCESS;
> + else if (ia_valid & ATTR_MTIME)
> + fsevent_mask |= FSEVENT_MODIFY;
> + if (ia_valid & ATTR_SIZE)
> + fsevent_mask |= FSEVENT_MODIFY;
> + if (fsevent_mask)
> + raise_fsevent(dentry, fsevent_mask);
> + }
> +#endif /* CONFIG_FS_EVENTS */
> }

Coding style?


> --- a/drivers/connector/connector.c.orig 2006-03-27 21:35:15.000000000 +0800
> +++ b/drivers/connector/connector.c 2006-03-27 21:35:53.000000000 +0800
> @@ -111,9 +111,7 @@ int cn_netlink_send(struct cn_msg *msg,
>
> NETLINK_CB(skb).dst_group = group;
>
> - netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
> -
> - return 0;
> + return (netlink_broadcast(dev->nls, skb, 0, group, gfp_mask));
>
> nlmsg_failure:
> kfree_skb(skb);

This error value is propageted back in current connector code already.

> +
> + /* The following definitions are commands for event filter
> + * , in acknowlege event for the corresponding command, it
> + * will set to type field of struct fsevent.
> + */

Not an eye-candy.

> + FSEVENT_FILTER_ALL = 0x08000000, /* For all events */
> + FSEVENT_FILTER_PID = 0x10000000, /* For some process ID */
> + FSEVENT_FILTER_UID = 0x20000000, /* For some user ID */
> + FSEVENT_FILTER_GID = 0x40000000, /* For some group ID */
> +
> + FSEVENT_ISDIR = 0x80000000 /* It is set for a dir */
> +};
> +
> +#define FSEVENT_MASK 0x800003ff
> +
> +typedef unsigned long fsevent_mask_t;
> +
> +struct fsevent_filter {
> + /* filter type, it just is one or bit-or of them
> + * FSEVENT_FILTER_ALL
> + * FSEVENT_FILTER_PID
> + * FSEVENT_FILTER_UID
> + * FSEVENT_FILTER_GID
> + */
> + enum fsevent_type type; /* filter type */
> +
> + /* mask of file system events the user listen or ignore
> + * if the user need to ignore all the events of some pid
> + * , gid or uid, he(she) must set mask to FSEVENT_MASK.
> + */

"," on the new line.

> +static void turn_off_fsevents(void)
> +{
> + write_lock(&fsevents_lock);
> + fsevents_mask = 0;
> + fsevents_pid_mask = 0;
> + filter_pid = -1;
> + fsevents_uid_mask = 0;
> + filter_uid = -1;
> + fsevents_gid_mask = 0;
> + filter_gid = -1;
> + write_unlock(&fsevents_lock);
> +}
> +
> +static int filter_fsevents(u32 * mask)
> +{
> + int ret = 0;
> +
> + (*mask) &= FSEVENT_MASK;
> + read_lock(&fsevents_lock);

You do want to use RCU locking here.
It is fast path and it is not allowed to get global
smp-unfriendly read lock.

> + if (current->pid == filter_pid) {
> + (*mask) &= fsevents_pid_mask;
> + if ((*mask) == 0) {
> + ret = -2;
> + }
> + goto release_lock;
> + }
> +
> + if (current->uid == filter_uid) {
> + (*mask) &= fsevents_uid_mask;
> + if ((*mask) == 0) {
> + ret = -3;
> + }
> + goto release_lock;
> + }
> +
> + if (current->gid == filter_gid) {
> + (*mask) &= fsevents_gid_mask;
> + if ((*mask) == 0) {
> + ret = -4;
> + }
> + goto release_lock;
> + }
> +
> + if ((((*mask) & FSEVENT_ISDIR) == FSEVENT_ISDIR)
> + & ((fsevents_mask & FSEVENT_ISDIR) == 0)) {
> + ret = -1;
> + goto release_lock;
> + }
> +
> + (*mask) &= fsevents_mask;
> + if ((*mask) == 0) {
> + ret = -5;
> + }
> +
> +release_lock:
> + read_unlock(&fsevents_lock);
> + return ret;
> +}

Can it be somehow turned off or moved into per-cpu variables?
It is a lot of smp-unfriendly access of global variables.

It of course costs much less than allocations and copies,
but no global lock at least.

> + if (newname) {
> + event->new_fname_len = strlen(newname);
> + append_string(&nameptr, newname, event->new_fname_len);
> + event->len += event->new_fname_len + 1;
> + }

A space from nowhere.

> + if (ret == -ESRCH) {
> + turn_off_fsevents();
> + }

Coding style.

> +void raise_fsevent(struct dentry * dentryp, u32 mask)
> +{
> + if (dentryp->d_inode && (MAJOR(dentryp->d_inode->i_rdev) == 4))
> + return;
> + __raise_fsevent(dentryp->d_name.name, NULL, mask);
> +}

Yep, tty can mess the things.
Maybe remove all special devices at all?

> +EXPORT_SYMBOL_GPL(raise_fsevent);
> +
> +void raise_fsevent_create(struct inode * inode, const char * name, u32 mask)
> +{
> + read_lock(&fsevents_lock);
> + __raise_fsevent(name, NULL, mask);
> +}

Lost read_lock here - you will grab it in
__raise_fsevent()->filter_fsevents().


> +static int __init cn_fs_init(void)
> +{
> + int err;
> +
> + if ((err = cn_add_callback(&cn_fs_event_id, "cn_fs",
> + &cn_fsevent_filter_ctl))) {
> + printk(KERN_WARNING "cn_fs failed to register\n");
> + return err;
> + }
> + return 0;
> +}
> +
> +module_init(cn_fs_init);

Add module_exit() too.

Main issue is locking in this patchset - it is not allowed to have such
a global lock in those pathes, moving this to RCU is the way to go and definitely not a
problem to implement.

Thank you.

--
Evgeniy Polyakov
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-03-28 10:54    [W:0.086 / U:1.884 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site