kernfs_notify() is used to indicate either new data is available or
the content of a file has changed. It currently only triggers poll
which may not be the most convenient to monitor especially when there
are a lot to monitor. Let's hook it up to fsnotify too so that the
events can be monitored via inotify too.
fsnotify_modify() requires file * but kernfs_notify() doesn't have any
specific file associated; however, we can walk all super_blocks
associated with a kernfs_root and as kernfs always associate one ino
with inode and one dentry with an inode, it's trivial to look up the
dentry associated with a given kernfs_node. As any active monitor
would pin dentry, just looking up existing dentry is enough. This
patch looks up the dentry associated with the specified kernfs_node
and generates events equivalent to fsnotify_modify().
Note that as fsnotify doesn't provide fsnotify_modify() equivalent
which can be called with dentry, kernfs_notify() directly calls
fsnotify_parent() and fsnotify(). It might be better to add a wrapper
in fsnotify.h instead.
Signed-off-by: Tejun Heo <t...@kernel.org>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: John McCutchan <j...@johnmccutchan.com>
Cc: Robert Love <rl...@rlove.org>
Cc: Eric Paris <epa...@parisplace.org>
---
fs/kernfs/file.c | 41 +++++++++++++++++++++++++++++++++++------
1 file changed, 35 insertions(+), 6 deletions(-)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 8034706..98bacd9 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -14,6 +14,7 @@
#include <linux/poll.h>
#include <linux/pagemap.h>
#include <linux/sched.h>
+#include <linux/fsnotify.h>
#include "kernfs-internal.h"
@@ -785,20 +786,48 @@ static unsigned int kernfs_fop_poll(struct file *filp,
poll_table *wait)
*/
void kernfs_notify(struct kernfs_node *kn)
{
+ struct kernfs_root *root = kernfs_root(kn);
struct kernfs_open_node *on;
+ struct kernfs_super_info *info;
unsigned long flags;
+ if (WARN_ON(kernfs_type(kn) != KERNFS_FILE))
+ return;
+
+ /* kick poll */
spin_lock_irqsave(&kernfs_open_node_lock, flags);
- if (!WARN_ON(kernfs_type(kn) != KERNFS_FILE)) {
- on = kn->attr.open;
- if (on) {
- atomic_inc(&on->event);
- wake_up_interruptible(&on->poll);
- }
+ on = kn->attr.open;
+ if (on) {
+ atomic_inc(&on->event);
+ wake_up_interruptible(&on->poll);
}
spin_unlock_irqrestore(&kernfs_open_node_lock, flags);
+
+ /* kick fsnotify */
+ mutex_lock(&kernfs_mutex);
+
+ list_for_each_entry(info, &root->supers, node) {
+ struct inode *inode;
+ struct dentry *dentry;
+
+ inode = ilookup(info->sb, kn->ino);
+ if (!inode)
+ continue;
+
+ dentry = d_find_any_alias(inode);
+ if (dentry) {
+ fsnotify_parent(NULL, dentry, FS_MODIFY);
+ fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
+ NULL, 0);
+ dput(dentry);
+ }
+
+ iput(inode);
+ }
+
+ mutex_unlock(&kernfs_mutex);
}
EXPORT_SYMBOL_GPL(kernfs_notify);
--
1.9.0
--
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