From: Suren Baghdasaryan <surenb@google.com>
To: gregkh@linuxfoundation.org
Cc: tj@kernel.org, lizefan@huawei.com, hannes@cmpxchg.org,
axboe@kernel.dk, dennis@kernel.org, dennisszhou@gmail.com,
mingo@redhat.com, peterz@infradead.org,
akpm@linux-foundation.org, corbet@lwn.net,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@android.com, Suren Baghdasaryan <surenb@google.com>
Subject: [PATCH 1/6] fs: kernfs: add poll file operation
Date: Fri, 14 Dec 2018 09:15:03 -0800 [thread overview]
Message-ID: <20181214171508.7791-2-surenb@google.com> (raw)
In-Reply-To: <20181214171508.7791-1-surenb@google.com>
From: Johannes Weiner <hannes@cmpxchg.org>
Kernfs has a standardized poll/notification mechanism for waking all
pollers on all fds when a filesystem node changes. To allow polling
for custom events, add a .poll callback that can override the default.
This is in preparation for pollable cgroup pressure files which have
per-fd trigger configurations.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
fs/kernfs/file.c | 31 ++++++++++++++++++++-----------
include/linux/kernfs.h | 6 ++++++
2 files changed, 26 insertions(+), 11 deletions(-)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index dbf5bc250bfd..2d8b91f4475d 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -832,26 +832,35 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
* to see if it supports poll (Neither 'poll' nor 'select' return
* an appropriate error code). When in doubt, set a suitable timeout value.
*/
+__poll_t kernfs_generic_poll(struct kernfs_open_file *of, poll_table *wait)
+{
+ struct kernfs_node *kn = kernfs_dentry_node(of->file->f_path.dentry);
+ struct kernfs_open_node *on = kn->attr.open;
+
+ poll_wait(of->file, &on->poll, wait);
+
+ if (of->event != atomic_read(&on->event))
+ return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI;
+
+ return DEFAULT_POLLMASK;
+}
+
static __poll_t kernfs_fop_poll(struct file *filp, poll_table *wait)
{
struct kernfs_open_file *of = kernfs_of(filp);
struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry);
- struct kernfs_open_node *on = kn->attr.open;
+ __poll_t ret;
if (!kernfs_get_active(kn))
- goto trigger;
+ return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI;
- poll_wait(filp, &on->poll, wait);
+ if (kn->attr.ops->poll)
+ ret = kn->attr.ops->poll(of, wait);
+ else
+ ret = kernfs_generic_poll(of, wait);
kernfs_put_active(kn);
-
- if (of->event != atomic_read(&on->event))
- goto trigger;
-
- return DEFAULT_POLLMASK;
-
- trigger:
- return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI;
+ return ret;
}
static void kernfs_notify_workfn(struct work_struct *work)
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 5b36b1287a5a..0cac1207bb00 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -25,6 +25,7 @@ struct seq_file;
struct vm_area_struct;
struct super_block;
struct file_system_type;
+struct poll_table_struct;
struct kernfs_open_node;
struct kernfs_iattrs;
@@ -261,6 +262,9 @@ struct kernfs_ops {
ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
loff_t off);
+ __poll_t (*poll)(struct kernfs_open_file *of,
+ struct poll_table_struct *pt);
+
int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -350,6 +354,8 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
const char *new_name, const void *new_ns);
int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
+__poll_t kernfs_generic_poll(struct kernfs_open_file *of,
+ struct poll_table_struct *pt);
void kernfs_notify(struct kernfs_node *kn);
const void *kernfs_super_ns(struct super_block *sb);
--
2.20.0.405.gbc1bbc6f85-goog
next prev parent reply other threads:[~2018-12-14 17:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 17:15 [PATCH 0/6] psi: pressure stall monitors Suren Baghdasaryan
2018-12-14 17:15 ` Suren Baghdasaryan [this message]
2018-12-14 17:15 ` [PATCH 2/6] kernel: cgroup: add poll file operation Suren Baghdasaryan
2018-12-14 17:15 ` [PATCH 3/6] psi: eliminate lazy clock mode Suren Baghdasaryan
2018-12-17 14:57 ` Peter Zijlstra
2018-12-18 1:10 ` Suren Baghdasaryan
2018-12-14 17:15 ` [PATCH 4/6] psi: introduce state_mask to represent stalled psi states Suren Baghdasaryan
2018-12-17 15:55 ` Peter Zijlstra
2018-12-18 1:14 ` Suren Baghdasaryan
2018-12-18 10:17 ` Peter Zijlstra
2018-12-14 17:15 ` [PATCH 5/6] psi: rename psi fields in preparation for psi trigger addition Suren Baghdasaryan
2018-12-14 17:15 ` [PATCH 6/6] psi: introduce psi monitor Suren Baghdasaryan
2018-12-17 16:22 ` Peter Zijlstra
2018-12-18 1:21 ` Suren Baghdasaryan
2018-12-18 10:46 ` Peter Zijlstra
2018-12-18 11:20 ` Peter Zijlstra
2018-12-18 17:30 ` Johannes Weiner
2018-12-18 17:58 ` Suren Baghdasaryan
2018-12-18 19:18 ` Joel Fernandes
2018-12-18 20:29 ` Suren Baghdasaryan
2018-12-17 16:27 ` Peter Zijlstra
2018-12-18 1:22 ` Suren Baghdasaryan
2018-12-18 16:51 ` kbuild test robot
2018-12-22 14:12 ` kbuild test robot
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