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auxiliary fdinfo, new round

PATCH In review Cyrill Gorcunov 2 participants 10 messages Sep 12, 2012 – Sep 27, 2012

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#0 lore raw

cover auxiliary fdinfo, new round

Hi Al, could you please share your opinion on this series? Is there something I should fix or redesign?

Cyrill

#1 lore raw

PATCH 1/7 procfs: Add ability to plug in auxiliary fdinfo providers

This patch brings ability to print out auxiliary data associated with file in procfs interface /proc/pid/fdinfo/fd.

In particular further patches make eventfd, evenpoll, signalfd and fsnotify to print additional information complete enough to restore these objects after checkpoint.

To simplify the code we add show_fdinfo callback inside struct file_operations (as Al and Pavel are proposing).

CC Pavel Emelyanov <[email protected]>
CC Al Viro <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Andrew Morton <[email protected]>
CC James Bottomley <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Matthew Helsley <[email protected]>
CC "J. Bruce Fields" <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
---
 fs/proc/fd.c       |    2 ++
 include/linux/fs.h |    3 +++
 2 files changed, 5 insertions(+)
fs/proc/fd.c +2 -0
Index: linux-2.6.git/fs/proc/fd.c
===================================================================
@@ -50,6 +50,8 @@ static int seq_show(struct seq_file *m,
 	if (!ret) {
                 seq_printf(m, "pos:\t%lli\nflags:\t0%o\n",
 			   (long long)file->f_pos, f_flags);
+		if (file->f_op->show_fdinfo)
+			ret = file->f_op->show_fdinfo(m, file);
 		fput(file);
 	}
 
include/linux/fs.h +3 -0
Index: linux-2.6.git/include/linux/fs.h
===================================================================
@@ -1774,6 +1774,8 @@ struct block_device_operations;
 #define HAVE_COMPAT_IOCTL 1
 #define HAVE_UNLOCKED_IOCTL 1
 
+struct seq_file;
+
 struct file_operations {
 	struct module *owner;
 	loff_t (*llseek) (struct file *, loff_t, int);
@@ -1802,6 +1804,7 @@ struct file_operations {
 	int (*setlease)(struct file *, long, struct file_lock **);
 	long (*fallocate)(struct file *file, int mode, loff_t offset,
 			  loff_t len);
+	int (*show_fdinfo)(struct seq_file *m, struct file *f);
 };
 
 struct inode_operations {
#2 lore raw

Re: [patch 1/7] procfs: Add ability to plug in auxiliary fdinfo providers

Quoted 10 lines · Cyrill Gorcunov

This patch brings ability to print out auxiliary data associated with file in procfs interface /proc/pid/fdinfo/fd.

In particular further patches make eventfd, evenpoll, signalfd and fsnotify to print additional information complete enough to restore these objects after checkpoint.

To simplify the code we add show_fdinfo callback inside struct file_operations (as Al and Pavel are proposing).

Hi, sorry for bothering but is there some opinions on this series?

(I've found that epoll change log has not been well refreshed and
says that this fdinfo feature is config-checkpoint-restore dependant, but in real this config entry was ripped off during conversation).

So, at moment I somehow confused since it's a bit unclear where to move, either this series is more-less acceptible or not. I could bring back all config-checkpoint-restore dependency (since I still believe this feature better to be enabled not by default but iif user has asked fo it).

#3 lore raw

Re: [patch 1/7] procfs: Add ability to plug in auxiliary fdinfo providers

Quoted 8 lines · Cyrill Gorcunov
Quoted 7 lines · Cyrill Gorcunov

This patch brings ability to print out auxiliary data associated with file in procfs interface /proc/pid/fdinfo/fd.

In particular further patches make eventfd, evenpoll, signalfd and fsnotify to print additional information complete enough to restore these objects after checkpoint.

Quoted 5 lines
Quoted 3 lines

To simplify the code we add show_fdinfo callback inside struct file_operations (as Al and Pavel are proposing).

Hi, sorry for bothering but is there some opinions on this series?

Al, we'd appreciate if you share your plans about this series. Please.

Quoted 11 lines

(I've found that epoll change log has not been well refreshed and
says that this fdinfo feature is config-checkpoint-restore dependant, but in real this config entry was ripped off during conversation).

So, at moment I somehow confused since it's a bit unclear where to move, either this series is more-less acceptible or not. I could bring back all config-checkpoint-restore dependency (since I still believe this feature better to be enabled not by default but iif user has asked fo it).
.

Thanks,
Pavel

#4 lore raw

PATCH 2/7 fs, exportfs: Escape nil dereference if no s_export_op present

In reply to Cyrill Gorcunov

This routine will be used to generate a file handle in fdinfo output for inotify subsystem, where if no s_export_op present the general export_encode_fh should be used. Thus add a test if s_export_op present inside exportfs_encode_fh itself.

CC Pavel Emelyanov <[email protected]>
CC Al Viro <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Andrew Morton <[email protected]>
CC James Bottomley <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Matthew Helsley <[email protected]>
CC "J. Bruce Fields" <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
---
 fs/exportfs/expfs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
fs/exportfs/expfs.c +1 -1
Index: linux-2.6.git/fs/exportfs/expfs.c
===================================================================
@@ -357,7 +357,7 @@ int exportfs_encode_fh(struct dentry *de
 		 */
 		parent = p->d_inode;
 	}
-	if (nop->encode_fh)
+	if (nop && nop->encode_fh)
 		error = nop->encode_fh(inode, fid->raw, max_len, parent);
 	else
 		error = export_encode_fh(inode, fid, max_len, parent);
#5 lore raw

PATCH 3/7 fs, notify: Add file handle entry into inotify_inode_mark

In reply to Cyrill Gorcunov

This file handle will be used in /proc/pid/fdinfo/fd output, which in turn will allow to restore a watch target after checkpoint.

CC Pavel Emelyanov <[email protected]>
CC Al Viro <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Andrew Morton <[email protected]>
CC James Bottomley <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Matthew Helsley <[email protected]>
CC "J. Bruce Fields" <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
---
 fs/notify/inotify/inotify.h      |    8 +++++++
 fs/notify/inotify/inotify_user.c |   42 ++++++++++++++++++++++++++++++++++-----
 2 files changed, 45 insertions(+), 5 deletions(-)
fs/notify/inotify/inotify.h +8 -0
Index: linux-2.6.git/fs/notify/inotify/inotify.h
===================================================================
@@ -1,6 +1,7 @@
 #include <linux/fsnotify_backend.h>
 #include <linux/inotify.h>
 #include <linux/slab.h> /* struct kmem_cache */
+#include <linux/exportfs.h>
 
 extern struct kmem_cache *event_priv_cachep;
 
@@ -9,9 +10,16 @@ struct inotify_event_private_data {
 	int wd;
 };
 
+#if defined(CONFIG_PROC_FS) && defined(CONFIG_EXPORTFS) && defined(CONFIG_CHECKPOINT_RESTORE)
+# define INOTIFY_USE_FHANDLE
+#endif
+
 struct inotify_inode_mark {
 	struct fsnotify_mark fsn_mark;
 	int wd;
+#ifdef INOTIFY_USE_FHANDLE
+	__u8 fhandle[sizeof(struct file_handle) + MAX_HANDLE_SZ];
+#endif
 };
 
 extern void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
fs/notify/inotify/inotify_user.c +37 -5

82 lines not on this page · raw message

#6 lore raw

PATCH 4/7 fs, notify: Add procfs fdinfo helper v4

In reply to Cyrill Gorcunov

This allow us to print out fsnotify details such as watchee inode, device, mask and optionally a file handle.

For inotify objects if kernel compiled with exportfs support the output will be

 | pos:	0
 | flags:	02000000
 | inotify wd:        3 ino:             9e7e sdev:   800013 mask:  800afce ignored_mask:        0 fhandle-bytes:        8 fhandle-type:        1 f_handle: 7e9e0000640d1b6d
 | inotify wd:        2 ino:             a111 sdev:   800013 mask:  800afce ignored_mask:        0 fhandle-bytes:        8 fhandle-type:        1 f_handle: 11a1000020542153
 | inotify wd:        1 ino:            6b149 sdev:   800013 mask:  800afce ignored_mask:        0 fhandle-bytes:        8 fhandle-type:        1 f_handle: 49b1060023552153

If kernel compiled without exportfs support, the file handle won't be provided but inode and device only.

 | pos:	0
 | flags:	02000000
 | inotify wd:        3 ino:             9e7e sdev:   800013 mask:  800afce ignored_mask:        0
 | inotify wd:        2 ino:             a111 sdev:   800013 mask:  800afce ignored_mask:        0
 | inotify wd:        1 ino:            6b149 sdev:   800013 mask:  800afce ignored_mask:        0

For fanotify the output is like

 | pos:	0
 | flags:	02
 | fanotify ino:            68f71 sdev:   800013 mask:        1 ignored_mask: 40000000
 | fanotify mnt_id:       13 mask:        1 ignored_mask: 40000000

To minimize impact on general fsnotify code the new functionality is gathered in fs/notify/fdinfo.c file.

CC Pavel Emelyanov <[email protected]>
CC Al Viro <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Andrew Morton <[email protected]>
CC James Bottomley <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Matthew Helsley <[email protected]>
CC "J. Bruce Fields" <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
---
 fs/notify/Makefile                 |    2 
 fs/notify/fanotify/fanotify_user.c |    4 +
 fs/notify/fdinfo.c                 |  124 +++++++++++++++++++++++++++++++++++++
 fs/notify/fdinfo.h                 |   22 ++++++
 fs/notify/inotify/inotify_user.c   |    4 +
 5 files changed, 155 insertions(+), 1 deletion(-)
fs/notify/Makefile +1 -1
Index: linux-2.6.git/fs/notify/Makefile
===================================================================
@@ -1,5 +1,5 @@
 obj-$(CONFIG_FSNOTIFY)		+= fsnotify.o notification.o group.o inode_mark.o \
-				   mark.o vfsmount_mark.o
+				   mark.o vfsmount_mark.o fdinfo.o
 
 obj-y			+= dnotify/
 obj-y			+= inotify/
fs/notify/fanotify/fanotify_user.c +4 -0
Index: linux-2.6.git/fs/notify/fanotify/fanotify_user.c
===================================================================
@@ -17,6 +17,7 @@
 #include <asm/ioctls.h>
 
 #include "../../mount.h"
+#include "../fdinfo.h"
 
 #define FANOTIFY_DEFAULT_MAX_EVENTS	16384
 #define FANOTIFY_DEFAULT_MAX_MARKS	8192
@@ -446,6 +447,9 @@ static long fanotify_ioctl(struct file *
 }
 
 static const struct file_operations fanotify_fops = {
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= fanotify_show_fdinfo,
+#endif
 	.poll		= fanotify_poll,
 	.read		= fanotify_read,
 	.write		= fanotify_write,
fs/notify/fdinfo.c new file +124 -0

124 lines not on this page · raw message

fs/notify/fdinfo.h new file +22 -0
Index: linux-2.6.git/fs/notify/fdinfo.h
===================================================================
@@ -0,0 +1,22 @@
+#ifndef __FSNOTIFY_FDINFO_H__
+#define __FSNOTIFY_FDINFO_H__
+
+#include <linux/errno.h>
+#include <linux/proc_fs.h>
+
+struct seq_file;
+struct file;
+
+#ifdef CONFIG_PROC_FS
+
+#ifdef CONFIG_INOTIFY_USER
+extern int inotify_show_fdinfo(struct seq_file *m, struct file *f);
+#endif
+
+#ifdef CONFIG_FANOTIFY
+extern int fanotify_show_fdinfo(struct seq_file *m, struct file *f);
+#endif
+
+#endif /* CONFIG_PROC_FS */
+
+#endif /* __FSNOTIFY_FDINFO_H__ */
fs/notify/inotify/inotify_user.c +4 -0
Index: linux-2.6.git/fs/notify/inotify/inotify_user.c
===================================================================
@@ -40,6 +40,7 @@
 #include <linux/wait.h>
 
 #include "inotify.h"
+#include "../fdinfo.h"
 
 #include <asm/ioctls.h>
 
@@ -335,6 +336,9 @@ static long inotify_ioctl(struct file *f
 }
 
 static const struct file_operations inotify_fops = {
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= inotify_show_fdinfo,
+#endif
 	.poll		= inotify_poll,
 	.read		= inotify_read,
 	.fasync		= inotify_fasync,
#7 lore raw

PATCH 5/7 fs, eventfd: Add procfs fdinfo helper

In reply to Cyrill Gorcunov

This allow us to print out raw counter value. The /proc/pid/fdinfo/fd output is

 | pos:	0
 | flags:	04002
 | eventfd-count:               5a
CC Pavel Emelyanov <[email protected]>
CC Al Viro <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Andrew Morton <[email protected]>
CC James Bottomley <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Matthew Helsley <[email protected]>
CC "J. Bruce Fields" <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
---
 fs/eventfd.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
fs/eventfd.c +20 -0
Index: linux-2.6.git/fs/eventfd.c
===================================================================
@@ -19,6 +19,8 @@
 #include <linux/export.h>
 #include <linux/kref.h>
 #include <linux/eventfd.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 
 struct eventfd_ctx {
 	struct kref kref;
@@ -284,7 +286,25 @@ static ssize_t eventfd_write(struct file
 	return res;
 }
 
+#ifdef CONFIG_PROC_FS
+static int eventfd_show_fdinfo(struct seq_file *m, struct file *f)
+{
+	struct eventfd_ctx *ctx = f->private_data;
+	int ret;
+
+	spin_lock_irq(&ctx->wqh.lock);
+	ret = seq_printf(m, "eventfd-count: %16llx\n",
+			 (unsigned long long)ctx->count);
+	spin_unlock_irq(&ctx->wqh.lock);
+
+	return ret;
+}
+#endif
+
 static const struct file_operations eventfd_fops = {
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= eventfd_show_fdinfo,
+#endif
 	.release	= eventfd_release,
 	.poll		= eventfd_poll,
 	.read		= eventfd_read,
#8 lore raw

PATCH 6/7 fs, epoll: Add procfs fdinfo helper v2

In reply to Cyrill Gorcunov

This allow us to print out eventpoll target file descriptor, events and data, the /proc/pid/fdinfo/fd consists of

 | pos:	0
 | flags:	02
 | tfd:        5 events:       1d data: ffffffffffffffff

This feature is CONFIG_CHECKPOINT_RESTORE only.

[avagin@: fix for unitialized ret variable]

CC Pavel Emelyanov <[email protected]>
CC Al Viro <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Andrew Morton <[email protected]>
CC James Bottomley <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Matthew Helsley <[email protected]>
CC "J. Bruce Fields" <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Andrey Vagin <[email protected]>
---
 fs/eventpoll.c |   28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
fs/eventpoll.c +28 -0
Index: linux-2.6.git/fs/eventpoll.c
===================================================================
@@ -38,6 +38,8 @@
 #include <asm/io.h>
 #include <asm/mman.h>
 #include <linux/atomic.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 
 /*
  * LOCKING:
@@ -783,8 +785,34 @@ static unsigned int ep_eventpoll_poll(st
 	return pollflags != -1 ? pollflags : 0;
 }
 
+#ifdef CONFIG_PROC_FS
+static int ep_show_fdinfo(struct seq_file *m, struct file *f)
+{
+	struct eventpoll *ep = f->private_data;
+	struct rb_node *rbp;
+	int ret = 0;
+
+	mutex_lock(&ep->mtx);
+	for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
+		struct epitem *epi = rb_entry(rbp, struct epitem, rbn);
+
+		ret = seq_printf(m, "tfd: %8d events: %8x data: %16llx\n",
+				 epi->ffd.fd, epi->event.events,
+				 (long long)epi->event.data);
+		if (ret)
+			break;
+	}
+	mutex_unlock(&ep->mtx);
+
+	return ret;
+}
+#endif
+
 /* File callbacks that implement the eventpoll file behaviour */
 static const struct file_operations eventpoll_fops = {
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= ep_show_fdinfo,
+#endif
 	.release	= ep_eventpoll_release,
 	.poll		= ep_eventpoll_poll,
 	.llseek		= noop_llseek,
#9 lore raw

PATCH 7/7 fdinfo: Show sigmask for signalfd fd v2

In reply to Cyrill Gorcunov
CC Al Viro <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Andrew Morton <[email protected]>
CC James Bottomley <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
CC Alexey Dobriyan <[email protected]>
CC Matthew Helsley <[email protected]>
CC "J. Bruce Fields" <[email protected]>
CC "Aneesh Kumar K.V" <[email protected]>
---
 fs/proc/array.c         |    2 +-
 fs/signalfd.c           |   26 ++++++++++++++++++++++++++
 include/linux/proc_fs.h |    3 +++
 3 files changed, 30 insertions(+), 1 deletion(-)
fs/proc/array.c +1 -1
Index: linux-2.6.git/fs/proc/array.c
===================================================================
@@ -220,7 +220,7 @@ static inline void task_state(struct seq
 	seq_putc(m, '\n');
 }
 
-static void render_sigset_t(struct seq_file *m, const char *header,
+void render_sigset_t(struct seq_file *m, const char *header,
 				sigset_t *set)
 {
 	int i;
fs/signalfd.c +26 -0
Index: linux-2.6.git/fs/signalfd.c
===================================================================
@@ -29,6 +29,7 @@
 #include <linux/anon_inodes.h>
 #include <linux/signalfd.h>
 #include <linux/syscalls.h>
+#include <linux/proc_fs.h>
 
 void signalfd_cleanup(struct sighand_struct *sighand)
 {
@@ -46,6 +47,7 @@ void signalfd_cleanup(struct sighand_str
 }
 
 struct signalfd_ctx {
+	seqcount_t cnt;
 	sigset_t sigmask;
 };
 
@@ -227,7 +229,28 @@ static ssize_t signalfd_read(struct file
 	return total ? total: ret;
 }
 
+#ifdef CONFIG_PROC_FS
+static int signalfd_show_fdinfo(struct seq_file *m, struct file *f)
+{
+	struct signalfd_ctx *ctx = f->private_data;
+	sigset_t sigmask;
+	unsigned seq;
+
+	do {
+		seq = read_seqcount_begin(&ctx->cnt);
+		sigmask = ctx->sigmask;
+	} while (read_seqcount_retry(&ctx->cnt, seq));
+
+	signotset(&sigmask);
+	render_sigset_t(m, "sigmask:\t", &sigmask);
+	return 0;
+}
+#endif
+
 static const struct file_operations signalfd_fops = {
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= signalfd_show_fdinfo,
+#endif
 	.release	= signalfd_release,
 	.poll		= signalfd_poll,
 	.read		= signalfd_read,
@@ -259,6 +282,7 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sig
 			return -ENOMEM;
 
 		ctx->sigmask = sigmask;
+		seqcount_init(&ctx->cnt);
 
 		/*
 		 * When we call this, the initialization must be complete, since
@@ -279,7 +303,9 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sig
 			return -EINVAL;
 		}
 		spin_lock_irq(&current->sighand->siglock);
+		write_seqcount_begin(&ctx->cnt);
 		ctx->sigmask = sigmask;
+		write_seqcount_end(&ctx->cnt);
 		spin_unlock_irq(&current->sighand->siglock);
 
 		wake_up(&current->sighand->signalfd_wqh);
include/linux/proc_fs.h +3 -0
Index: linux-2.6.git/include/linux/proc_fs.h
===================================================================
@@ -290,4 +290,7 @@ static inline struct net *PDE_NET(struct
 	return pde->parent->data;
 }
 
+#include <asm/signal.h>
+
+void render_sigset_t(struct seq_file *m, const char *header, sigset_t *set);
 #endif /* _LINUX_PROC_FS_H */