fs, notify: add procfs fdinfo helper

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:	04002
 | fanotify flags:10 event-flags:0
 | fanotify mnt_id:12 mask:3b ignored_mask:0
 | fanotify ino:50205 sdev:800013 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:05020500fb1d47e7

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

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Helsley <matt.helsley@gmail.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@onelan.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 175 insertions, 0 deletions

diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c
new file mode 100644
index 000000000000..cb996179abfd
--- /dev/null
+++ b/fs/notify/fdinfo.c
@@ -0,0 +1,175 @@
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/fsnotify_backend.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/inotify.h>
+#include <linux/fanotify.h>
+#include <linux/kernel.h>
+#include <linux/namei.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+#include <linux/exportfs.h>
+
+#include "inotify/inotify.h"
+#include "../fs/mount.h"
+
+#if defined(CONFIG_PROC_FS)
+
+#if defined(CONFIG_INOTIFY_USER) || defined(CONFIG_FANOTIFY)
+
+static int show_fdinfo(struct seq_file *m, struct file *f,
+                       int (*show)(struct seq_file *m, struct fsnotify_mark *mark))
+{
+        struct fsnotify_group *group = f->private_data;
+        struct fsnotify_mark *mark;
+        int ret = 0;
+
+        spin_lock(&group->mark_lock);
+        list_for_each_entry(mark, &group->marks_list, g_list) {
+                ret = show(m, mark);
+                if (ret)
+                        break;
+        }
+        spin_unlock(&group->mark_lock);
+        return ret;
+}
+
+#if defined(CONFIG_EXPORTFS)
+static int show_mark_fhandle(struct seq_file *m, struct inode *inode)
+{
+        struct {
+                struct file_handle handle;
+                u8 pad[64];
+        } f;
+        int size, ret, i;
+
+        f.handle.handle_bytes = sizeof(f.pad);
+        size = f.handle.handle_bytes >> 2;
+
+        ret = exportfs_encode_inode_fh(inode, (struct fid *)f.handle.f_handle, &size, 0);
+        if ((ret == 255) || (ret == -ENOSPC)) {
+                WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret);
+                return 0;
+        }
+
+        f.handle.handle_type = ret;
+        f.handle.handle_bytes = size * sizeof(u32);
+
+        ret = seq_printf(m, "fhandle-bytes:%x fhandle-type:%x f_handle:",
+                         f.handle.handle_bytes, f.handle.handle_type);
+
+        for (i = 0; i < f.handle.handle_bytes; i++)
+                ret |= seq_printf(m, "%02x", (int)f.handle.f_handle[i]);
+
+        return ret;
+}
+#else
+static int show_mark_fhandle(struct seq_file *m, struct inode *inode)
+{
+        return 0;
+}
+#endif
+
+#ifdef CONFIG_INOTIFY_USER
+
+static int inotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
+{
+        struct inotify_inode_mark *inode_mark;
+        struct inode *inode;
+        int ret = 0;
+
+        if (!(mark->flags & (FSNOTIFY_MARK_FLAG_ALIVE | FSNOTIFY_MARK_FLAG_INODE)))
+                return 0;
+
+        inode_mark = container_of(mark, struct inotify_inode_mark, fsn_mark);
+        inode = igrab(mark->i.inode);
+        if (inode) {
+                ret = seq_printf(m, "inotify wd:%x ino:%lx sdev:%x "
+                                 "mask:%x ignored_mask:%x ",
+                                 inode_mark->wd, inode->i_ino,
+                                 inode->i_sb->s_dev,
+                                 mark->mask, mark->ignored_mask);
+                ret |= show_mark_fhandle(m, inode);
+                ret |= seq_putc(m, '\n');
+                iput(inode);
+        }
+
+        return ret;
+}
+
+int inotify_show_fdinfo(struct seq_file *m, struct file *f)
+{
+        return show_fdinfo(m, f, inotify_fdinfo);
+}
+
+#endif /* CONFIG_INOTIFY_USER */
+
+#ifdef CONFIG_FANOTIFY
+
+static int fanotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
+{
+        struct inode *inode;
+        int ret = 0;
+
+        if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE))
+                return 0;
+
+        if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) {
+                inode = igrab(mark->i.inode);
+                if (!inode)
+                        goto out;
+                ret = seq_printf(m, "fanotify ino:%lx sdev:%x "
+                                 "mask:%x ignored_mask:%x ",
+                                 inode->i_ino, inode->i_sb->s_dev,
+                                 mark->mask, mark->ignored_mask);
+                ret |= show_mark_fhandle(m, inode);
+                ret |= seq_putc(m, '\n');
+                iput(inode);
+        } else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT) {
+                struct mount *mnt = real_mount(mark->m.mnt);
+
+                ret = seq_printf(m, "fanotify mnt_id:%x mask:%x "
+                                 "ignored_mask:%x\n",
+                                 mnt->mnt_id, mark->mask, mark->ignored_mask);
+        }
+out:
+        return ret;
+}
+
+int fanotify_show_fdinfo(struct seq_file *m, struct file *f)
+{
+        struct fsnotify_group *group = f->private_data;
+        unsigned int flags = 0;
+
+        switch (group->priority) {
+        case FS_PRIO_0:
+                flags |= FAN_CLASS_NOTIF;
+                break;
+        case FS_PRIO_1:
+                flags |= FAN_CLASS_CONTENT;
+                break;
+        case FS_PRIO_2:
+                flags |= FAN_CLASS_PRE_CONTENT;
+                break;
+        }
+
+        if (group->max_events == UINT_MAX)
+                flags |= FAN_UNLIMITED_QUEUE;
+
+        if (group->fanotify_data.max_marks == UINT_MAX)
+                flags |= FAN_UNLIMITED_MARKS;
+
+        seq_printf(m, "fanotify flags:%x event-flags:%x\n",
+                   flags, group->fanotify_data.f_flags);
+
+        return show_fdinfo(m, f, fanotify_fdinfo);
+}
+
+#endif /* CONFIG_FANOTIFY */
+
+#endif /* CONFIG_INOTIFY_USER || CONFIG_FANOTIFY */
+
+#endif /* CONFIG_PROC_FS */