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Date: Tue, 6 Oct 2009 12:51:42 +0900
From: Toshiyuki Okajima <toshi.okajima@...fujitsu.com>
To: viro@...iv.linux.org.uk, tytso@....edu
Cc: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: [PATCH][RFC] vfs: add message print mechanism for the mount/umount
into the VFS layer
Hi.
Now, on the VFS-layer any messages aren't printed at mount/umount time
(when the operation normally terminates).
But there are some filesystems which print their own specific messages at those
times.
For the purpose of the system management and so on, users (especially,
enterprise users) want to observe their system operations from the system logs.
We may manage to observe some filesystems' operations (mount/umount) from the
logs. But the filesystems of which we can observe the operations are not all.
Therefore to achieve the observations for all filesystems is to add the message
mechanism into the VFS layer. If any filesystems' specific messages at
mount/umount time are added into this, we can distinguish more easily each
message among the system logs for our systems' observations.
This patch provides the following:
- message output at mount/umount time
- the functions of printing the filesystem's specific information at
mount/umount time
(NOTE: This mechanism becomes effective only when the users call
the mount system call because they don't want to observe the pseudo
filesystems.)
P.S.
This concept derives from the following:
- http://marc.info/?l=linux-ext4&m=125429349122986&w=2
- http://marc.info/?l=linux-ext4&m=125436936109125&w=2
Cc: "Theodore Ts'o" <tytso@....edu>
Signed-off-by: Toshiyuki Okajima <toshi.okajima@...fujitsu.com>
--
fs/namespace.c | 19 ++++++++++++++++++-
fs/super.c | 18 ++++++++++++++++--
include/linux/fs.h | 3 +++
include/linux/mount.h | 3 +++
4 files changed, 40 insertions(+), 3 deletions(-)
diff -Nurp linux-2.6.32-rc3.orig/fs/namespace.c linux-2.6.32-rc3/fs/namespace.c
--- linux-2.6.32-rc3.orig/fs/namespace.c 2009-10-05 09:12:30.000000000 +0900
+++ linux-2.6.32-rc3/fs/namespace.c 2009-10-06 09:58:19.000000000 +0900
@@ -599,6 +599,7 @@ static struct vfsmount *clone_mnt(struct
static inline void __mntput(struct vfsmount *mnt)
{
struct super_block *sb = mnt->mnt_sb;
+ int silent = !(mnt->mnt_flags & MNT_VERBOSE_MSG);
/*
* This probably indicates that somebody messed
* up a mnt_want/drop_write() pair. If this
@@ -612,7 +613,7 @@ static inline void __mntput(struct vfsmo
WARN_ON(count_mnt_writers(mnt));
dput(mnt->mnt_root);
free_vfsmnt(mnt);
- deactivate_super(sb);
+ __deactivate_super(sb, silent);
}
void mntput_no_expire(struct vfsmount *mnt)
@@ -1653,6 +1654,9 @@ static int do_new_mount(struct path *pat
if (IS_ERR(mnt))
return PTR_ERR(mnt);
+ /* for verbose messages on VFS layer at mount/umount */
+ if (!(flags & MS_SILENT))
+ mnt_flags |= MNT_VERBOSE_MSG;
return do_add_mount(mnt, path, mnt_flags, NULL);
}
@@ -1664,6 +1668,7 @@ int do_add_mount(struct vfsmount *newmnt
int mnt_flags, struct list_head *fslist)
{
int err;
+ struct super_block *sb = newmnt->mnt_sb;
down_write(&namespace_sem);
/* Something was mounted here while we slept */
@@ -1692,10 +1697,22 @@ int do_add_mount(struct vfsmount *newmnt
list_add_tail(&newmnt->mnt_expire, fslist);
up_write(&namespace_sem);
+ /*
+ * message output at mount for log observers
+ */
+ if (newmnt->mnt_flags & MNT_VERBOSE_MSG) {
+ printk(KERN_INFO "Device %s mounted file system type %s read-%s\n",
+ sb->s_id, sb->s_type->name,
+ sb->s_flags & MS_RDONLY ? "only" : "write");
+ /* fs specific messages for mount */
+ if (sb->s_op != NULL && sb->s_op->mount_msg != NULL)
+ sb->s_op->mount_msg(sb);
+ }
return 0;
unlock:
up_write(&namespace_sem);
+ newmnt->mnt_flags &= ~MNT_VERBOSE_MSG;
mntput(newmnt);
return err;
}
diff -Nurp linux-2.6.32-rc3.orig/fs/super.c linux-2.6.32-rc3/fs/super.c
--- linux-2.6.32-rc3.orig/fs/super.c 2009-10-05 09:12:30.000000000 +0900
+++ linux-2.6.32-rc3/fs/super.c 2009-10-06 09:58:19.000000000 +0900
@@ -177,15 +177,16 @@ void put_super(struct super_block *sb)
/**
- * deactivate_super - drop an active reference to superblock
+ * __deactivate_super - drop an active reference to superblock
* @s: superblock to deactivate
+ * @silent: disable verbose messages for umount from mount-tree
*
* Drops an active reference to superblock, acquiring a temprory one if
* there is no active references left. In that case we lock superblock,
* tell fs driver to shut it down and drop the temporary reference we
* had just acquired.
*/
-void deactivate_super(struct super_block *s)
+void __deactivate_super(struct super_block *s, int silent)
{
struct file_system_type *fs = s->s_type;
if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
@@ -193,12 +194,25 @@ void deactivate_super(struct super_block
spin_unlock(&sb_lock);
vfs_dq_off(s, 0);
down_write(&s->s_umount);
+ /* fs specific messages for umount */
+ if (!silent && s->s_op != NULL && s->s_op->umount_msg != NULL)
+ s->s_op->umount_msg(s);
fs->kill_sb(s);
+ /*
+ * message output at umount for log observers
+ */
+ if (!silent)
+ printk(KERN_INFO "Device %s unmounted\n", s->s_id);
put_filesystem(fs);
put_super(s);
}
}
+void deactivate_super(struct super_block *s)
+{
+ __deactivate_super(s, !0);
+}
+
EXPORT_SYMBOL(deactivate_super);
/**
diff -Nurp linux-2.6.32-rc3.orig/include/linux/fs.h linux-2.6.32-rc3/include/linux/fs.h
--- linux-2.6.32-rc3.orig/include/linux/fs.h 2009-10-05 09:12:30.000000000 +0900
+++ linux-2.6.32-rc3/include/linux/fs.h 2009-10-06 09:58:19.000000000 +0900
@@ -1577,6 +1577,8 @@ struct super_operations {
ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
#endif
int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
+ void (*mount_msg)(struct super_block*);
+ void (*umount_msg)(struct super_block*);
};
/*
@@ -1774,6 +1776,7 @@ void kill_block_super(struct super_block
void kill_anon_super(struct super_block *sb);
void kill_litter_super(struct super_block *sb);
void deactivate_super(struct super_block *sb);
+void __deactivate_super(struct super_block *sb, int silent);
void deactivate_locked_super(struct super_block *sb);
int set_anon_super(struct super_block *s, void *data);
struct super_block *sget(struct file_system_type *type,
diff -Nurp linux-2.6.32-rc3.orig/include/linux/mount.h linux-2.6.32-rc3/include/linux/mount.h
--- linux-2.6.32-rc3.orig/include/linux/mount.h 2009-10-05 09:12:30.000000000 +0900
+++ linux-2.6.32-rc3/include/linux/mount.h 2009-10-06 09:58:19.000000000 +0900
@@ -36,6 +36,9 @@ struct mnt_namespace;
#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
#define MNT_PNODE_MASK 0x3000 /* propagation flag mask */
+#define MNT_VERBOSE_MSG 0x10000 /* verbose messages on the VFS layer at mount
+ /umount only when called from do_new_mount */
+
struct vfsmount {
struct list_head mnt_hash;
struct vfsmount *mnt_parent; /* fs we are mounted on */
--
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