On Mon, Feb 06, 2012 at 01:52:15PM +0000, Al Viro wrote:
> On Mon, Feb 06, 2012 at 07:18:24AM -0500, Christoph Hellwig wrote:
> > On Mon, Feb 06, 2012 at 12:53:21PM +0100, David Sterba wrote:
> > > On Sun, Feb 05, 2012 at 12:30:42PM +0200, Nikos Voutsinas wrote:
> > > > It's quite old, but what was this about;
> > > >
> > > > http://thread.gmane.org/gmane.comp.file-systems.btrfs/4487
> > >
> > > Thanks, the patch looks ok and works as expected.
> > >
> > > Goffredo, do you want to resend it? (The lock around the mnt_root is not
> > > necessary.) I think it's a -rc material, more people came to ask about
> > > this on irc channel lately, we don't need to wait a full release cycle
> > > to merge this fix.
> >
> > No, it doesn't look good. Please do not introduce anything touching
> > non-superblock fields in ->show_options, thanks.
Sorry, I'll be more carefull with vfs patches.
> Umm... seq_dentry() on root dentry (which is what's getting passed to
> ->show_options() now) would be OK; this kind of playing with ->d_name
> is not.
Thanks for the suggestion. This should do it,
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -766,6 +766,9 @@ static int btrfs_show_options(struct seq_file *seq, struct
vfsmount *vfs)
seq_puts(seq, ",inode_cache");
if (btrfs_test_opt(root, SKIP_BALANCE))
seq_puts(seq, ",skip_balance");
+ seq_puts(seq, ",subvol=");
+ seq_dentry(seq, vfs->mnt_root, " \t\n\\");
+
return 0;
}
( plus EXPORT_SYMBOL(seq_dentry) )
The 3rd argument (chars to be escaped in the path), is same as passed to other
seq_* funcs, though I'm not sure if we don't want to escape ',' as well, since
it may confuse option parsers out there. If the subvol= is kept as the last
one, then actual path is from '=' up to the first unescaped ' '.
If touching dentry name is forbidden, then we could entirely skip checking
whether it's '/', and always show subvol path. I don't see a problem from
user's/administrator's POV (and I'm not going to invent another way to check
for '/' by looking to other internal vfs items).
Full patch:
From: David Sterba <[email protected]>
Although it's not necessarily needed to show the mount option for the
toplevel subvolume, we cannot touch dentry name or other internal items
to check for it.
Signed-off-by: David Sterba <[email protected]>
---
fs/btrfs/super.c | 6 ++++++
fs/seq_file.c | 1 +
2 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 61717a4..dda5d6e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -766,6 +766,12 @@ static int btrfs_show_options(struct seq_file *seq, struct
vfsmount *vfs)
seq_puts(seq, ",inode_cache");
if (btrfs_test_opt(root, SKIP_BALANCE))
seq_puts(seq, ",skip_balance");
+ /*
+ * Keep this one at the end
+ */
+ seq_puts(seq, ",subvol=");
+ seq_dentry(seq, vfs->mnt_root, " \t\n\\");
+
return 0;
}
diff --git a/fs/seq_file.c b/fs/seq_file.c
index dba43c3..ccbcc56 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -498,6 +498,7 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry,
char *esc)
return res;
}
+EXPORT_SYMBOL(seq_dentry);
int seq_bitmap(struct seq_file *m, const unsigned long *bits,
unsigned int nr_bits)
--
1.7.8
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