| Message ID | 213f0b6a4cffcc82688894b4edbaeb51f8e71137.1428471096.git.osandov@osandov.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
-------- Original Message -------- Subject: [PATCH 3/3] Btrfs: show subvol= and subvolid= in /proc/mounts From: Omar Sandoval <osandov@osandov.com> To: Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>, David Sterba <dsterba@suse.cz>, <linux-btrfs@vger.kernel.org> Date: 2015?04?08? 13:34 > Currently, userspace has no way to know which subvolume is mounted.But, > now that we're guaranteed to have a meaningful root dentry, we can just > export and use seq_dentry() in btrfs_show_options(). The subvolume ID is > easy to get, so put that in there, too. Oh, I sent patch like this long long ago but still not merged. http://comments.gmane.org/gmane.comp.file-systems.btrfs/36997 My patch doesn't do it in mount options, but add it to /proc/self/mountinfo. In fact, if you mount subvolume with "-o subvol=", then /proc/self/mountinfo should has the result like below: 73 33 0:35 / /mnt/test rw,relatime shared:57 - btrfs /dev/sdb rw,space_cache 75 33 0:35 /test /mnt/scratch rw,relatime shared:59 - btrfs /dev/sdb rw,space_cache The only problem is, if you mount with "-o subvolid=" as the *FIRST* mount of the fs, then mountinfo can't show it. My patch will fix the above problem but not merged yet... Thanks, Qu > > Signed-off-by: Omar Sandoval <osandov@osandov.com> > --- > fs/btrfs/super.c | 4 ++++ > fs/seq_file.c | 1 + > 2 files changed, 5 insertions(+) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 5ab9801..5e14bb6 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -1193,6 +1193,10 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry) > seq_puts(seq, ",fatal_errors=panic"); > if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL) > seq_printf(seq, ",commit=%d", info->commit_interval); > + seq_puts(seq, ",subvol="); > + seq_dentry(seq, dentry, " \t\n\\"); > + seq_printf(seq, ",subvolid=%llu", > + BTRFS_I(d_inode(dentry))->root->root_key.objectid); > return 0; > } > > diff --git a/fs/seq_file.c b/fs/seq_file.c > index 555f821..52b4927 100644 > --- a/fs/seq_file.c > +++ b/fs/seq_file.c > @@ -538,6 +538,7 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc) > > return res; > } > +EXPORT_SYMBOL(seq_dentry); > > static void *single_start(struct seq_file *p, loff_t *pos) > { > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Apr 07, 2015 at 10:34:02PM -0700, Omar Sandoval wrote: > Currently, userspace has no way to know which subvolume is mounted. Oh, there is a way, 'btrfs inspect-internal rootid /path/to/mount', just we'd like to see it in the mount options as well. > But, > now that we're guaranteed to have a meaningful root dentry, we can just > export and use seq_dentry() in btrfs_show_options(). The subvolume ID is > easy to get, so put that in there, too. > > Signed-off-by: Omar Sandoval <osandov@osandov.com> > --- > fs/btrfs/super.c | 4 ++++ > fs/seq_file.c | 1 + > 2 files changed, 5 insertions(+) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 5ab9801..5e14bb6 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -1193,6 +1193,10 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry) > seq_puts(seq, ",fatal_errors=panic"); > if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL) > seq_printf(seq, ",commit=%d", info->commit_interval); > + seq_puts(seq, ",subvol="); Please make subvol= the last one, as it can contain any string that could be confused with other options. Although nobody would probably call their subvolume "name,autodefrag" etc, the way to obtain the full path is to either resolve the subvolid, or take the whole text after "subvol=" to the end of the line. > + seq_dentry(seq, dentry, " \t\n\\"); > + seq_printf(seq, ",subvolid=%llu", > + BTRFS_I(d_inode(dentry))->root->root_key.objectid); > return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 5ab9801..5e14bb6 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1193,6 +1193,10 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry) seq_puts(seq, ",fatal_errors=panic"); if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL) seq_printf(seq, ",commit=%d", info->commit_interval); + seq_puts(seq, ",subvol="); + seq_dentry(seq, dentry, " \t\n\\"); + seq_printf(seq, ",subvolid=%llu", + BTRFS_I(d_inode(dentry))->root->root_key.objectid); return 0; } diff --git a/fs/seq_file.c b/fs/seq_file.c index 555f821..52b4927 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -538,6 +538,7 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc) return res; } +EXPORT_SYMBOL(seq_dentry); static void *single_start(struct seq_file *p, loff_t *pos) {
Currently, userspace has no way to know which subvolume is mounted. But, now that we're guaranteed to have a meaningful root dentry, we can just export and use seq_dentry() in btrfs_show_options(). The subvolume ID is easy to get, so put that in there, too. Signed-off-by: Omar Sandoval <osandov@osandov.com> --- fs/btrfs/super.c | 4 ++++ fs/seq_file.c | 1 + 2 files changed, 5 insertions(+)