RE: [PATCH] Btrfs: fix subvolume mount by name problem when default mount subvolume is set

2011-04-06 Thread Zhong, Xin 
 -Original Message-
 From: Chris Mason [mailto:chris.ma...@oracle.com]
 Sent: Tuesday, April 05, 2011 1:07 PM
 To: Zhong, Xin
 Cc: linux-btrfs
 Subject: Re: [PATCH] Btrfs: fix subvolume mount by name problem when
 default mount subvolume is set
 
 Excerpts from Zhong, Xin's message of 2011-03-31 03:59:22 -0400:
  We create two subvolumes (meego_root and meego_home) in
  btrfs root directory. And set meego_root as default mount
  subvolume. After we remount btrfs, meego_root is mounted
  to top directory by default. Then when we try to mount
  meego_home (subvol=meego_home) to a subdirectory, it failed.
  The problem is when default mount subvolume is set to
  meego_root, we search meego_home in it but can not find it.
  So the solution is to search meego_home in btrfs root
  directory instead when subvol=meego_home is given.
 
 I think this one is difficult because if they have set the default
 subvolume they might have done so because the original default has the
 result of a busted upgrade or something in it.
 
 So, I think the subvol= should be relative to the default.  Would it
 work for you to add a new mount option to specify the subvol id to
 search for subvol=?
 

Sounds good. I will submit a new version. Thanks!

 -chris
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Re: [PATCH] Btrfs: fix subvolume mount by name problem when default mount subvolume is set

2011-04-04 Thread Chris Mason 
Excerpts from Zhong, Xin's message of 2011-03-31 03:59:22 -0400:
 We create two subvolumes (meego_root and meego_home) in
 btrfs root directory. And set meego_root as default mount
 subvolume. After we remount btrfs, meego_root is mounted
 to top directory by default. Then when we try to mount
 meego_home (subvol=meego_home) to a subdirectory, it failed.
 The problem is when default mount subvolume is set to
 meego_root, we search meego_home in it but can not find it.
 So the solution is to search meego_home in btrfs root
 directory instead when subvol=meego_home is given.

I think this one is difficult because if they have set the default
subvolume they might have done so because the original default has the
result of a busted upgrade or something in it.

So, I think the subvol= should be relative to the default.  Would it
work for you to add a new mount option to specify the subvol id to
search for subvol=?

-chris
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[PATCH] Btrfs: fix subvolume mount by name problem when default mount subvolume is set

2011-03-31 Thread Zhong, Xin 
We create two subvolumes (meego_root and meego_home) in
btrfs root directory. And set meego_root as default mount
subvolume. After we remount btrfs, meego_root is mounted
to top directory by default. Then when we try to mount
meego_home (subvol=meego_home) to a subdirectory, it failed.
The problem is when default mount subvolume is set to
meego_root, we search meego_home in it but can not find it.
So the solution is to search meego_home in btrfs root
directory instead when subvol=meego_home is given.

Detail information can be found in meego bugzilla:
https://bugs.meego.com/show_bug.cgi?id=15055

Signed-off-by: Zhong, Xin xin.zh...@intel.com
---
 fs/btrfs/super.c |   23 +--
 1 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index db0a827..138bc4c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -786,15 +786,18 @@ static int btrfs_get_sb(struct file_system_type *fs_type, 
int flags,
s-s_flags |= MS_ACTIVE;
}
 
-   root = get_default_root(s, subvol_objectid);
-   if (IS_ERR(root)) {
-   error = PTR_ERR(root);
-   deactivate_locked_super(s);
-   goto error_free_subvol_name;
-   }
/* if they gave us a subvolume name bind mount into that */
if (strcmp(subvol_name, .)) {
struct dentry *new_root;
+   
+   /* we search subvolume name in the btrfs root, not the default 
mount subvolume */
+   root = get_default_root(s, BTRFS_FS_TREE_OBJECTID);
+   if (IS_ERR(root)) {
+   error = PTR_ERR(root);
+   deactivate_locked_super(s);
+   goto error_free_subvol_name;
+   }
+
mutex_lock(root-d_inode-i_mutex);
new_root = lookup_one_len(subvol_name, root,
  strlen(subvol_name));
@@ -816,6 +819,14 @@ static int btrfs_get_sb(struct file_system_type *fs_type, 
int flags,
dput(root);
root = new_root;
}
+   else {
+   root = get_default_root(s, subvol_objectid);
+   if (IS_ERR(root)) {
+   error = PTR_ERR(root);
+   deactivate_locked_super(s);
+   goto error_free_subvol_name;
+   }
+   }
 
mnt-mnt_sb = s;
mnt-mnt_root = root;
-- 
1.7.0.4

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