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authorHarald Hoyer <harald@redhat.com>2013-11-19 11:36:05 +0100
committerChris Mason <clm@fb.com>2014-04-10 13:32:50 -0700
commit0723a0473fb48a1c93b113a28665b64ce5faf35a (patch)
tree59f5dc31dd82e06dc8d836b4544e676c7b85d23d /fs
parent36523e95129c0e69bf1592cd009261b1c6d96e77 (diff)
btrfs: allow mounting btrfs subvolumes with different ro/rw options
Given the following /etc/fstab entries: /dev/sda3 /mnt/foo btrfs subvol=foo,ro 0 0 /dev/sda3 /mnt/bar btrfs subvol=bar,rw 0 0 you can't issue: $ mount /mnt/foo $ mount /mnt/bar You would have to do: $ mount /mnt/foo $ mount -o remount,rw /mnt/foo $ mount --bind -o remount,ro /mnt/foo $ mount /mnt/bar or $ mount /mnt/bar $ mount --rw /mnt/foo $ mount --bind -o remount,ro /mnt/foo With this patch you can do $ mount /mnt/foo $ mount /mnt/bar $ cat /proc/self/mountinfo 49 33 0:41 /foo /mnt/foo ro,relatime shared:36 - btrfs /dev/sda3 rw,ssd,space_cache 87 33 0:41 /bar /mnt/bar rw,relatime shared:74 - btrfs /dev/sda3 rw,ssd,space_cache Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/super.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index d4878ddba87a..994c40955315 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -66,6 +66,8 @@
static const struct super_operations btrfs_super_ops;
static struct file_system_type btrfs_fs_type;
+static int btrfs_remount(struct super_block *sb, int *flags, char *data);
+
static const char *btrfs_decode_error(int errno)
{
char *errstr = "unknown";
@@ -1185,6 +1187,26 @@ static struct dentry *mount_subvol(const char *subvol_name, int flags,
mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
newargs);
kfree(newargs);
+
+ if (PTR_RET(mnt) == -EBUSY) {
+ if (flags & MS_RDONLY) {
+ mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY, device_name,
+ newargs);
+ } else {
+ int r;
+ mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY, device_name,
+ newargs);
+ if (IS_ERR(mnt))
+ return ERR_CAST(mnt);
+
+ r = btrfs_remount(mnt->mnt_sb, &flags, NULL);
+ if (r < 0) {
+ /* FIXME: release vfsmount mnt ??*/
+ return ERR_PTR(r);
+ }
+ }
+ }
+
if (IS_ERR(mnt))
return ERR_CAST(mnt);