Because btrfs can remove the device that was mounted we need to have a ->show_devname so that in this case we can print out some other device in the file system to /proc/mount. So if there are multiple devices in a btrfs file system we will just print the device with the lowest devid that we can find. This will make everything consistent and deal with device removal properly. The drawback is if you mount with a device that is higher than the lowest devicd it won't show up as the mounted device in /proc/mounts, but this is a small price to pay. This was inspired by Miao Xie's patch. Thanks,
Signed-off-by: Josef Bacik <[email protected]> --- V1->V2: Dropped the mounted tracking stuff since it doesn't work right if you mount the same thing twice fs/btrfs/super.c | 33 +++++++++++++++++++++++++++++++++ 1 files changed, 33 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 85cef50..0874dba 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -54,6 +54,7 @@ #include "version.h" #include "export.h" #include "compression.h" +#include "rcu-string.h" #define CREATE_TRACE_POINTS #include <trace/events/btrfs.h> @@ -1472,12 +1473,44 @@ static int btrfs_unfreeze(struct super_block *sb) return 0; } +static int btrfs_show_devname(struct seq_file *m, struct dentry *root) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb); + struct btrfs_fs_devices *cur_devices; + struct btrfs_device *dev, *first_dev = NULL; + struct list_head *head; + struct rcu_string *name; + + mutex_lock(&fs_info->fs_devices->device_list_mutex); + cur_devices = fs_info->fs_devices; + while (cur_devices) { + head = &cur_devices->devices; + list_for_each_entry(dev, head, dev_list) { + if (!first_dev || dev->devid < first_dev->devid) + first_dev = dev; + } + cur_devices = cur_devices->seed; + } + + if (first_dev) { + rcu_read_lock(); + name = rcu_dereference(first_dev->name); + seq_escape(m, name->str, " \t\n\\"); + rcu_read_unlock(); + } else { + WARN_ON(1); + } + mutex_unlock(&fs_info->fs_devices->device_list_mutex); + return 0; +} + static const struct super_operations btrfs_super_ops = { .drop_inode = btrfs_drop_inode, .evict_inode = btrfs_evict_inode, .put_super = btrfs_put_super, .sync_fs = btrfs_sync_fs, .show_options = btrfs_show_options, + .show_devname = btrfs_show_devname, .write_inode = btrfs_write_inode, .alloc_inode = btrfs_alloc_inode, .destroy_inode = btrfs_destroy_inode, -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
