| Message ID | 20200710063738.28368-1-anand.jain@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs_show_devname don't traverse into the seed fsid | expand |
On 7/10/20 2:37 AM, Anand Jain wrote: > ->show_devname currently shows the lowest devid in the list. As the seed > devices have the lowest devid in the sprouted filesystem, the userland > tool such as findmnt end up seeing seed device instead of the device from > the read-writable sprouted filesystem. As shown below. > > mount /dev/sda /btrfs > mount: /btrfs: WARNING: device write-protected, mounted read-only. > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > btrfs dev add -f /dev/sdb /btrfs > > umount /btrfs > mount /dev/sdb /btrfs > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > > All sprouts from a single seed will show the same seed device and the > same fsid. That's messy. > This is causing problems in our prototype as there isn't any reference > to the sprout file-system(s) which is being used for actual read and > write. > > This was added in the patch which implemented the show_devname in btrfs > commit 9c5085c14798 (Btrfs: implement ->show_devname). > I tried to look for any particular reason that we need to show the seed > device, there isn't any. > > So instead, do not traverse through the seed devices, just show the > lowest devid in the sprouted fsid. > > After the patch: > > mount /dev/sda /btrfs > mount: /btrfs: WARNING: device write-protected, mounted read-only. > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > btrfs dev add -f /dev/sdb /btrfs > mount -o rw,remount /dev/sdb /btrfs > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sdb /btrfs 595ca0e6-b82e-46b5-b9e2-c72a6928be48 > > mount /dev/sda /btrfs1 > mount: /btrfs1: WARNING: device write-protected, mounted read-only. > > btrfs dev add -f /dev/sdc /btrfs1 > > findmnt --output SOURCE,TARGET,UUID /btrfs1 > SOURCE TARGET UUID > /dev/sdc /btrfs1 ca1dbb7a-8446-4f95-853c-a20f3f82bdbb > > cat /proc/self/mounts | grep btrfs > /dev/sdb /btrfs btrfs rw,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 > /dev/sdc /btrfs1 btrfs ro,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 > > Signed-off-by: Anand Jain <anand.jain@oracle.com> This needs to come with an xfstest so we do not regress this in the future. Thanks, Josef
> > This needs to come with an xfstest so we do not regress this in the > future. Thanks, Oh yes. Makes sense. An xfstests test case is on its way. Thanks, Anand > > Josef
Anand, > So instead, do not traverse through the seed devices, just show the > lowest devid in the sprouted fsid. Reported-by: Martin K. Petersen <martin.petersen@oracle.com> Tested-by: Martin K. Petersen <martin.petersen@oracle.com>
On 10.07.20 г. 9:37 ч., Anand Jain wrote: > ->show_devname currently shows the lowest devid in the list. As the seed > devices have the lowest devid in the sprouted filesystem, the userland > tool such as findmnt end up seeing seed device instead of the device from > the read-writable sprouted filesystem. As shown below. > > mount /dev/sda /btrfs > mount: /btrfs: WARNING: device write-protected, mounted read-only. > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > btrfs dev add -f /dev/sdb /btrfs > > umount /btrfs > mount /dev/sdb /btrfs > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > > All sprouts from a single seed will show the same seed device and the > same fsid. That's messy. > This is causing problems in our prototype as there isn't any reference > to the sprout file-system(s) which is being used for actual read and > write. > > This was added in the patch which implemented the show_devname in btrfs > commit 9c5085c14798 (Btrfs: implement ->show_devname). > I tried to look for any particular reason that we need to show the seed > device, there isn't any. > > So instead, do not traverse through the seed devices, just show the > lowest devid in the sprouted fsid. > > After the patch: > > mount /dev/sda /btrfs > mount: /btrfs: WARNING: device write-protected, mounted read-only. > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > btrfs dev add -f /dev/sdb /btrfs > mount -o rw,remount /dev/sdb /btrfs > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sdb /btrfs 595ca0e6-b82e-46b5-b9e2-c72a6928be48 > > mount /dev/sda /btrfs1 > mount: /btrfs1: WARNING: device write-protected, mounted read-only. > > btrfs dev add -f /dev/sdc /btrfs1 > > findmnt --output SOURCE,TARGET,UUID /btrfs1 > SOURCE TARGET UUID > /dev/sdc /btrfs1 ca1dbb7a-8446-4f95-853c-a20f3f82bdbb > > cat /proc/self/mounts | grep btrfs > /dev/sdb /btrfs btrfs rw,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 > /dev/sdc /btrfs1 btrfs ro,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 > > Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Tested-by: Nikolay Borisov <nborisov@suse.com> > --- > This has passed the xfstests/btrfs sucessfully with no new > regressions. Thanks. > > fs/btrfs/super.c | 21 +++++++-------------- > 1 file changed, 7 insertions(+), 14 deletions(-) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index c7ee119cffa1..1e2a36f5c792 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -2377,9 +2377,7 @@ static int btrfs_unfreeze(struct super_block *sb) > 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; > > /* > * Lightweight locking of the devices. We should not need > @@ -2389,18 +2387,13 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root) > * least until the rcu_read_unlock. > */ > rcu_read_lock(); > - cur_devices = fs_info->fs_devices; > - while (cur_devices) { > - head = &cur_devices->devices; > - list_for_each_entry_rcu(dev, head, dev_list) { > - if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) > - continue; > - if (!dev->name) > - continue; > - if (!first_dev || dev->devid < first_dev->devid) > - first_dev = dev; > - } > - cur_devices = cur_devices->seed; > + list_for_each_entry_rcu(dev, &fs_info->fs_devices->devices, dev_list) { > + if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) > + continue; > + if (!dev->name) > + continue; > + if (!first_dev || dev->devid < first_dev->devid) > + first_dev = dev; > } > > if (first_dev) >
On Fri, Jul 10, 2020 at 02:37:38PM +0800, Anand Jain wrote: > ->show_devname currently shows the lowest devid in the list. As the seed > devices have the lowest devid in the sprouted filesystem, the userland > tool such as findmnt end up seeing seed device instead of the device from > the read-writable sprouted filesystem. As shown below. > > mount /dev/sda /btrfs > mount: /btrfs: WARNING: device write-protected, mounted read-only. > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > btrfs dev add -f /dev/sdb /btrfs > > umount /btrfs > mount /dev/sdb /btrfs > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > > All sprouts from a single seed will show the same seed device and the > same fsid. That's messy. > This is causing problems in our prototype as there isn't any reference > to the sprout file-system(s) which is being used for actual read and > write. > > This was added in the patch which implemented the show_devname in btrfs > commit 9c5085c14798 (Btrfs: implement ->show_devname). > I tried to look for any particular reason that we need to show the seed > device, there isn't any. > > So instead, do not traverse through the seed devices, just show the > lowest devid in the sprouted fsid. > > After the patch: > > mount /dev/sda /btrfs > mount: /btrfs: WARNING: device write-protected, mounted read-only. > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 > > btrfs dev add -f /dev/sdb /btrfs > mount -o rw,remount /dev/sdb /btrfs > > findmnt --output SOURCE,TARGET,UUID /btrfs > SOURCE TARGET UUID > /dev/sdb /btrfs 595ca0e6-b82e-46b5-b9e2-c72a6928be48 > > mount /dev/sda /btrfs1 > mount: /btrfs1: WARNING: device write-protected, mounted read-only. > > btrfs dev add -f /dev/sdc /btrfs1 > > findmnt --output SOURCE,TARGET,UUID /btrfs1 > SOURCE TARGET UUID > /dev/sdc /btrfs1 ca1dbb7a-8446-4f95-853c-a20f3f82bdbb > > cat /proc/self/mounts | grep btrfs > /dev/sdb /btrfs btrfs rw,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 > /dev/sdc /btrfs1 btrfs ro,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 > > Signed-off-by: Anand Jain <anand.jain@oracle.com> Added to misc-next, thanks.
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index c7ee119cffa1..1e2a36f5c792 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2377,9 +2377,7 @@ static int btrfs_unfreeze(struct super_block *sb) 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; /* * Lightweight locking of the devices. We should not need @@ -2389,18 +2387,13 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root) * least until the rcu_read_unlock. */ rcu_read_lock(); - cur_devices = fs_info->fs_devices; - while (cur_devices) { - head = &cur_devices->devices; - list_for_each_entry_rcu(dev, head, dev_list) { - if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) - continue; - if (!dev->name) - continue; - if (!first_dev || dev->devid < first_dev->devid) - first_dev = dev; - } - cur_devices = cur_devices->seed; + list_for_each_entry_rcu(dev, &fs_info->fs_devices->devices, dev_list) { + if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) + continue; + if (!dev->name) + continue; + if (!first_dev || dev->devid < first_dev->devid) + first_dev = dev; } if (first_dev)
->show_devname currently shows the lowest devid in the list. As the seed devices have the lowest devid in the sprouted filesystem, the userland tool such as findmnt end up seeing seed device instead of the device from the read-writable sprouted filesystem. As shown below. mount /dev/sda /btrfs mount: /btrfs: WARNING: device write-protected, mounted read-only. findmnt --output SOURCE,TARGET,UUID /btrfs SOURCE TARGET UUID /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 btrfs dev add -f /dev/sdb /btrfs umount /btrfs mount /dev/sdb /btrfs findmnt --output SOURCE,TARGET,UUID /btrfs SOURCE TARGET UUID /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 All sprouts from a single seed will show the same seed device and the same fsid. That's messy. This is causing problems in our prototype as there isn't any reference to the sprout file-system(s) which is being used for actual read and write. This was added in the patch which implemented the show_devname in btrfs commit 9c5085c14798 (Btrfs: implement ->show_devname). I tried to look for any particular reason that we need to show the seed device, there isn't any. So instead, do not traverse through the seed devices, just show the lowest devid in the sprouted fsid. After the patch: mount /dev/sda /btrfs mount: /btrfs: WARNING: device write-protected, mounted read-only. findmnt --output SOURCE,TARGET,UUID /btrfs SOURCE TARGET UUID /dev/sda /btrfs 899f7027-3e46-4626-93e7-7d4c9ad19111 btrfs dev add -f /dev/sdb /btrfs mount -o rw,remount /dev/sdb /btrfs findmnt --output SOURCE,TARGET,UUID /btrfs SOURCE TARGET UUID /dev/sdb /btrfs 595ca0e6-b82e-46b5-b9e2-c72a6928be48 mount /dev/sda /btrfs1 mount: /btrfs1: WARNING: device write-protected, mounted read-only. btrfs dev add -f /dev/sdc /btrfs1 findmnt --output SOURCE,TARGET,UUID /btrfs1 SOURCE TARGET UUID /dev/sdc /btrfs1 ca1dbb7a-8446-4f95-853c-a20f3f82bdbb cat /proc/self/mounts | grep btrfs /dev/sdb /btrfs btrfs rw,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 /dev/sdc /btrfs1 btrfs ro,relatime,noacl,space_cache,subvolid=5,subvol=/ 0 0 Signed-off-by: Anand Jain <anand.jain@oracle.com> --- This has passed the xfstests/btrfs sucessfully with no new regressions. Thanks. fs/btrfs/super.c | 21 +++++++-------------- 1 file changed, 7 insertions(+), 14 deletions(-)