Re: [PATCH 1/2] btrfs: match btrfs_device->mode same as it used for open

[Anand Jain]

On 10/20/2017 08:26 PM, Nikolay Borisov wrote:

On 20.10.2017 13:33, Anand Jain wrote:

We aren't saving the fmode_t flags at %struct btrfs_device->mode same
as it used to open the device at device replace, so fix that.

I think this could use a bit of rewording to better explain what the
problem and what it can potentially cause.

OK will do it.

Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
  fs/btrfs/volumes.c | 16 ++++++++--------
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b39737568c22..765c2bd2d8d9 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2323,12 +2323,12 @@ int btrfs_init_new_device(struct btrfs_fs_info 
*fs_info, const char *device_path
        u64 tmp;
        int seeding_dev = 0;
        int ret = 0;
+       fmode_t flag = FMODE_WRITE | FMODE_EXCL;

if (sb_rdonly(sb) && !fs_info->fs_devices->seeding)

                return -EROFS;

- bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,

-                                 fs_info->bdev_holder);
+       bdev = blkdev_get_by_path(device_path, flag, fs_info->bdev_holder);
        if (IS_ERR(bdev))
                return PTR_ERR(bdev);

@@ -2392,7 +2392,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path

        device->bdev = bdev;
        device->in_fs_metadata = 1;
        device->is_tgtdev_for_dev_replace = 0;
-       device->mode = FMODE_EXCL;
+       device->mode = flag;

So the actual bug being fixed by this patch is that currently we aren't
setting the FMODE_WRITE when initializing btrfs_device structure and
when calling blkdev_put, correct?

yes.

Thanks, Anand

        device->dev_stats_valid = 1;
        set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);

@@ -2506,7 +2506,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path

        btrfs_sysfs_rm_device_link(fs_info->fs_devices, device);
        kfree(device);
  error:
-       blkdev_put(bdev, FMODE_EXCL);
+       blkdev_put(bdev, flag);
        if (seeding_dev) {
                mutex_unlock(&uuid_mutex);
                up_write(&sb->s_umount);
@@ -2526,6 +2526,7 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info 
*fs_info,
        struct rcu_string *name;
        u64 devid = BTRFS_DEV_REPLACE_DEVID;
        int ret = 0;
+       fmode_t flags = FMODE_WRITE | FMODE_EXCL;

*device_out = NULL;

        if (fs_info->fs_devices->seeding) {
@@ -2533,8 +2534,7 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info 
*fs_info,
                return -EINVAL;
        }

- bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,

-                                 fs_info->bdev_holder);
+       bdev = blkdev_get_by_path(device_path, flags, fs_info->bdev_holder);
        if (IS_ERR(bdev)) {
                btrfs_err(fs_info, "target device %s is invalid!", device_path);
                return PTR_ERR(bdev);
@@ -2595,7 +2595,7 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info 
*fs_info,
        device->bdev = bdev;
        device->in_fs_metadata = 1;
        device->is_tgtdev_for_dev_replace = 1;
-       device->mode = FMODE_EXCL;
+       device->mode = flags;
        device->dev_stats_valid = 1;
        set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
        device->fs_devices = fs_info->fs_devices;
@@ -2608,7 +2608,7 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info 
*fs_info,
        return ret;

error:

-       blkdev_put(bdev, FMODE_EXCL);
+       blkdev_put(bdev, flags);
        return ret;
  }

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