lkml.org 
[lkml]   [2018]   [Sep]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.18 148/197] btrfs: lift uuid_mutex to callers of btrfs_scan_one_device
    Date
    4.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: David Sterba <dsterba@suse.com>

    [ Upstream commit 899f9307c33ce4758c30a076b10ed54d5c91c6e7 ]

    Prepartory work to fix race between mount and device scan.

    The callers will have to manage the critical section, eg. mount wants to
    scan and then call btrfs_open_devices without the ioctl scan walking in
    and modifying the fs devices in the meantime.

    Reviewed-by: Anand Jain <anand.jain@oracle.com>
    Signed-off-by: David Sterba <dsterba@suse.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    fs/btrfs/super.c | 12 +++++++++++-
    fs/btrfs/volumes.c | 4 ++--
    2 files changed, 13 insertions(+), 3 deletions(-)

    --- a/fs/btrfs/super.c
    +++ b/fs/btrfs/super.c
    @@ -917,8 +917,10 @@ static int btrfs_parse_early_options(con
    error = -ENOMEM;
    goto out;
    }
    + mutex_lock(&uuid_mutex);
    error = btrfs_scan_one_device(device_name,
    flags, holder, fs_devices);
    + mutex_unlock(&uuid_mutex);
    kfree(device_name);
    if (error)
    goto out;
    @@ -1539,7 +1541,9 @@ static struct dentry *btrfs_mount_root(s
    return ERR_PTR(error);
    }

    + mutex_lock(&uuid_mutex);
    error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
    + mutex_unlock(&uuid_mutex);
    if (error)
    goto error_sec_opts;

    @@ -2236,15 +2240,21 @@ static long btrfs_control_ioctl(struct f

    switch (cmd) {
    case BTRFS_IOC_SCAN_DEV:
    + mutex_lock(&uuid_mutex);
    ret = btrfs_scan_one_device(vol->name, FMODE_READ,
    &btrfs_root_fs_type, &fs_devices);
    + mutex_unlock(&uuid_mutex);
    break;
    case BTRFS_IOC_DEVICES_READY:
    + mutex_lock(&uuid_mutex);
    ret = btrfs_scan_one_device(vol->name, FMODE_READ,
    &btrfs_root_fs_type, &fs_devices);
    - if (ret)
    + if (ret) {
    + mutex_unlock(&uuid_mutex);
    break;
    + }
    ret = !(fs_devices->num_devices == fs_devices->total_devices);
    + mutex_unlock(&uuid_mutex);
    break;
    case BTRFS_IOC_GET_SUPPORTED_FEATURES:
    ret = btrfs_ioctl_get_supported_features((void __user*)arg);
    --- a/fs/btrfs/volumes.c
    +++ b/fs/btrfs/volumes.c
    @@ -1241,6 +1241,8 @@ int btrfs_scan_one_device(const char *pa
    int ret = 0;
    u64 bytenr;

    + lockdep_assert_held(&uuid_mutex);
    +
    /*
    * we would like to check all the supers, but that would make
    * a btrfs mount succeed after a mkfs from a different FS.
    @@ -1259,7 +1261,6 @@ int btrfs_scan_one_device(const char *pa
    goto error_bdev_put;
    }

    - mutex_lock(&uuid_mutex);
    device = device_list_add(path, disk_super, &new_device_added);
    if (IS_ERR(device)) {
    ret = PTR_ERR(device);
    @@ -1268,7 +1269,6 @@ int btrfs_scan_one_device(const char *pa
    if (new_device_added)
    btrfs_free_stale_devices(path, device);
    }
    - mutex_unlock(&uuid_mutex);

    btrfs_release_disk_super(page);


    \
     
     \ /
      Last update: 2018-09-13 16:03    [W:4.085 / U:0.252 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site