| Message ID | 81dbac2d7ddba00de5e2c69813138f71752f74ff.1529516228.git.dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/21/2018 01:51 AM, David Sterba wrote: > 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. > > Signed-off-by: David Sterba <dsterba@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Thanks, Anand > --- > fs/btrfs/super.c | 12 +++++++++++- > fs/btrfs/volumes.c | 4 ++-- > 2 files changed, 13 insertions(+), 3 deletions(-) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 81107ad49f3a..735402ed3154 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -917,8 +917,10 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags, > 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(struct file_system_type *fs_type, > 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; > > @@ -2234,15 +2238,21 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd, > > 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); > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 02246f9af0a3..958bfe1a725c 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -1226,6 +1226,8 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, > 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. > @@ -1244,13 +1246,11 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, > goto error_bdev_put; > } > > - mutex_lock(&uuid_mutex); > device = device_list_add(path, disk_super); > if (IS_ERR(device)) > ret = PTR_ERR(device); > else > *fs_devices_ret = device->fs_devices; > - mutex_unlock(&uuid_mutex); > > btrfs_release_disk_super(page); > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 81107ad49f3a..735402ed3154 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -917,8 +917,10 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags, 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(struct file_system_type *fs_type, 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; @@ -2234,15 +2238,21 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd, 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); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 02246f9af0a3..958bfe1a725c 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1226,6 +1226,8 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, 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. @@ -1244,13 +1246,11 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, goto error_bdev_put; } - mutex_lock(&uuid_mutex); device = device_list_add(path, disk_super); if (IS_ERR(device)) ret = PTR_ERR(device); else *fs_devices_ret = device->fs_devices; - mutex_unlock(&uuid_mutex); btrfs_release_disk_super(page);
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. Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/super.c | 12 +++++++++++- fs/btrfs/volumes.c | 4 ++-- 2 files changed, 13 insertions(+), 3 deletions(-)