| Message ID | 20171205085258.4038-4-anand.jain@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Dec 05, 2017 at 04:52:58PM +0800, Anand Jain wrote: > Support for a new command is being added here: > btrfs dev ignore <dev> > Which shall undo the effects of the command > btrfs dev scan <dev> > > This cli/ioctl is needed as there is no way to continue to mount in > degraded mode if the device is already scanned, which is required to > recover from the split brain raid conditions. > > This patch proposes to use ioctl #5 as it was empty. > IOW(BTRFS_IOCTL_MAGIC, 5, ..) > If #5 is reserved for some other purpose, I think I should change this. I think 5 is free for use. > Signed-off-by: Anand Jain <anand.jain@oracle.com> > --- > v2: Use -EBUSY instead of -ENOENT > Since now delete_device_from_list() holds device_list_mutex > so dont hold device_list_mutex in its parent. Reword and indent > pr_err/info. > v3: Send to correct ML > v4: no change. > > fs/btrfs/super.c | 4 +++ > fs/btrfs/volumes.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++ > fs/btrfs/volumes.h | 2 ++ > include/uapi/linux/btrfs.h | 2 ++ > 4 files changed, 72 insertions(+) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index f443517fa2f8..fcc4a6ef4795 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -2212,6 +2212,10 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd, > ret = btrfs_scan_one_device(vol->name, FMODE_READ, > &btrfs_fs_type, &fs_devices); > break; > + case BTRFS_IOC_IGNORE_DEV: > + ret = btrfs_ignore_one_device(vol->name, FMODE_READ, > + &btrfs_fs_type, &fs_devices); > + break; > case BTRFS_IOC_DEVICES_READY: > ret = btrfs_scan_one_device(vol->name, FMODE_READ, > &btrfs_fs_type, &fs_devices); > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 5deda80316f0..2bae2ccd262d 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -1205,6 +1205,70 @@ static int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr, > return 0; > } > > +static int device_list_remove(struct btrfs_super_block *disk_super, u64 devid) > +{ > + int ret = 0; > + struct btrfs_fs_devices *fs_devices; > + struct btrfs_device *device; > + > + fs_devices = find_fsid(disk_super->fsid); Don't we need uuid mutext to call find_fsid? All other users do that. > + if (!fs_devices) > + return -ENOENT; > + > + if (fs_devices->opened) > + return -EBUSY; > + > + mutex_lock(&uuid_mutex); > + > + device = find_device(fs_devices, devid, disk_super->dev_item.uuid); > + if (device) > + delete_device_from_list(device); > + > + mutex_unlock(&uuid_mutex); > + > + return ret; > +} > + > +int btrfs_ignore_one_device(const char *path, fmode_t flags, void *holder, > + struct btrfs_fs_devices **fs_devices_ret) > +{ > + struct btrfs_super_block *disk_super; > + struct block_device *bdev; > + struct page *page; > + int ret = -EINVAL; Please move EINVAL to the point where this happens (ie. after the btrfs_read_disk_super call). This is the common pattern and makes reading the code smooth. > + u64 devid; > + u64 bytenr; > + > + bytenr = btrfs_sb_offset(0); > + flags |= FMODE_EXCL; > + > + bdev = blkdev_get_by_path(path, flags, holder); > + if (IS_ERR(bdev)) { > + ret = PTR_ERR(bdev); > + goto error; > + } > + > + if (btrfs_read_disk_super(bdev, bytenr, &page, &disk_super)) > + goto error_bdev_put; > + > + devid = btrfs_stack_device_id(&disk_super->dev_item); > + > + ret = device_list_remove(disk_super, devid); > + if (ret) > + pr_err("BTRFS: %pU device %s devid %llu failed to ignore: %d\n", > + disk_super->fsid, path, devid, ret); So we can't easily use btrfs_printk here due to lack of fs_info that would appear as "<unknown>" in place of the device. Ok. > + else > + pr_info("BTRFS: %pU device %s devid %llu ignored\n", > + disk_super->fsid, path, devid); > + > + btrfs_release_disk_super(page); > + > +error_bdev_put: > + blkdev_put(bdev, flags); > +error: > + return ret; > +} > + > /* > * Look for a btrfs signature on a device. This may be called out of the mount path > * and we are not allowed to call set_blocksize during the scan. The superblock > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h > index 7acfd61611aa..08d3425bc880 100644 > --- a/fs/btrfs/volumes.h > +++ b/fs/btrfs/volumes.h > @@ -423,6 +423,8 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, > fmode_t flags, void *holder); > int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, > struct btrfs_fs_devices **fs_devices_ret); > +int btrfs_ignore_one_device(const char *path, fmode_t flags, void *holder, > + struct btrfs_fs_devices **fs_devices_ret); > int btrfs_close_devices(struct btrfs_fs_devices *fs_devices); > void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices, int step); > void btrfs_assign_next_active_device(struct btrfs_fs_info *fs_info, > diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h > index ce615b75e855..bb13bad41b30 100644 > --- a/include/uapi/linux/btrfs.h > +++ b/include/uapi/linux/btrfs.h > @@ -744,6 +744,8 @@ enum btrfs_err_code { > struct btrfs_ioctl_vol_args) > #define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \ > struct btrfs_ioctl_vol_args) > +#define BTRFS_IOC_IGNORE_DEV _IOW(BTRFS_IOCTL_MAGIC, 5, \ > + struct btrfs_ioctl_vol_args) While reading the patches, I realized we may want to extend the ioctl to unregister/forge all devices that are not currently mounted. For that purpose using the btrfs_ioctl_vol_args_v2 would be suitable as it has more struct members. Another extension is to unregister only stale devices (when there's no device node under /dev), eg. after the device is unuplugged and readded by another name. -- 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 f443517fa2f8..fcc4a6ef4795 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2212,6 +2212,10 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd, ret = btrfs_scan_one_device(vol->name, FMODE_READ, &btrfs_fs_type, &fs_devices); break; + case BTRFS_IOC_IGNORE_DEV: + ret = btrfs_ignore_one_device(vol->name, FMODE_READ, + &btrfs_fs_type, &fs_devices); + break; case BTRFS_IOC_DEVICES_READY: ret = btrfs_scan_one_device(vol->name, FMODE_READ, &btrfs_fs_type, &fs_devices); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 5deda80316f0..2bae2ccd262d 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1205,6 +1205,70 @@ static int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr, return 0; } +static int device_list_remove(struct btrfs_super_block *disk_super, u64 devid) +{ + int ret = 0; + struct btrfs_fs_devices *fs_devices; + struct btrfs_device *device; + + fs_devices = find_fsid(disk_super->fsid); + if (!fs_devices) + return -ENOENT; + + if (fs_devices->opened) + return -EBUSY; + + mutex_lock(&uuid_mutex); + + device = find_device(fs_devices, devid, disk_super->dev_item.uuid); + if (device) + delete_device_from_list(device); + + mutex_unlock(&uuid_mutex); + + return ret; +} + +int btrfs_ignore_one_device(const char *path, fmode_t flags, void *holder, + struct btrfs_fs_devices **fs_devices_ret) +{ + struct btrfs_super_block *disk_super; + struct block_device *bdev; + struct page *page; + int ret = -EINVAL; + u64 devid; + u64 bytenr; + + bytenr = btrfs_sb_offset(0); + flags |= FMODE_EXCL; + + bdev = blkdev_get_by_path(path, flags, holder); + if (IS_ERR(bdev)) { + ret = PTR_ERR(bdev); + goto error; + } + + if (btrfs_read_disk_super(bdev, bytenr, &page, &disk_super)) + goto error_bdev_put; + + devid = btrfs_stack_device_id(&disk_super->dev_item); + + ret = device_list_remove(disk_super, devid); + if (ret) + pr_err("BTRFS: %pU device %s devid %llu failed to ignore: %d\n", + disk_super->fsid, path, devid, ret); + else + pr_info("BTRFS: %pU device %s devid %llu ignored\n", + disk_super->fsid, path, devid); + + btrfs_release_disk_super(page); + +error_bdev_put: + blkdev_put(bdev, flags); +error: + return ret; +} + /* * Look for a btrfs signature on a device. This may be called out of the mount path * and we are not allowed to call set_blocksize during the scan. The superblock diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 7acfd61611aa..08d3425bc880 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -423,6 +423,8 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, fmode_t flags, void *holder); int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, struct btrfs_fs_devices **fs_devices_ret); +int btrfs_ignore_one_device(const char *path, fmode_t flags, void *holder, + struct btrfs_fs_devices **fs_devices_ret); int btrfs_close_devices(struct btrfs_fs_devices *fs_devices); void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices, int step); void btrfs_assign_next_active_device(struct btrfs_fs_info *fs_info, diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h index ce615b75e855..bb13bad41b30 100644 --- a/include/uapi/linux/btrfs.h +++ b/include/uapi/linux/btrfs.h @@ -744,6 +744,8 @@ enum btrfs_err_code { struct btrfs_ioctl_vol_args) #define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \ struct btrfs_ioctl_vol_args) +#define BTRFS_IOC_IGNORE_DEV _IOW(BTRFS_IOCTL_MAGIC, 5, \ + struct btrfs_ioctl_vol_args) /* trans start and trans end are dangerous, and only for * use by applications that know how to avoid the * resulting deadlocks
Support for a new command is being added here: btrfs dev ignore <dev> Which shall undo the effects of the command btrfs dev scan <dev> This cli/ioctl is needed as there is no way to continue to mount in degraded mode if the device is already scanned, which is required to recover from the split brain raid conditions. This patch proposes to use ioctl #5 as it was empty. IOW(BTRFS_IOCTL_MAGIC, 5, ..) If #5 is reserved for some other purpose, I think I should change this. Signed-off-by: Anand Jain <anand.jain@oracle.com> --- v2: Use -EBUSY instead of -ENOENT Since now delete_device_from_list() holds device_list_mutex so dont hold device_list_mutex in its parent. Reword and indent pr_err/info. v3: Send to correct ML v4: no change. fs/btrfs/super.c | 4 +++ fs/btrfs/volumes.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/volumes.h | 2 ++ include/uapi/linux/btrfs.h | 2 ++ 4 files changed, 72 insertions(+)