From 02db0844beffc1c4e99d750be58ffb3ed95d6d62 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 21 Jun 2012 16:03:58 -0400 Subject: [PATCH] Btrfs: add DEVICE_READY ioctl This will be used in conjunction with btrfs device ready . This is needed for initrd's to have a nice and lightweight way to tell if all of the devices needed for a file system are in the cache currently. This keeps them from having to do mount+sleep loops waiting for devices to show up. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/ioctl.h | 3 ++- fs/btrfs/super.c | 7 +++++++ fs/btrfs/volumes.c | 9 ++++++++- fs/btrfs/volumes.h | 1 + 4 files changed, 18 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h index 021c55ed8aed..4e3e5d342a2b 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h @@ -363,7 +363,8 @@ struct btrfs_ioctl_get_dev_stats { struct btrfs_ioctl_ino_path_args) #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \ struct btrfs_ioctl_ino_path_args) +#define BTRFS_IOC_DEVICES_READY _IOR(BTRFS_IOCTL_MAGIC, 39, \ + struct btrfs_ioctl_vol_args) #define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \ struct btrfs_ioctl_get_dev_stats) - #endif diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 88a2d2bb2d75..26da344231ac 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1462,6 +1462,13 @@ 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_DEVICES_READY: + ret = btrfs_scan_one_device(vol->name, FMODE_READ, + &btrfs_fs_type, &fs_devices); + if (ret) + break; + ret = !(fs_devices->num_devices == fs_devices->total_devices); + break; } kfree(vol); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 957bf393ab46..39a0d04759f8 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -429,6 +429,7 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig) mutex_init(&fs_devices->device_list_mutex); fs_devices->latest_devid = orig->latest_devid; fs_devices->latest_trans = orig->latest_trans; + fs_devices->total_devices = orig->total_devices; memcpy(fs_devices->fsid, orig->fsid, sizeof(fs_devices->fsid)); /* We have held the volume lock, it is safe to get the devices. */ @@ -739,6 +740,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, int ret; u64 devid; u64 transid; + u64 total_devices; flags |= FMODE_EXCL; bdev = blkdev_get_by_path(path, flags, holder); @@ -760,6 +762,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, disk_super = (struct btrfs_super_block *)bh->b_data; devid = btrfs_stack_device_id(&disk_super->dev_item); transid = btrfs_super_generation(disk_super); + total_devices = btrfs_super_num_devices(disk_super); if (disk_super->label[0]) printk(KERN_INFO "device label %s ", disk_super->label); else @@ -767,7 +770,8 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, printk(KERN_CONT "devid %llu transid %llu %s\n", (unsigned long long)devid, (unsigned long long)transid, path); ret = device_list_add(path, disk_super, devid, fs_devices_ret); - + if (!ret && fs_devices_ret) + (*fs_devices_ret)->total_devices = total_devices; brelse(bh); error_close: mutex_unlock(&uuid_mutex); @@ -1433,6 +1437,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path) list_del_rcu(&device->dev_list); device->fs_devices->num_devices--; + device->fs_devices->total_devices--; if (device->missing) root->fs_info->fs_devices->missing_devices--; @@ -1550,6 +1555,7 @@ static int btrfs_prepare_sprout(struct btrfs_root *root) fs_devices->seeding = 0; fs_devices->num_devices = 0; fs_devices->open_devices = 0; + fs_devices->total_devices = 0; fs_devices->seed = seed_devices; generate_random_uuid(fs_devices->fsid); @@ -1749,6 +1755,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path) root->fs_info->fs_devices->num_devices++; root->fs_info->fs_devices->open_devices++; root->fs_info->fs_devices->rw_devices++; + root->fs_info->fs_devices->total_devices++; if (device->can_discard) root->fs_info->fs_devices->num_can_discard++; root->fs_info->fs_devices->total_rw_bytes += device->total_bytes; diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index e404414a95a9..5479325987b3 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -126,6 +126,7 @@ struct btrfs_fs_devices { u64 missing_devices; u64 total_rw_bytes; u64 num_can_discard; + u64 total_devices; struct block_device *latest_bdev; /* all of the devices in the FS, protected by a mutex -- 2.20.1