Thanks sent out v3. On 11/07/13 04:13 AM, Josef Bacik wrote:
On Mon, Nov 04, 2013 at 11:45:43AM +0800, Anand Jain wrote:need fsinfo from btrfs-control that is when mount path is not known. current method of going through each mount points isn't efficient, and multiple subvol of a fsid could be mounted means extra logic to handle that. Further this will help to revamp check_mounted() (planned) check_mounted is heavily used in the btrfs-progs, it does full scan of all the disks in the system to confirm if a multi-disk btrfs is mounted it doesn't scalable well with few hundreds luns, check_mounted for sure needs a revamp. using this it can be done easily. which is planned. v2: commit reword Signed-off-by: Anand Jain<anand.jain@xxxxxxxxxx> --- ioctl.h | 19 +++++++++++++++ utils.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ utils.h | 1 + 3 files changed, 100 insertions(+), 0 deletions(-) diff --git a/ioctl.h b/ioctl.h index d21413f..29575d8 100644 --- a/ioctl.h +++ b/ioctl.h @@ -506,6 +506,23 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code) } } +/* fs flags */ +#define BTRFS_FS_MOUNTED (1LLU<< 0) + +struct btrfs_ioctl_fslist { + __u64 self_sz; /* in/out */ + __u8 fsid[BTRFS_FSID_SIZE]; /* out */ + __u64 num_devices; + __u64 missing_devices; + __u64 total_devices; + __u64 flags; +}; + +struct btrfs_ioctl_fslist_args { + __u64 self_sz; /* in/out */ + __u64 count; /* out */ +}; + #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \ struct btrfs_ioctl_vol_args) #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \ @@ -604,6 +621,8 @@ struct btrfs_ioctl_clone_range_args { struct btrfs_ioctl_dev_replace_args) #define BTRFS_IOC_DEDUP_CTL _IOWR(BTRFS_IOCTL_MAGIC, 55, \ struct btrfs_ioctl_dedup_args) +#define BTRFS_IOC_GET_FSLIST _IOWR(BTRFS_IOCTL_MAGIC, 56, \ + struct btrfs_ioctl_fslist_args) #ifdef __cplusplus } #endif diff --git a/utils.c b/utils.c index 5bedd97..1798a7c 100644 --- a/utils.c +++ b/utils.c @@ -2087,3 +2087,83 @@ int lookup_ino_rootid(int fd, u64 *rootid) return 0; } + +/* scans for fsid(s) in the kernel using the btrfs-control + * interface. + */ +int get_fslist(struct btrfs_ioctl_fslist **out_fslist, int *out_count) +{ + int ret, fd, e; + struct btrfs_ioctl_fslist_args *fsargs; + struct btrfs_ioctl_fslist *fslist; + struct btrfs_ioctl_fslist *fslist_tmp; + u64 sz; + int count; + + fd = open("/dev/btrfs-control", O_RDWR); + e = errno; + if (fd< 0) { + perror("failed to open /dev/btrfs-control"); + return -e; + } + + /* space to hold 512 fsids, doesn't matter if small + * it would fail and return count so then we try again + */ + count = 512; +again: + sz = sizeof(*fsargs) + sizeof(*fslist) * count; + + fsargs = (struct btrfs_ioctl_fslist_args *) malloc(sz);No need to cast the return value of malloc.+ memset(fsargs, 0, sz); + + if (!fsargs) { + close(fd); + return -ENOMEM; + }Should check !fsargs before memsetting it.+ fsargs->count = count; + + ret = ioctl(fd, BTRFS_IOC_GET_FSLIST, fsargs); + e = errno; + if (ret == 1) { + /* out of size so reallocate */ + count = fsargs->count; + free(fsargs); + goto again; + } else if (ret< 0) { + printf("ERROR: scan_fsid ioctl failed - %s\n", + strerror(e)); + ret = -e; + goto out; + } + + /* ioctl returns fsid count in count parameter*/ + + *out_count = count = fsargs->count; + if (count == 0) { + *out_fslist = NULL; + ret = 0; + goto out; + } + + fslist = (struct btrfs_ioctl_fslist *) (fsargs + + sizeof(*fsargs)); + + fslist_tmp = *out_fslist = (struct btrfs_ioctl_fslist *) + malloc(sizeof(*fslist) * count);No need to cast. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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