From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:38142 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752431Ab3KDDh0 (ORCPT ); Sun, 3 Nov 2013 22:37:26 -0500 From: Anand Jain To: linux-btrfs@vger.kernel.org Cc: jbacik@fusionio.com, zab@redhat.com, dsterba@suse.cz Subject: [PATCH 2/4 v2] btrfs-progs: mechanism to fetch fsinfo from btrfs-control Date: Mon, 4 Nov 2013 11:45:43 +0800 Message-Id: <1383536745-4635-2-git-send-email-anand.jain@oracle.com> In-Reply-To: <1383536745-4635-1-git-send-email-anand.jain@oracle.com> References: <1383536745-4635-1-git-send-email-anand.jain@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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 --- 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); + memset(fsargs, 0, sz); + + if (!fsargs) { + close(fd); + return -ENOMEM; + } + 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); + if (!fslist_tmp) { + ret = -ENOMEM; + goto out; + } + + while (count--) { + memcpy(fslist_tmp, fslist, sizeof(*fslist)); + fslist_tmp = fslist_tmp + sizeof(*fslist_tmp); + fslist = fslist + sizeof(*fslist); + } + ret = 0; +out: + free(fsargs); + close(fd); + return 0; +} diff --git a/utils.h b/utils.h index 6f4b10c..e20ad74 100644 --- a/utils.h +++ b/utils.h @@ -94,5 +94,6 @@ int ask_user(char *question); int lookup_ino_rootid(int fd, u64 *rootid); int btrfs_scan_lblkid(int update_kernel); int get_btrfs_mount(const char *dev, char *mp, size_t mp_size); +int get_fslist(struct btrfs_ioctl_fslist **out_fslist, int *out_count); #endif -- 1.7.1