From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dkim1.fusionio.com ([66.114.96.53]:41183 "EHLO dkim1.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755178Ab3KFUNo (ORCPT ); Wed, 6 Nov 2013 15:13:44 -0500 Received: from mx2.fusionio.com (unknown [10.101.1.160]) by dkim1.fusionio.com (Postfix) with ESMTP id 77D757C0430 for ; Wed, 6 Nov 2013 13:13:43 -0700 (MST) Date: Wed, 6 Nov 2013 15:13:41 -0500 From: Josef Bacik To: Anand Jain CC: , , , Subject: Re: [PATCH 2/4 v2] btrfs-progs: mechanism to fetch fsinfo from btrfs-control Message-ID: <20131106201341.GE27784@localhost.localdomain> References: <1383536745-4635-1-git-send-email-anand.jain@oracle.com> <1383536745-4635-2-git-send-email-anand.jain@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <1383536745-4635-2-git-send-email-anand.jain@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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 > --- > 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