Hello Hugo, Is this issue specific to the receive ioctl?
Because what you are describing applies to any user-kernel ioctl-based interface, when you compile the user-space as 32-bit, which the kernel space has been compiled as 64-bit. For that purpose, I believe, there exists the "compat_ioctl" callback. It's implementation should do "thunking", i.e., treat the user-space structure as if it were compiled for 32-bit, and unpack it properly. Today, however, btrfs supplies the same callback both for "unlocked_ioctl" and "compat_ioctl". So we should see the same problem with all ioctls, if I am not missing anything. Thanks, Alex. On Mon, Jan 6, 2014 at 10:50 AM, Hugo Mills <h...@carfax.org.uk> wrote: > On Sun, Jan 05, 2014 at 06:26:11PM +0000, Hugo Mills wrote: >> On Sun, Jan 05, 2014 at 05:55:27PM +0000, Hugo Mills wrote: >> > The structure for BTRFS_SET_RECEIVED_IOCTL packs differently on 32-bit >> > and 64-bit systems. This means that it is impossible to use btrfs >> > receive on a system with a 64-bit kernel and 32-bit userspace, because >> > the structure size (and hence the ioctl number) is different. >> > >> > This patch adds a compatibility structure and ioctl to deal with the >> > above case. >> >> Oops, forgot to mention -- this has been compile tested, but not >> actually run yet. The machine in question is several miles away and is >> a production machine (it's my work desktop, and I can't afford much >> downtime on it). > > ... And it doesn't even compile properly, now I come to build a > .deb. I'm still interested in comments about the general approach, but > the specific patch is a load of balls. > > Hugo. > >> Hugo. >> >> > Signed-off-by: Hugo Mills <h...@carfax.org.uk> >> > --- >> > fs/btrfs/ioctl.c | 95 >> > +++++++++++++++++++++++++++++++++++++++++++++++++++----- >> > 1 file changed, 87 insertions(+), 8 deletions(-) >> > >> > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c >> > index 21da576..e186439 100644 >> > --- a/fs/btrfs/ioctl.c >> > +++ b/fs/btrfs/ioctl.c >> > @@ -57,6 +57,32 @@ >> > #include "send.h" >> > #include "dev-replace.h" >> > >> > +#ifdef CONFIG_64BIT >> > +/* If we have a 32-bit userspace and 64-bit kernel, then the UAPI >> > + * structures are incorrect, as the timespec structure from userspace >> > + * is 4 bytes too small. We define these alternatives here to teach >> > + * the kernel about the 32-bit struct packing. >> > + */ >> > +struct btrfs_ioctl_timespec { >> > + __u64 sec; >> > + __u32 nsec; >> > +} ((__packed__)); >> > + >> > +struct btrfs_ioctl_received_subvol_args { >> > + char uuid[BTRFS_UUID_SIZE]; /* in */ >> > + __u64 stransid; /* in */ >> > + __u64 rtransid; /* out */ >> > + struct btrfs_ioctl_timespec stime; /* in */ >> > + struct btrfs_ioctl_timespec rtime; /* out */ >> > + __u64 flags; /* in */ >> > + __u64 reserved[16]; /* in */ >> > +} ((__packed__)); >> > +#endif >> > + >> > +#define BTRFS_IOC_SET_RECEIVED_SUBVOL_32 _IOWR(BTRFS_IOCTL_MAGIC, 37, \ >> > + struct btrfs_ioctl_received_subvol_args_32) >> > + >> > + >> > static int btrfs_clone(struct inode *src, struct inode *inode, >> > u64 off, u64 olen, u64 olen_aligned, u64 destoff); >> > >> > @@ -4313,10 +4339,69 @@ static long btrfs_ioctl_quota_rescan_wait(struct >> > file *file, void __user *arg) >> > return btrfs_qgroup_wait_for_completion(root->fs_info); >> > } >> > >> > +#ifdef CONFIG_64BIT >> > +static long btrfs_ioctl_set_received_subvol_32(struct file *file, >> > + void __user *arg) >> > +{ >> > + struct btrfs_ioctl_received_subvol_args_32 *args32 = NULL; >> > + struct btrfs_ioctl_received_subvol_args *args64 = NULL; >> > + int ret = 0; >> > + >> > + args32 = memdup_user(arg, sizeof(*args32)); >> > + if (IS_ERR(args32)) { >> > + ret = PTR_ERR(args32); >> > + args32 = NULL; >> > + goto out; >> > + } >> > + >> > + args64 = malloc(sizeof(*args64)); >> > + if (IS_ERR(args64)) { >> > + ret = PTR_ERR(args64); >> > + args64 = NULL; >> > + goto out; >> > + } >> > + >> > + memcpy(args64->uuid, args32->uuid, BTRFS_UUID_SIZE); >> > + args64->stransid = args32->stransid; >> > + args64->rtransid = args32->rtransid; >> > + args64->stime.sec = args32->stime.sec; >> > + args64->stime.nsec = args32->stime.nsec; >> > + args64->rtime.sec = args32->rtime.sec; >> > + args64->rtime.nsec = args32->rtime.nsec; >> > + args64->flags = args32->flags; >> > + >> > + ret = _btrfs_ioctl_set_received_subvol(file, args64); >> > + >> > +out: >> > + kfree(args32); >> > + kfree(args64); >> > + return ret; >> > +} >> > +#endif >> > + >> > static long btrfs_ioctl_set_received_subvol(struct file *file, >> > void __user *arg) >> > { >> > struct btrfs_ioctl_received_subvol_args *sa = NULL; >> > + int ret = 0; >> > + >> > + sa = memdup_user(arg, sizeof(*sa)); >> > + if (IS_ERR(sa)) { >> > + ret = PTR_ERR(sa); >> > + sa = NULL; >> > + goto out; >> > + } >> > + >> > + ret = _btrfs_ioctl_set_received_subvol(file, sa); >> > + >> > +out: >> > + kfree(sa); >> > + return ret; >> > +} >> > + >> > +static long _btrfs_ioctl_set_received_subvol(struct file *file, >> > + struct >> > btrfs_ioctl_received_subvol_args *sa) >> > +{ >> > struct inode *inode = file_inode(file); >> > struct btrfs_root *root = BTRFS_I(inode)->root; >> > struct btrfs_root_item *root_item = &root->root_item; >> > @@ -4346,13 +4431,6 @@ static long btrfs_ioctl_set_received_subvol(struct >> > file *file, >> > goto out; >> > } >> > >> > - sa = memdup_user(arg, sizeof(*sa)); >> > - if (IS_ERR(sa)) { >> > - ret = PTR_ERR(sa); >> > - sa = NULL; >> > - goto out; >> > - } >> > - >> > /* >> > * 1 - root item >> > * 2 - uuid items (received uuid + subvol uuid) >> > @@ -4411,7 +4489,6 @@ static long btrfs_ioctl_set_received_subvol(struct >> > file *file, >> > ret = -EFAULT; >> > >> > out: >> > - kfree(sa); >> > up_write(&root->fs_info->subvol_sem); >> > mnt_drop_write_file(file); >> > return ret; >> > @@ -4572,6 +4649,8 @@ long btrfs_ioctl(struct file *file, unsigned int >> > return btrfs_ioctl_balance_progress(root, argp); >> > case BTRFS_IOC_SET_RECEIVED_SUBVOL: >> > return btrfs_ioctl_set_received_subvol(file, argp); >> > + case BTRFS_IOC_SET_RECEIVED_SUBVOL_32: >> > + return btrfs_ioctl_set_received_subvol_32(file, argp); >> > case BTRFS_IOC_SEND: >> > return btrfs_ioctl_send(file, argp); >> > case BTRFS_IOC_GET_DEV_STATS: >> > > -- > === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === > PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk > --- Nothing right in my left brain. Nothing left in --- > my right brain. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html