| Message ID | 201505131715.27483.luke@dashjr.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, May 13, 2015 at 05:15:26PM +0000, Luke Dashjr wrote: > 32-bit ioctl uses these rather than the regular FS_IOC_* versions. They can be > handled in btrfs using the same code. Without this, 32-bit {ch,ls}attr fail. > > Signed-off-by: Luke Dashjr <luke-jr+git@utopios.org> > --- > fs/btrfs/ioctl.c | 3 +++ > 1 file changed, 3 insertions(+) <formletter> This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read Documentation/stable_kernel_rules.txt for how to do this properly. </formletter> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, May 13, 2015 at 05:15:26PM +0000, Luke Dashjr wrote: > 32-bit ioctl uses these rather than the regular FS_IOC_* versions. They can be > handled in btrfs using the same code. Without this, 32-bit {ch,ls}attr fail. Yes, but this has to be implemented in another way. See eg. https://git.kernel.org/linus/e9750824114ff -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thursday, May 14, 2015 2:06:17 PM David Sterba wrote: > On Wed, May 13, 2015 at 05:15:26PM +0000, Luke Dashjr wrote: > > 32-bit ioctl uses these rather than the regular FS_IOC_* versions. They > > can be handled in btrfs using the same code. Without this, 32-bit > > {ch,ls}attr fail. > > Yes, but this has to be implemented in another way. See eg. > https://git.kernel.org/linus/e9750824114ff I don't see what is different with that implementation. All f2fs_compat_ioctl does is change cmd to the plain-IOC equivalent and call f2fs_ioctl with the same arg (compat_ptr merely causes a cast to void* and back, which AFAIK is a noop on 64-bit?). Am I missing something? I could try to just imitate it, but I'd rather know what is significant/going on to ensure I don't waste your time with code I don't even properly understand myself. Perhaps by coincidence, the patch does at least in practice work (although at least `btrfs send` appears to be broken still, and I'm at a loss for how to approach fixing that). Luke -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, May 14, 2015 at 04:27:54PM +0000, Luke Dashjr wrote: > On Thursday, May 14, 2015 2:06:17 PM David Sterba wrote: > > On Wed, May 13, 2015 at 05:15:26PM +0000, Luke Dashjr wrote: > > > 32-bit ioctl uses these rather than the regular FS_IOC_* versions. They > > > can be handled in btrfs using the same code. Without this, 32-bit > > > {ch,ls}attr fail. > > > > Yes, but this has to be implemented in another way. See eg. > > https://git.kernel.org/linus/e9750824114ff > > I don't see what is different with that implementation. All f2fs_compat_ioctl > does is change cmd to the plain-IOC equivalent and call f2fs_ioctl with the > same arg (compat_ptr merely causes a cast to void* and back, which AFAIK is a > noop on 64-bit?). Am I missing something? No, that's the idea. Add new calback for compat_ioctl, put it under #ifdef CONFIG_COMPAT and do the same number switch. > I could try to just imitate it, but > I'd rather know what is significant/going on to ensure I don't waste your time > with code I don't even properly understand myself. > > Perhaps by coincidence, the patch does at least in practice work (although at > least `btrfs send` appears to be broken still, and I'm at a loss for how to > approach fixing that). The 'receive' 32bit/64bit was broken due to size difference in the ioctl structure that led to different ioctl. This is transparently fixed, see BTRFS_IOC_SET_RECEIVED_SUBVOL_32 at the top of ioctl.c. In what way is SEND broken? There are only u64/s64 members in btrfs_ioctl_send_args, I don't see how this could break on 32/64 userspace/kernel. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday, May 15, 2015 11:19:22 AM David Sterba wrote: > On Thu, May 14, 2015 at 04:27:54PM +0000, Luke Dashjr wrote: > > On Thursday, May 14, 2015 2:06:17 PM David Sterba wrote: > > > On Wed, May 13, 2015 at 05:15:26PM +0000, Luke Dashjr wrote: > > > > 32-bit ioctl uses these rather than the regular FS_IOC_* versions. > > > > They can be handled in btrfs using the same code. Without this, > > > > 32-bit {ch,ls}attr fail. > > > > > > Yes, but this has to be implemented in another way. See eg. > > > https://git.kernel.org/linus/e9750824114ff > > > > I don't see what is different with that implementation. All > > f2fs_compat_ioctl does is change cmd to the plain-IOC equivalent and > > call f2fs_ioctl with the same arg (compat_ptr merely causes a cast to > > void* and back, which AFAIK is a noop on 64-bit?). Am I missing > > something? > > No, that's the idea. Add new calback for compat_ioctl, put it under > #ifdef CONFIG_COMPAT and do the same number switch. The idea is to wrap it in a way that doesn't actually change any of the logic? I'm not sure I understand still :( > > I could try to just imitate it, but > > I'd rather know what is significant/going on to ensure I don't waste your > > time with code I don't even properly understand myself. > > > > Perhaps by coincidence, the patch does at least in practice work > > (although at least `btrfs send` appears to be broken still, and I'm at a > > loss for how to approach fixing that). > > The 'receive' 32bit/64bit was broken due to size difference in the ioctl > structure that led to different ioctl. This is transparently fixed, see > BTRFS_IOC_SET_RECEIVED_SUBVOL_32 at the top of ioctl.c. > > In what way is SEND broken? There are only u64/s64 members in > btrfs_ioctl_send_args, I don't see how this could break on 32/64 > userspace/kernel. # btrfs send -p home/initial/ home/20150514_1431573370/ At subvol home/20150514_1431573370/ ERROR: send ioctl failed with -25: Inappropriate ioctl for device But I am stuck on 3.14.41 due to Linux being unstable in newer versions[1], so maybe this is unrelated to 32-bit and already fixed in 4.0? Luke 1. https://bugzilla.kernel.org/show_bug.cgi?id=87891 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday, May 15, 2015 11:19:22 AM David Sterba wrote: > On Thu, May 14, 2015 at 04:27:54PM +0000, Luke Dashjr wrote: > > On Thursday, May 14, 2015 2:06:17 PM David Sterba wrote: > > > On Wed, May 13, 2015 at 05:15:26PM +0000, Luke Dashjr wrote: > > > > 32-bit ioctl uses these rather than the regular FS_IOC_* versions. > > > > They can be handled in btrfs using the same code. Without this, > > > > 32-bit {ch,ls}attr fail. > > > > > > Yes, but this has to be implemented in another way. See eg. > > > https://git.kernel.org/linus/e9750824114ff > > > > I don't see what is different with that implementation. All > > f2fs_compat_ioctl does is change cmd to the plain-IOC equivalent and > > call f2fs_ioctl with the same arg (compat_ptr merely causes a cast to > > void* and back, which AFAIK is a noop on 64-bit?). Am I missing > > something? > > No, that's the idea. Add new calback for compat_ioctl, put it under > #ifdef CONFIG_COMPAT and do the same number switch. Ok, someone else explained this to me. Please let me know if PATCHv2 (sent separately) does not address the needed changes. > > I could try to just imitate it, but > > I'd rather know what is significant/going on to ensure I don't waste your > > time with code I don't even properly understand myself. > > > > Perhaps by coincidence, the patch does at least in practice work > > (although at least `btrfs send` appears to be broken still, and I'm at a > > loss for how to approach fixing that). > > The 'receive' 32bit/64bit was broken due to size difference in the ioctl > structure that led to different ioctl. This is transparently fixed, see > BTRFS_IOC_SET_RECEIVED_SUBVOL_32 at the top of ioctl.c. > > In what way is SEND broken? There are only u64/s64 members in > btrfs_ioctl_send_args, I don't see how this could break on 32/64 > userspace/kernel. I've investigated this now, and it seems to be the pointer-type clone_sources member of struct btrfs_ioctl_send_args. I can't think of a perfect way to fix this, but it might not be *too* ugly to: - replace the current clone_sources with a u64 that must always be (u64)-1; this causes older kernels to error cleanly if called with a new ioctl data - use the top 1 or 2 bits of flags to indicate sizeof(void*) as it appears to userspace OR just use up reserved[0] for pointer size: io_send.ptr_size = sizeof(void*); - replace one of the reserved fields with the new clone_sources The way it was done for receive seems like it might not work for non-x86 compat interfaces (eg, MIPS n32) - but I could be wrong. Thoughts? Luke -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 29, 2015 at 08:22:34AM +0000, Luke Dashjr wrote: > > > I don't see what is different with that implementation. All > > > f2fs_compat_ioctl does is change cmd to the plain-IOC equivalent and > > > call f2fs_ioctl with the same arg (compat_ptr merely causes a cast to > > > void* and back, which AFAIK is a noop on 64-bit?). Am I missing > > > something? > > > > No, that's the idea. Add new calback for compat_ioctl, put it under > > #ifdef CONFIG_COMPAT and do the same number switch. > > Ok, someone else explained this to me. Please let me know if PATCHv2 (sent > separately) does not address the needed changes. Patch is ok, thanks. > > > I could try to just imitate it, but > > > I'd rather know what is significant/going on to ensure I don't waste your > > > time with code I don't even properly understand myself. > > > > > > Perhaps by coincidence, the patch does at least in practice work > > > (although at least `btrfs send` appears to be broken still, and I'm at a > > > loss for how to approach fixing that). > > > > The 'receive' 32bit/64bit was broken due to size difference in the ioctl > > structure that led to different ioctl. This is transparently fixed, see > > BTRFS_IOC_SET_RECEIVED_SUBVOL_32 at the top of ioctl.c. > > > > In what way is SEND broken? There are only u64/s64 members in > > btrfs_ioctl_send_args, I don't see how this could break on 32/64 > > userspace/kernel. > > I've investigated this now, and it seems to be the pointer-type clone_sources > member of struct btrfs_ioctl_send_args. I can't think of a perfect way to fix > this, but it might not be *too* ugly to: > - replace the current clone_sources with a u64 that must always be (u64)-1; > this causes older kernels to error cleanly if called with a new ioctl data > - use the top 1 or 2 bits of flags to indicate sizeof(void*) as it appears to > userspace OR just use up reserved[0] for pointer size: > io_send.ptr_size = sizeof(void*); > - replace one of the reserved fields with the new clone_sources All the change seem too intrusive or not so easy to use. I suggest to add an anonymous union and add a u64 member that would force the type width: struct btrfs_ioctl_send_args { __s64 send_fd; /* in */ __u64 clone_sources_count; /* in */ union { __u64 __user *clone_sources; /* in */ u64 __pointer_alignment; }; __u64 parent_root; /* in */ __u64 flags; /* in */ __u64 reserved[4]; /* in */ }; > The way it was done for receive seems like it might not work for non-x86 > compat interfaces (eg, MIPS n32) - but I could be wrong. Possible, but I don't see right now how it would not work on eg. mips32. unless sizeof(long) is 8 bytes there and CONFIG_64BIT is not defined. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thursday, October 29, 2015 2:39:32 PM David Sterba wrote: > On Thu, Oct 29, 2015 at 08:22:34AM +0000, Luke Dashjr wrote: > > > In what way is SEND broken? There are only u64/s64 members in > > > btrfs_ioctl_send_args, I don't see how this could break on 32/64 > > > userspace/kernel. > > > > I've investigated this now, and it seems to be the pointer-type > > clone_sources member of struct btrfs_ioctl_send_args. I can't think of a > > perfect way to fix this, but it might not be *too* ugly to: > > - replace the current clone_sources with a u64 that must always be > > (u64)-1; > > > > this causes older kernels to error cleanly if called with a new ioctl > > data > > > > - use the top 1 or 2 bits of flags to indicate sizeof(void*) as it > > appears to > > > > userspace OR just use up reserved[0] for pointer size: > > io_send.ptr_size = sizeof(void*); > > > > - replace one of the reserved fields with the new clone_sources > > All the change seem too intrusive or not so easy to use. > > I suggest to add an anonymous union and add a u64 member that would > force the type width: > > struct btrfs_ioctl_send_args { > __s64 send_fd; /* in */ > __u64 clone_sources_count; /* in */ > union { > __u64 __user *clone_sources; /* in */ > u64 __pointer_alignment; > }; > __u64 parent_root; /* in */ > __u64 flags; /* in */ > __u64 reserved[4]; /* in */ > }; What guarantees the union to position clone_sources in the LSB of __pointer_alignment (rather than the MSB side)? > > The way it was done for receive seems like it might not work for non-x86 > > compat interfaces (eg, MIPS n32) - but I could be wrong. > > Possible, but I don't see right now how it would not work on eg. mips32. > unless sizeof(long) is 8 bytes there and CONFIG_64BIT is not defined. n32 is a MIPS64 ABI, like the new x32 ABI for x86_64 machines, so I would expect sizeof(long) to be 8 bytes, and am uncertain of if this implies any particular alignment. (But I don't have any MIPS systems, so this isn't something I'm too concerned with myself.) Luke -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> I suggest to add an anonymous union and add a u64 member that would > force the type width: > > struct btrfs_ioctl_send_args { > __s64 send_fd; /* in */ > __u64 clone_sources_count; /* in */ > union { > __u64 __user *clone_sources; /* in */ > u64 __pointer_alignment; > }; > __u64 parent_root; /* in */ > __u64 flags; /* in */ > __u64 reserved[4]; /* in */ > }; I am no expert, but would this change alone modify the user space ABI of a 32-bit Linux kernel? I.e. people in the (presumably currently working) btrfs-send situation (32-bit) user space/32-bit kernel would have to upgrade user space tools and kernel at the same time. Otherwise, they will encounter a non-working setup. I think, my suggested patch does not change any working ABI, and no change to the user space tools are necessary. Sincerely, Thomas Rohwer -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thursday, October 29, 2015 7:36:35 PM Thomas Rohwer wrote: > > I suggest to add an anonymous union and add a u64 member that would > > force the type width: > > > > struct btrfs_ioctl_send_args { > > > > __s64 send_fd; /* in */ > > __u64 clone_sources_count; /* in */ > > > > union { > > > > __u64 __user *clone_sources; /* in */ > > u64 __pointer_alignment; > > > > }; > > > > __u64 parent_root; /* in */ > > __u64 flags; /* in */ > > __u64 reserved[4]; /* in */ > > > > }; > > I am no expert, but would this change alone modify the user space ABI of a > 32-bit Linux kernel? I.e. people in the (presumably currently working) > btrfs-send situation (32-bit) user space/32-bit kernel would have to > upgrade user space tools and kernel at the same time. Otherwise, they will > encounter a non-working setup. Yes, it would, but this appears to already be the case for btrfs-progs in general. > I think, my suggested patch does not change any working ABI, and no change > to the user space tools are necessary. Don't the user space tools need to call a different ioctl? Luke -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 1c22c65..31af093 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -5225,10 +5225,13 @@ long btrfs_ioctl(struct file *file, unsigned int switch (cmd) { case FS_IOC_GETFLAGS: + case FS_IOC32_GETFLAGS: return btrfs_ioctl_getflags(file, argp); case FS_IOC_SETFLAGS: + case FS_IOC32_SETFLAGS: return btrfs_ioctl_setflags(file, argp); case FS_IOC_GETVERSION: + case FS_IOC32_GETVERSION: return btrfs_ioctl_getversion(file, argp); case FITRIM: return btrfs_ioctl_fitrim(file, argp);
32-bit ioctl uses these rather than the regular FS_IOC_* versions. They can be handled in btrfs using the same code. Without this, 32-bit {ch,ls}attr fail. Signed-off-by: Luke Dashjr <luke-jr+git@utopios.org> --- fs/btrfs/ioctl.c | 3 +++ 1 file changed, 3 insertions(+)