Date: Fri, 28 Jun 2019 00:09:40 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Alan Somers <asomers@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r349231 - in head/sys: kern sys ufs/ufs Message-ID: <20190627210940.GR8697@kib.kiev.ua> In-Reply-To: <CAOtMX2hO3ed=GevyDmzh8VOVT3Zw5yYNKpCBENrWSm_w2nuM3g@mail.gmail.com> References: <201906201413.x5KEDB5u010923@repo.freebsd.org> <20190627191843.GQ8697@kib.kiev.ua> <CAOtMX2hO3ed=GevyDmzh8VOVT3Zw5yYNKpCBENrWSm_w2nuM3g@mail.gmail.com>
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On Thu, Jun 27, 2019 at 02:01:11PM -0600, Alan Somers wrote: > On Thu, Jun 27, 2019 at 1:18 PM Konstantin Belousov <kostikbel@gmail.com> wrote: > > > > On Thu, Jun 20, 2019 at 02:13:11PM +0000, Alan Somers wrote: > > > Author: asomers > > > Date: Thu Jun 20 14:13:10 2019 > > > New Revision: 349231 > > > URL: https://svnweb.freebsd.org/changeset/base/349231 > > > > > > Log: > > > Add FIOBMAP2 ioctl > > > > > > > > This ioctl exposes VOP_BMAP information to userland. It can be used by > > > programs like fragmentation analyzers and optimized cp implementations. But > > > I'm using it to test fusefs's VOP_BMAP implementation. The "2" in the name > > > distinguishes it from the similar but incompatible FIBMAP ioctls in NetBSD > > > and Linux. FIOBMAP2 differs from FIBMAP in that it uses a 64-bit block > > > number instead of 32-bit, and it also returns runp and runb. > > > > > > Reviewed by: mckusick > > > MFC after: 2 weeks > > > Sponsored by: The FreeBSD Foundation > > > Differential Revision: https://reviews.freebsd.org/D20705 > > > > > > Modified: > > > head/sys/kern/vfs_vnops.c > > > head/sys/sys/filio.h > > > head/sys/ufs/ufs/ufs_bmap.c > > > > > > Modified: head/sys/kern/vfs_vnops.c > > > ============================================================================== > > > --- head/sys/kern/vfs_vnops.c Thu Jun 20 13:59:46 2019 (r349230) > > > +++ head/sys/kern/vfs_vnops.c Thu Jun 20 14:13:10 2019 (r349231) > > > @@ -1458,6 +1458,25 @@ vn_stat(struct vnode *vp, struct stat *sb, struct ucre > > > return (0); > > > } > > > > > > +/* generic FIOBMAP2 implementation */ > > > +static int > > > +vn_ioc_bmap2(struct file *fp, struct fiobmap2_arg *arg, struct ucred *cred) > > I do not like the fact that internal kernel function takes the > > user-visible structure which results in the mix of ABI and KBI. > > Traditionally we pass explicit arguments to kern_XXX, vn_XXX and similar > > internal implementations. > > Ok. It will increase the number of function arguments, which is ugly, > but I can do it if you prefer. > > > > > > +{ > > > + struct vnode *vp = fp->f_vnode; > > Why do you pass fp to the function that > > 1. Has vn_ namespace, i.e. operating on vnode. > > 2. Only needs vnode to operate on. > > Please change the argument from fp to vp. You would need to pass f_cred > > as additional argument, or move mac check to vn_ioctl (I think this is > > a better approach). > > Ok. > > > > > > + daddr_t lbn = arg->bn; > > Style: initialization in declaration. > > > > > + int error; > > > + > > > + vn_lock(vp, LK_SHARED | LK_RETRY); > > > +#ifdef MAC > > > + error = mac_vnode_check_read(cred, fp->f_cred, vp); > > > + if (error == 0) > > > +#endif > > > + error = VOP_BMAP(vp, lbn, NULL, &arg->bn, &arg->runp, > > > + &arg->runb); > > Wrong indent for continuation line. > > > > > + VOP_UNLOCK(vp, 0); > > > + return (error); > > > +} > > > + > > > /* > > > * File table vnode ioctl routine. > > > */ > > > @@ -1481,6 +1500,9 @@ vn_ioctl(struct file *fp, u_long com, void *data, stru > > > if (error == 0) > > > *(int *)data = vattr.va_size - fp->f_offset; > > > return (error); > > > + case FIOBMAP2: > > > + return (vn_ioc_bmap2(fp, (struct fiobmap2_arg*)data, > > Need space between fiobmap2_arg and '*'. > > > + active_cred)); > > Wrong indent. > > > > > case FIONBIO: > > > case FIOASYNC: > > > return (0); > > > > > > Modified: head/sys/sys/filio.h > > > ============================================================================== > > > --- head/sys/sys/filio.h Thu Jun 20 13:59:46 2019 (r349230) > > > +++ head/sys/sys/filio.h Thu Jun 20 14:13:10 2019 (r349231) > > > @@ -62,6 +62,13 @@ struct fiodgname_arg { > > > /* Handle lseek SEEK_DATA and SEEK_HOLE for holey file knowledge. */ > > > #define FIOSEEKDATA _IOWR('f', 97, off_t) /* SEEK_DATA */ > > > #define FIOSEEKHOLE _IOWR('f', 98, off_t) /* SEEK_HOLE */ > > > +struct fiobmap2_arg { > > > + int64_t bn; > > > + int runp; > > > + int runb; > > > +}; > > This structure has different layout for LP64 and ILP32, and you did not > > provided the compat shims. > > Really? How so? All of the fields have the same width on 64 and 32 > bit archs, and there shouldn't be any need for padding, either. Sorry, you are right. > > > > > > +/* Get the file's bmap info for the logical block bn */ > > > +#define FIOBMAP2 _IOWR('f', 99, struct fiobmap2_arg) > > > > > > #ifdef _KERNEL > > > #ifdef COMPAT_FREEBSD32 > > > > > > Modified: head/sys/ufs/ufs/ufs_bmap.c > > > ============================================================================== > > > --- head/sys/ufs/ufs/ufs_bmap.c Thu Jun 20 13:59:46 2019 (r349230) > > > +++ head/sys/ufs/ufs/ufs_bmap.c Thu Jun 20 14:13:10 2019 (r349231) > > > @@ -200,12 +200,15 @@ ufs_bmaparray(vp, bn, bnp, nbp, runp, runb) > > > *bnp = blkptrtodb(ump, ip->i_din2->di_extb[-1 - bn]); > > > if (*bnp == 0) > > > *bnp = -1; > > > - if (nbp == NULL) > > > - panic("ufs_bmaparray: mapping ext data"); > > > + if (nbp == NULL) { > > > + /* indirect block not found */ > > > + return (EINVAL); > > > + } > > This (and next chunk) loose useful checks for in-kernel interfaces. > > mckusick disagrees with you on this. He thought that changing the > panics into errors was a good idea. Note that ufs_bmap was already > capable of returning errors that not all callers check. For user-callable code, this is of course the requirement. But for in-kernel use, IMO it makes the interfaces loose.
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