The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=a0895e394d3fec374e61a207bdfa0245dae86f53
commit a0895e394d3fec374e61a207bdfa0245dae86f53 Author: Mark Johnston <[email protected]> AuthorDate: 2024-04-05 15:14:36 +0000 Commit: Mark Johnston <[email protected]> CommitDate: 2024-04-05 15:14:36 +0000 tarfs: Implement VOP_BMAP This lets tarfs provide readahead/behind hints to the VFS, which helps memory-mapped I/O performance, important when running faulting in executables out of a tarfs mount as one might if tarfs is used to back the root filesystem, for example. The improvement is particularly noticeable when the backing tarball is zstd-compressed. The implementation simply returns the extent of the virtual block containing the target offset, clamped by the maximum I/O size. This is perhaps simplistic; it effectively just chooses values that would correspond to a single VOP_READ call in tarfs_read_file(). Reviewed by: des, kib MFC after: 1 month Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D44626 --- sys/fs/tarfs/tarfs_vnops.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/sys/fs/tarfs/tarfs_vnops.c b/sys/fs/tarfs/tarfs_vnops.c index 7a04f891350e..f2828c60f8a7 100644 --- a/sys/fs/tarfs/tarfs_vnops.c +++ b/sys/fs/tarfs/tarfs_vnops.c @@ -125,6 +125,60 @@ tarfs_access(struct vop_access_args *ap) return (error); } +static int +tarfs_bmap(struct vop_bmap_args *ap) +{ + struct tarfs_node *tnp; + struct vnode *vp; + off_t off; + uint64_t iosize; + int ra, rb, rmax; + + vp = ap->a_vp; + iosize = vp->v_mount->mnt_stat.f_iosize; + + if (ap->a_bop != NULL) + *ap->a_bop = &vp->v_bufobj; + if (ap->a_bnp != NULL) + *ap->a_bnp = ap->a_bn * btodb(iosize); + if (ap->a_runp == NULL) + return (0); + + tnp = VP_TO_TARFS_NODE(vp); + off = ap->a_bn * iosize; + + ra = rb = 0; + for (u_int i = 0; i < tnp->nblk; i++) { + off_t bs, be; + + bs = tnp->blk[i].o; + be = tnp->blk[i].o + tnp->blk[i].l; + if (off > be) + continue; + else if (off < bs) { + /* We're in a hole. */ + ra = bs - off < iosize ? + 0 : howmany(bs - (off + iosize), iosize); + rb = howmany(off - (i == 0 ? + 0 : tnp->blk[i - 1].o + tnp->blk[i - 1].l), + iosize); + break; + } else { + /* We'll be reading from the backing file. */ + ra = be - off < iosize ? + 0 : howmany(be - (off + iosize), iosize); + rb = howmany(off - bs, iosize); + break; + } + } + + rmax = vp->v_mount->mnt_iosize_max / iosize - 1; + *ap->a_runp = imin(ra, rmax); + if (ap->a_runb != NULL) + *ap->a_runb = imin(rb, rmax); + return (0); +} + static int tarfs_getattr(struct vop_getattr_args *ap) { @@ -629,6 +683,7 @@ struct vop_vector tarfs_vnodeops = { .vop_default = &default_vnodeops, .vop_access = tarfs_access, + .vop_bmap = tarfs_bmap, .vop_cachedlookup = tarfs_lookup, .vop_close = tarfs_close, .vop_getattr = tarfs_getattr,
