On Thu, 8 Feb 2018 19:00:19 +0100 <antonios.mota...@huawei.com> wrote:
> From: Antonios Motakis <antonios.mota...@huawei.com> > > stat_to_qid attempts via qid_path_prefixmap to map unique files > (which are identified by 64bt inode nr and 32 bit device id) > to a 64 QID path value. However this implementation makes some > assumptions about inode number generation on the host. > > If qid_path_prefixmap fails, we still have 48bits available in > the QID path to fall back to a less memory efficient full mapping. > > Signed-off-by: Antonios Motakis <antonios.mota...@huawei.com> > --- > hw/9pfs/9p.c | 66 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++----- > hw/9pfs/9p.h | 9 +++++++++ > 2 files changed, 70 insertions(+), 5 deletions(-) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index f434f05..ae7845d 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -581,23 +581,72 @@ static uint32_t qpp_hash(QppEntry e) > return tb_hash_func7(e.ino_prefix, e.dev, 0, 0, 0); > } > > +static uint32_t qpf_hash(QpfEntry e) > +{ > + return tb_hash_func7(e.ino, e.dev, 0, 0, 0); Same remark as with previous patch, obviously :) > +} > + > static bool qpp_lookup_func(const void *obj, const void *userp) > { > const QppEntry *e1 = obj, *e2 = userp; > return (e1->dev == e2->dev) && (e1->ino_prefix == e2->ino_prefix); Parenthesitis ? ;) > } > > -static void qpp_table_remove(struct qht *ht, void *p, uint32_t h, void *up) > +static bool qpf_lookup_func(const void *obj, const void *userp) > +{ > + const QpfEntry *e1 = obj, *e2 = userp; > + return (e1->dev == e2->dev) && (e1->ino == e2->ino); Parenthesitis ? ;) > +} > + > +static void qp_table_remove(struct qht *ht, void *p, uint32_t h, void *up) > { > g_free(p); > } > > -static void qpp_table_destroy(struct qht *ht) > +static void qp_table_destroy(struct qht *ht) > { > - qht_iter(ht, qpp_table_remove, NULL); > + qht_iter(ht, qp_table_remove, NULL); > qht_destroy(ht); > } > > +static int qid_path_fullmap(V9fsPDU *pdu, const struct stat *stbuf, > + uint64_t *path) > +{ > + QpfEntry lookup = { > + .dev = stbuf->st_dev, > + .ino = stbuf->st_ino > + }, *val; > + uint32_t hash = qpf_hash(lookup); > + > + /* most users won't need the fullmap, so init the table lazily */ > + if (!pdu->s->qpf_table.map) { > + qht_init(&pdu->s->qpf_table, 1 << 16, QHT_MODE_AUTO_RESIZE); > + } > + > + val = qht_lookup(&pdu->s->qpf_table, qpf_lookup_func, &lookup, hash); > + > + if (!val) { > + if (pdu->s->qp_fullpath_next == 0) { > + /* no more files can be mapped :'( */ > + return -ENFILE; > + } > + > + val = g_malloc0(sizeof(QppEntry)); > + if (!val) { > + return -ENOMEM; > + } > + *val = lookup; > + > + /* new unique inode and device combo */ > + val->path = pdu->s->qp_fullpath_next++; > + pdu->s->qp_fullpath_next &= QPATH_INO_MASK; > + qht_insert(&pdu->s->qpf_table, val, hash); > + } > + > + *path = val->path; > + return 0; > +} > + > /* stat_to_qid needs to map inode number (64 bits) and device id (32 bits) > * to a unique QID path (64 bits). To avoid having to map and keep track > * of up to 2^64 objects, we map only the 16 highest bits of the inode plus > @@ -646,6 +695,10 @@ static int stat_to_qid(V9fsPDU *pdu, const struct stat > *stbuf, V9fsQID *qidp) > > /* map inode+device to qid path (fast path) */ > err = qid_path_prefixmap(pdu, stbuf, &qidp->path); > + if (err == -ENFILE) { > + /* fast path didn't work, fal back to full map */ > + err = qid_path_fullmap(pdu, stbuf, &qidp->path); Hmm... if we have already generate QIDs with fast path, how can we be sure we won't collide with the ones from the full map ? IIRC, Emilio had suggested to use bit 63 to distinguish between fast and slow path. > + } > if (err) { > return err; > } > @@ -3693,6 +3746,7 @@ int v9fs_device_realize_common(V9fsState *s, const > V9fsTransport *t, > /* QID path hash table. 1 entry ought to be enough for anybody ;) */ > qht_init(&s->qpp_table, 1, QHT_MODE_AUTO_RESIZE); > s->qp_prefix_next = 1; /* reserve 0 to detect overflow */ > + s->qp_fullpath_next = 1; > > s->ctx.fst = &fse->fst; > fsdev_throttle_init(s->ctx.fst); > @@ -3707,7 +3761,8 @@ out: > } > g_free(s->tag); > g_free(s->ctx.fs_root); > - qpp_table_destroy(&s->qpp_table); > + qp_table_destroy(&s->qpp_table); > + qp_table_destroy(&s->qpf_table); > v9fs_path_free(&path); > } > return rc; > @@ -3720,7 +3775,8 @@ void v9fs_device_unrealize_common(V9fsState *s, Error > **errp) > } > fsdev_throttle_cleanup(s->ctx.fst); > g_free(s->tag); > - qpp_table_destroy(&s->qpp_table); > + qp_table_destroy(&s->qpp_table); > + qp_table_destroy(&s->qpf_table); > g_free(s->ctx.fs_root); > } > > diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h > index 80428f7..b561f4a 100644 > --- a/hw/9pfs/9p.h > +++ b/hw/9pfs/9p.h > @@ -241,6 +241,13 @@ typedef struct { > uint16_t qp_prefix; > } QppEntry; > > +/* QID path full entry, as above */ > +typedef struct { > + dev_t dev; > + ino_t ino; > + uint64_t path; > +} QpfEntry; > + > struct V9fsState > { > QLIST_HEAD(, V9fsPDU) free_list; > @@ -263,7 +270,9 @@ struct V9fsState > V9fsConf fsconf; > V9fsQID root_qid; > struct qht qpp_table; > + struct qht qpf_table; > uint16_t qp_prefix_next; > + uint64_t qp_fullpath_next; > }; > > /* 9p2000.L open flags */