diff options
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/9pfs/9p-local.c | 21 | ||||
| -rw-r--r-- | hw/9pfs/9p.c | 188 | ||||
| -rw-r--r-- | hw/9pfs/9p.h | 12 |
3 files changed, 200 insertions, 21 deletions
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c index 5c7f4cd..4708c0b 100644 --- a/hw/9pfs/9p-local.c +++ b/hw/9pfs/9p-local.c @@ -1483,6 +1483,7 @@ static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp) { const char *sec_model = qemu_opt_get(opts, "security_model"); const char *path = qemu_opt_get(opts, "path"); + const char *multidevs = qemu_opt_get(opts, "multidevs"); Error *local_err = NULL; if (!sec_model) { @@ -1506,6 +1507,26 @@ static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp) return -1; } + if (multidevs) { + if (!strcmp(multidevs, "remap")) { + fse->export_flags &= ~V9FS_FORBID_MULTIDEVS; + fse->export_flags |= V9FS_REMAP_INODES; + } else if (!strcmp(multidevs, "forbid")) { + fse->export_flags &= ~V9FS_REMAP_INODES; + fse->export_flags |= V9FS_FORBID_MULTIDEVS; + } else if (!strcmp(multidevs, "warn")) { + fse->export_flags &= ~V9FS_FORBID_MULTIDEVS; + fse->export_flags &= ~V9FS_REMAP_INODES; + } else { + error_setg(&local_err, "invalid multidevs property '%s'", + multidevs); + error_append_hint(&local_err, "Valid options are: multidevs=" + "[remap|forbid|warn]\n"); + error_propagate(errp, local_err); + return -1; + } + } + if (!path) { error_setg(errp, "path property not set"); return -1; diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 5a895ae..8eb89c5 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -26,6 +26,7 @@ #include "trace.h" #include "migration/blocker.h" #include "sysemu/qtest.h" +#include "qemu/xxhash.h" int open_fd_hw; int total_open_fd; @@ -572,23 +573,117 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu) P9_STAT_MODE_NAMED_PIPE | \ P9_STAT_MODE_SOCKET) -/* This is the algorithm from ufs in spfs */ +/* creative abuse of tb_hash_func7, which is based on xxhash */ +static uint32_t qpp_hash(QppEntry e) +{ + return qemu_xxhash7(e.ino_prefix, e.dev, 0, 0, 0); +} + +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; +} + +static void qpp_table_remove(void *p, uint32_t h, void *up) +{ + g_free(p); +} + +static void qpp_table_destroy(struct qht *ht) +{ + if (!ht || !ht->map) { + return; + } + qht_iter(ht, qpp_table_remove, NULL); + qht_destroy(ht); +} + +static void qpp_table_init(struct qht *ht) +{ + qht_init(ht, qpp_lookup_func, 1, QHT_MODE_AUTO_RESIZE); +} + +/* + * 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 + * the device id to the 16 highest bits of the QID path. The 48 lowest bits + * of the QID path equal to the lowest bits of the inode number. + * + * This takes advantage of the fact that inode number are usually not + * random but allocated sequentially, so we have fewer items to keep + * track of. + */ +static int qid_path_prefixmap(V9fsPDU *pdu, const struct stat *stbuf, + uint64_t *path) +{ + QppEntry lookup = { + .dev = stbuf->st_dev, + .ino_prefix = (uint16_t) (stbuf->st_ino >> 48) + }, *val; + uint32_t hash = qpp_hash(lookup); + + val = qht_lookup(&pdu->s->qpp_table, &lookup, hash); + + if (!val) { + if (pdu->s->qp_prefix_next == 0) { + /* we ran out of prefixes */ + error_report_once( + "9p: No more prefixes available for remapping inodes from " + "host to guest." + ); + return -ENFILE; + } + + val = g_malloc0(sizeof(QppEntry)); + *val = lookup; + + /* new unique inode prefix and device combo */ + val->qp_prefix = pdu->s->qp_prefix_next++; + qht_insert(&pdu->s->qpp_table, val, hash, NULL); + } + + *path = ((uint64_t)val->qp_prefix << 48) | (stbuf->st_ino & QPATH_INO_MASK); + return 0; +} + static int stat_to_qid(V9fsPDU *pdu, const struct stat *stbuf, V9fsQID *qidp) { + int err; size_t size; - if (pdu->s->dev_id != stbuf->st_dev) { - warn_report_once( - "9p: Multiple devices detected in same VirtFS export, " - "which might lead to file ID collisions and severe " - "misbehaviours on guest! You should use a separate " - "export for each device shared from host." - ); + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { + /* map inode+device to qid path (fast path) */ + err = qid_path_prefixmap(pdu, stbuf, &qidp->path); + if (err) { + return err; + } + } else { + if (pdu->s->dev_id != stbuf->st_dev) { + if (pdu->s->ctx.export_flags & V9FS_FORBID_MULTIDEVS) { + error_report_once( + "9p: Multiple devices detected in same VirtFS export. " + "Access of guest to additional devices is (partly) " + "denied due to virtfs option 'multidevs=forbid' being " + "effective." + ); + return -ENODEV; + } else { + warn_report_once( + "9p: Multiple devices detected in same VirtFS export, " + "which might lead to file ID collisions and severe " + "misbehaviours on guest! You should either use a " + "separate export for each device shared from host or " + "use virtfs option 'multidevs=remap'!" + ); + } + } + memset(&qidp->path, 0, sizeof(qidp->path)); + size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); + memcpy(&qidp->path, &stbuf->st_ino, size); } - memset(&qidp->path, 0, sizeof(qidp->path)); - size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); - memcpy(&qidp->path, &stbuf->st_ino, size); qidp->version = stbuf->st_mtime ^ (stbuf->st_size << 8); qidp->type = 0; if (S_ISDIR(stbuf->st_mode)) { @@ -618,6 +713,30 @@ static int coroutine_fn fid_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, return 0; } +static int coroutine_fn dirent_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, + struct dirent *dent, V9fsQID *qidp) +{ + struct stat stbuf; + V9fsPath path; + int err; + + v9fs_path_init(&path); + + err = v9fs_co_name_to_path(pdu, &fidp->path, dent->d_name, &path); + if (err < 0) { + goto out; + } + err = v9fs_co_lstat(pdu, &path, &stbuf); + if (err < 0) { + goto out; + } + err = stat_to_qid(pdu, &stbuf, qidp); + +out: + v9fs_path_free(&path); + return err; +} + V9fsPDU *pdu_alloc(V9fsState *s) { V9fsPDU *pdu = NULL; @@ -1966,16 +2085,39 @@ static int coroutine_fn v9fs_do_readdir(V9fsPDU *pdu, V9fsFidState *fidp, v9fs_string_free(&name); return count; } - /* - * Fill up just the path field of qid because the client uses - * only that. To fill the entire qid structure we will have - * to stat each dirent found, which is expensive - */ - size = MIN(sizeof(dent->d_ino), sizeof(qid.path)); - memcpy(&qid.path, &dent->d_ino, size); - /* Fill the other fields with dummy values */ - qid.type = 0; - qid.version = 0; + + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { + /* + * dirent_to_qid() implies expensive stat call for each entry, + * we must do that here though since inode remapping requires + * the device id, which in turn might be different for + * different entries; we cannot make any assumption to avoid + * that here. + */ + err = dirent_to_qid(pdu, fidp, dent, &qid); + if (err < 0) { + v9fs_readdir_unlock(&fidp->fs.dir); + v9fs_co_seekdir(pdu, fidp, saved_dir_pos); + v9fs_string_free(&name); + return err; + } + } else { + /* + * Fill up just the path field of qid because the client uses + * only that. To fill the entire qid structure we will have + * to stat each dirent found, which is expensive. For the + * latter reason we don't call dirent_to_qid() here. Only drawback + * is that no multi-device export detection of stat_to_qid() + * would be done and provided as error to the user here. But + * user would get that error anyway when accessing those + * files/dirs through other ways. + */ + size = MIN(sizeof(dent->d_ino), sizeof(qid.path)); + memcpy(&qid.path, &dent->d_ino, size); + /* Fill the other fields with dummy values */ + qid.type = 0; + qid.version = 0; + } /* 11 = 7 + 4 (7 = start offset, 4 = space for storing count) */ len = pdu_marshal(pdu, 11 + count, "Qqbs", @@ -3676,6 +3818,9 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, s->dev_id = stat.st_dev; + qpp_table_init(&s->qpp_table); + s->qp_prefix_next = 1; /* reserve 0 to detect overflow */ + s->ctx.fst = &fse->fst; fsdev_throttle_init(s->ctx.fst); @@ -3697,6 +3842,7 @@ 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); g_free(s->ctx.fs_root); } diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index 5e31617..7262fe8 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -8,6 +8,7 @@ #include "fsdev/9p-iov-marshal.h" #include "qemu/thread.h" #include "qemu/coroutine.h" +#include "qemu/qht.h" enum { P9_TLERROR = 6, @@ -235,6 +236,15 @@ struct V9fsFidState V9fsFidState *rclm_lst; }; +#define QPATH_INO_MASK ((1ULL << 48) - 1) + +/* QID path prefix entry, see stat_to_qid */ +typedef struct { + dev_t dev; + uint16_t ino_prefix; + uint16_t qp_prefix; +} QppEntry; + struct V9fsState { QLIST_HEAD(, V9fsPDU) free_list; @@ -257,6 +267,8 @@ struct V9fsState V9fsConf fsconf; V9fsQID root_qid; dev_t dev_id; + struct qht qpp_table; + uint16_t qp_prefix_next; }; /* 9p2000.L open flags */ |