| Message ID | 20191212163904.159893-91-dgilbert@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtiofs daemon [all] | expand |
On 12/12/19 5:38 PM, Dr. David Alan Gilbert (git) wrote: > From: Stefan Hajnoczi <stefanha@redhat.com> > > This reference counter plays a specific role in the FUSE protocol. It's > not a generic object reference counter and the FUSE kernel code calls it > "nlookup". > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > tools/virtiofsd/passthrough_ll.c | 37 +++++++++++++++++++++----------- > 1 file changed, 25 insertions(+), 12 deletions(-) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 7663e574d8..b19c9ee328 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -101,7 +101,20 @@ struct lo_inode { > int fd; > bool is_symlink; > struct lo_key key; > - uint64_t refcount; /* protected by lo->mutex */ > + > + /* > + * This counter keeps the inode alive during the FUSE session. > + * Incremented when the FUSE inode number is sent in a reply > + * (FUSE_LOOKUP, FUSE_READDIRPLUS, etc). Decremented when an inode is > + * released by requests like FUSE_FORGET, FUSE_RMDIR, FUSE_RENAME, etc. > + * > + * Note that this value is untrusted because the client can manipulate > + * it arbitrarily using FUSE_FORGET requests. > + * > + * Protected by lo->mutex. > + */ > + uint64_t nlookup; > + > fuse_ino_t fuse_ino; > pthread_mutex_t plock_mutex; > GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */ > @@ -570,7 +583,7 @@ retry: > if (last == path) { > p = &lo->root; > pthread_mutex_lock(&lo->mutex); > - p->refcount++; > + p->nlookup++; > pthread_mutex_unlock(&lo->mutex); > } else { > *last = '\0'; > @@ -788,8 +801,8 @@ static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st) > pthread_mutex_lock(&lo->mutex); > p = g_hash_table_lookup(lo->inodes, &key); > if (p) { > - assert(p->refcount > 0); > - p->refcount++; > + assert(p->nlookup > 0); > + p->nlookup++; > } > pthread_mutex_unlock(&lo->mutex); > > @@ -857,7 +870,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name, > } > > inode->is_symlink = S_ISLNK(e->attr.st_mode); > - inode->refcount = 1; > + inode->nlookup = 1; > inode->fd = newfd; > newfd = -1; > inode->key.ino = e->attr.st_ino; > @@ -1097,7 +1110,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, > } > > pthread_mutex_lock(&lo->mutex); > - inode->refcount++; > + inode->nlookup++; > pthread_mutex_unlock(&lo->mutex); > e.ino = inode->fuse_ino; > > @@ -1226,9 +1239,9 @@ static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode, > } > > pthread_mutex_lock(&lo->mutex); > - assert(inode->refcount >= n); > - inode->refcount -= n; > - if (!inode->refcount) { > + assert(inode->nlookup >= n); > + inode->nlookup -= n; > + if (!inode->nlookup) { > lo_map_remove(&lo->ino_map, inode->fuse_ino); > g_hash_table_remove(lo->inodes, &inode->key); > if (g_hash_table_size(inode->posix_locks)) { > @@ -1249,7 +1262,7 @@ static int unref_all_inodes_cb(gpointer key, gpointer value, gpointer user_data) > struct lo_inode *inode = value; > struct lo_data *lo = user_data; > > - inode->refcount = 0; > + inode->nlookup = 0; > lo_map_remove(&lo->ino_map, inode->fuse_ino); > close(inode->fd); > > @@ -1274,7 +1287,7 @@ static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup) > } > > fuse_log(FUSE_LOG_DEBUG, " forget %lli %lli -%lli\n", > - (unsigned long long)ino, (unsigned long long)inode->refcount, > + (unsigned long long)ino, (unsigned long long)inode->nlookup, > (unsigned long long)nlookup); > > unref_inode_lolocked(lo, inode, nlookup); > @@ -2642,7 +2655,7 @@ static void setup_root(struct lo_data *lo, struct lo_inode *root) > root->fd = fd; > root->key.ino = stat.st_ino; > root->key.dev = stat.st_dev; > - root->refcount = 2; > + root->nlookup = 2; > } > > static guint lo_key_hash(gconstpointer key) > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 7663e574d8..b19c9ee328 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -101,7 +101,20 @@ struct lo_inode { int fd; bool is_symlink; struct lo_key key; - uint64_t refcount; /* protected by lo->mutex */ + + /* + * This counter keeps the inode alive during the FUSE session. + * Incremented when the FUSE inode number is sent in a reply + * (FUSE_LOOKUP, FUSE_READDIRPLUS, etc). Decremented when an inode is + * released by requests like FUSE_FORGET, FUSE_RMDIR, FUSE_RENAME, etc. + * + * Note that this value is untrusted because the client can manipulate + * it arbitrarily using FUSE_FORGET requests. + * + * Protected by lo->mutex. + */ + uint64_t nlookup; + fuse_ino_t fuse_ino; pthread_mutex_t plock_mutex; GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */ @@ -570,7 +583,7 @@ retry: if (last == path) { p = &lo->root; pthread_mutex_lock(&lo->mutex); - p->refcount++; + p->nlookup++; pthread_mutex_unlock(&lo->mutex); } else { *last = '\0'; @@ -788,8 +801,8 @@ static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st) pthread_mutex_lock(&lo->mutex); p = g_hash_table_lookup(lo->inodes, &key); if (p) { - assert(p->refcount > 0); - p->refcount++; + assert(p->nlookup > 0); + p->nlookup++; } pthread_mutex_unlock(&lo->mutex); @@ -857,7 +870,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name, } inode->is_symlink = S_ISLNK(e->attr.st_mode); - inode->refcount = 1; + inode->nlookup = 1; inode->fd = newfd; newfd = -1; inode->key.ino = e->attr.st_ino; @@ -1097,7 +1110,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, } pthread_mutex_lock(&lo->mutex); - inode->refcount++; + inode->nlookup++; pthread_mutex_unlock(&lo->mutex); e.ino = inode->fuse_ino; @@ -1226,9 +1239,9 @@ static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode, } pthread_mutex_lock(&lo->mutex); - assert(inode->refcount >= n); - inode->refcount -= n; - if (!inode->refcount) { + assert(inode->nlookup >= n); + inode->nlookup -= n; + if (!inode->nlookup) { lo_map_remove(&lo->ino_map, inode->fuse_ino); g_hash_table_remove(lo->inodes, &inode->key); if (g_hash_table_size(inode->posix_locks)) { @@ -1249,7 +1262,7 @@ static int unref_all_inodes_cb(gpointer key, gpointer value, gpointer user_data) struct lo_inode *inode = value; struct lo_data *lo = user_data; - inode->refcount = 0; + inode->nlookup = 0; lo_map_remove(&lo->ino_map, inode->fuse_ino); close(inode->fd); @@ -1274,7 +1287,7 @@ static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup) } fuse_log(FUSE_LOG_DEBUG, " forget %lli %lli -%lli\n", - (unsigned long long)ino, (unsigned long long)inode->refcount, + (unsigned long long)ino, (unsigned long long)inode->nlookup, (unsigned long long)nlookup); unref_inode_lolocked(lo, inode, nlookup); @@ -2642,7 +2655,7 @@ static void setup_root(struct lo_data *lo, struct lo_inode *root) root->fd = fd; root->key.ino = stat.st_ino; root->key.dev = stat.st_dev; - root->refcount = 2; + root->nlookup = 2; } static guint lo_key_hash(gconstpointer key)