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virtiofsd: rename inode->refcount to inode->nlookup

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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>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2019-07-31 17:10:04 +01:00 committed by Dr. David Alan Gilbert
parent acefdde73b
commit 1222f01555
1 changed files with 25 additions and 12 deletions
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37
tools/virtiofsd/passthrough_ll.c
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@ -99,7 +99,20 @@ 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 */
@ -568,7 +581,7 @@ retry:
if (last == path) {
p = &lo->root;
pthread_mutex_lock(&lo->mutex);
p->refcount++;
p->nlookup++;
pthread_mutex_unlock(&lo->mutex);
} else {
*last = '\0';
@ -786,8 +799,8 @@ 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);
@ -855,7 +868,7 @@ 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;
@ -1112,7 +1125,7 @@ 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;
@ -1193,9 +1206,9 @@ 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)) {
@ -1216,7 +1229,7 @@ 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);
@ -1241,7 +1254,7 @@ 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);
@ -2609,7 +2622,7 @@ 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)