124 lines
4.3 KiB
Diff
124 lines
4.3 KiB
Diff
From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Mon, 27 Jan 2020 19:02:08 +0000
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Subject: [PATCH] virtiofsd: rename inode->refcount to inode->nlookup
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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This reference counter plays a specific role in the FUSE protocol. It's
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not a generic object reference counter and the FUSE kernel code calls it
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"nlookup".
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 1222f015558fc34cea02aa3a5a92de608c82cec8)
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---
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tools/virtiofsd/passthrough_ll.c | 37 +++++++++++++++++++++-----------
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1 file changed, 25 insertions(+), 12 deletions(-)
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index 2d703b57e5..c819b5f782 100644
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--- a/tools/virtiofsd/passthrough_ll.c
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+++ b/tools/virtiofsd/passthrough_ll.c
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@@ -99,7 +99,20 @@ struct lo_inode {
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int fd;
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bool is_symlink;
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struct lo_key key;
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- uint64_t refcount; /* protected by lo->mutex */
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+
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+ /*
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+ * This counter keeps the inode alive during the FUSE session.
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+ * Incremented when the FUSE inode number is sent in a reply
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+ * (FUSE_LOOKUP, FUSE_READDIRPLUS, etc). Decremented when an inode is
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+ * released by requests like FUSE_FORGET, FUSE_RMDIR, FUSE_RENAME, etc.
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+ *
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+ * Note that this value is untrusted because the client can manipulate
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+ * it arbitrarily using FUSE_FORGET requests.
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+ *
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+ * Protected by lo->mutex.
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+ */
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+ uint64_t nlookup;
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+
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fuse_ino_t fuse_ino;
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pthread_mutex_t plock_mutex;
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GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */
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@@ -568,7 +581,7 @@ retry:
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if (last == path) {
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p = &lo->root;
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pthread_mutex_lock(&lo->mutex);
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- p->refcount++;
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+ p->nlookup++;
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pthread_mutex_unlock(&lo->mutex);
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} else {
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*last = '\0';
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@@ -786,8 +799,8 @@ static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st)
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pthread_mutex_lock(&lo->mutex);
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p = g_hash_table_lookup(lo->inodes, &key);
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if (p) {
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- assert(p->refcount > 0);
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- p->refcount++;
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+ assert(p->nlookup > 0);
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+ p->nlookup++;
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}
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pthread_mutex_unlock(&lo->mutex);
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@@ -855,7 +868,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
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}
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inode->is_symlink = S_ISLNK(e->attr.st_mode);
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- inode->refcount = 1;
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+ inode->nlookup = 1;
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inode->fd = newfd;
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newfd = -1;
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inode->key.ino = e->attr.st_ino;
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@@ -1112,7 +1125,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,
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}
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pthread_mutex_lock(&lo->mutex);
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- inode->refcount++;
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+ inode->nlookup++;
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pthread_mutex_unlock(&lo->mutex);
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e.ino = inode->fuse_ino;
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@@ -1193,9 +1206,9 @@ static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode,
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}
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pthread_mutex_lock(&lo->mutex);
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- assert(inode->refcount >= n);
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- inode->refcount -= n;
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- if (!inode->refcount) {
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+ assert(inode->nlookup >= n);
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+ inode->nlookup -= n;
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+ if (!inode->nlookup) {
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lo_map_remove(&lo->ino_map, inode->fuse_ino);
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g_hash_table_remove(lo->inodes, &inode->key);
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if (g_hash_table_size(inode->posix_locks)) {
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@@ -1216,7 +1229,7 @@ static int unref_all_inodes_cb(gpointer key, gpointer value, gpointer user_data)
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struct lo_inode *inode = value;
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struct lo_data *lo = user_data;
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- inode->refcount = 0;
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+ inode->nlookup = 0;
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lo_map_remove(&lo->ino_map, inode->fuse_ino);
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close(inode->fd);
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@@ -1241,7 +1254,7 @@ static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup)
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}
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fuse_log(FUSE_LOG_DEBUG, " forget %lli %lli -%lli\n",
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- (unsigned long long)ino, (unsigned long long)inode->refcount,
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+ (unsigned long long)ino, (unsigned long long)inode->nlookup,
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(unsigned long long)nlookup);
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unref_inode_lolocked(lo, inode, nlookup);
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@@ -2609,7 +2622,7 @@ static void setup_root(struct lo_data *lo, struct lo_inode *root)
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root->fd = fd;
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root->key.ino = stat.st_ino;
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root->key.dev = stat.st_dev;
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- root->refcount = 2;
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+ root->nlookup = 2;
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}
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static guint lo_key_hash(gconstpointer key)
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