From: Miklos Szeredi <mszeredi@redhat.com>

Date: Mon, 27 Jan 2020 19:01:52 +0000

Subject: [PATCH] virtiofsd: passthrough_ll: use hashtable

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Improve performance of inode lookup by using a hash table.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

(cherry picked from commit bfc50a6e06b10b2f9dbaf6c1a89dd523322e016f)

---

 tools/virtiofsd/passthrough_ll.c | 81 ++++++++++++++++++--------------

 1 file changed, 45 insertions(+), 36 deletions(-)

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c

index b40f2874a7..b176a314d6 100644

--- a/tools/virtiofsd/passthrough_ll.c

+++ b/tools/virtiofsd/passthrough_ll.c

@@ -84,13 +84,15 @@ struct lo_map {

     ssize_t freelist;

 };

+struct lo_key {

+    ino_t ino;

+    dev_t dev;

+};

+

 struct lo_inode {

-    struct lo_inode *next; /* protected by lo->mutex */

-    struct lo_inode *prev; /* protected by lo->mutex */

     int fd;

     bool is_symlink;

-    ino_t ino;

-    dev_t dev;

+    struct lo_key key;

     uint64_t refcount; /* protected by lo->mutex */

     fuse_ino_t fuse_ino;

 };

@@ -119,7 +121,8 @@ struct lo_data {

     int timeout_set;

     int readdirplus_set;

     int readdirplus_clear;

-    struct lo_inode root; /* protected by lo->mutex */

+    struct lo_inode root;

+    GHashTable *inodes; /* protected by lo->mutex */

     struct lo_map ino_map; /* protected by lo->mutex */

     struct lo_map dirp_map; /* protected by lo->mutex */

     struct lo_map fd_map; /* protected by lo->mutex */

@@ -573,7 +576,7 @@ retry:

         }

         goto fail_unref;

     }

-    if (stat.st_dev != inode->dev || stat.st_ino != inode->ino) {

+    if (stat.st_dev != inode->key.dev || stat.st_ino != inode->key.ino) {

         if (!retries) {

             fuse_log(FUSE_LOG_WARNING,

                      "%s: failed to match last\n", __func__);

@@ -753,19 +756,20 @@ out_err:

 static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st)

 {

     struct lo_inode *p;

-    struct lo_inode *ret = NULL;

+    struct lo_key key = {

+        .ino = st->st_ino,

+        .dev = st->st_dev,

+    };

     pthread_mutex_lock(&lo->mutex);

-    for (p = lo->root.next; p != &lo->root; p = p->next) {

-        if (p->ino == st->st_ino && p->dev == st->st_dev) {

-            assert(p->refcount > 0);

-            ret = p;

-            ret->refcount++;

-            break;

-        }

+    p = g_hash_table_lookup(lo->inodes, &key);

+    if (p) {

+        assert(p->refcount > 0);

+        p->refcount++;

     }

     pthread_mutex_unlock(&lo->mutex);

-    return ret;

+

+    return p;

 }

 static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,

@@ -810,8 +814,6 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,

         close(newfd);

         newfd = -1;

     } else {

-        struct lo_inode *prev, *next;

-

         saverr = ENOMEM;

         inode = calloc(1, sizeof(struct lo_inode));

         if (!inode) {

@@ -822,17 +824,12 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,

         inode->refcount = 1;

         inode->fd = newfd;

         newfd = -1;

-        inode->ino = e->attr.st_ino;

-        inode->dev = e->attr.st_dev;

+        inode->key.ino = e->attr.st_ino;

+        inode->key.dev = e->attr.st_dev;

         pthread_mutex_lock(&lo->mutex);

         inode->fuse_ino = lo_add_inode_mapping(req, inode);

-        prev = &lo->root;

-        next = prev->next;

-        next->prev = inode;

-        inode->next = next;

-        inode->prev = prev;

-        prev->next = inode;

+        g_hash_table_insert(lo->inodes, &inode->key, inode);

         pthread_mutex_unlock(&lo->mutex);

     }

     e->ino = inode->fuse_ino;

@@ -1162,14 +1159,8 @@ static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode,

     assert(inode->refcount >= n);

     inode->refcount -= n;

     if (!inode->refcount) {

-        struct lo_inode *prev, *next;

-

-        prev = inode->prev;

-        next = inode->next;

-        next->prev = prev;

-        prev->next = next;

-

         lo_map_remove(&lo->ino_map, inode->fuse_ino);

+        g_hash_table_remove(lo->inodes, &inode->key);

         pthread_mutex_unlock(&lo->mutex);

         close(inode->fd);

         free(inode);

@@ -1369,7 +1360,7 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,

         /* Hide root's parent directory */

         if (dinode == &lo->root && strcmp(name, "..") == 0) {

-            e.attr.st_ino = lo->root.ino;

+            e.attr.st_ino = lo->root.key.ino;

             e.attr.st_mode = DT_DIR << 12;

         }

@@ -2370,11 +2361,26 @@ static void setup_root(struct lo_data *lo, struct lo_inode *root)

     root->is_symlink = false;

     root->fd = fd;

-    root->ino = stat.st_ino;

-    root->dev = stat.st_dev;

+    root->key.ino = stat.st_ino;

+    root->key.dev = stat.st_dev;

     root->refcount = 2;

 }

+static guint lo_key_hash(gconstpointer key)

+{

+    const struct lo_key *lkey = key;

+

+    return (guint)lkey->ino + (guint)lkey->dev;

+}

+

+static gboolean lo_key_equal(gconstpointer a, gconstpointer b)

+{

+    const struct lo_key *la = a;

+    const struct lo_key *lb = b;

+

+    return la->ino == lb->ino && la->dev == lb->dev;

+}

+

 int main(int argc, char *argv[])

 {

     struct fuse_args args = FUSE_ARGS_INIT(argc, argv);

@@ -2392,7 +2398,7 @@ int main(int argc, char *argv[])

     umask(0);

     pthread_mutex_init(&lo.mutex, NULL);

-    lo.root.next = lo.root.prev = &lo.root;

+    lo.inodes = g_hash_table_new(lo_key_hash, lo_key_equal);

     lo.root.fd = -1;

     lo.root.fuse_ino = FUSE_ROOT_ID;

     lo.cache = CACHE_AUTO;

@@ -2522,6 +2528,9 @@ err_out2:

 err_out1:

     fuse_opt_free_args(&args);

+    if (lo.inodes) {

+        g_hash_table_destroy(lo.inodes);

+    }

     lo_map_destroy(&lo.fd_map);

     lo_map_destroy(&lo.dirp_map);

     lo_map_destroy(&lo.ino_map);