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Blame SOURCES/kvm-virtiofsd-passthrough_ll-add-dirp_map-to-hide-lo_dir.patch

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From 474d0adafed4d73720d6413b2903d6c4b529e5e6 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:01:15 +0100
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Subject: [PATCH 044/116] virtiofsd: passthrough_ll: add dirp_map to hide
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 lo_dirp pointers
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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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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20200127190227.40942-41-dgilbert@redhat.com>
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Patchwork-id: 93495
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O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 040/112] virtiofsd: passthrough_ll: add dirp_map to hide lo_dirp pointers
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Bugzilla: 1694164
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Do not expose lo_dirp pointers to clients.
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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 b39bce121bfad8757eec0ee41f14607b883935d3)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 tools/virtiofsd/passthrough_ll.c | 103 +++++++++++++++++++++++++++++----------
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 1 file changed, 76 insertions(+), 27 deletions(-)
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index a3ebf74..5f5a72f 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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@@ -56,27 +56,10 @@
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 #include "passthrough_helpers.h"
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-/*
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- * We are re-using pointers to our `struct lo_inode`
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- * elements as inodes. This means that we must be able to
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- * store uintptr_t values in a fuse_ino_t variable. The following
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- * incantation checks this condition at compile time.
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- */
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-#if defined(__GNUC__) &&                                      \
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-    (__GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ >= 6) && \
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-    !defined __cplusplus
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-_Static_assert(sizeof(fuse_ino_t) >= sizeof(uintptr_t),
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-               "fuse_ino_t too small to hold uintptr_t values!");
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-#else
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-struct _uintptr_to_must_hold_fuse_ino_t_dummy_struct {
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-    unsigned _uintptr_to_must_hold_fuse_ino_t
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-        : ((sizeof(fuse_ino_t) >= sizeof(uintptr_t)) ? 1 : -1);
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-};
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-#endif
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-
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 struct lo_map_elem {
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     union {
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         struct lo_inode *inode;
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+        struct lo_dirp *dirp;
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         ssize_t freelist;
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     };
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     bool in_use;
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@@ -123,6 +106,7 @@ struct lo_data {
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     int timeout_set;
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     struct lo_inode root; /* protected by lo->mutex */
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     struct lo_map ino_map; /* protected by lo->mutex */
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+    struct lo_map dirp_map; /* protected by lo->mutex */
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 };
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 static const struct fuse_opt lo_opts[] = {
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@@ -253,6 +237,20 @@ static void lo_map_remove(struct lo_map *map, size_t key)
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 }
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 /* Assumes lo->mutex is held */
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+static ssize_t lo_add_dirp_mapping(fuse_req_t req, struct lo_dirp *dirp)
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+{
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+    struct lo_map_elem *elem;
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+
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+    elem = lo_map_alloc_elem(&lo_data(req)->dirp_map);
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+    if (!elem) {
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+        return -1;
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+    }
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+
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+    elem->dirp = dirp;
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+    return elem - lo_data(req)->dirp_map.elems;
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+}
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+
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+/* Assumes lo->mutex is held */
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 static ssize_t lo_add_inode_mapping(fuse_req_t req, struct lo_inode *inode)
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 {
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     struct lo_map_elem *elem;
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@@ -861,9 +859,19 @@ struct lo_dirp {
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     off_t offset;
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 };
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-static struct lo_dirp *lo_dirp(struct fuse_file_info *fi)
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+static struct lo_dirp *lo_dirp(fuse_req_t req, struct fuse_file_info *fi)
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 {
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-    return (struct lo_dirp *)(uintptr_t)fi->fh;
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+    struct lo_data *lo = lo_data(req);
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+    struct lo_map_elem *elem;
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+
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+    pthread_mutex_lock(&lo->mutex);
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+    elem = lo_map_get(&lo->dirp_map, fi->fh);
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+    pthread_mutex_unlock(&lo->mutex);
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+    if (!elem) {
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+        return NULL;
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+    }
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+
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+    return elem->dirp;
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 }
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 static void lo_opendir(fuse_req_t req, fuse_ino_t ino,
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@@ -873,6 +881,7 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t ino,
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     struct lo_data *lo = lo_data(req);
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     struct lo_dirp *d;
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     int fd;
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+    ssize_t fh;
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     d = calloc(1, sizeof(struct lo_dirp));
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     if (d == NULL) {
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@@ -892,7 +901,14 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t ino,
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     d->offset = 0;
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     d->entry = NULL;
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-    fi->fh = (uintptr_t)d;
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+    pthread_mutex_lock(&lo->mutex);
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+    fh = lo_add_dirp_mapping(req, d);
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+    pthread_mutex_unlock(&lo->mutex);
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+    if (fh == -1) {
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+        goto out_err;
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+    }
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+
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+    fi->fh = fh;
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     if (lo->cache == CACHE_ALWAYS) {
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         fi->keep_cache = 1;
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     }
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@@ -903,6 +919,9 @@ out_errno:
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     error = errno;
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 out_err:
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     if (d) {
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+        if (d->dp) {
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+            closedir(d->dp);
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+        }
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         if (fd != -1) {
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             close(fd);
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         }
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@@ -920,17 +939,21 @@ static int is_dot_or_dotdot(const char *name)
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 static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
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                           off_t offset, struct fuse_file_info *fi, int plus)
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 {
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-    struct lo_dirp *d = lo_dirp(fi);
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-    char *buf;
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+    struct lo_dirp *d;
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+    char *buf = NULL;
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     char *p;
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     size_t rem = size;
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-    int err;
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+    int err = ENOMEM;
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     (void)ino;
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+    d = lo_dirp(req, fi);
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+    if (!d) {
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+        goto error;
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+    }
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+
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     buf = calloc(1, size);
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     if (!buf) {
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-        err = ENOMEM;
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         goto error;
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     }
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     p = buf;
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@@ -1028,8 +1051,21 @@ static void lo_readdirplus(fuse_req_t req, fuse_ino_t ino, size_t size,
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 static void lo_releasedir(fuse_req_t req, fuse_ino_t ino,
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                           struct fuse_file_info *fi)
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 {
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-    struct lo_dirp *d = lo_dirp(fi);
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+    struct lo_data *lo = lo_data(req);
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+    struct lo_dirp *d;
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+
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     (void)ino;
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+
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+    d = lo_dirp(req, fi);
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+    if (!d) {
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+        fuse_reply_err(req, EBADF);
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+        return;
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+    }
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+
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+    pthread_mutex_lock(&lo->mutex);
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+    lo_map_remove(&lo->dirp_map, fi->fh);
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+    pthread_mutex_unlock(&lo->mutex);
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+
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     closedir(d->dp);
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     free(d);
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     fuse_reply_err(req, 0);
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@@ -1081,8 +1117,18 @@ static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync,
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                         struct fuse_file_info *fi)
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 {
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     int res;
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-    int fd = dirfd(lo_dirp(fi)->dp);
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+    struct lo_dirp *d;
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+    int fd;
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+
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     (void)ino;
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+
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+    d = lo_dirp(req, fi);
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+    if (!d) {
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+        fuse_reply_err(req, EBADF);
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+        return;
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+    }
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+
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+    fd = dirfd(d->dp);
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     if (datasync) {
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         res = fdatasync(fd);
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     } else {
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@@ -1614,6 +1660,8 @@ int main(int argc, char *argv[])
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     root_elem = lo_map_reserve(&lo.ino_map, lo.root.fuse_ino);
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     root_elem->inode = &lo.root;
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+    lo_map_init(&lo.dirp_map);
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+
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     if (fuse_parse_cmdline(&args, &opts) != 0) {
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         return 1;
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     }
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@@ -1710,6 +1758,7 @@ err_out2:
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 err_out1:
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     fuse_opt_free_args(&args);
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+    lo_map_destroy(&lo.dirp_map);
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     lo_map_destroy(&lo.ino_map);
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     if (lo.root.fd >= 0) {
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-- 
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1.8.3.1
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