97 lines
3.2 KiB
Diff
97 lines
3.2 KiB
Diff
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:02:23 +0000
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Subject: [PATCH] virtiofsd: Convert lo_destroy to take the lo->mutex lock
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itself
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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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lo_destroy was relying on some implicit knowledge of the locking;
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we can avoid this if we create an unref_inode that doesn't take
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the lock and then grab it for the whole of the lo_destroy.
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Suggested-by: Vivek Goyal <vgoyal@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@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 fe4c15798a48143dd6b1f58d2d3cad12206ce211)
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---
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tools/virtiofsd/passthrough_ll.c | 31 +++++++++++++++++--------------
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1 file changed, 17 insertions(+), 14 deletions(-)
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index eb001b9d1e..fc15d61510 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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@@ -1344,14 +1344,13 @@ static void lo_unlink(fuse_req_t req, fuse_ino_t parent, const char *name)
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lo_inode_put(lo, &inode);
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}
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-static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode,
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- uint64_t n)
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+/* To be called with lo->mutex held */
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+static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n)
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{
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if (!inode) {
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return;
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}
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- pthread_mutex_lock(&lo->mutex);
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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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@@ -1362,15 +1361,24 @@ static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode,
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}
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g_hash_table_destroy(inode->posix_locks);
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pthread_mutex_destroy(&inode->plock_mutex);
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- pthread_mutex_unlock(&lo->mutex);
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/* Drop our refcount from lo_do_lookup() */
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lo_inode_put(lo, &inode);
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- } else {
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- pthread_mutex_unlock(&lo->mutex);
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}
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}
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+static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode,
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+ uint64_t n)
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+{
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+ if (!inode) {
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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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+ unref_inode(lo, inode, n);
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+ pthread_mutex_unlock(&lo->mutex);
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+}
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+
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static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup)
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{
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struct lo_data *lo = lo_data(req);
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@@ -2458,13 +2466,7 @@ static void lo_destroy(void *userdata)
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{
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struct lo_data *lo = (struct lo_data *)userdata;
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- /*
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- * Normally lo->mutex must be taken when traversing lo->inodes but
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- * lo_destroy() is a serialized request so no races are possible here.
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- *
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- * In addition, we cannot acquire lo->mutex since unref_inode() takes it
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- * too and this would result in a recursive lock.
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- */
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+ pthread_mutex_lock(&lo->mutex);
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while (true) {
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GHashTableIter iter;
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gpointer key, value;
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@@ -2475,8 +2477,9 @@ static void lo_destroy(void *userdata)
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}
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struct lo_inode *inode = value;
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- unref_inode_lolocked(lo, inode, inode->nlookup);
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+ unref_inode(lo, inode, inode->nlookup);
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}
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+ pthread_mutex_unlock(&lo->mutex);
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}
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static struct fuse_lowlevel_ops lo_oper = {
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