add patch series

1 files changed, 310 insertions, 0 deletions

diff --git a/debian/patches/0003-isofs-use-a-seperate-lock-to-protect-node_cache.patch b/debian/patches/0003-isofs-use-a-seperate-lock-to-protect-node_cache.patch
new file mode 100644
index 00000000..02e7fa4f
--- /dev/null
+++ b/debian/patches/0003-isofs-use-a-seperate-lock-to-protect-node_cache.patch
@@ -0,0 +1,310 @@
+From 912151f13737af551d3d3dd2e45faef3bd7c78cb Mon Sep 17 00:00:00 2001
+From: Justus Winter <4winter@informatik.uni-hamburg.de>
+Date: Tue, 13 May 2014 15:16:31 +0200
+Subject: [PATCH hurd 03/10] isofs: use a seperate lock to protect node_cache
+
+Previously, isofs used diskfs_node_refcnt_lock to serialize access to
+the node_cache.
+
+Use a separate lock to protect node_cache.  Adjust the reference
+counting accordingly.  Every node in the node_cache carries a light
+reference.  When we are asked to give up that light reference, we
+reacquire our lock momentarily to check whether someone else
+reacquired a reference through the node_cache.
+
+* isofs/inode.c (nodecache_lock): New lock.
+(inode_cache_find): Use a separate lock to protect node_cache.
+Adjust the reference counting accordingly.
+(diskfs_cached_lookup): Likewise.
+(load_inode): Likewise.
+(cache_inode): Update comment accordingly.
+(diskfs_node_iterate): Likewise.
+(diskfs_node_norefs): Move the code removing the node from node_cache...
+(diskfs_try_dropping_softrefs): ... here, where we check whether
+someone reacquired a reference, and if so hold on to our light
+reference.
+---
+ isofs/inode.c | 146 +++++++++++++++++++++++++++++++++++++++++-----------------
+ 1 file changed, 105 insertions(+), 41 deletions(-)
+
+diff --git a/isofs/inode.c b/isofs/inode.c
+index 247d8ac..37bf1ac 100644
+--- a/isofs/inode.c
++++ b/isofs/inode.c
+@@ -48,35 +48,53 @@ struct node_cache
+   struct node *np;		/* if live */
+ };
+ 
++/* The node_cache is a cache of nodes.
++
++   Access to node_cache, node_cache_size, and node_cache_alloced is
++   protected by nodecache_lock.
++
++   Every node in the node_cache carries a light reference.  When we
++   are asked to give up that light reference, we reacquire our lock
++   momentarily to check whether someone else reacquired a reference
++   through the node_cache.  */
+ static int node_cache_size = 0;
+ static int node_cache_alloced = 0;
+ struct node_cache *node_cache = 0;
++/* nodecache_lock must be acquired before diskfs_node_refcnt_lock.  */
++static pthread_rwlock_t nodecache_lock = PTHREAD_RWLOCK_INITIALIZER;
+ 
+ /* Forward */
+ static error_t read_disknode (struct node *,
+ 			      struct dirrect *, struct rrip_lookup *);
+ 
+ 
++/* Lookup node with id ID.  Returns NULL if the node is not found in
++   the node cache.  */
++static struct node *
++lookup (off_t id)
++{
++  int i;
++  for (i = 0; i < node_cache_size; i++)
++    if (node_cache[i].id == id
++	&& node_cache[i].np)
++      return node_cache[i].np;
++  return NULL;
++}
++
+ /* See if node with identifier ID is in the cache.  If so, return it,
+-   with one additional reference. diskfs_node_refcnt_lock must be held
++   with one additional reference. nodecache_lock must be held
+    on entry to the call, and will be released iff the node was found
+    in the cache. */
+ void
+ inode_cache_find (off_t id, struct node **npp)
+ {
+-  int i;
+-
+-  for (i = 0; i < node_cache_size; i++)
+-    if (node_cache[i].id == id
+-	&& node_cache[i].np)
+-      {
+-	*npp = node_cache[i].np;
+-	(*npp)->references++;
+-	pthread_spin_unlock (&diskfs_node_refcnt_lock);
+-	pthread_mutex_lock (&(*npp)->lock);
+-	return;
+-      }
+-  *npp = 0;
++  *npp = lookup (id);
++  if (*npp)
++    {
++      diskfs_nref (*npp);
++      pthread_rwlock_unlock (&nodecache_lock);
++      pthread_mutex_lock (&(*npp)->lock);
++    }
+ }
+ 
+ 
+@@ -92,7 +110,7 @@ use_file_start_id (struct dirrect *record, struct rrip_lookup *rr)
+ }
+ 
+ /* Enter NP into the cache.  The directory entry we used is DR, the
+-   cached Rock-Ridge info RR. diskfs_node_refcnt_lock must be held. */
++   cached Rock-Ridge info RR. nodecache_lock must be held. */
+ void
+ cache_inode (struct node *np, struct dirrect *record,
+ 	    struct rrip_lookup *rr)
+@@ -137,6 +155,7 @@ cache_inode (struct node *np, struct dirrect *record,
+   c->id = id;
+   c->dr = record;
+   c->file_start = np->dn->file_start;
++  diskfs_nref_light (np);
+   c->np = np;
+ 
+   /* PLUS 1 so that we don't store zero cache ID's (not allowed by diskfs) */
+@@ -155,7 +174,7 @@ diskfs_cached_lookup (ino_t id, struct node **npp)
+      to avoid presenting zero cache ID's. */
+   id--;
+ 
+-  pthread_spin_lock (&diskfs_node_refcnt_lock);
++  pthread_rwlock_rdlock (&nodecache_lock);
+   assert (id < node_cache_size);
+ 
+   np = node_cache[id].np;
+@@ -166,6 +185,8 @@ diskfs_cached_lookup (ino_t id, struct node **npp)
+       struct rrip_lookup rr;
+       struct disknode *dn;
+ 
++      pthread_rwlock_unlock (&nodecache_lock);
++
+       rrip_lookup (node_cache[id].dr, &rr, 1);
+ 
+       /* We should never cache the wrong directory entry */
+@@ -174,7 +195,7 @@ diskfs_cached_lookup (ino_t id, struct node **npp)
+       dn = malloc (sizeof (struct disknode));
+       if (!dn)
+ 	{
+-	  pthread_spin_unlock (&diskfs_node_refcnt_lock);
++	  pthread_rwlock_unlock (&nodecache_lock);
+ 	  release_rrip (&rr);
+ 	  return ENOMEM;
+ 	}
+@@ -185,16 +206,26 @@ diskfs_cached_lookup (ino_t id, struct node **npp)
+       if (!np)
+ 	{
+ 	  free (dn);
+-	  pthread_spin_unlock (&diskfs_node_refcnt_lock);
++	  pthread_rwlock_unlock (&nodecache_lock);
+ 	  release_rrip (&rr);
+ 	  return ENOMEM;
+ 	}
+       np->cache_id = id + 1;	/* see above for rationale for increment */
+       pthread_mutex_lock (&np->lock);
++
++      pthread_rwlock_wrlock (&nodecache_lock);
++      if (c->np != NULL)
++        {
++          /* We lost a race.  */
++          diskfs_nput (np);
++          np = c->np;
++          goto gotit;
++        }
+       c->np = np;
+-      pthread_spin_unlock (&diskfs_node_refcnt_lock);
++      diskfs_nref_light (np);
++      pthread_rwlock_unlock (&nodecache_lock);
+ 
+-      err = read_disknode (np, node_cache[id].dr, &rr);
++      err = read_disknode (np, dn->dr, &rr);
+       if (!err)
+ 	*npp = np;
+ 
+@@ -203,9 +234,9 @@ diskfs_cached_lookup (ino_t id, struct node **npp)
+       return err;
+     }
+ 
+-
+-  np->references++;
+-  pthread_spin_unlock (&diskfs_node_refcnt_lock);
++ gotit:
++  diskfs_nref (np);
++  pthread_rwlock_unlock (&nodecache_lock);
+   pthread_mutex_lock (&np->lock);
+   *npp = np;
+   return 0;
+@@ -307,7 +338,8 @@ load_inode (struct node **npp, struct dirrect *record,
+   error_t err;
+   off_t file_start;
+   struct disknode *dn;
+-  struct node *np;
++  struct node *np, *tmp;
++  off_t id;
+ 
+   err = calculate_file_start (record, &file_start, rr);
+   if (err)
+@@ -315,27 +347,23 @@ load_inode (struct node **npp, struct dirrect *record,
+   if (rr->valid & VALID_CL)
+     record = rr->realdirent;
+ 
+-  pthread_spin_lock (&diskfs_node_refcnt_lock);
+-
+   /* First check the cache */
+   if (use_file_start_id (record, rr))
+-    inode_cache_find (file_start << store->log2_block_size, npp);
++    id = file_start << store->log2_block_size;
+   else
+-    inode_cache_find ((off_t) ((void *) record - (void *) disk_image), npp);
++    id = (off_t) ((void *) record - (void *) disk_image);
+ 
++  pthread_rwlock_rdlock (&nodecache_lock);
++  inode_cache_find (id, npp);
+   if (*npp)
+-    {
+-      pthread_spin_unlock (&diskfs_node_refcnt_lock);
+-      return 0;
+-    }
++    return 0;
++  pthread_rwlock_unlock (&nodecache_lock);
+ 
+   /* Create a new node */
+   dn = malloc (sizeof (struct disknode));
+   if (!dn)
+-    {
+-      pthread_spin_unlock (&diskfs_node_refcnt_lock);
+-      return ENOMEM;
+-    }
++    return ENOMEM;
++
+   dn->fileinfo = 0;
+   dn->dr = record;
+   dn->file_start = file_start;
+@@ -344,14 +372,25 @@ load_inode (struct node **npp, struct dirrect *record,
+   if (!np)
+     {
+       free (dn);
+-      pthread_spin_unlock (&diskfs_node_refcnt_lock);
+       return ENOMEM;
+     }
+ 
+   pthread_mutex_lock (&np->lock);
+ 
++  pthread_rwlock_wrlock (&nodecache_lock);
++  tmp = lookup (id);
++  if (tmp)
++    {
++      /* We lost a race.  */
++      diskfs_nput (np);
++      diskfs_nref (tmp);
++      *npp = tmp;
++      pthread_rwlock_unlock (&nodecache_lock);
++      return 0;
++    }
++
+   cache_inode (np, record, rr);
+-  pthread_spin_unlock (&diskfs_node_refcnt_lock);
++  pthread_rwlock_unlock (&nodecache_lock);
+ 
+   err = read_disknode (np, record, rr);
+   *npp = np;
+@@ -505,9 +544,6 @@ error_t (*diskfs_read_symlink_hook) (struct node *, char *)
+ void
+ diskfs_node_norefs (struct node *np)
+ {
+-  assert (node_cache[np->cache_id - 1].np == np);
+-  node_cache[np->cache_id - 1].np = 0;
+-
+   if (np->dn->translator)
+     free (np->dn->translator);
+ 
+@@ -521,6 +557,34 @@ diskfs_node_norefs (struct node *np)
+ void
+ diskfs_try_dropping_softrefs (struct node *np)
+ {
++  pthread_rwlock_wrlock (&nodecache_lock);
++  if (np->cache_id != 0)
++    {
++      assert (node_cache[np->cache_id - 1].np == np);
++
++      /* Check if someone reacquired a reference through the
++	 node_cache.  */
++      unsigned int references;
++      pthread_spin_lock (&diskfs_node_refcnt_lock);
++      references = np->references;
++      pthread_spin_unlock (&diskfs_node_refcnt_lock);
++
++      /* An additional reference is acquired by libdiskfs across calls
++	 to diskfs_try_dropping_softrefs.  */
++      if (references > 1)
++	{
++	  /* A reference was reacquired through a hash table lookup.
++	     It's fine, we didn't touch anything yet. */
++	  pthread_rwlock_unlock (&nodecache_lock);
++	  return;
++	}
++
++      node_cache[np->cache_id - 1].np = 0;
++      np->cache_id = 0;
++      diskfs_nrele_light (np);
++    }
++  pthread_rwlock_unlock (&nodecache_lock);
++
+   drop_pager_softrefs (np);
+ }
+ 
+-- 
+2.1.4
+