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-rw-r--r--debian/patches/0004-tmpfs-use-a-seperate-lock-to-protect-all_nodes.patch314
1 files changed, 0 insertions, 314 deletions
diff --git a/debian/patches/0004-tmpfs-use-a-seperate-lock-to-protect-all_nodes.patch b/debian/patches/0004-tmpfs-use-a-seperate-lock-to-protect-all_nodes.patch
deleted file mode 100644
index d6d9fd09..00000000
--- a/debian/patches/0004-tmpfs-use-a-seperate-lock-to-protect-all_nodes.patch
+++ /dev/null
@@ -1,314 +0,0 @@
-From ba3560bd19188297a2bc51447b2006ced7d5c615 Mon Sep 17 00:00:00 2001
-From: Justus Winter <4winter@informatik.uni-hamburg.de>
-Date: Tue, 13 May 2014 15:35:42 +0200
-Subject: [PATCH hurd 04/16] tmpfs: use a seperate lock to protect all_nodes
-
-Previously, tmpfs used diskfs_node_refcnt_lock to serialize access to
-the all_nodes and some other related global state related to memory
-consumption.
-
-Use a separate lock to protect all_nodes, and atomic operations to
-access the state related to memory consumption. Adjust the reference
-counting accordingly. Every node in the all_nodes 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 all_nodes.
-
-* tmpfs/tmpfs.h (num_files, tmpfs_space_used): Use atomic operations
-for these variables.
-(adjust_used): Use atomic operations.
-(get_used): New convenience function to atomically retrieve
-tmpfs_space_used.
-* tmpfs/node.c (all_nodes_lock): New lock.
-(diskfs_alloc_node): Use a separate lock to protect all_nodes.
-Adjust the reference counting accordingly.
-(diskfs_free_node): Likewise.
-(diskfs_cached_lookup):Likewise.
-(diskfs_node_iterate): Likewise.
-(diskfs_node_norefs): Do not remove the node from all_nodes. This
-actually looks like a mistake, I do not know why they did that here as
-well as in diskfs_free_node.
-(diskfs_try_dropping_softrefs): Check whether someone reacquired a
-reference, and if so hold on to our light reference.
-(diskfs_grow): Use atomic operations.
-* tmpfs/tmpfs.c (diskfs_set_statfs): Likewise.
----
- tmpfs/node.c | 107 ++++++++++++++++++++++++++++++++++++++++++----------------
- tmpfs/tmpfs.c | 6 ++--
- tmpfs/tmpfs.h | 20 +++++++----
- 3 files changed, 94 insertions(+), 39 deletions(-)
-
-diff --git a/tmpfs/node.c b/tmpfs/node.c
-index 02d7a60..428b6d9 100644
---- a/tmpfs/node.c
-+++ b/tmpfs/node.c
-@@ -29,8 +29,19 @@
- unsigned int num_files;
- static unsigned int gen;
-
-+/* all_nodes is a list of all nodes.
-+
-+ Access to all_nodes and all_nodes_nr_items is protected by
-+ all_nodes_lock.
-+
-+ Every node in all_nodes 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. */
- struct node *all_nodes;
- static size_t all_nodes_nr_items;
-+/* all_nodes_lock must be acquired before diskfs_node_refcnt_lock. */
-+pthread_rwlock_t all_nodes_lock = PTHREAD_RWLOCK_INITIALIZER;
-
- error_t
- diskfs_alloc_node (struct node *dp, mode_t mode, struct node **npp)
-@@ -40,18 +51,17 @@ diskfs_alloc_node (struct node *dp, mode_t mode, struct node **npp)
- dn = calloc (1, sizeof *dn);
- if (dn == 0)
- return ENOSPC;
-- pthread_spin_lock (&diskfs_node_refcnt_lock);
-- if (round_page (tmpfs_space_used + sizeof *dn) / vm_page_size
-+
-+ if (round_page (get_used () + sizeof *dn) / vm_page_size
- > tmpfs_page_limit)
- {
-- pthread_spin_unlock (&diskfs_node_refcnt_lock);
-+ pthread_rwlock_unlock (&all_nodes_lock);
- free (dn);
- return ENOSPC;
- }
- dn->gen = gen++;
-- ++num_files;
-- tmpfs_space_used += sizeof *dn;
-- pthread_spin_unlock (&diskfs_node_refcnt_lock);
-+ __atomic_add_fetch (&num_files, 1, __ATOMIC_RELAXED);
-+ adjust_used (sizeof *dn);
-
- dn->type = IFTODT (mode & S_IFMT);
- return diskfs_cached_lookup ((ino_t) (uintptr_t) dn, npp);
-@@ -75,15 +85,19 @@ diskfs_free_node (struct node *np, mode_t mode)
- free (np->dn->u.lnk);
- break;
- }
-+
-+ pthread_rwlock_wrlock (&all_nodes_lock);
- *np->dn->hprevp = np->dn->hnext;
- if (np->dn->hnext != 0)
- np->dn->hnext->dn->hprevp = np->dn->hprevp;
- all_nodes_nr_items -= 1;
-+ pthread_rwlock_unlock (&all_nodes_lock);
-+
- free (np->dn);
- np->dn = 0;
-
-- --num_files;
-- tmpfs_space_used -= sizeof *np->dn;
-+ __atomic_sub_fetch (&num_files, 1, __ATOMIC_RELAXED);
-+ adjust_used (-sizeof *np->dn);
- }
-
- void
-@@ -117,14 +131,6 @@ diskfs_node_norefs (struct node *np)
- np->dn->u.chr = np->dn_stat.st_rdev;
- break;
- }
--
-- /* Remove this node from the cache list rooted at `all_nodes'. */
-- *np->dn->hprevp = np->dn->hnext;
-- if (np->dn->hnext != 0)
-- np->dn->hnext->dn->hprevp = np->dn->hprevp;
-- all_nodes_nr_items -= 1;
-- np->dn->hnext = 0;
-- np->dn->hprevp = 0;
- }
-
- free (np);
-@@ -167,30 +173,34 @@ diskfs_cached_lookup (ino_t inum, struct node **npp)
-
- assert (npp);
-
-+ pthread_rwlock_rdlock (&all_nodes_lock);
- if (dn->hprevp != 0) /* There is already a node. */
-- {
-- np = *dn->hprevp;
-- assert (np->dn == dn);
-- assert (*dn->hprevp == np);
--
-- diskfs_nref (np);
-- }
-+ goto gotit;
- else
- /* Create the new node. */
- {
- struct stat *st;
-+ pthread_rwlock_unlock (&all_nodes_lock);
-
- np = diskfs_make_node (dn);
- np->cache_id = (ino_t) (uintptr_t) dn;
-
-- pthread_spin_lock (&diskfs_node_refcnt_lock);
-+ pthread_rwlock_wrlock (&all_nodes_lock);
-+ if (dn->hprevp != NULL)
-+ {
-+ /* We lost a race. */
-+ diskfs_nrele (np);
-+ goto gotit;
-+ }
-+
- dn->hnext = all_nodes;
- if (dn->hnext)
- dn->hnext->dn->hprevp = &dn->hnext;
- dn->hprevp = &all_nodes;
- all_nodes = np;
- all_nodes_nr_items += 1;
-- pthread_spin_unlock (&diskfs_node_refcnt_lock);
-+ diskfs_nref_light (np);
-+ pthread_rwlock_unlock (&all_nodes_lock);
-
- st = &np->dn_stat;
- memset (st, 0, sizeof *st);
-@@ -220,6 +230,16 @@ diskfs_cached_lookup (ino_t inum, struct node **npp)
- pthread_mutex_lock (&np->lock);
- *npp = np;
- return 0;
-+
-+ gotit:
-+ np = *dn->hprevp;
-+ assert (np->dn == dn);
-+ assert (*dn->hprevp == np);
-+ diskfs_nref (np);
-+ pthread_rwlock_unlock (&all_nodes_lock);
-+ pthread_mutex_lock (&np->lock);
-+ *npp = np;
-+ return 0;
- }
-
- error_t
-@@ -229,12 +249,12 @@ diskfs_node_iterate (error_t (*fun) (struct node *))
- size_t num_nodes;
- struct node *node, **node_list, **p;
-
-- pthread_spin_lock (&diskfs_node_refcnt_lock);
-+ pthread_rwlock_rdlock (&all_nodes_lock);
-
- /* We must copy everything from the hash table into another data structure
- to avoid running into any problems with the hash-table being modified
- during processing (normally we delegate access to hash-table with
-- diskfs_node_refcnt_lock, but we can't hold this while locking the
-+ all_nodes_lock, but we can't hold this while locking the
- individual node locks). */
-
- num_nodes = all_nodes_nr_items;
-@@ -243,10 +263,14 @@ diskfs_node_iterate (error_t (*fun) (struct node *))
- for (node = all_nodes; node != 0; node = node->dn->hnext)
- {
- *p++ = node;
-+
-+ /* We acquire a hard reference for node, but without using
-+ diskfs_nref. We do this so that diskfs_new_hardrefs will not
-+ get called. */
- node->references++;
- }
-
-- pthread_spin_unlock (&diskfs_node_refcnt_lock);
-+ pthread_rwlock_unlock (&all_nodes_lock);
-
- p = node_list;
- while (num_nodes-- > 0)
-@@ -272,6 +296,31 @@ diskfs_node_iterate (error_t (*fun) (struct node *))
- void
- diskfs_try_dropping_softrefs (struct node *np)
- {
-+ pthread_rwlock_wrlock (&all_nodes_lock);
-+ if (np->cache_id != 0)
-+ {
-+ /* Check if someone reacquired a reference. */
-+ 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. It's fine, we didn't touch
-+ anything yet. */
-+ pthread_rwlock_unlock (&all_nodes_lock);
-+ return;
-+ }
-+
-+ /* Just let go of the weak reference. The node will be removed
-+ from all_nodes in diskfs_free_node. */
-+ np->cache_id = 0;
-+ diskfs_nrele_light (np);
-+ }
-+ pthread_rwlock_unlock (&all_nodes_lock);
- }
-
- /* The user must define this funcction. Node NP has some light
-@@ -447,7 +496,7 @@ diskfs_grow (struct node *np, off_t size, struct protid *cred)
-
- off_t set_size = size;
- size = round_page (size);
-- if (round_page (tmpfs_space_used + size - np->allocsize)
-+ if (round_page (get_used () + size - np->allocsize)
- / vm_page_size > tmpfs_page_limit)
- return ENOSPC;
-
-diff --git a/tmpfs/tmpfs.c b/tmpfs/tmpfs.c
-index 1b5b374..fd1c9aa 100644
---- a/tmpfs/tmpfs.c
-+++ b/tmpfs/tmpfs.c
-@@ -67,10 +67,8 @@ diskfs_set_statfs (struct statfs *st)
- st->f_bsize = vm_page_size;
- st->f_blocks = tmpfs_page_limit;
-
-- pthread_spin_lock (&diskfs_node_refcnt_lock);
-- st->f_files = num_files;
-- pages = round_page (tmpfs_space_used) / vm_page_size;
-- pthread_spin_unlock (&diskfs_node_refcnt_lock);
-+ st->f_files = __atomic_load_n (&num_files, __ATOMIC_RELAXED);
-+ pages = round_page (get_used ()) / vm_page_size;
-
- st->f_bfree = pages < tmpfs_page_limit ? tmpfs_page_limit - pages : 0;
- st->f_bavail = st->f_bfree;
-diff --git a/tmpfs/tmpfs.h b/tmpfs/tmpfs.h
-index b3c636d..ad47200 100644
---- a/tmpfs/tmpfs.h
-+++ b/tmpfs/tmpfs.h
-@@ -69,17 +69,25 @@ struct tmpfs_dirent
- char name[0];
- };
-
--extern unsigned int num_files;
--extern off_t tmpfs_page_limit, tmpfs_space_used;
--
-+extern off_t tmpfs_page_limit;
- extern mach_port_t default_pager;
-
-+/* These two must be accessed using atomic operations. */
-+extern unsigned int num_files;
-+extern off_t tmpfs_space_used;
-+
-+/* Convenience function to adjust tmpfs_space_used. */
- static inline void
- adjust_used (off_t change)
- {
-- pthread_spin_lock (&diskfs_node_refcnt_lock);
-- tmpfs_space_used += change;
-- pthread_spin_unlock (&diskfs_node_refcnt_lock);
-+ __atomic_add_fetch (&num_files, change, __ATOMIC_RELAXED);
-+}
-+
-+/* Convenience function to get tmpfs_space_used. */
-+static inline off_t
-+get_used (void)
-+{
-+ return __atomic_load_n (&num_files, __ATOMIC_RELAXED);
- }
-
- #endif
---
-2.1.4
-
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