---

yaml
---
r: 23028
b: refs/heads/master
c: 0c9e63f
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d8733c2956968a01394a4d2a9e97a8b431a78776
+refs/heads/master: 0c9e63fd38a2fb2181668a0cdd622a3c23cfd567

trunk/fs/fcntl.c

@@ -73,8 +73,8 @@ static int locate_fd(struct files_struct *files,
 	 * orig_start..fdt->next_fd
 	 */
 	start = orig_start;
-	if (start < fdt->next_fd)
-		start = fdt->next_fd;
+	if (start < files->next_fd)
+		start = files->next_fd;
 
 	newfd = start;
 	if (start < fdt->max_fdset) {
@@ -102,9 +102,8 @@ static int locate_fd(struct files_struct *files,
 	 * we reacquire the fdtable pointer and use it while holding
 	 * the lock, no one can free it during that time.
 	 */
-	fdt = files_fdtable(files);
-	if (start <= fdt->next_fd)
-		fdt->next_fd = newfd + 1;
+	if (start <= files->next_fd)
+		files->next_fd = newfd + 1;
 
 	error = newfd;
 

trunk/fs/file.c

@@ -125,7 +125,8 @@ static void free_fdtable_rcu(struct rcu_head *rcu)
 		kmem_cache_free(files_cachep, fdt->free_files);
 		return;
 	}
-	if (fdt->max_fdset <= __FD_SETSIZE && fdt->max_fds <= NR_OPEN_DEFAULT) {
+	if (fdt->max_fdset <= EMBEDDED_FD_SET_SIZE &&
+		fdt->max_fds <= NR_OPEN_DEFAULT) {
 		/*
 		 * The fdtable was embedded
 		 */
@@ -155,8 +156,9 @@ static void free_fdtable_rcu(struct rcu_head *rcu)
 
 void free_fdtable(struct fdtable *fdt)
 {
-	if (fdt->free_files || fdt->max_fdset > __FD_SETSIZE ||
-					fdt->max_fds > NR_OPEN_DEFAULT)
+	if (fdt->free_files ||
+		fdt->max_fdset > EMBEDDED_FD_SET_SIZE ||
+		fdt->max_fds > NR_OPEN_DEFAULT)
 		call_rcu(&fdt->rcu, free_fdtable_rcu);
 }
 
@@ -199,7 +201,6 @@ static void copy_fdtable(struct fdtable *nfdt, struct fdtable *fdt)
 		       (nfdt->max_fds - fdt->max_fds) *
 					sizeof(struct file *));
 	}
-	nfdt->next_fd = fdt->next_fd;
 }
 
 /*
@@ -220,11 +221,9 @@ fd_set * alloc_fdset(int num)
 
 void free_fdset(fd_set *array, int num)
 {
-	int size = num / 8;
-
-	if (num <= __FD_SETSIZE) /* Don't free an embedded fdset */
+	if (num <= EMBEDDED_FD_SET_SIZE) /* Don't free an embedded fdset */
 		return;
-	else if (size <= PAGE_SIZE)
+	else if (num <= 8 * PAGE_SIZE)
 		kfree(array);
 	else
 		vfree(array);
@@ -237,22 +236,17 @@ static struct fdtable *alloc_fdtable(int nr)
   	fd_set *new_openset = NULL, *new_execset = NULL;
 	struct file **new_fds;
 
-	fdt = kmalloc(sizeof(*fdt), GFP_KERNEL);
+	fdt = kzalloc(sizeof(*fdt), GFP_KERNEL);
 	if (!fdt)
   		goto out;
-	memset(fdt, 0, sizeof(*fdt));
 
-	nfds = __FD_SETSIZE;
+	nfds = 8 * L1_CACHE_BYTES;
   	/* Expand to the max in easy steps */
-  	do {
-		if (nfds < (PAGE_SIZE * 8))
-			nfds = PAGE_SIZE * 8;
-		else {
-			nfds = nfds * 2;
-			if (nfds > NR_OPEN)
-				nfds = NR_OPEN;
-		}
-	} while (nfds <= nr);
+  	while (nfds <= nr) {
+		nfds = nfds * 2;
+		if (nfds > NR_OPEN)
+			nfds = NR_OPEN;
+	}
 
   	new_openset = alloc_fdset(nfds);
   	new_execset = alloc_fdset(nfds);

trunk/fs/open.c

@@ -973,7 +973,7 @@ int get_unused_fd(void)
 	fdt = files_fdtable(files);
  	fd = find_next_zero_bit(fdt->open_fds->fds_bits,
 				fdt->max_fdset,
-				fdt->next_fd);
+				files->next_fd);
 
 	/*
 	 * N.B. For clone tasks sharing a files structure, this test
@@ -998,7 +998,7 @@ int get_unused_fd(void)
 
 	FD_SET(fd, fdt->open_fds);
 	FD_CLR(fd, fdt->close_on_exec);
-	fdt->next_fd = fd + 1;
+	files->next_fd = fd + 1;
 #if 1
 	/* Sanity check */
 	if (fdt->fd[fd] != NULL) {
@@ -1019,8 +1019,8 @@ static void __put_unused_fd(struct files_struct *files, unsigned int fd)
 {
 	struct fdtable *fdt = files_fdtable(files);
 	__FD_CLR(fd, fdt->open_fds);
-	if (fd < fdt->next_fd)
-		fdt->next_fd = fd;
+	if (fd < files->next_fd)
+		files->next_fd = fd;
 }
 
 void fastcall put_unused_fd(unsigned int fd)

trunk/include/linux/file.h

@@ -10,17 +10,30 @@
 #include <linux/compiler.h>
 #include <linux/spinlock.h>
 #include <linux/rcupdate.h>
+#include <linux/types.h>
 
 /*
  * The default fd array needs to be at least BITS_PER_LONG,
  * as this is the granularity returned by copy_fdset().
  */
 #define NR_OPEN_DEFAULT BITS_PER_LONG
 
+/*
+ * The embedded_fd_set is a small fd_set,
+ * suitable for most tasks (which open <= BITS_PER_LONG files)
+ */
+struct embedded_fd_set {
+	unsigned long fds_bits[1];
+};
+
+/*
+ * More than this number of fds: we use a separately allocated fd_set
+ */
+#define EMBEDDED_FD_SET_SIZE (BITS_PER_BYTE * sizeof(struct embedded_fd_set))
+
 struct fdtable {
 	unsigned int max_fds;
 	int max_fdset;
-	int next_fd;
 	struct file ** fd;      /* current fd array */
 	fd_set *close_on_exec;
 	fd_set *open_fds;
@@ -33,13 +46,20 @@ struct fdtable {
  * Open file table structure
  */
 struct files_struct {
+  /*
+   * read mostly part
+   */
 	atomic_t count;
 	struct fdtable *fdt;
 	struct fdtable fdtab;
-	fd_set close_on_exec_init;
-	fd_set open_fds_init;
+  /*
+   * written part on a separate cache line in SMP
+   */
+	spinlock_t file_lock ____cacheline_aligned_in_smp;
+	int next_fd;
+	struct embedded_fd_set close_on_exec_init;
+	struct embedded_fd_set open_fds_init;
 	struct file * fd_array[NR_OPEN_DEFAULT];
-	spinlock_t file_lock;     /* Protects concurrent writers.  Nests inside tsk->alloc_lock */
 };
 
 #define files_fdtable(files) (rcu_dereference((files)->fdt))

trunk/include/linux/init_task.h

@@ -7,11 +7,10 @@
 #define INIT_FDTABLE \
 {							\
 	.max_fds	= NR_OPEN_DEFAULT, 		\
-	.max_fdset	= __FD_SETSIZE, 		\
-	.next_fd	= 0, 				\
+	.max_fdset	= EMBEDDED_FD_SET_SIZE,		\
 	.fd		= &init_files.fd_array[0], 	\
-	.close_on_exec	= &init_files.close_on_exec_init, \
-	.open_fds	= &init_files.open_fds_init, 	\
+	.close_on_exec	= (fd_set *)&init_files.close_on_exec_init, \
+	.open_fds	= (fd_set *)&init_files.open_fds_init, 	\
 	.rcu		= RCU_HEAD_INIT, 		\
 	.free_files	= NULL,		 		\
 	.next		= NULL,		 		\
@@ -20,9 +19,10 @@
 #define INIT_FILES \
 { 							\
 	.count		= ATOMIC_INIT(1), 		\
-	.file_lock	= SPIN_LOCK_UNLOCKED, 		\
 	.fdt		= &init_files.fdtab, 		\
 	.fdtab		= INIT_FDTABLE,			\
+	.file_lock	= SPIN_LOCK_UNLOCKED, 		\
+	.next_fd	= 0, 				\
 	.close_on_exec_init = { { 0, } }, 		\
 	.open_fds_init	= { { 0, } }, 			\
 	.fd_array	= { NULL, } 			\

trunk/kernel/fork.c

@@ -607,12 +607,12 @@ static struct files_struct *alloc_files(void)
 	atomic_set(&newf->count, 1);
 
 	spin_lock_init(&newf->file_lock);
+	newf->next_fd = 0;
 	fdt = &newf->fdtab;
-	fdt->next_fd = 0;
 	fdt->max_fds = NR_OPEN_DEFAULT;
-	fdt->max_fdset = __FD_SETSIZE;
-	fdt->close_on_exec = &newf->close_on_exec_init;
-	fdt->open_fds = &newf->open_fds_init;
+	fdt->max_fdset = EMBEDDED_FD_SET_SIZE;
+	fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
+	fdt->open_fds = (fd_set *)&newf->open_fds_init;
 	fdt->fd = &newf->fd_array[0];
 	INIT_RCU_HEAD(&fdt->rcu);
 	fdt->free_files = NULL;