6 files changed, 55 insertions, 42 deletions

diff --git a/fs/fcntl.c b/fs/fcntl.c
index dc4a7007f4e7..03c789560fb8 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -73,8 +73,8 @@ repeat:
          * 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 @@ repeat:
          * 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;
         
diff --git a/fs/file.c b/fs/file.c
index cea7cbea11d0..bbc743314730 100644
--- a/fs/file.c
+++ b/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);
diff --git a/fs/open.c b/fs/open.c
index 70e0230d8e77..1091dadd6c38 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -973,7 +973,7 @@ repeat:
         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 @@ repeat:
 
         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)
diff --git a/include/linux/file.h b/include/linux/file.h
index 9901b850f2e4..9f7c2513866f 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -10,6 +10,7 @@
 #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,
@@ -17,10 +18,22 @@
  */
 #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))
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index dcfd2ecccb5d..92146f3b7423 100644
--- a/include/linux/init_task.h
+++ b/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, }                     \
diff --git a/kernel/fork.c b/kernel/fork.c
index 9bd7b65ee418..c79ae0b19a49 100644
--- a/kernel/fork.c
+++ b/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;