diff options
Diffstat (limited to 'include/linux/file.h')
| -rw-r--r-- | include/linux/file.h | 28 |
1 files changed, 24 insertions, 4 deletions
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)) |