diff --git a/fs/fcntl.c b/fs/fcntl.c index dc4a7007f4e742c4e30563db78b34bd21d39ab58..03c789560fb87b6213abc2b33cf5dea494fb583d 100644 --- a/fs/fcntl.c +++ b/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; diff --git a/fs/file.c b/fs/file.c index cea7cbea11d0d5fca944ab11a331568fe0949fb7..bbc743314730b6eeadcc7d9a183f485f58875c81 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 70e0230d8e77b79a5becb1cecece91e95a062a2e..1091dadd6c381e6ff0b7e69adad80734d9502792 100644 --- a/fs/open.c +++ b/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) diff --git a/include/linux/file.h b/include/linux/file.h index 9901b850f2e466158556711303829d6d114686ce..9f7c2513866f4d1a857398711f09864239b7162c 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -10,6 +10,7 @@ #include #include #include +#include /* * 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 dcfd2ecccb5d63dbcb2718a2f3e827aef9d68a23..92146f3b7423594f496b5051f6cb14d6b7d23297 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 9bd7b65ee418b8a05498d3cd8b89c53dcb66e6fc..c79ae0b19a4922da1ff651f802eb199afe4fe7c0 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;