X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Ffile.c;h=87e129030ab1564a69061b82b9608c59cced9f1a;hb=b5ff992b09dbe06a4a020fbb702e29ab61290cc5;hp=6491b2b5bc3828fd012a094d93216b67b31b9f0e;hpb=9dec3c4d306b09b31331e475e895bb9674e16d81;p=safe%2Fjmp%2Flinux-2.6 diff --git a/fs/file.c b/fs/file.c index 6491b2b..87e1290 100644 --- a/fs/file.c +++ b/fs/file.c @@ -6,9 +6,11 @@ * Manage the dynamic fd arrays in the process files_struct. */ +#include #include #include #include +#include #include #include #include @@ -26,6 +28,8 @@ struct fdtable_defer { }; int sysctl_nr_open __read_mostly = 1024*1024; +int sysctl_nr_open_min = BITS_PER_LONG; +int sysctl_nr_open_max = 1024 * 1024; /* raised later */ /* * We use this list to defer free fdtables that have vmalloced @@ -248,9 +252,18 @@ int expand_files(struct files_struct *files, int nr) struct fdtable *fdt; fdt = files_fdtable(files); + + /* + * N.B. For clone tasks sharing a files structure, this test + * will limit the total number of files that can be opened. + */ + if (nr >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) + return -EMFILE; + /* Do we need to expand? */ if (nr < fdt->max_fds) return 0; + /* Can we expand? */ if (nr >= sysctl_nr_open) return -EMFILE; @@ -273,31 +286,6 @@ static int count_open_files(struct fdtable *fdt) return i; } -static struct files_struct *alloc_files(void) -{ - struct files_struct *newf; - struct fdtable *fdt; - - newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); - if (!newf) - goto out; - - atomic_set(&newf->count, 1); - - spin_lock_init(&newf->file_lock); - newf->next_fd = 0; - fdt = &newf->fdtab; - fdt->max_fds = NR_OPEN_DEFAULT; - 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->next = NULL; - rcu_assign_pointer(newf->fdt, fdt); -out: - return newf; -} - /* * Allocate a new files structure and copy contents from the * passed in files structure. @@ -311,22 +299,38 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) struct fdtable *old_fdt, *new_fdt; *errorp = -ENOMEM; - newf = alloc_files(); + newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); if (!newf) goto out; + atomic_set(&newf->count, 1); + + spin_lock_init(&newf->file_lock); + newf->next_fd = 0; + new_fdt = &newf->fdtab; + new_fdt->max_fds = NR_OPEN_DEFAULT; + new_fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init; + new_fdt->open_fds = (fd_set *)&newf->open_fds_init; + new_fdt->fd = &newf->fd_array[0]; + INIT_RCU_HEAD(&new_fdt->rcu); + new_fdt->next = NULL; + spin_lock(&oldf->file_lock); old_fdt = files_fdtable(oldf); - new_fdt = files_fdtable(newf); open_files = count_open_files(old_fdt); /* * Check whether we need to allocate a larger fd array and fd set. - * Note: we're not a clone task, so the open count won't change. */ - if (open_files > new_fdt->max_fds) { + while (unlikely(open_files > new_fdt->max_fds)) { spin_unlock(&oldf->file_lock); + if (new_fdt != &newf->fdtab) { + free_fdarr(new_fdt); + free_fdset(new_fdt); + kfree(new_fdt); + } + new_fdt = alloc_fdtable(open_files - 1); if (!new_fdt) { *errorp = -ENOMEM; @@ -341,7 +345,6 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) *errorp = -EMFILE; goto out_release; } - rcu_assign_pointer(files->fdt, new_fdt); /* * Reacquire the oldf lock and a pointer to its fd table @@ -350,6 +353,7 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) */ spin_lock(&oldf->file_lock); old_fdt = files_fdtable(oldf); + open_files = count_open_files(old_fdt); } old_fds = old_fdt->fd; @@ -391,6 +395,8 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) memset(&new_fdt->close_on_exec->fds_bits[start], 0, left); } + rcu_assign_pointer(newf->fdt, new_fdt); + return newf; out_release: @@ -412,6 +418,8 @@ void __init files_defer_init(void) int i; for_each_possible_cpu(i) fdtable_defer_list_init(i); + sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) & + -BITS_PER_LONG; } struct files_struct init_files = { @@ -426,3 +434,63 @@ struct files_struct init_files = { }, .file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock), }; + +/* + * allocate a file descriptor, mark it busy. + */ +int alloc_fd(unsigned start, unsigned flags) +{ + struct files_struct *files = current->files; + unsigned int fd; + int error; + struct fdtable *fdt; + + spin_lock(&files->file_lock); +repeat: + fdt = files_fdtable(files); + fd = start; + if (fd < files->next_fd) + fd = files->next_fd; + + if (fd < fdt->max_fds) + fd = find_next_zero_bit(fdt->open_fds->fds_bits, + fdt->max_fds, fd); + + error = expand_files(files, fd); + if (error < 0) + goto out; + + /* + * If we needed to expand the fs array we + * might have blocked - try again. + */ + if (error) + goto repeat; + + if (start <= files->next_fd) + files->next_fd = fd + 1; + + FD_SET(fd, fdt->open_fds); + if (flags & O_CLOEXEC) + FD_SET(fd, fdt->close_on_exec); + else + FD_CLR(fd, fdt->close_on_exec); + error = fd; +#if 1 + /* Sanity check */ + if (rcu_dereference(fdt->fd[fd]) != NULL) { + printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); + rcu_assign_pointer(fdt->fd[fd], NULL); + } +#endif + +out: + spin_unlock(&files->file_lock); + return error; +} + +int get_unused_fd(void) +{ + return alloc_fd(0, 0); +} +EXPORT_SYMBOL(get_unused_fd);