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-rw-r--r--fs/file_table.c667
1 files changed, 667 insertions, 0 deletions
diff --git a/fs/file_table.c b/fs/file_table.c
new file mode 100644
index 000000000..c68b8c0a4
--- /dev/null
+++ b/fs/file_table.c
@@ -0,0 +1,667 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/file_table.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
+ */
+
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/filelock.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include <linux/eventpoll.h>
+#include <linux/rcupdate.h>
+#include <linux/mount.h>
+#include <linux/capability.h>
+#include <linux/cdev.h>
+#include <linux/fsnotify.h>
+#include <linux/sysctl.h>
+#include <linux/percpu_counter.h>
+#include <linux/percpu.h>
+#include <linux/task_work.h>
+#include <linux/swap.h>
+#include <linux/kmemleak.h>
+
+#include <linux/atomic.h>
+
+#include <asm/runtime-const.h>
+
+#include "internal.h"
+
+/* sysctl tunables... */
+static struct files_stat_struct files_stat = {
+ .max_files = NR_FILE
+};
+
+/* SLAB cache for file structures */
+static struct kmem_cache *__filp_cache __ro_after_init;
+#define filp_cache runtime_const_ptr(__filp_cache)
+static struct kmem_cache *__bfilp_cache __ro_after_init;
+#define bfilp_cache runtime_const_ptr(__bfilp_cache)
+
+static struct percpu_counter nr_files __cacheline_aligned_in_smp;
+
+/* Container for backing file with optional user path */
+struct backing_file {
+ struct file file;
+ union {
+ struct path user_path;
+ freeptr_t bf_freeptr;
+ };
+#ifdef CONFIG_SECURITY
+ void *security;
+#endif
+};
+
+#define backing_file(f) container_of(f, struct backing_file, file)
+
+const struct path *backing_file_user_path(const struct file *f)
+{
+ return &backing_file(f)->user_path;
+}
+EXPORT_SYMBOL_GPL(backing_file_user_path);
+
+void backing_file_set_user_path(struct file *f, const struct path *path)
+{
+ backing_file(f)->user_path = *path;
+}
+EXPORT_SYMBOL_GPL(backing_file_set_user_path);
+
+#ifdef CONFIG_SECURITY
+void *backing_file_security(const struct file *f)
+{
+ return backing_file(f)->security;
+}
+
+void backing_file_set_security(struct file *f, void *security)
+{
+ backing_file(f)->security = security;
+}
+#endif /* CONFIG_SECURITY */
+
+static inline void backing_file_free(struct backing_file *ff)
+{
+ security_backing_file_free(&ff->file);
+ path_put(&ff->user_path);
+ kmem_cache_free(bfilp_cache, ff);
+}
+
+static inline void file_free(struct file *f)
+{
+ security_file_free(f);
+ if (likely(!(f->f_mode & FMODE_NOACCOUNT)))
+ percpu_counter_dec(&nr_files);
+ put_cred(f->f_cred);
+ if (unlikely(f->f_mode & FMODE_BACKING)) {
+ backing_file_free(backing_file(f));
+ } else {
+ kmem_cache_free(filp_cache, f);
+ }
+}
+
+/*
+ * Return the total number of open files in the system
+ */
+static long get_nr_files(void)
+{
+ return percpu_counter_read_positive(&nr_files);
+}
+
+/*
+ * Return the maximum number of open files in the system
+ */
+unsigned long get_max_files(void)
+{
+ return files_stat.max_files;
+}
+EXPORT_SYMBOL_GPL(get_max_files);
+
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
+
+/*
+ * Handle nr_files sysctl
+ */
+static int proc_nr_files(const struct ctl_table *table, int write, void *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ files_stat.nr_files = percpu_counter_sum_positive(&nr_files);
+ return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+}
+
+static const struct ctl_table fs_stat_sysctls[] = {
+ {
+ .procname = "file-nr",
+ .data = &files_stat,
+ .maxlen = sizeof(files_stat),
+ .mode = 0444,
+ .proc_handler = proc_nr_files,
+ },
+ {
+ .procname = "file-max",
+ .data = &files_stat.max_files,
+ .maxlen = sizeof(files_stat.max_files),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ .extra1 = SYSCTL_LONG_ZERO,
+ .extra2 = SYSCTL_LONG_MAX,
+ },
+ {
+ .procname = "nr_open",
+ .data = &sysctl_nr_open,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_douintvec_minmax,
+ .extra1 = &sysctl_nr_open_min,
+ .extra2 = &sysctl_nr_open_max,
+ },
+};
+
+static int __init init_fs_stat_sysctls(void)
+{
+ register_sysctl_init("fs", fs_stat_sysctls);
+ if (IS_ENABLED(CONFIG_BINFMT_MISC)) {
+ struct ctl_table_header *hdr;
+
+ hdr = register_sysctl_mount_point("fs/binfmt_misc");
+ kmemleak_not_leak(hdr);
+ }
+ return 0;
+}
+fs_initcall(init_fs_stat_sysctls);
+#endif
+
+static int init_file(struct file *f, int flags, const struct cred *cred)
+{
+ int error;
+
+ f->f_cred = get_cred(cred);
+ error = security_file_alloc(f);
+ if (unlikely(error)) {
+ put_cred(f->f_cred);
+ return error;
+ }
+
+ spin_lock_init(&f->f_lock);
+ /*
+ * Note that f_pos_lock is only used for files raising
+ * FMODE_ATOMIC_POS and directories. Other files such as pipes
+ * don't need it and since f_pos_lock is in a union may reuse
+ * the space for other purposes. They are expected to initialize
+ * the respective member when opening the file.
+ */
+ mutex_init(&f->f_pos_lock);
+ memset(&f->__f_path, 0, sizeof(f->f_path));
+ memset(&f->f_ra, 0, sizeof(f->f_ra));
+
+ f->f_flags = flags;
+ f->f_mode = OPEN_FMODE(flags);
+ /*
+ * Disable permission and pre-content events for all files by default.
+ * They may be enabled later by fsnotify_open_perm_and_set_mode().
+ */
+ file_set_fsnotify_mode(f, FMODE_NONOTIFY_PERM);
+
+ f->f_op = NULL;
+ f->f_mapping = NULL;
+ f->private_data = NULL;
+ f->f_inode = NULL;
+ f->f_owner = NULL;
+#ifdef CONFIG_EPOLL
+ f->f_ep = NULL;
+#endif
+
+ f->f_iocb_flags = 0;
+ f->f_pos = 0;
+ f->f_wb_err = 0;
+ f->f_sb_err = 0;
+
+ /*
+ * We're SLAB_TYPESAFE_BY_RCU so initialize f_ref last. While
+ * fget-rcu pattern users need to be able to handle spurious
+ * refcount bumps we should reinitialize the reused file first.
+ */
+ file_ref_init(&f->f_ref, 1);
+ return 0;
+}
+
+/* Find an unused file structure and return a pointer to it.
+ * Returns an error pointer if some error happened, e.g., we exceed the file
+ * structures limit, run out of memory or operation is not permitted.
+ *
+ * Be very careful using this. You are responsible for
+ * getting write access to any mount that you might assign
+ * to this filp, if it is opened for write. If this is not
+ * done, the mount's writer count will be wrong
+ * and a warning at __fput() time.
+ */
+struct file *alloc_empty_file(int flags, const struct cred *cred)
+{
+ static long old_max;
+ struct file *f;
+ int error;
+
+ /*
+ * Privileged users can go above max_files
+ */
+ if (unlikely(get_nr_files() >= files_stat.max_files) &&
+ !capable(CAP_SYS_ADMIN)) {
+ /*
+ * percpu_counters are inaccurate. Do an expensive check before
+ * we go and fail.
+ */
+ if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
+ goto over;
+ }
+
+ f = kmem_cache_alloc(filp_cache, GFP_KERNEL);
+ if (unlikely(!f))
+ return ERR_PTR(-ENOMEM);
+
+ error = init_file(f, flags, cred);
+ if (unlikely(error)) {
+ kmem_cache_free(filp_cache, f);
+ return ERR_PTR(error);
+ }
+
+ percpu_counter_inc(&nr_files);
+
+ return f;
+
+over:
+ /* Ran out of filps - report that */
+ if (get_nr_files() > old_max) {
+ pr_info("VFS: file-max limit %lu reached\n", get_max_files());
+ old_max = get_nr_files();
+ }
+ return ERR_PTR(-ENFILE);
+}
+
+/*
+ * Variant of alloc_empty_file() that doesn't check and modify nr_files.
+ *
+ * This is only for kernel internal use, and the allocate file must not be
+ * installed into file tables or such.
+ */
+struct file *alloc_empty_file_noaccount(int flags, const struct cred *cred)
+{
+ struct file *f;
+ int error;
+
+ f = kmem_cache_alloc(filp_cache, GFP_KERNEL);
+ if (unlikely(!f))
+ return ERR_PTR(-ENOMEM);
+
+ error = init_file(f, flags, cred);
+ if (unlikely(error)) {
+ kmem_cache_free(filp_cache, f);
+ return ERR_PTR(error);
+ }
+
+ f->f_mode |= FMODE_NOACCOUNT;
+
+ return f;
+}
+
+static int init_backing_file(struct backing_file *ff,
+ const struct file *user_file)
+{
+ memset(&ff->user_path, 0, sizeof(ff->user_path));
+ backing_file_set_security(&ff->file, NULL);
+ return security_backing_file_alloc(&ff->file, user_file);
+}
+
+/*
+ * Variant of alloc_empty_file() that allocates a backing_file container
+ * and doesn't check and modify nr_files.
+ *
+ * This is only for kernel internal use, and the allocate file must not be
+ * installed into file tables or such.
+ */
+struct file *alloc_empty_backing_file(int flags, const struct cred *cred,
+ const struct file *user_file)
+{
+ struct backing_file *ff;
+ int error;
+
+ ff = kmem_cache_alloc(bfilp_cache, GFP_KERNEL);
+ if (unlikely(!ff))
+ return ERR_PTR(-ENOMEM);
+
+ error = init_file(&ff->file, flags, cred);
+ if (unlikely(error)) {
+ kmem_cache_free(bfilp_cache, ff);
+ return ERR_PTR(error);
+ }
+
+ /* The f_mode flags must be set before fput(). */
+ ff->file.f_mode |= FMODE_BACKING | FMODE_NOACCOUNT;
+ error = init_backing_file(ff, user_file);
+ if (unlikely(error)) {
+ fput(&ff->file);
+ return ERR_PTR(error);
+ }
+
+ return &ff->file;
+}
+EXPORT_SYMBOL_GPL(alloc_empty_backing_file);
+
+/**
+ * file_init_path - initialize a 'struct file' based on path
+ *
+ * @file: the file to set up
+ * @path: the (dentry, vfsmount) pair for the new file
+ * @fop: the 'struct file_operations' for the new file
+ */
+static void file_init_path(struct file *file, const struct path *path,
+ const struct file_operations *fop)
+{
+ file->__f_path = *path;
+ file->f_inode = path->dentry->d_inode;
+ file->f_mapping = path->dentry->d_inode->i_mapping;
+ file->f_wb_err = filemap_sample_wb_err(file->f_mapping);
+ file->f_sb_err = file_sample_sb_err(file);
+ if (fop->llseek)
+ file->f_mode |= FMODE_LSEEK;
+ if ((file->f_mode & FMODE_READ) &&
+ likely(fop->read || fop->read_iter))
+ file->f_mode |= FMODE_CAN_READ;
+ if ((file->f_mode & FMODE_WRITE) &&
+ likely(fop->write || fop->write_iter))
+ file->f_mode |= FMODE_CAN_WRITE;
+ file->f_iocb_flags = iocb_flags(file);
+ file->f_mode |= FMODE_OPENED;
+ file->f_op = fop;
+ if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+ i_readcount_inc(path->dentry->d_inode);
+}
+
+/**
+ * alloc_file - allocate and initialize a 'struct file'
+ *
+ * @path: the (dentry, vfsmount) pair for the new file
+ * @flags: O_... flags with which the new file will be opened
+ * @fop: the 'struct file_operations' for the new file
+ */
+static struct file *alloc_file(const struct path *path, int flags,
+ const struct file_operations *fop)
+{
+ struct file *file;
+
+ file = alloc_empty_file(flags, current_cred());
+ if (!IS_ERR(file))
+ file_init_path(file, path, fop);
+ return file;
+}
+
+static inline int alloc_path_pseudo(const char *name, struct inode *inode,
+ struct vfsmount *mnt, struct path *path)
+{
+ if (WARN_ON_ONCE(S_ISDIR(inode->i_mode)))
+ return -EINVAL;
+ path->dentry = d_alloc_pseudo(mnt->mnt_sb, &QSTR(name));
+ if (!path->dentry)
+ return -ENOMEM;
+ path->mnt = mntget(mnt);
+ d_instantiate(path->dentry, inode);
+ return 0;
+}
+
+struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt,
+ const char *name, int flags,
+ const struct file_operations *fops)
+{
+ int ret;
+ struct path path;
+ struct file *file;
+
+ ret = alloc_path_pseudo(name, inode, mnt, &path);
+ if (ret)
+ return ERR_PTR(ret);
+
+ file = alloc_file(&path, flags, fops);
+ if (IS_ERR(file)) {
+ ihold(inode);
+ path_put(&path);
+ return file;
+ }
+ /*
+ * Disable all fsnotify events for pseudo files by default.
+ * They may be enabled by caller with file_set_fsnotify_mode().
+ */
+ file_set_fsnotify_mode(file, FMODE_NONOTIFY);
+ return file;
+}
+EXPORT_SYMBOL(alloc_file_pseudo);
+
+struct file *alloc_file_pseudo_noaccount(struct inode *inode,
+ struct vfsmount *mnt, const char *name,
+ int flags,
+ const struct file_operations *fops)
+{
+ int ret;
+ struct path path;
+ struct file *file;
+
+ ret = alloc_path_pseudo(name, inode, mnt, &path);
+ if (ret)
+ return ERR_PTR(ret);
+
+ file = alloc_empty_file_noaccount(flags, current_cred());
+ if (IS_ERR(file)) {
+ ihold(inode);
+ path_put(&path);
+ return file;
+ }
+ file_init_path(file, &path, fops);
+ /*
+ * Disable all fsnotify events for pseudo files by default.
+ * They may be enabled by caller with file_set_fsnotify_mode().
+ */
+ file_set_fsnotify_mode(file, FMODE_NONOTIFY);
+ return file;
+}
+EXPORT_SYMBOL_GPL(alloc_file_pseudo_noaccount);
+
+struct file *alloc_file_clone(struct file *base, int flags,
+ const struct file_operations *fops)
+{
+ struct file *f;
+
+ f = alloc_file(&base->f_path, flags, fops);
+ if (!IS_ERR(f)) {
+ path_get(&f->f_path);
+ f->f_mapping = base->f_mapping;
+ }
+ return f;
+}
+
+/* the real guts of fput() - releasing the last reference to file
+ */
+static void __fput(struct file *file)
+{
+ struct dentry *dentry = file->f_path.dentry;
+ struct vfsmount *mnt = file->f_path.mnt;
+ struct inode *inode = file->f_inode;
+ fmode_t mode = file->f_mode;
+
+ if (unlikely(!(file->f_mode & FMODE_OPENED)))
+ goto out;
+
+ might_sleep();
+
+ fsnotify_close(file);
+ /*
+ * The function eventpoll_release() should be the first called
+ * in the file cleanup chain.
+ */
+ eventpoll_release(file);
+ locks_remove_file(file);
+
+ security_file_release(file);
+ if (unlikely(file->f_flags & FASYNC)) {
+ if (file->f_op->fasync)
+ file->f_op->fasync(-1, file, 0);
+ }
+ if (file->f_op->release)
+ file->f_op->release(inode, file);
+ if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
+ !(mode & FMODE_PATH))) {
+ cdev_put(inode->i_cdev);
+ }
+ fops_put(file->f_op);
+ file_f_owner_release(file);
+ put_file_access(file);
+ dput(dentry);
+ if (unlikely(mode & FMODE_NEED_UNMOUNT))
+ dissolve_on_fput(mnt);
+ mntput(mnt);
+out:
+ file_free(file);
+}
+
+static LLIST_HEAD(delayed_fput_list);
+static void delayed_fput(struct work_struct *unused)
+{
+ struct llist_node *node = llist_del_all(&delayed_fput_list);
+ struct file *f, *t;
+
+ llist_for_each_entry_safe(f, t, node, f_llist)
+ __fput(f);
+}
+
+static void ____fput(struct callback_head *work)
+{
+ __fput(container_of(work, struct file, f_task_work));
+}
+
+static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
+
+/*
+ * If kernel thread really needs to have the final fput() it has done
+ * to complete, call this. The only user right now is the boot - we
+ * *do* need to make sure our writes to binaries on initramfs has
+ * not left us with opened struct file waiting for __fput() - execve()
+ * won't work without that. Please, don't add more callers without
+ * very good reasons; in particular, never call that with locks
+ * held and never call that from a thread that might need to do
+ * some work on any kind of umount.
+ */
+void flush_delayed_fput(void)
+{
+ delayed_fput(NULL);
+ flush_delayed_work(&delayed_fput_work);
+}
+EXPORT_SYMBOL_GPL(flush_delayed_fput);
+
+static void __fput_deferred(struct file *file)
+{
+ struct task_struct *task = current;
+
+ if (unlikely(!(file->f_mode & (FMODE_BACKING | FMODE_OPENED)))) {
+ file_free(file);
+ return;
+ }
+
+ if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
+ init_task_work(&file->f_task_work, ____fput);
+ if (!task_work_add(task, &file->f_task_work, TWA_RESUME))
+ return;
+ /*
+ * After this task has run exit_task_work(),
+ * task_work_add() will fail. Fall through to delayed
+ * fput to avoid leaking *file.
+ */
+ }
+
+ if (llist_add(&file->f_llist, &delayed_fput_list))
+ schedule_delayed_work(&delayed_fput_work, 1);
+}
+
+void fput(struct file *file)
+{
+ if (unlikely(file_ref_put(&file->f_ref)))
+ __fput_deferred(file);
+}
+EXPORT_SYMBOL(fput);
+
+/*
+ * synchronous analog of fput(); for kernel threads that might be needed
+ * in some umount() (and thus can't use flush_delayed_fput() without
+ * risking deadlocks), need to wait for completion of __fput() and know
+ * for this specific struct file it won't involve anything that would
+ * need them. Use only if you really need it - at the very least,
+ * don't blindly convert fput() by kernel thread to that.
+ */
+void __fput_sync(struct file *file)
+{
+ if (file_ref_put(&file->f_ref))
+ __fput(file);
+}
+EXPORT_SYMBOL(__fput_sync);
+
+/*
+ * Equivalent to __fput_sync(), but optimized for being called with the last
+ * reference.
+ *
+ * See file_ref_put_close() for details.
+ */
+void fput_close_sync(struct file *file)
+{
+ if (likely(file_ref_put_close(&file->f_ref)))
+ __fput(file);
+}
+
+/*
+ * Equivalent to fput(), but optimized for being called with the last
+ * reference.
+ *
+ * See file_ref_put_close() for details.
+ */
+void fput_close(struct file *file)
+{
+ if (file_ref_put_close(&file->f_ref))
+ __fput_deferred(file);
+}
+
+void __init files_init(void)
+{
+ struct kmem_cache_args args = {
+ .use_freeptr_offset = true,
+ .freeptr_offset = offsetof(struct file, f_freeptr),
+ };
+
+ __filp_cache = kmem_cache_create("filp", sizeof(struct file), &args,
+ SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+ SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU);
+ runtime_const_init(ptr, __filp_cache);
+
+ args.freeptr_offset = offsetof(struct backing_file, bf_freeptr);
+ __bfilp_cache = kmem_cache_create("bfilp", sizeof(struct backing_file),
+ &args, SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+ SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU);
+ runtime_const_init(ptr, __bfilp_cache);
+
+ percpu_counter_init(&nr_files, 0, GFP_KERNEL);
+}
+
+/*
+ * One file with associated inode and dcache is very roughly 1K. Per default
+ * do not use more than 10% of our memory for files.
+ */
+void __init files_maxfiles_init(void)
+{
+ unsigned long n;
+ unsigned long nr_pages = totalram_pages();
+ unsigned long memreserve = (nr_pages - nr_free_pages()) * 3/2;
+
+ memreserve = min(memreserve, nr_pages - 1);
+ n = ((nr_pages - memreserve) * (PAGE_SIZE / 1024)) / 10;
+
+ files_stat.max_files = max_t(unsigned long, n, NR_FILE);
+}
generated by cgit v1.3.1 (git 2.54.0) at 2026-10-11 19:24:49 +0000