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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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#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_SECURITYvoid *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);
#ifdef CONFIG_SYSCTL
/* * 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); else 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);}