X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;ds=sidebyside;f=fs%2Ffile_table.c;h=32d12b78bac8e2c05a80dc53386b355bdc10ef73;hb=4434ade8c9334a3ab975d8993de456f06841899e;hp=ce3f39a4798a362c615ed51a2be83e4b616c8a86;hpb=4975e45ff66845c9acc6c8619e80ef15eadf785e;p=safe%2Fjmp%2Flinux-2.6 diff --git a/fs/file_table.c b/fs/file_table.c index ce3f39a..32d12b7 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -20,9 +21,12 @@ #include #include #include +#include #include +#include "internal.h" + /* sysctl tunables... */ struct files_stat_struct files_stat = { .max_files = NR_FILE @@ -31,17 +35,23 @@ struct files_stat_struct files_stat = { /* public. Not pretty! */ __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); +/* SLAB cache for file structures */ +static struct kmem_cache *filp_cachep __read_mostly; + static struct percpu_counter nr_files __cacheline_aligned_in_smp; static inline void file_free_rcu(struct rcu_head *head) { - struct file *f = container_of(head, struct file, f_u.fu_rcuhead); + struct file *f = container_of(head, struct file, f_u.fu_rcuhead); + + put_cred(f->f_cred); kmem_cache_free(filp_cachep, f); } static inline void file_free(struct file *f) { percpu_counter_dec(&nr_files); + file_check_state(f); call_rcu(&f->f_u.fu_rcuhead, file_free_rcu); } @@ -66,14 +76,14 @@ EXPORT_SYMBOL_GPL(get_max_files); * Handle nr_files sysctl */ #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) -int proc_nr_files(ctl_table *table, int write, struct file *filp, +int proc_nr_files(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { files_stat.nr_files = get_nr_files(); - return proc_dointvec(table, write, filp, buffer, lenp, ppos); + return proc_dointvec(table, write, buffer, lenp, ppos); } #else -int proc_nr_files(ctl_table *table, int write, struct file *filp, +int proc_nr_files(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; @@ -83,10 +93,16 @@ int proc_nr_files(ctl_table *table, int write, struct file *filp, /* Find an unused file structure and return a pointer to it. * Returns NULL, if there are no more free file structures or * we run out of memory. + * + * 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, you will imbalance int the mount's writer count + * and a warning at __fput() time. */ struct file *get_empty_filp(void) { - struct task_struct *tsk; + const struct cred *cred = current_cred(); static int old_max; struct file * f; @@ -110,12 +126,11 @@ struct file *get_empty_filp(void) if (security_file_alloc(f)) goto fail_sec; - tsk = current; INIT_LIST_HEAD(&f->f_u.fu_list); - atomic_set(&f->f_count, 1); + atomic_long_set(&f->f_count, 1); rwlock_init(&f->f_owner.lock); - f->f_uid = tsk->fsuid; - f->f_gid = tsk->fsgid; + f->f_cred = get_cred(cred); + spin_lock_init(&f->f_lock); eventpoll_init_file(f); /* f->f_version: 0 */ return f; @@ -135,20 +150,87 @@ fail: return NULL; } -EXPORT_SYMBOL(get_empty_filp); +/** + * alloc_file - allocate and initialize a 'struct file' + * @mnt: the vfsmount on which the file will reside + * @dentry: the dentry representing the new file + * @mode: the mode with which the new file will be opened + * @fop: the 'struct file_operations' for the new file + * + * Use this instead of get_empty_filp() to get a new + * 'struct file'. Do so because of the same initialization + * pitfalls reasons listed for init_file(). This is a + * preferred interface to using init_file(). + * + * If all the callers of init_file() are eliminated, its + * code should be moved into this function. + */ +struct file *alloc_file(struct path *path, fmode_t mode, + const struct file_operations *fop) +{ + struct file *file; + + file = get_empty_filp(); + if (!file) + return NULL; + + file->f_path = *path; + file->f_mapping = path->dentry->d_inode->i_mapping; + file->f_mode = mode; + file->f_op = fop; + + /* + * These mounts don't really matter in practice + * for r/o bind mounts. They aren't userspace- + * visible. We do this for consistency, and so + * that we can do debugging checks at __fput() + */ + if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) { + file_take_write(file); + WARN_ON(mnt_clone_write(path->mnt)); + } + ima_counts_get(file); + return file; +} +EXPORT_SYMBOL(alloc_file); -void fastcall fput(struct file *file) +void fput(struct file *file) { - if (atomic_dec_and_test(&file->f_count)) + if (atomic_long_dec_and_test(&file->f_count)) __fput(file); } EXPORT_SYMBOL(fput); +/** + * drop_file_write_access - give up ability to write to a file + * @file: the file to which we will stop writing + * + * This is a central place which will give up the ability + * to write to @file, along with access to write through + * its vfsmount. + */ +void drop_file_write_access(struct file *file) +{ + struct vfsmount *mnt = file->f_path.mnt; + struct dentry *dentry = file->f_path.dentry; + struct inode *inode = dentry->d_inode; + + put_write_access(inode); + + if (special_file(inode->i_mode)) + return; + if (file_check_writeable(file) != 0) + return; + mnt_drop_write(mnt); + file_release_write(file); +} +EXPORT_SYMBOL_GPL(drop_file_write_access); + /* __fput is called from task context when aio completion releases the last * last use of a struct file *. Do not use otherwise. */ -void fastcall __fput(struct file *file) +void __fput(struct file *file) { struct dentry *dentry = file->f_path.dentry; struct vfsmount *mnt = file->f_path.mnt; @@ -164,16 +246,21 @@ void fastcall __fput(struct file *file) eventpoll_release(file); locks_remove_flock(file); + if (unlikely(file->f_flags & FASYNC)) { + if (file->f_op && file->f_op->fasync) + file->f_op->fasync(-1, file, 0); + } if (file->f_op && file->f_op->release) file->f_op->release(inode, file); security_file_free(file); + ima_file_free(file); if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL)) cdev_put(inode->i_cdev); fops_put(file->f_op); - if (file->f_mode & FMODE_WRITE) - put_write_access(inode); put_pid(file->f_owner.pid); file_kill(file); + if (file->f_mode & FMODE_WRITE) + drop_file_write_access(file); file->f_path.dentry = NULL; file->f_path.mnt = NULL; file_free(file); @@ -181,7 +268,7 @@ void fastcall __fput(struct file *file) mntput(mnt); } -struct file fastcall *fget(unsigned int fd) +struct file *fget(unsigned int fd) { struct file *file; struct files_struct *files = current->files; @@ -189,7 +276,7 @@ struct file fastcall *fget(unsigned int fd) rcu_read_lock(); file = fcheck_files(files, fd); if (file) { - if (!atomic_inc_not_zero(&file->f_count)) { + if (!atomic_long_inc_not_zero(&file->f_count)) { /* File object ref couldn't be taken */ rcu_read_unlock(); return NULL; @@ -209,7 +296,7 @@ EXPORT_SYMBOL(fget); * and a flag is returned to be passed to the corresponding fput_light(). * There must not be a cloning between an fget_light/fput_light pair. */ -struct file fastcall *fget_light(unsigned int fd, int *fput_needed) +struct file *fget_light(unsigned int fd, int *fput_needed) { struct file *file; struct files_struct *files = current->files; @@ -221,7 +308,7 @@ struct file fastcall *fget_light(unsigned int fd, int *fput_needed) rcu_read_lock(); file = fcheck_files(files, fd); if (file) { - if (atomic_inc_not_zero(&file->f_count)) + if (atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ @@ -236,7 +323,7 @@ struct file fastcall *fget_light(unsigned int fd, int *fput_needed) void put_filp(struct file *file) { - if (atomic_dec_and_test(&file->f_count)) { + if (atomic_long_dec_and_test(&file->f_count)) { security_file_free(file); file_kill(file); file_free(file); @@ -263,12 +350,11 @@ void file_kill(struct file *file) int fs_may_remount_ro(struct super_block *sb) { - struct list_head *p; + struct file *file; /* Check that no files are currently opened for writing. */ file_list_lock(); - list_for_each(p, &sb->s_files) { - struct file *file = list_entry(p, struct file, f_u.fu_list); + list_for_each_entry(file, &sb->s_files, f_u.fu_list) { struct inode *inode = file->f_path.dentry->d_inode; /* File with pending delete? */ @@ -286,10 +372,55 @@ too_bad: return 0; } +/** + * mark_files_ro - mark all files read-only + * @sb: superblock in question + * + * All files are marked read-only. We don't care about pending + * delete files so this should be used in 'force' mode only. + */ +void mark_files_ro(struct super_block *sb) +{ + struct file *f; + +retry: + file_list_lock(); + list_for_each_entry(f, &sb->s_files, f_u.fu_list) { + struct vfsmount *mnt; + if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) + continue; + if (!file_count(f)) + continue; + if (!(f->f_mode & FMODE_WRITE)) + continue; + spin_lock(&f->f_lock); + f->f_mode &= ~FMODE_WRITE; + spin_unlock(&f->f_lock); + if (file_check_writeable(f) != 0) + continue; + file_release_write(f); + mnt = mntget(f->f_path.mnt); + file_list_unlock(); + /* + * This can sleep, so we can't hold + * the file_list_lock() spinlock. + */ + mnt_drop_write(mnt); + mntput(mnt); + goto retry; + } + file_list_unlock(); +} + void __init files_init(unsigned long mempages) { int n; - /* One file with associated inode and dcache is very roughly 1K. + + filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, + SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); + + /* + * One file with associated inode and dcache is very roughly 1K. * Per default don't use more than 10% of our memory for files. */