11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * fs/libfs.c 31da177e4SLinus Torvalds * Library for filesystems writers. 41da177e4SLinus Torvalds */ 51da177e4SLinus Torvalds 6ac13a829SFabian Frederick #include <linux/blkdev.h> 7630d9c47SPaul Gortmaker #include <linux/export.h> 81da177e4SLinus Torvalds #include <linux/pagemap.h> 95a0e3ad6STejun Heo #include <linux/slab.h> 101da177e4SLinus Torvalds #include <linux/mount.h> 111da177e4SLinus Torvalds #include <linux/vfs.h> 127bb46a67Snpiggin@suse.de #include <linux/quotaops.h> 137cf34c76SIngo Molnar #include <linux/mutex.h> 1487dc800bSAl Viro #include <linux/namei.h> 152596110aSChristoph Hellwig #include <linux/exportfs.h> 16d5aacad5SAl Viro #include <linux/writeback.h> 17ff01bb48SAl Viro #include <linux/buffer_head.h> /* sync_mapping_buffers */ 187cf34c76SIngo Molnar 191da177e4SLinus Torvalds #include <asm/uaccess.h> 201da177e4SLinus Torvalds 21a4464dbcSAl Viro #include "internal.h" 22a4464dbcSAl Viro 231da177e4SLinus Torvalds int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, 241da177e4SLinus Torvalds struct kstat *stat) 251da177e4SLinus Torvalds { 26dea655c2SDavid Howells struct inode *inode = d_inode(dentry); 271da177e4SLinus Torvalds generic_fillattr(inode, stat); 2809cbfeafSKirill A. Shutemov stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9); 291da177e4SLinus Torvalds return 0; 301da177e4SLinus Torvalds } 3112f38872SAl Viro EXPORT_SYMBOL(simple_getattr); 321da177e4SLinus Torvalds 33726c3342SDavid Howells int simple_statfs(struct dentry *dentry, struct kstatfs *buf) 341da177e4SLinus Torvalds { 35726c3342SDavid Howells buf->f_type = dentry->d_sb->s_magic; 3609cbfeafSKirill A. Shutemov buf->f_bsize = PAGE_SIZE; 371da177e4SLinus Torvalds buf->f_namelen = NAME_MAX; 381da177e4SLinus Torvalds return 0; 391da177e4SLinus Torvalds } 4012f38872SAl Viro EXPORT_SYMBOL(simple_statfs); 411da177e4SLinus Torvalds 421da177e4SLinus Torvalds /* 431da177e4SLinus Torvalds * Retaining negative dentries for an in-memory filesystem just wastes 441da177e4SLinus Torvalds * memory and lookup time: arrange for them to be deleted immediately. 451da177e4SLinus Torvalds */ 46b26d4cd3SAl Viro int always_delete_dentry(const struct dentry *dentry) 471da177e4SLinus Torvalds { 481da177e4SLinus Torvalds return 1; 491da177e4SLinus Torvalds } 50b26d4cd3SAl Viro EXPORT_SYMBOL(always_delete_dentry); 51b26d4cd3SAl Viro 52b26d4cd3SAl Viro const struct dentry_operations simple_dentry_operations = { 53b26d4cd3SAl Viro .d_delete = always_delete_dentry, 54b26d4cd3SAl Viro }; 55b26d4cd3SAl Viro EXPORT_SYMBOL(simple_dentry_operations); 561da177e4SLinus Torvalds 571da177e4SLinus Torvalds /* 581da177e4SLinus Torvalds * Lookup the data. This is trivial - if the dentry didn't already 591da177e4SLinus Torvalds * exist, we know it is negative. Set d_op to delete negative dentries. 601da177e4SLinus Torvalds */ 6100cd8dd3SAl Viro struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 621da177e4SLinus Torvalds { 631da177e4SLinus Torvalds if (dentry->d_name.len > NAME_MAX) 641da177e4SLinus Torvalds return ERR_PTR(-ENAMETOOLONG); 6574931da7SAl Viro if (!dentry->d_sb->s_d_op) 66fb045adbSNick Piggin d_set_d_op(dentry, &simple_dentry_operations); 671da177e4SLinus Torvalds d_add(dentry, NULL); 681da177e4SLinus Torvalds return NULL; 691da177e4SLinus Torvalds } 7012f38872SAl Viro EXPORT_SYMBOL(simple_lookup); 711da177e4SLinus Torvalds 721da177e4SLinus Torvalds int dcache_dir_open(struct inode *inode, struct file *file) 731da177e4SLinus Torvalds { 74ba65dc5eSAl Viro file->private_data = d_alloc_cursor(file->f_path.dentry); 751da177e4SLinus Torvalds 761da177e4SLinus Torvalds return file->private_data ? 0 : -ENOMEM; 771da177e4SLinus Torvalds } 7812f38872SAl Viro EXPORT_SYMBOL(dcache_dir_open); 791da177e4SLinus Torvalds 801da177e4SLinus Torvalds int dcache_dir_close(struct inode *inode, struct file *file) 811da177e4SLinus Torvalds { 821da177e4SLinus Torvalds dput(file->private_data); 831da177e4SLinus Torvalds return 0; 841da177e4SLinus Torvalds } 8512f38872SAl Viro EXPORT_SYMBOL(dcache_dir_close); 861da177e4SLinus Torvalds 874f42c1b5SAl Viro /* parent is locked at least shared */ 884f42c1b5SAl Viro static struct dentry *next_positive(struct dentry *parent, 894f42c1b5SAl Viro struct list_head *from, 904f42c1b5SAl Viro int count) 914f42c1b5SAl Viro { 92ebaaa80eSAl Viro unsigned *seq = &parent->d_inode->i_dir_seq, n; 93ebaaa80eSAl Viro struct dentry *res; 944f42c1b5SAl Viro struct list_head *p; 95ebaaa80eSAl Viro bool skipped; 96ebaaa80eSAl Viro int i; 974f42c1b5SAl Viro 98ebaaa80eSAl Viro retry: 99ebaaa80eSAl Viro i = count; 100ebaaa80eSAl Viro skipped = false; 101ebaaa80eSAl Viro n = smp_load_acquire(seq) & ~1; 102ebaaa80eSAl Viro res = NULL; 103ebaaa80eSAl Viro rcu_read_lock(); 1044f42c1b5SAl Viro for (p = from->next; p != &parent->d_subdirs; p = p->next) { 1054f42c1b5SAl Viro struct dentry *d = list_entry(p, struct dentry, d_child); 106ebaaa80eSAl Viro if (!simple_positive(d)) { 107ebaaa80eSAl Viro skipped = true; 108ebaaa80eSAl Viro } else if (!--i) { 1094f42c1b5SAl Viro res = d; 1104f42c1b5SAl Viro break; 1114f42c1b5SAl Viro } 1124f42c1b5SAl Viro } 113ebaaa80eSAl Viro rcu_read_unlock(); 114ebaaa80eSAl Viro if (skipped) { 115ebaaa80eSAl Viro smp_rmb(); 116ebaaa80eSAl Viro if (unlikely(*seq != n)) 117ebaaa80eSAl Viro goto retry; 118ebaaa80eSAl Viro } 1194f42c1b5SAl Viro return res; 1204f42c1b5SAl Viro } 1214f42c1b5SAl Viro 1224f42c1b5SAl Viro static void move_cursor(struct dentry *cursor, struct list_head *after) 1234f42c1b5SAl Viro { 1244f42c1b5SAl Viro struct dentry *parent = cursor->d_parent; 125ebaaa80eSAl Viro unsigned n, *seq = &parent->d_inode->i_dir_seq; 1264f42c1b5SAl Viro spin_lock(&parent->d_lock); 127ebaaa80eSAl Viro for (;;) { 128ebaaa80eSAl Viro n = *seq; 129ebaaa80eSAl Viro if (!(n & 1) && cmpxchg(seq, n, n + 1) == n) 130ebaaa80eSAl Viro break; 131ebaaa80eSAl Viro cpu_relax(); 132ebaaa80eSAl Viro } 1334f42c1b5SAl Viro __list_del(cursor->d_child.prev, cursor->d_child.next); 1344f42c1b5SAl Viro if (after) 1354f42c1b5SAl Viro list_add(&cursor->d_child, after); 1364f42c1b5SAl Viro else 1374f42c1b5SAl Viro list_add_tail(&cursor->d_child, &parent->d_subdirs); 138ebaaa80eSAl Viro smp_store_release(seq, n + 2); 1394f42c1b5SAl Viro spin_unlock(&parent->d_lock); 1404f42c1b5SAl Viro } 1414f42c1b5SAl Viro 142965c8e59SAndrew Morton loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) 1431da177e4SLinus Torvalds { 1442fd6b7f5SNick Piggin struct dentry *dentry = file->f_path.dentry; 145965c8e59SAndrew Morton switch (whence) { 1461da177e4SLinus Torvalds case 1: 1471da177e4SLinus Torvalds offset += file->f_pos; 1481da177e4SLinus Torvalds case 0: 1491da177e4SLinus Torvalds if (offset >= 0) 1501da177e4SLinus Torvalds break; 1511da177e4SLinus Torvalds default: 1521da177e4SLinus Torvalds return -EINVAL; 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds if (offset != file->f_pos) { 1551da177e4SLinus Torvalds file->f_pos = offset; 1561da177e4SLinus Torvalds if (file->f_pos >= 2) { 1571da177e4SLinus Torvalds struct dentry *cursor = file->private_data; 1584f42c1b5SAl Viro struct dentry *to; 1591da177e4SLinus Torvalds loff_t n = file->f_pos - 2; 1601da177e4SLinus Torvalds 161274f5b04SAl Viro inode_lock_shared(dentry->d_inode); 1624f42c1b5SAl Viro to = next_positive(dentry, &dentry->d_subdirs, n); 1634f42c1b5SAl Viro move_cursor(cursor, to ? &to->d_child : NULL); 164274f5b04SAl Viro inode_unlock_shared(dentry->d_inode); 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds } 1671da177e4SLinus Torvalds return offset; 1681da177e4SLinus Torvalds } 16912f38872SAl Viro EXPORT_SYMBOL(dcache_dir_lseek); 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds /* Relationship between i_mode and the DT_xxx types */ 1721da177e4SLinus Torvalds static inline unsigned char dt_type(struct inode *inode) 1731da177e4SLinus Torvalds { 1741da177e4SLinus Torvalds return (inode->i_mode >> 12) & 15; 1751da177e4SLinus Torvalds } 1761da177e4SLinus Torvalds 1771da177e4SLinus Torvalds /* 1781da177e4SLinus Torvalds * Directory is locked and all positive dentries in it are safe, since 1791da177e4SLinus Torvalds * for ramfs-type trees they can't go away without unlink() or rmdir(), 1801da177e4SLinus Torvalds * both impossible due to the lock on directory. 1811da177e4SLinus Torvalds */ 1821da177e4SLinus Torvalds 1835f99f4e7SAl Viro int dcache_readdir(struct file *file, struct dir_context *ctx) 1841da177e4SLinus Torvalds { 1855f99f4e7SAl Viro struct dentry *dentry = file->f_path.dentry; 1865f99f4e7SAl Viro struct dentry *cursor = file->private_data; 1874f42c1b5SAl Viro struct list_head *p = &cursor->d_child; 1884f42c1b5SAl Viro struct dentry *next; 1894f42c1b5SAl Viro bool moved = false; 1901da177e4SLinus Torvalds 1915f99f4e7SAl Viro if (!dir_emit_dots(file, ctx)) 1925f99f4e7SAl Viro return 0; 1934f42c1b5SAl Viro 1945f99f4e7SAl Viro if (ctx->pos == 2) 1954f42c1b5SAl Viro p = &dentry->d_subdirs; 1964f42c1b5SAl Viro while ((next = next_positive(dentry, p, 1)) != NULL) { 1975f99f4e7SAl Viro if (!dir_emit(ctx, next->d_name.name, next->d_name.len, 198dea655c2SDavid Howells d_inode(next)->i_ino, dt_type(d_inode(next)))) 1994f42c1b5SAl Viro break; 2004f42c1b5SAl Viro moved = true; 2014f42c1b5SAl Viro p = &next->d_child; 2025f99f4e7SAl Viro ctx->pos++; 2031da177e4SLinus Torvalds } 2044f42c1b5SAl Viro if (moved) 2054f42c1b5SAl Viro move_cursor(cursor, p); 2061da177e4SLinus Torvalds return 0; 2071da177e4SLinus Torvalds } 20812f38872SAl Viro EXPORT_SYMBOL(dcache_readdir); 2091da177e4SLinus Torvalds 2101da177e4SLinus Torvalds ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) 2111da177e4SLinus Torvalds { 2121da177e4SLinus Torvalds return -EISDIR; 2131da177e4SLinus Torvalds } 21412f38872SAl Viro EXPORT_SYMBOL(generic_read_dir); 2151da177e4SLinus Torvalds 2164b6f5d20SArjan van de Ven const struct file_operations simple_dir_operations = { 2171da177e4SLinus Torvalds .open = dcache_dir_open, 2181da177e4SLinus Torvalds .release = dcache_dir_close, 2191da177e4SLinus Torvalds .llseek = dcache_dir_lseek, 2201da177e4SLinus Torvalds .read = generic_read_dir, 2214e82901cSAl Viro .iterate_shared = dcache_readdir, 2221b061d92SChristoph Hellwig .fsync = noop_fsync, 2231da177e4SLinus Torvalds }; 22412f38872SAl Viro EXPORT_SYMBOL(simple_dir_operations); 2251da177e4SLinus Torvalds 22692e1d5beSArjan van de Ven const struct inode_operations simple_dir_inode_operations = { 2271da177e4SLinus Torvalds .lookup = simple_lookup, 2281da177e4SLinus Torvalds }; 22912f38872SAl Viro EXPORT_SYMBOL(simple_dir_inode_operations); 2301da177e4SLinus Torvalds 231759b9775SHugh Dickins static const struct super_operations simple_super_operations = { 232759b9775SHugh Dickins .statfs = simple_statfs, 233759b9775SHugh Dickins }; 234759b9775SHugh Dickins 2351da177e4SLinus Torvalds /* 2361da177e4SLinus Torvalds * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that 2371da177e4SLinus Torvalds * will never be mountable) 2381da177e4SLinus Torvalds */ 239bba0bd31SAndreas Gruenbacher struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name, 240bba0bd31SAndreas Gruenbacher const struct super_operations *ops, const struct xattr_handler **xattr, 241c74a1cbbSAl Viro const struct dentry_operations *dops, unsigned long magic) 2421da177e4SLinus Torvalds { 2439249e17fSDavid Howells struct super_block *s; 2441da177e4SLinus Torvalds struct dentry *dentry; 2451da177e4SLinus Torvalds struct inode *root; 24626fe5750SLinus Torvalds struct qstr d_name = QSTR_INIT(name, strlen(name)); 2471da177e4SLinus Torvalds 2489249e17fSDavid Howells s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); 2491da177e4SLinus Torvalds if (IS_ERR(s)) 25051139adaSAl Viro return ERR_CAST(s); 2511da177e4SLinus Torvalds 25289a4eb4bSJeff Layton s->s_maxbytes = MAX_LFS_FILESIZE; 2533971e1a9SAlex Nixon s->s_blocksize = PAGE_SIZE; 2543971e1a9SAlex Nixon s->s_blocksize_bits = PAGE_SHIFT; 2551da177e4SLinus Torvalds s->s_magic = magic; 256759b9775SHugh Dickins s->s_op = ops ? ops : &simple_super_operations; 257bba0bd31SAndreas Gruenbacher s->s_xattr = xattr; 2581da177e4SLinus Torvalds s->s_time_gran = 1; 2591da177e4SLinus Torvalds root = new_inode(s); 2601da177e4SLinus Torvalds if (!root) 2611da177e4SLinus Torvalds goto Enomem; 2621a1c9bb4SJeff Layton /* 2631a1c9bb4SJeff Layton * since this is the first inode, make it number 1. New inodes created 2641a1c9bb4SJeff Layton * after this must take care not to collide with it (by passing 2651a1c9bb4SJeff Layton * max_reserved of 1 to iunique). 2661a1c9bb4SJeff Layton */ 2671a1c9bb4SJeff Layton root->i_ino = 1; 2681da177e4SLinus Torvalds root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; 2691da177e4SLinus Torvalds root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; 270a4464dbcSAl Viro dentry = __d_alloc(s, &d_name); 2711da177e4SLinus Torvalds if (!dentry) { 2721da177e4SLinus Torvalds iput(root); 2731da177e4SLinus Torvalds goto Enomem; 2741da177e4SLinus Torvalds } 2751da177e4SLinus Torvalds d_instantiate(dentry, root); 2761da177e4SLinus Torvalds s->s_root = dentry; 277c74a1cbbSAl Viro s->s_d_op = dops; 2781da177e4SLinus Torvalds s->s_flags |= MS_ACTIVE; 27951139adaSAl Viro return dget(s->s_root); 2801da177e4SLinus Torvalds 2811da177e4SLinus Torvalds Enomem: 2826f5bbff9SAl Viro deactivate_locked_super(s); 28351139adaSAl Viro return ERR_PTR(-ENOMEM); 2841da177e4SLinus Torvalds } 285bba0bd31SAndreas Gruenbacher EXPORT_SYMBOL(mount_pseudo_xattr); 2861da177e4SLinus Torvalds 28720955e89SStephen Boyd int simple_open(struct inode *inode, struct file *file) 28820955e89SStephen Boyd { 28920955e89SStephen Boyd if (inode->i_private) 29020955e89SStephen Boyd file->private_data = inode->i_private; 29120955e89SStephen Boyd return 0; 29220955e89SStephen Boyd } 29312f38872SAl Viro EXPORT_SYMBOL(simple_open); 29420955e89SStephen Boyd 2951da177e4SLinus Torvalds int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 2961da177e4SLinus Torvalds { 297dea655c2SDavid Howells struct inode *inode = d_inode(old_dentry); 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 300d8c76e6fSDave Hansen inc_nlink(inode); 3017de9c6eeSAl Viro ihold(inode); 3021da177e4SLinus Torvalds dget(dentry); 3031da177e4SLinus Torvalds d_instantiate(dentry, inode); 3041da177e4SLinus Torvalds return 0; 3051da177e4SLinus Torvalds } 30612f38872SAl Viro EXPORT_SYMBOL(simple_link); 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds int simple_empty(struct dentry *dentry) 3091da177e4SLinus Torvalds { 3101da177e4SLinus Torvalds struct dentry *child; 3111da177e4SLinus Torvalds int ret = 0; 3121da177e4SLinus Torvalds 3132fd6b7f5SNick Piggin spin_lock(&dentry->d_lock); 314946e51f2SAl Viro list_for_each_entry(child, &dentry->d_subdirs, d_child) { 315da502956SNick Piggin spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); 316da502956SNick Piggin if (simple_positive(child)) { 317da502956SNick Piggin spin_unlock(&child->d_lock); 3181da177e4SLinus Torvalds goto out; 319da502956SNick Piggin } 320da502956SNick Piggin spin_unlock(&child->d_lock); 321da502956SNick Piggin } 3221da177e4SLinus Torvalds ret = 1; 3231da177e4SLinus Torvalds out: 3242fd6b7f5SNick Piggin spin_unlock(&dentry->d_lock); 3251da177e4SLinus Torvalds return ret; 3261da177e4SLinus Torvalds } 32712f38872SAl Viro EXPORT_SYMBOL(simple_empty); 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds int simple_unlink(struct inode *dir, struct dentry *dentry) 3301da177e4SLinus Torvalds { 331dea655c2SDavid Howells struct inode *inode = d_inode(dentry); 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 3349a53c3a7SDave Hansen drop_nlink(inode); 3351da177e4SLinus Torvalds dput(dentry); 3361da177e4SLinus Torvalds return 0; 3371da177e4SLinus Torvalds } 33812f38872SAl Viro EXPORT_SYMBOL(simple_unlink); 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds int simple_rmdir(struct inode *dir, struct dentry *dentry) 3411da177e4SLinus Torvalds { 3421da177e4SLinus Torvalds if (!simple_empty(dentry)) 3431da177e4SLinus Torvalds return -ENOTEMPTY; 3441da177e4SLinus Torvalds 345dea655c2SDavid Howells drop_nlink(d_inode(dentry)); 3461da177e4SLinus Torvalds simple_unlink(dir, dentry); 3479a53c3a7SDave Hansen drop_nlink(dir); 3481da177e4SLinus Torvalds return 0; 3491da177e4SLinus Torvalds } 35012f38872SAl Viro EXPORT_SYMBOL(simple_rmdir); 3511da177e4SLinus Torvalds 3521da177e4SLinus Torvalds int simple_rename(struct inode *old_dir, struct dentry *old_dentry, 3531da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 3541da177e4SLinus Torvalds { 355dea655c2SDavid Howells struct inode *inode = d_inode(old_dentry); 356e36cb0b8SDavid Howells int they_are_dirs = d_is_dir(old_dentry); 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds if (!simple_empty(new_dentry)) 3591da177e4SLinus Torvalds return -ENOTEMPTY; 3601da177e4SLinus Torvalds 361dea655c2SDavid Howells if (d_really_is_positive(new_dentry)) { 3621da177e4SLinus Torvalds simple_unlink(new_dir, new_dentry); 363841590ceSAl Viro if (they_are_dirs) { 364dea655c2SDavid Howells drop_nlink(d_inode(new_dentry)); 3659a53c3a7SDave Hansen drop_nlink(old_dir); 366841590ceSAl Viro } 3671da177e4SLinus Torvalds } else if (they_are_dirs) { 3689a53c3a7SDave Hansen drop_nlink(old_dir); 369d8c76e6fSDave Hansen inc_nlink(new_dir); 3701da177e4SLinus Torvalds } 3711da177e4SLinus Torvalds 3721da177e4SLinus Torvalds old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = 3731da177e4SLinus Torvalds new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; 3741da177e4SLinus Torvalds 3751da177e4SLinus Torvalds return 0; 3761da177e4SLinus Torvalds } 37712f38872SAl Viro EXPORT_SYMBOL(simple_rename); 3781da177e4SLinus Torvalds 3797bb46a67Snpiggin@suse.de /** 380eef2380cSChristoph Hellwig * simple_setattr - setattr for simple filesystem 3817bb46a67Snpiggin@suse.de * @dentry: dentry 3827bb46a67Snpiggin@suse.de * @iattr: iattr structure 3837bb46a67Snpiggin@suse.de * 3847bb46a67Snpiggin@suse.de * Returns 0 on success, -error on failure. 3857bb46a67Snpiggin@suse.de * 386eef2380cSChristoph Hellwig * simple_setattr is a simple ->setattr implementation without a proper 387eef2380cSChristoph Hellwig * implementation of size changes. 388eef2380cSChristoph Hellwig * 389eef2380cSChristoph Hellwig * It can either be used for in-memory filesystems or special files 390eef2380cSChristoph Hellwig * on simple regular filesystems. Anything that needs to change on-disk 391eef2380cSChristoph Hellwig * or wire state on size changes needs its own setattr method. 3927bb46a67Snpiggin@suse.de */ 3937bb46a67Snpiggin@suse.de int simple_setattr(struct dentry *dentry, struct iattr *iattr) 3947bb46a67Snpiggin@suse.de { 395dea655c2SDavid Howells struct inode *inode = d_inode(dentry); 3967bb46a67Snpiggin@suse.de int error; 3977bb46a67Snpiggin@suse.de 3987bb46a67Snpiggin@suse.de error = inode_change_ok(inode, iattr); 3997bb46a67Snpiggin@suse.de if (error) 4007bb46a67Snpiggin@suse.de return error; 4017bb46a67Snpiggin@suse.de 4022c27c65eSChristoph Hellwig if (iattr->ia_valid & ATTR_SIZE) 4032c27c65eSChristoph Hellwig truncate_setsize(inode, iattr->ia_size); 4046a1a90adSChristoph Hellwig setattr_copy(inode, iattr); 405eef2380cSChristoph Hellwig mark_inode_dirty(inode); 406eef2380cSChristoph Hellwig return 0; 4077bb46a67Snpiggin@suse.de } 4087bb46a67Snpiggin@suse.de EXPORT_SYMBOL(simple_setattr); 4097bb46a67Snpiggin@suse.de 4101da177e4SLinus Torvalds int simple_readpage(struct file *file, struct page *page) 4111da177e4SLinus Torvalds { 412c0d92cbcSPekka J Enberg clear_highpage(page); 4131da177e4SLinus Torvalds flush_dcache_page(page); 4141da177e4SLinus Torvalds SetPageUptodate(page); 4151da177e4SLinus Torvalds unlock_page(page); 4161da177e4SLinus Torvalds return 0; 4171da177e4SLinus Torvalds } 41812f38872SAl Viro EXPORT_SYMBOL(simple_readpage); 4191da177e4SLinus Torvalds 420afddba49SNick Piggin int simple_write_begin(struct file *file, struct address_space *mapping, 421afddba49SNick Piggin loff_t pos, unsigned len, unsigned flags, 422afddba49SNick Piggin struct page **pagep, void **fsdata) 423afddba49SNick Piggin { 424afddba49SNick Piggin struct page *page; 425afddba49SNick Piggin pgoff_t index; 426afddba49SNick Piggin 42709cbfeafSKirill A. Shutemov index = pos >> PAGE_SHIFT; 428afddba49SNick Piggin 42954566b2cSNick Piggin page = grab_cache_page_write_begin(mapping, index, flags); 430afddba49SNick Piggin if (!page) 431afddba49SNick Piggin return -ENOMEM; 432afddba49SNick Piggin 433afddba49SNick Piggin *pagep = page; 434afddba49SNick Piggin 43509cbfeafSKirill A. Shutemov if (!PageUptodate(page) && (len != PAGE_SIZE)) { 43609cbfeafSKirill A. Shutemov unsigned from = pos & (PAGE_SIZE - 1); 437193cf4b9SBoaz Harrosh 43809cbfeafSKirill A. Shutemov zero_user_segments(page, 0, from, from + len, PAGE_SIZE); 439193cf4b9SBoaz Harrosh } 440193cf4b9SBoaz Harrosh return 0; 441afddba49SNick Piggin } 44212f38872SAl Viro EXPORT_SYMBOL(simple_write_begin); 443afddba49SNick Piggin 444ad2a722fSBoaz Harrosh /** 445ad2a722fSBoaz Harrosh * simple_write_end - .write_end helper for non-block-device FSes 446ad2a722fSBoaz Harrosh * @available: See .write_end of address_space_operations 447ad2a722fSBoaz Harrosh * @file: " 448ad2a722fSBoaz Harrosh * @mapping: " 449ad2a722fSBoaz Harrosh * @pos: " 450ad2a722fSBoaz Harrosh * @len: " 451ad2a722fSBoaz Harrosh * @copied: " 452ad2a722fSBoaz Harrosh * @page: " 453ad2a722fSBoaz Harrosh * @fsdata: " 454ad2a722fSBoaz Harrosh * 455ad2a722fSBoaz Harrosh * simple_write_end does the minimum needed for updating a page after writing is 456ad2a722fSBoaz Harrosh * done. It has the same API signature as the .write_end of 457ad2a722fSBoaz Harrosh * address_space_operations vector. So it can just be set onto .write_end for 458ad2a722fSBoaz Harrosh * FSes that don't need any other processing. i_mutex is assumed to be held. 459ad2a722fSBoaz Harrosh * Block based filesystems should use generic_write_end(). 460ad2a722fSBoaz Harrosh * NOTE: Even though i_size might get updated by this function, mark_inode_dirty 461ad2a722fSBoaz Harrosh * is not called, so a filesystem that actually does store data in .write_inode 462ad2a722fSBoaz Harrosh * should extend on what's done here with a call to mark_inode_dirty() in the 463ad2a722fSBoaz Harrosh * case that i_size has changed. 464ad2a722fSBoaz Harrosh */ 465ad2a722fSBoaz Harrosh int simple_write_end(struct file *file, struct address_space *mapping, 466ad2a722fSBoaz Harrosh loff_t pos, unsigned len, unsigned copied, 467ad2a722fSBoaz Harrosh struct page *page, void *fsdata) 4681da177e4SLinus Torvalds { 4691da177e4SLinus Torvalds struct inode *inode = page->mapping->host; 470ad2a722fSBoaz Harrosh loff_t last_pos = pos + copied; 471ad2a722fSBoaz Harrosh 472ad2a722fSBoaz Harrosh /* zero the stale part of the page if we did a short copy */ 473ad2a722fSBoaz Harrosh if (copied < len) { 47409cbfeafSKirill A. Shutemov unsigned from = pos & (PAGE_SIZE - 1); 475ad2a722fSBoaz Harrosh 476ad2a722fSBoaz Harrosh zero_user(page, from + copied, len - copied); 477ad2a722fSBoaz Harrosh } 4781da177e4SLinus Torvalds 479955eff5aSNick Piggin if (!PageUptodate(page)) 480955eff5aSNick Piggin SetPageUptodate(page); 4811da177e4SLinus Torvalds /* 4821da177e4SLinus Torvalds * No need to use i_size_read() here, the i_size 4831b1dcc1bSJes Sorensen * cannot change under us because we hold the i_mutex. 4841da177e4SLinus Torvalds */ 485ad2a722fSBoaz Harrosh if (last_pos > inode->i_size) 486ad2a722fSBoaz Harrosh i_size_write(inode, last_pos); 487ad2a722fSBoaz Harrosh 4881da177e4SLinus Torvalds set_page_dirty(page); 489afddba49SNick Piggin unlock_page(page); 49009cbfeafSKirill A. Shutemov put_page(page); 491afddba49SNick Piggin 492afddba49SNick Piggin return copied; 493afddba49SNick Piggin } 49412f38872SAl Viro EXPORT_SYMBOL(simple_write_end); 495afddba49SNick Piggin 4961a1c9bb4SJeff Layton /* 4971a1c9bb4SJeff Layton * the inodes created here are not hashed. If you use iunique to generate 4981a1c9bb4SJeff Layton * unique inode values later for this filesystem, then you must take care 4991a1c9bb4SJeff Layton * to pass it an appropriate max_reserved value to avoid collisions. 5001a1c9bb4SJeff Layton */ 5017d683a09SRoberto Sassu int simple_fill_super(struct super_block *s, unsigned long magic, 5027d683a09SRoberto Sassu struct tree_descr *files) 5031da177e4SLinus Torvalds { 5041da177e4SLinus Torvalds struct inode *inode; 5051da177e4SLinus Torvalds struct dentry *root; 5061da177e4SLinus Torvalds struct dentry *dentry; 5071da177e4SLinus Torvalds int i; 5081da177e4SLinus Torvalds 50909cbfeafSKirill A. Shutemov s->s_blocksize = PAGE_SIZE; 51009cbfeafSKirill A. Shutemov s->s_blocksize_bits = PAGE_SHIFT; 5111da177e4SLinus Torvalds s->s_magic = magic; 512759b9775SHugh Dickins s->s_op = &simple_super_operations; 5131da177e4SLinus Torvalds s->s_time_gran = 1; 5141da177e4SLinus Torvalds 5151da177e4SLinus Torvalds inode = new_inode(s); 5161da177e4SLinus Torvalds if (!inode) 5171da177e4SLinus Torvalds return -ENOMEM; 5181a1c9bb4SJeff Layton /* 5191a1c9bb4SJeff Layton * because the root inode is 1, the files array must not contain an 5201a1c9bb4SJeff Layton * entry at index 1 5211a1c9bb4SJeff Layton */ 5221a1c9bb4SJeff Layton inode->i_ino = 1; 5231da177e4SLinus Torvalds inode->i_mode = S_IFDIR | 0755; 5241da177e4SLinus Torvalds inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 5251da177e4SLinus Torvalds inode->i_op = &simple_dir_inode_operations; 5261da177e4SLinus Torvalds inode->i_fop = &simple_dir_operations; 527bfe86848SMiklos Szeredi set_nlink(inode, 2); 52848fde701SAl Viro root = d_make_root(inode); 52948fde701SAl Viro if (!root) 5301da177e4SLinus Torvalds return -ENOMEM; 5311da177e4SLinus Torvalds for (i = 0; !files->name || files->name[0]; i++, files++) { 5321da177e4SLinus Torvalds if (!files->name) 5331da177e4SLinus Torvalds continue; 5341a1c9bb4SJeff Layton 5351a1c9bb4SJeff Layton /* warn if it tries to conflict with the root inode */ 5361a1c9bb4SJeff Layton if (unlikely(i == 1)) 5371a1c9bb4SJeff Layton printk(KERN_WARNING "%s: %s passed in a files array" 5381a1c9bb4SJeff Layton "with an index of 1!\n", __func__, 5391a1c9bb4SJeff Layton s->s_type->name); 5401a1c9bb4SJeff Layton 5411da177e4SLinus Torvalds dentry = d_alloc_name(root, files->name); 5421da177e4SLinus Torvalds if (!dentry) 5431da177e4SLinus Torvalds goto out; 5441da177e4SLinus Torvalds inode = new_inode(s); 54532096ea1SKonstantin Khlebnikov if (!inode) { 54632096ea1SKonstantin Khlebnikov dput(dentry); 5471da177e4SLinus Torvalds goto out; 54832096ea1SKonstantin Khlebnikov } 5491da177e4SLinus Torvalds inode->i_mode = S_IFREG | files->mode; 5501da177e4SLinus Torvalds inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 5511da177e4SLinus Torvalds inode->i_fop = files->ops; 5521da177e4SLinus Torvalds inode->i_ino = i; 5531da177e4SLinus Torvalds d_add(dentry, inode); 5541da177e4SLinus Torvalds } 5551da177e4SLinus Torvalds s->s_root = root; 5561da177e4SLinus Torvalds return 0; 5571da177e4SLinus Torvalds out: 5581da177e4SLinus Torvalds d_genocide(root); 559640946f2SAl Viro shrink_dcache_parent(root); 5601da177e4SLinus Torvalds dput(root); 5611da177e4SLinus Torvalds return -ENOMEM; 5621da177e4SLinus Torvalds } 56312f38872SAl Viro EXPORT_SYMBOL(simple_fill_super); 5641da177e4SLinus Torvalds 5651da177e4SLinus Torvalds static DEFINE_SPINLOCK(pin_fs_lock); 5661da177e4SLinus Torvalds 5671f5ce9e9STrond Myklebust int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) 5681da177e4SLinus Torvalds { 5691da177e4SLinus Torvalds struct vfsmount *mnt = NULL; 5701da177e4SLinus Torvalds spin_lock(&pin_fs_lock); 5711da177e4SLinus Torvalds if (unlikely(!*mount)) { 5721da177e4SLinus Torvalds spin_unlock(&pin_fs_lock); 5732452992aSAl Viro mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL); 5741da177e4SLinus Torvalds if (IS_ERR(mnt)) 5751da177e4SLinus Torvalds return PTR_ERR(mnt); 5761da177e4SLinus Torvalds spin_lock(&pin_fs_lock); 5771da177e4SLinus Torvalds if (!*mount) 5781da177e4SLinus Torvalds *mount = mnt; 5791da177e4SLinus Torvalds } 5801da177e4SLinus Torvalds mntget(*mount); 5811da177e4SLinus Torvalds ++*count; 5821da177e4SLinus Torvalds spin_unlock(&pin_fs_lock); 5831da177e4SLinus Torvalds mntput(mnt); 5841da177e4SLinus Torvalds return 0; 5851da177e4SLinus Torvalds } 58612f38872SAl Viro EXPORT_SYMBOL(simple_pin_fs); 5871da177e4SLinus Torvalds 5881da177e4SLinus Torvalds void simple_release_fs(struct vfsmount **mount, int *count) 5891da177e4SLinus Torvalds { 5901da177e4SLinus Torvalds struct vfsmount *mnt; 5911da177e4SLinus Torvalds spin_lock(&pin_fs_lock); 5921da177e4SLinus Torvalds mnt = *mount; 5931da177e4SLinus Torvalds if (!--*count) 5941da177e4SLinus Torvalds *mount = NULL; 5951da177e4SLinus Torvalds spin_unlock(&pin_fs_lock); 5961da177e4SLinus Torvalds mntput(mnt); 5971da177e4SLinus Torvalds } 59812f38872SAl Viro EXPORT_SYMBOL(simple_release_fs); 5991da177e4SLinus Torvalds 6006d1029b5SAkinobu Mita /** 6016d1029b5SAkinobu Mita * simple_read_from_buffer - copy data from the buffer to user space 6026d1029b5SAkinobu Mita * @to: the user space buffer to read to 6036d1029b5SAkinobu Mita * @count: the maximum number of bytes to read 6046d1029b5SAkinobu Mita * @ppos: the current position in the buffer 6056d1029b5SAkinobu Mita * @from: the buffer to read from 6066d1029b5SAkinobu Mita * @available: the size of the buffer 6076d1029b5SAkinobu Mita * 6086d1029b5SAkinobu Mita * The simple_read_from_buffer() function reads up to @count bytes from the 6096d1029b5SAkinobu Mita * buffer @from at offset @ppos into the user space address starting at @to. 6106d1029b5SAkinobu Mita * 6116d1029b5SAkinobu Mita * On success, the number of bytes read is returned and the offset @ppos is 6126d1029b5SAkinobu Mita * advanced by this number, or negative value is returned on error. 6136d1029b5SAkinobu Mita **/ 6141da177e4SLinus Torvalds ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, 6151da177e4SLinus Torvalds const void *from, size_t available) 6161da177e4SLinus Torvalds { 6171da177e4SLinus Torvalds loff_t pos = *ppos; 61814be2746SSteven Rostedt size_t ret; 61914be2746SSteven Rostedt 6201da177e4SLinus Torvalds if (pos < 0) 6211da177e4SLinus Torvalds return -EINVAL; 62214be2746SSteven Rostedt if (pos >= available || !count) 6231da177e4SLinus Torvalds return 0; 6241da177e4SLinus Torvalds if (count > available - pos) 6251da177e4SLinus Torvalds count = available - pos; 62614be2746SSteven Rostedt ret = copy_to_user(to, from + pos, count); 62714be2746SSteven Rostedt if (ret == count) 6281da177e4SLinus Torvalds return -EFAULT; 62914be2746SSteven Rostedt count -= ret; 6301da177e4SLinus Torvalds *ppos = pos + count; 6311da177e4SLinus Torvalds return count; 6321da177e4SLinus Torvalds } 63312f38872SAl Viro EXPORT_SYMBOL(simple_read_from_buffer); 6341da177e4SLinus Torvalds 6356d1029b5SAkinobu Mita /** 6366a727b43SJiri Slaby * simple_write_to_buffer - copy data from user space to the buffer 6376a727b43SJiri Slaby * @to: the buffer to write to 6386a727b43SJiri Slaby * @available: the size of the buffer 6396a727b43SJiri Slaby * @ppos: the current position in the buffer 6406a727b43SJiri Slaby * @from: the user space buffer to read from 6416a727b43SJiri Slaby * @count: the maximum number of bytes to read 6426a727b43SJiri Slaby * 6436a727b43SJiri Slaby * The simple_write_to_buffer() function reads up to @count bytes from the user 6446a727b43SJiri Slaby * space address starting at @from into the buffer @to at offset @ppos. 6456a727b43SJiri Slaby * 6466a727b43SJiri Slaby * On success, the number of bytes written is returned and the offset @ppos is 6476a727b43SJiri Slaby * advanced by this number, or negative value is returned on error. 6486a727b43SJiri Slaby **/ 6496a727b43SJiri Slaby ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, 6506a727b43SJiri Slaby const void __user *from, size_t count) 6516a727b43SJiri Slaby { 6526a727b43SJiri Slaby loff_t pos = *ppos; 6536a727b43SJiri Slaby size_t res; 6546a727b43SJiri Slaby 6556a727b43SJiri Slaby if (pos < 0) 6566a727b43SJiri Slaby return -EINVAL; 6576a727b43SJiri Slaby if (pos >= available || !count) 6586a727b43SJiri Slaby return 0; 6596a727b43SJiri Slaby if (count > available - pos) 6606a727b43SJiri Slaby count = available - pos; 6616a727b43SJiri Slaby res = copy_from_user(to + pos, from, count); 6626a727b43SJiri Slaby if (res == count) 6636a727b43SJiri Slaby return -EFAULT; 6646a727b43SJiri Slaby count -= res; 6656a727b43SJiri Slaby *ppos = pos + count; 6666a727b43SJiri Slaby return count; 6676a727b43SJiri Slaby } 66812f38872SAl Viro EXPORT_SYMBOL(simple_write_to_buffer); 6696a727b43SJiri Slaby 6706a727b43SJiri Slaby /** 6716d1029b5SAkinobu Mita * memory_read_from_buffer - copy data from the buffer 6726d1029b5SAkinobu Mita * @to: the kernel space buffer to read to 6736d1029b5SAkinobu Mita * @count: the maximum number of bytes to read 6746d1029b5SAkinobu Mita * @ppos: the current position in the buffer 6756d1029b5SAkinobu Mita * @from: the buffer to read from 6766d1029b5SAkinobu Mita * @available: the size of the buffer 6776d1029b5SAkinobu Mita * 6786d1029b5SAkinobu Mita * The memory_read_from_buffer() function reads up to @count bytes from the 6796d1029b5SAkinobu Mita * buffer @from at offset @ppos into the kernel space address starting at @to. 6806d1029b5SAkinobu Mita * 6816d1029b5SAkinobu Mita * On success, the number of bytes read is returned and the offset @ppos is 6826d1029b5SAkinobu Mita * advanced by this number, or negative value is returned on error. 6836d1029b5SAkinobu Mita **/ 68493b07113SAkinobu Mita ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, 68593b07113SAkinobu Mita const void *from, size_t available) 68693b07113SAkinobu Mita { 68793b07113SAkinobu Mita loff_t pos = *ppos; 68893b07113SAkinobu Mita 68993b07113SAkinobu Mita if (pos < 0) 69093b07113SAkinobu Mita return -EINVAL; 69193b07113SAkinobu Mita if (pos >= available) 69293b07113SAkinobu Mita return 0; 69393b07113SAkinobu Mita if (count > available - pos) 69493b07113SAkinobu Mita count = available - pos; 69593b07113SAkinobu Mita memcpy(to, from + pos, count); 69693b07113SAkinobu Mita *ppos = pos + count; 69793b07113SAkinobu Mita 69893b07113SAkinobu Mita return count; 69993b07113SAkinobu Mita } 70012f38872SAl Viro EXPORT_SYMBOL(memory_read_from_buffer); 70193b07113SAkinobu Mita 7021da177e4SLinus Torvalds /* 7031da177e4SLinus Torvalds * Transaction based IO. 7041da177e4SLinus Torvalds * The file expects a single write which triggers the transaction, and then 7051da177e4SLinus Torvalds * possibly a read which collects the result - which is stored in a 7061da177e4SLinus Torvalds * file-local buffer. 7071da177e4SLinus Torvalds */ 70876791ab2SIngo Molnar 70976791ab2SIngo Molnar void simple_transaction_set(struct file *file, size_t n) 71076791ab2SIngo Molnar { 71176791ab2SIngo Molnar struct simple_transaction_argresp *ar = file->private_data; 71276791ab2SIngo Molnar 71376791ab2SIngo Molnar BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); 71476791ab2SIngo Molnar 71576791ab2SIngo Molnar /* 71676791ab2SIngo Molnar * The barrier ensures that ar->size will really remain zero until 71776791ab2SIngo Molnar * ar->data is ready for reading. 71876791ab2SIngo Molnar */ 71976791ab2SIngo Molnar smp_mb(); 72076791ab2SIngo Molnar ar->size = n; 72176791ab2SIngo Molnar } 72212f38872SAl Viro EXPORT_SYMBOL(simple_transaction_set); 72376791ab2SIngo Molnar 7241da177e4SLinus Torvalds char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) 7251da177e4SLinus Torvalds { 7261da177e4SLinus Torvalds struct simple_transaction_argresp *ar; 7271da177e4SLinus Torvalds static DEFINE_SPINLOCK(simple_transaction_lock); 7281da177e4SLinus Torvalds 7291da177e4SLinus Torvalds if (size > SIMPLE_TRANSACTION_LIMIT - 1) 7301da177e4SLinus Torvalds return ERR_PTR(-EFBIG); 7311da177e4SLinus Torvalds 7321da177e4SLinus Torvalds ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); 7331da177e4SLinus Torvalds if (!ar) 7341da177e4SLinus Torvalds return ERR_PTR(-ENOMEM); 7351da177e4SLinus Torvalds 7361da177e4SLinus Torvalds spin_lock(&simple_transaction_lock); 7371da177e4SLinus Torvalds 7381da177e4SLinus Torvalds /* only one write allowed per open */ 7391da177e4SLinus Torvalds if (file->private_data) { 7401da177e4SLinus Torvalds spin_unlock(&simple_transaction_lock); 7411da177e4SLinus Torvalds free_page((unsigned long)ar); 7421da177e4SLinus Torvalds return ERR_PTR(-EBUSY); 7431da177e4SLinus Torvalds } 7441da177e4SLinus Torvalds 7451da177e4SLinus Torvalds file->private_data = ar; 7461da177e4SLinus Torvalds 7471da177e4SLinus Torvalds spin_unlock(&simple_transaction_lock); 7481da177e4SLinus Torvalds 7491da177e4SLinus Torvalds if (copy_from_user(ar->data, buf, size)) 7501da177e4SLinus Torvalds return ERR_PTR(-EFAULT); 7511da177e4SLinus Torvalds 7521da177e4SLinus Torvalds return ar->data; 7531da177e4SLinus Torvalds } 75412f38872SAl Viro EXPORT_SYMBOL(simple_transaction_get); 7551da177e4SLinus Torvalds 7561da177e4SLinus Torvalds ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) 7571da177e4SLinus Torvalds { 7581da177e4SLinus Torvalds struct simple_transaction_argresp *ar = file->private_data; 7591da177e4SLinus Torvalds 7601da177e4SLinus Torvalds if (!ar) 7611da177e4SLinus Torvalds return 0; 7621da177e4SLinus Torvalds return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); 7631da177e4SLinus Torvalds } 76412f38872SAl Viro EXPORT_SYMBOL(simple_transaction_read); 7651da177e4SLinus Torvalds 7661da177e4SLinus Torvalds int simple_transaction_release(struct inode *inode, struct file *file) 7671da177e4SLinus Torvalds { 7681da177e4SLinus Torvalds free_page((unsigned long)file->private_data); 7691da177e4SLinus Torvalds return 0; 7701da177e4SLinus Torvalds } 77112f38872SAl Viro EXPORT_SYMBOL(simple_transaction_release); 7721da177e4SLinus Torvalds 773acaefc25SArnd Bergmann /* Simple attribute files */ 774acaefc25SArnd Bergmann 775acaefc25SArnd Bergmann struct simple_attr { 7768b88b099SChristoph Hellwig int (*get)(void *, u64 *); 7778b88b099SChristoph Hellwig int (*set)(void *, u64); 778acaefc25SArnd Bergmann char get_buf[24]; /* enough to store a u64 and "\n\0" */ 779acaefc25SArnd Bergmann char set_buf[24]; 780acaefc25SArnd Bergmann void *data; 781acaefc25SArnd Bergmann const char *fmt; /* format for read operation */ 7827cf34c76SIngo Molnar struct mutex mutex; /* protects access to these buffers */ 783acaefc25SArnd Bergmann }; 784acaefc25SArnd Bergmann 785acaefc25SArnd Bergmann /* simple_attr_open is called by an actual attribute open file operation 786acaefc25SArnd Bergmann * to set the attribute specific access operations. */ 787acaefc25SArnd Bergmann int simple_attr_open(struct inode *inode, struct file *file, 7888b88b099SChristoph Hellwig int (*get)(void *, u64 *), int (*set)(void *, u64), 789acaefc25SArnd Bergmann const char *fmt) 790acaefc25SArnd Bergmann { 791acaefc25SArnd Bergmann struct simple_attr *attr; 792acaefc25SArnd Bergmann 793acaefc25SArnd Bergmann attr = kmalloc(sizeof(*attr), GFP_KERNEL); 794acaefc25SArnd Bergmann if (!attr) 795acaefc25SArnd Bergmann return -ENOMEM; 796acaefc25SArnd Bergmann 797acaefc25SArnd Bergmann attr->get = get; 798acaefc25SArnd Bergmann attr->set = set; 7998e18e294STheodore Ts'o attr->data = inode->i_private; 800acaefc25SArnd Bergmann attr->fmt = fmt; 8017cf34c76SIngo Molnar mutex_init(&attr->mutex); 802acaefc25SArnd Bergmann 803acaefc25SArnd Bergmann file->private_data = attr; 804acaefc25SArnd Bergmann 805acaefc25SArnd Bergmann return nonseekable_open(inode, file); 806acaefc25SArnd Bergmann } 80712f38872SAl Viro EXPORT_SYMBOL_GPL(simple_attr_open); 808acaefc25SArnd Bergmann 80974bedc4dSChristoph Hellwig int simple_attr_release(struct inode *inode, struct file *file) 810acaefc25SArnd Bergmann { 811acaefc25SArnd Bergmann kfree(file->private_data); 812acaefc25SArnd Bergmann return 0; 813acaefc25SArnd Bergmann } 81412f38872SAl Viro EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */ 815acaefc25SArnd Bergmann 816acaefc25SArnd Bergmann /* read from the buffer that is filled with the get function */ 817acaefc25SArnd Bergmann ssize_t simple_attr_read(struct file *file, char __user *buf, 818acaefc25SArnd Bergmann size_t len, loff_t *ppos) 819acaefc25SArnd Bergmann { 820acaefc25SArnd Bergmann struct simple_attr *attr; 821acaefc25SArnd Bergmann size_t size; 822acaefc25SArnd Bergmann ssize_t ret; 823acaefc25SArnd Bergmann 824acaefc25SArnd Bergmann attr = file->private_data; 825acaefc25SArnd Bergmann 826acaefc25SArnd Bergmann if (!attr->get) 827acaefc25SArnd Bergmann return -EACCES; 828acaefc25SArnd Bergmann 8299261303aSChristoph Hellwig ret = mutex_lock_interruptible(&attr->mutex); 8309261303aSChristoph Hellwig if (ret) 8319261303aSChristoph Hellwig return ret; 8329261303aSChristoph Hellwig 8338b88b099SChristoph Hellwig if (*ppos) { /* continued read */ 834acaefc25SArnd Bergmann size = strlen(attr->get_buf); 8358b88b099SChristoph Hellwig } else { /* first read */ 8368b88b099SChristoph Hellwig u64 val; 8378b88b099SChristoph Hellwig ret = attr->get(attr->data, &val); 8388b88b099SChristoph Hellwig if (ret) 8398b88b099SChristoph Hellwig goto out; 8408b88b099SChristoph Hellwig 841acaefc25SArnd Bergmann size = scnprintf(attr->get_buf, sizeof(attr->get_buf), 8428b88b099SChristoph Hellwig attr->fmt, (unsigned long long)val); 8438b88b099SChristoph Hellwig } 844acaefc25SArnd Bergmann 845acaefc25SArnd Bergmann ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); 8468b88b099SChristoph Hellwig out: 8477cf34c76SIngo Molnar mutex_unlock(&attr->mutex); 848acaefc25SArnd Bergmann return ret; 849acaefc25SArnd Bergmann } 85012f38872SAl Viro EXPORT_SYMBOL_GPL(simple_attr_read); 851acaefc25SArnd Bergmann 852acaefc25SArnd Bergmann /* interpret the buffer as a number to call the set function with */ 853acaefc25SArnd Bergmann ssize_t simple_attr_write(struct file *file, const char __user *buf, 854acaefc25SArnd Bergmann size_t len, loff_t *ppos) 855acaefc25SArnd Bergmann { 856acaefc25SArnd Bergmann struct simple_attr *attr; 857acaefc25SArnd Bergmann u64 val; 858acaefc25SArnd Bergmann size_t size; 859acaefc25SArnd Bergmann ssize_t ret; 860acaefc25SArnd Bergmann 861acaefc25SArnd Bergmann attr = file->private_data; 862acaefc25SArnd Bergmann if (!attr->set) 863acaefc25SArnd Bergmann return -EACCES; 864acaefc25SArnd Bergmann 8659261303aSChristoph Hellwig ret = mutex_lock_interruptible(&attr->mutex); 8669261303aSChristoph Hellwig if (ret) 8679261303aSChristoph Hellwig return ret; 8689261303aSChristoph Hellwig 869acaefc25SArnd Bergmann ret = -EFAULT; 870acaefc25SArnd Bergmann size = min(sizeof(attr->set_buf) - 1, len); 871acaefc25SArnd Bergmann if (copy_from_user(attr->set_buf, buf, size)) 872acaefc25SArnd Bergmann goto out; 873acaefc25SArnd Bergmann 874acaefc25SArnd Bergmann attr->set_buf[size] = '\0'; 875f7b88631SAkinobu Mita val = simple_strtoll(attr->set_buf, NULL, 0); 87605cc0ceeSWu Fengguang ret = attr->set(attr->data, val); 87705cc0ceeSWu Fengguang if (ret == 0) 87805cc0ceeSWu Fengguang ret = len; /* on success, claim we got the whole input */ 879acaefc25SArnd Bergmann out: 8807cf34c76SIngo Molnar mutex_unlock(&attr->mutex); 881acaefc25SArnd Bergmann return ret; 882acaefc25SArnd Bergmann } 88312f38872SAl Viro EXPORT_SYMBOL_GPL(simple_attr_write); 884acaefc25SArnd Bergmann 8852596110aSChristoph Hellwig /** 8862596110aSChristoph Hellwig * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation 8872596110aSChristoph Hellwig * @sb: filesystem to do the file handle conversion on 8882596110aSChristoph Hellwig * @fid: file handle to convert 8892596110aSChristoph Hellwig * @fh_len: length of the file handle in bytes 8902596110aSChristoph Hellwig * @fh_type: type of file handle 8912596110aSChristoph Hellwig * @get_inode: filesystem callback to retrieve inode 8922596110aSChristoph Hellwig * 8932596110aSChristoph Hellwig * This function decodes @fid as long as it has one of the well-known 8942596110aSChristoph Hellwig * Linux filehandle types and calls @get_inode on it to retrieve the 8952596110aSChristoph Hellwig * inode for the object specified in the file handle. 8962596110aSChristoph Hellwig */ 8972596110aSChristoph Hellwig struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, 8982596110aSChristoph Hellwig int fh_len, int fh_type, struct inode *(*get_inode) 8992596110aSChristoph Hellwig (struct super_block *sb, u64 ino, u32 gen)) 9002596110aSChristoph Hellwig { 9012596110aSChristoph Hellwig struct inode *inode = NULL; 9022596110aSChristoph Hellwig 9032596110aSChristoph Hellwig if (fh_len < 2) 9042596110aSChristoph Hellwig return NULL; 9052596110aSChristoph Hellwig 9062596110aSChristoph Hellwig switch (fh_type) { 9072596110aSChristoph Hellwig case FILEID_INO32_GEN: 9082596110aSChristoph Hellwig case FILEID_INO32_GEN_PARENT: 9092596110aSChristoph Hellwig inode = get_inode(sb, fid->i32.ino, fid->i32.gen); 9102596110aSChristoph Hellwig break; 9112596110aSChristoph Hellwig } 9122596110aSChristoph Hellwig 9134ea3ada2SChristoph Hellwig return d_obtain_alias(inode); 9142596110aSChristoph Hellwig } 9152596110aSChristoph Hellwig EXPORT_SYMBOL_GPL(generic_fh_to_dentry); 9162596110aSChristoph Hellwig 9172596110aSChristoph Hellwig /** 918ca186830SYanchuan Nian * generic_fh_to_parent - generic helper for the fh_to_parent export operation 9192596110aSChristoph Hellwig * @sb: filesystem to do the file handle conversion on 9202596110aSChristoph Hellwig * @fid: file handle to convert 9212596110aSChristoph Hellwig * @fh_len: length of the file handle in bytes 9222596110aSChristoph Hellwig * @fh_type: type of file handle 9232596110aSChristoph Hellwig * @get_inode: filesystem callback to retrieve inode 9242596110aSChristoph Hellwig * 9252596110aSChristoph Hellwig * This function decodes @fid as long as it has one of the well-known 9262596110aSChristoph Hellwig * Linux filehandle types and calls @get_inode on it to retrieve the 9272596110aSChristoph Hellwig * inode for the _parent_ object specified in the file handle if it 9282596110aSChristoph Hellwig * is specified in the file handle, or NULL otherwise. 9292596110aSChristoph Hellwig */ 9302596110aSChristoph Hellwig struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, 9312596110aSChristoph Hellwig int fh_len, int fh_type, struct inode *(*get_inode) 9322596110aSChristoph Hellwig (struct super_block *sb, u64 ino, u32 gen)) 9332596110aSChristoph Hellwig { 9342596110aSChristoph Hellwig struct inode *inode = NULL; 9352596110aSChristoph Hellwig 9362596110aSChristoph Hellwig if (fh_len <= 2) 9372596110aSChristoph Hellwig return NULL; 9382596110aSChristoph Hellwig 9392596110aSChristoph Hellwig switch (fh_type) { 9402596110aSChristoph Hellwig case FILEID_INO32_GEN_PARENT: 9412596110aSChristoph Hellwig inode = get_inode(sb, fid->i32.parent_ino, 9422596110aSChristoph Hellwig (fh_len > 3 ? fid->i32.parent_gen : 0)); 9432596110aSChristoph Hellwig break; 9442596110aSChristoph Hellwig } 9452596110aSChristoph Hellwig 9464ea3ada2SChristoph Hellwig return d_obtain_alias(inode); 9472596110aSChristoph Hellwig } 9482596110aSChristoph Hellwig EXPORT_SYMBOL_GPL(generic_fh_to_parent); 9492596110aSChristoph Hellwig 9501b061d92SChristoph Hellwig /** 951ac13a829SFabian Frederick * __generic_file_fsync - generic fsync implementation for simple filesystems 952ac13a829SFabian Frederick * 9531b061d92SChristoph Hellwig * @file: file to synchronize 954ac13a829SFabian Frederick * @start: start offset in bytes 955ac13a829SFabian Frederick * @end: end offset in bytes (inclusive) 9561b061d92SChristoph Hellwig * @datasync: only synchronize essential metadata if true 9571b061d92SChristoph Hellwig * 9581b061d92SChristoph Hellwig * This is a generic implementation of the fsync method for simple 9591b061d92SChristoph Hellwig * filesystems which track all non-inode metadata in the buffers list 9601b061d92SChristoph Hellwig * hanging off the address_space structure. 9611b061d92SChristoph Hellwig */ 962ac13a829SFabian Frederick int __generic_file_fsync(struct file *file, loff_t start, loff_t end, 96302c24a82SJosef Bacik int datasync) 964d5aacad5SAl Viro { 9657ea80859SChristoph Hellwig struct inode *inode = file->f_mapping->host; 966d5aacad5SAl Viro int err; 967d5aacad5SAl Viro int ret; 968d5aacad5SAl Viro 96902c24a82SJosef Bacik err = filemap_write_and_wait_range(inode->i_mapping, start, end); 97002c24a82SJosef Bacik if (err) 97102c24a82SJosef Bacik return err; 97202c24a82SJosef Bacik 9735955102cSAl Viro inode_lock(inode); 974d5aacad5SAl Viro ret = sync_mapping_buffers(inode->i_mapping); 9750ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL)) 97602c24a82SJosef Bacik goto out; 977d5aacad5SAl Viro if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 97802c24a82SJosef Bacik goto out; 979d5aacad5SAl Viro 980c3765016SChristoph Hellwig err = sync_inode_metadata(inode, 1); 981d5aacad5SAl Viro if (ret == 0) 982d5aacad5SAl Viro ret = err; 983ac13a829SFabian Frederick 98402c24a82SJosef Bacik out: 9855955102cSAl Viro inode_unlock(inode); 986d5aacad5SAl Viro return ret; 987d5aacad5SAl Viro } 988ac13a829SFabian Frederick EXPORT_SYMBOL(__generic_file_fsync); 989ac13a829SFabian Frederick 990ac13a829SFabian Frederick /** 991ac13a829SFabian Frederick * generic_file_fsync - generic fsync implementation for simple filesystems 992ac13a829SFabian Frederick * with flush 993ac13a829SFabian Frederick * @file: file to synchronize 994ac13a829SFabian Frederick * @start: start offset in bytes 995ac13a829SFabian Frederick * @end: end offset in bytes (inclusive) 996ac13a829SFabian Frederick * @datasync: only synchronize essential metadata if true 997ac13a829SFabian Frederick * 998ac13a829SFabian Frederick */ 999ac13a829SFabian Frederick 1000ac13a829SFabian Frederick int generic_file_fsync(struct file *file, loff_t start, loff_t end, 1001ac13a829SFabian Frederick int datasync) 1002ac13a829SFabian Frederick { 1003ac13a829SFabian Frederick struct inode *inode = file->f_mapping->host; 1004ac13a829SFabian Frederick int err; 1005ac13a829SFabian Frederick 1006ac13a829SFabian Frederick err = __generic_file_fsync(file, start, end, datasync); 1007ac13a829SFabian Frederick if (err) 1008ac13a829SFabian Frederick return err; 1009ac13a829SFabian Frederick return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 1010ac13a829SFabian Frederick } 10111b061d92SChristoph Hellwig EXPORT_SYMBOL(generic_file_fsync); 10121b061d92SChristoph Hellwig 101330ca22c7SPatrick J. LoPresti /** 101430ca22c7SPatrick J. LoPresti * generic_check_addressable - Check addressability of file system 101530ca22c7SPatrick J. LoPresti * @blocksize_bits: log of file system block size 101630ca22c7SPatrick J. LoPresti * @num_blocks: number of blocks in file system 101730ca22c7SPatrick J. LoPresti * 101830ca22c7SPatrick J. LoPresti * Determine whether a file system with @num_blocks blocks (and a 101930ca22c7SPatrick J. LoPresti * block size of 2**@blocksize_bits) is addressable by the sector_t 102030ca22c7SPatrick J. LoPresti * and page cache of the system. Return 0 if so and -EFBIG otherwise. 102130ca22c7SPatrick J. LoPresti */ 102230ca22c7SPatrick J. LoPresti int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) 102330ca22c7SPatrick J. LoPresti { 102430ca22c7SPatrick J. LoPresti u64 last_fs_block = num_blocks - 1; 1025a33f13efSJoel Becker u64 last_fs_page = 102609cbfeafSKirill A. Shutemov last_fs_block >> (PAGE_SHIFT - blocksize_bits); 102730ca22c7SPatrick J. LoPresti 102830ca22c7SPatrick J. LoPresti if (unlikely(num_blocks == 0)) 102930ca22c7SPatrick J. LoPresti return 0; 103030ca22c7SPatrick J. LoPresti 103109cbfeafSKirill A. Shutemov if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT)) 103230ca22c7SPatrick J. LoPresti return -EINVAL; 103330ca22c7SPatrick J. LoPresti 1034a33f13efSJoel Becker if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || 1035a33f13efSJoel Becker (last_fs_page > (pgoff_t)(~0ULL))) { 103630ca22c7SPatrick J. LoPresti return -EFBIG; 103730ca22c7SPatrick J. LoPresti } 103830ca22c7SPatrick J. LoPresti return 0; 103930ca22c7SPatrick J. LoPresti } 104030ca22c7SPatrick J. LoPresti EXPORT_SYMBOL(generic_check_addressable); 104130ca22c7SPatrick J. LoPresti 10421b061d92SChristoph Hellwig /* 10431b061d92SChristoph Hellwig * No-op implementation of ->fsync for in-memory filesystems. 10441b061d92SChristoph Hellwig */ 104502c24a82SJosef Bacik int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) 10461b061d92SChristoph Hellwig { 10471b061d92SChristoph Hellwig return 0; 10481b061d92SChristoph Hellwig } 10491b061d92SChristoph Hellwig EXPORT_SYMBOL(noop_fsync); 105087dc800bSAl Viro 1051fceef393SAl Viro /* Because kfree isn't assignment-compatible with void(void*) ;-/ */ 1052fceef393SAl Viro void kfree_link(void *p) 105387dc800bSAl Viro { 1054fceef393SAl Viro kfree(p); 105587dc800bSAl Viro } 1056fceef393SAl Viro EXPORT_SYMBOL(kfree_link); 10576987843fSAl Viro 10586987843fSAl Viro /* 10596987843fSAl Viro * nop .set_page_dirty method so that people can use .page_mkwrite on 10606987843fSAl Viro * anon inodes. 10616987843fSAl Viro */ 10626987843fSAl Viro static int anon_set_page_dirty(struct page *page) 10636987843fSAl Viro { 10646987843fSAl Viro return 0; 10656987843fSAl Viro }; 10666987843fSAl Viro 10676987843fSAl Viro /* 10686987843fSAl Viro * A single inode exists for all anon_inode files. Contrary to pipes, 10696987843fSAl Viro * anon_inode inodes have no associated per-instance data, so we need 10706987843fSAl Viro * only allocate one of them. 10716987843fSAl Viro */ 10726987843fSAl Viro struct inode *alloc_anon_inode(struct super_block *s) 10736987843fSAl Viro { 10746987843fSAl Viro static const struct address_space_operations anon_aops = { 10756987843fSAl Viro .set_page_dirty = anon_set_page_dirty, 10766987843fSAl Viro }; 10776987843fSAl Viro struct inode *inode = new_inode_pseudo(s); 10786987843fSAl Viro 10796987843fSAl Viro if (!inode) 10806987843fSAl Viro return ERR_PTR(-ENOMEM); 10816987843fSAl Viro 10826987843fSAl Viro inode->i_ino = get_next_ino(); 10836987843fSAl Viro inode->i_mapping->a_ops = &anon_aops; 10846987843fSAl Viro 10856987843fSAl Viro /* 10866987843fSAl Viro * Mark the inode dirty from the very beginning, 10876987843fSAl Viro * that way it will never be moved to the dirty 10886987843fSAl Viro * list because mark_inode_dirty() will think 10896987843fSAl Viro * that it already _is_ on the dirty list. 10906987843fSAl Viro */ 10916987843fSAl Viro inode->i_state = I_DIRTY; 10926987843fSAl Viro inode->i_mode = S_IRUSR | S_IWUSR; 10936987843fSAl Viro inode->i_uid = current_fsuid(); 10946987843fSAl Viro inode->i_gid = current_fsgid(); 10956987843fSAl Viro inode->i_flags |= S_PRIVATE; 10966987843fSAl Viro inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 10976987843fSAl Viro return inode; 10986987843fSAl Viro } 10996987843fSAl Viro EXPORT_SYMBOL(alloc_anon_inode); 11001c994a09SJeff Layton 11011c994a09SJeff Layton /** 11021c994a09SJeff Layton * simple_nosetlease - generic helper for prohibiting leases 11031c994a09SJeff Layton * @filp: file pointer 11041c994a09SJeff Layton * @arg: type of lease to obtain 11051c994a09SJeff Layton * @flp: new lease supplied for insertion 1106e6f5c789SJeff Layton * @priv: private data for lm_setup operation 11071c994a09SJeff Layton * 11081c994a09SJeff Layton * Generic helper for filesystems that do not wish to allow leases to be set. 11091c994a09SJeff Layton * All arguments are ignored and it just returns -EINVAL. 11101c994a09SJeff Layton */ 11111c994a09SJeff Layton int 1112e6f5c789SJeff Layton simple_nosetlease(struct file *filp, long arg, struct file_lock **flp, 1113e6f5c789SJeff Layton void **priv) 11141c994a09SJeff Layton { 11151c994a09SJeff Layton return -EINVAL; 11161c994a09SJeff Layton } 11171c994a09SJeff Layton EXPORT_SYMBOL(simple_nosetlease); 111861ba64fcSAl Viro 11196b255391SAl Viro const char *simple_get_link(struct dentry *dentry, struct inode *inode, 1120fceef393SAl Viro struct delayed_call *done) 112161ba64fcSAl Viro { 11226b255391SAl Viro return inode->i_link; 112361ba64fcSAl Viro } 11246b255391SAl Viro EXPORT_SYMBOL(simple_get_link); 112561ba64fcSAl Viro 112661ba64fcSAl Viro const struct inode_operations simple_symlink_inode_operations = { 11276b255391SAl Viro .get_link = simple_get_link, 112861ba64fcSAl Viro .readlink = generic_readlink 112961ba64fcSAl Viro }; 113061ba64fcSAl Viro EXPORT_SYMBOL(simple_symlink_inode_operations); 1131fbabfd0fSEric W. Biederman 1132fbabfd0fSEric W. Biederman /* 1133fbabfd0fSEric W. Biederman * Operations for a permanently empty directory. 1134fbabfd0fSEric W. Biederman */ 1135fbabfd0fSEric W. Biederman static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 1136fbabfd0fSEric W. Biederman { 1137fbabfd0fSEric W. Biederman return ERR_PTR(-ENOENT); 1138fbabfd0fSEric W. Biederman } 1139fbabfd0fSEric W. Biederman 1140fbabfd0fSEric W. Biederman static int empty_dir_getattr(struct vfsmount *mnt, struct dentry *dentry, 1141fbabfd0fSEric W. Biederman struct kstat *stat) 1142fbabfd0fSEric W. Biederman { 1143fbabfd0fSEric W. Biederman struct inode *inode = d_inode(dentry); 1144fbabfd0fSEric W. Biederman generic_fillattr(inode, stat); 1145fbabfd0fSEric W. Biederman return 0; 1146fbabfd0fSEric W. Biederman } 1147fbabfd0fSEric W. Biederman 1148fbabfd0fSEric W. Biederman static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr) 1149fbabfd0fSEric W. Biederman { 1150fbabfd0fSEric W. Biederman return -EPERM; 1151fbabfd0fSEric W. Biederman } 1152fbabfd0fSEric W. Biederman 1153fbabfd0fSEric W. Biederman static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size) 1154fbabfd0fSEric W. Biederman { 1155fbabfd0fSEric W. Biederman return -EOPNOTSUPP; 1156fbabfd0fSEric W. Biederman } 1157fbabfd0fSEric W. Biederman 1158fbabfd0fSEric W. Biederman static const struct inode_operations empty_dir_inode_operations = { 1159fbabfd0fSEric W. Biederman .lookup = empty_dir_lookup, 1160fbabfd0fSEric W. Biederman .permission = generic_permission, 1161fbabfd0fSEric W. Biederman .setattr = empty_dir_setattr, 1162fbabfd0fSEric W. Biederman .getattr = empty_dir_getattr, 1163fbabfd0fSEric W. Biederman .listxattr = empty_dir_listxattr, 1164fbabfd0fSEric W. Biederman }; 1165fbabfd0fSEric W. Biederman 1166fbabfd0fSEric W. Biederman static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence) 1167fbabfd0fSEric W. Biederman { 1168fbabfd0fSEric W. Biederman /* An empty directory has two entries . and .. at offsets 0 and 1 */ 1169fbabfd0fSEric W. Biederman return generic_file_llseek_size(file, offset, whence, 2, 2); 1170fbabfd0fSEric W. Biederman } 1171fbabfd0fSEric W. Biederman 1172fbabfd0fSEric W. Biederman static int empty_dir_readdir(struct file *file, struct dir_context *ctx) 1173fbabfd0fSEric W. Biederman { 1174fbabfd0fSEric W. Biederman dir_emit_dots(file, ctx); 1175fbabfd0fSEric W. Biederman return 0; 1176fbabfd0fSEric W. Biederman } 1177fbabfd0fSEric W. Biederman 1178fbabfd0fSEric W. Biederman static const struct file_operations empty_dir_operations = { 1179fbabfd0fSEric W. Biederman .llseek = empty_dir_llseek, 1180fbabfd0fSEric W. Biederman .read = generic_read_dir, 1181c51da20cSAl Viro .iterate_shared = empty_dir_readdir, 1182fbabfd0fSEric W. Biederman .fsync = noop_fsync, 1183fbabfd0fSEric W. Biederman }; 1184fbabfd0fSEric W. Biederman 1185fbabfd0fSEric W. Biederman 1186fbabfd0fSEric W. Biederman void make_empty_dir_inode(struct inode *inode) 1187fbabfd0fSEric W. Biederman { 1188fbabfd0fSEric W. Biederman set_nlink(inode, 2); 1189fbabfd0fSEric W. Biederman inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO; 1190fbabfd0fSEric W. Biederman inode->i_uid = GLOBAL_ROOT_UID; 1191fbabfd0fSEric W. Biederman inode->i_gid = GLOBAL_ROOT_GID; 1192fbabfd0fSEric W. Biederman inode->i_rdev = 0; 11934b75de86SEric W. Biederman inode->i_size = 0; 1194fbabfd0fSEric W. Biederman inode->i_blkbits = PAGE_SHIFT; 1195fbabfd0fSEric W. Biederman inode->i_blocks = 0; 1196fbabfd0fSEric W. Biederman 1197fbabfd0fSEric W. Biederman inode->i_op = &empty_dir_inode_operations; 1198f5c24438SAndreas Gruenbacher inode->i_opflags &= ~IOP_XATTR; 1199fbabfd0fSEric W. Biederman inode->i_fop = &empty_dir_operations; 1200fbabfd0fSEric W. Biederman } 1201fbabfd0fSEric W. Biederman 1202fbabfd0fSEric W. Biederman bool is_empty_dir_inode(struct inode *inode) 1203fbabfd0fSEric W. Biederman { 1204fbabfd0fSEric W. Biederman return (inode->i_fop == &empty_dir_operations) && 1205fbabfd0fSEric W. Biederman (inode->i_op == &empty_dir_inode_operations); 1206fbabfd0fSEric W. Biederman } 1207