diff options
Diffstat (limited to 'fs/libfs.c')
| -rw-r--r-- | fs/libfs.c | 1624 |
1 files changed, 1358 insertions, 266 deletions
diff --git a/fs/libfs.c b/fs/libfs.c index 0fb590d79f30..9264523be85c 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * fs/libfs.c * Library for filesystems writers. @@ -14,18 +15,26 @@ #include <linux/mutex.h> #include <linux/namei.h> #include <linux/exportfs.h> +#include <linux/iversion.h> #include <linux/writeback.h> #include <linux/buffer_head.h> /* sync_mapping_buffers */ +#include <linux/fs_context.h> +#include <linux/pseudo_fs.h> +#include <linux/fsnotify.h> +#include <linux/unicode.h> +#include <linux/fscrypt.h> +#include <linux/pidfs.h> #include <linux/uaccess.h> #include "internal.h" -int simple_getattr(const struct path *path, struct kstat *stat, - u32 request_mask, unsigned int query_flags) +int simple_getattr(struct mnt_idmap *idmap, const struct path *path, + struct kstat *stat, u32 request_mask, + unsigned int query_flags) { struct inode *inode = d_inode(path->dentry); - generic_fillattr(inode, stat); + generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat); stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9); return 0; } @@ -33,6 +42,9 @@ EXPORT_SYMBOL(simple_getattr); int simple_statfs(struct dentry *dentry, struct kstatfs *buf) { + u64 id = huge_encode_dev(dentry->d_sb->s_dev); + + buf->f_fsid = u64_to_fsid(id); buf->f_type = dentry->d_sb->s_magic; buf->f_bsize = PAGE_SIZE; buf->f_namelen = NAME_MAX; @@ -50,11 +62,6 @@ int always_delete_dentry(const struct dentry *dentry) } EXPORT_SYMBOL(always_delete_dentry); -const struct dentry_operations simple_dentry_operations = { - .d_delete = always_delete_dentry, -}; -EXPORT_SYMBOL(simple_dentry_operations); - /* * Lookup the data. This is trivial - if the dentry didn't already * exist, we know it is negative. Set d_op to delete negative dentries. @@ -63,8 +70,14 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned { if (dentry->d_name.len > NAME_MAX) return ERR_PTR(-ENAMETOOLONG); - if (!dentry->d_sb->s_d_op) - d_set_d_op(dentry, &simple_dentry_operations); + if (!dentry->d_op && !(dentry->d_flags & DCACHE_DONTCACHE)) { + spin_lock(&dentry->d_lock); + dentry->d_flags |= DCACHE_DONTCACHE; + spin_unlock(&dentry->d_lock); + } + if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir)) + return NULL; + d_add(dentry, NULL); return NULL; } @@ -86,58 +99,48 @@ int dcache_dir_close(struct inode *inode, struct file *file) EXPORT_SYMBOL(dcache_dir_close); /* parent is locked at least shared */ -static struct dentry *next_positive(struct dentry *parent, - struct list_head *from, - int count) -{ - unsigned *seq = &parent->d_inode->i_dir_seq, n; - struct dentry *res; - struct list_head *p; - bool skipped; - int i; +/* + * Returns an element of siblings' list. + * We are looking for <count>th positive after <p>; if + * found, dentry is grabbed and returned to caller. + * If no such element exists, NULL is returned. + */ +static struct dentry *scan_positives(struct dentry *cursor, + struct hlist_node **p, + loff_t count, + struct dentry *last) +{ + struct dentry *dentry = cursor->d_parent, *found = NULL; -retry: - i = count; - skipped = false; - n = smp_load_acquire(seq) & ~1; - res = NULL; - rcu_read_lock(); - for (p = from->next; p != &parent->d_subdirs; p = p->next) { - struct dentry *d = list_entry(p, struct dentry, d_child); - if (!simple_positive(d)) { - skipped = true; - } else if (!--i) { - res = d; - break; + spin_lock(&dentry->d_lock); + while (*p) { + struct dentry *d = hlist_entry(*p, struct dentry, d_sib); + p = &d->d_sib.next; + // we must at least skip cursors, to avoid livelocks + if (d->d_flags & DCACHE_DENTRY_CURSOR) + continue; + if (simple_positive(d) && !--count) { + spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(d)) + found = dget_dlock(d); + spin_unlock(&d->d_lock); + if (likely(found)) + break; + count = 1; + } + if (need_resched()) { + if (!hlist_unhashed(&cursor->d_sib)) + __hlist_del(&cursor->d_sib); + hlist_add_behind(&cursor->d_sib, &d->d_sib); + p = &cursor->d_sib.next; + spin_unlock(&dentry->d_lock); + cond_resched(); + spin_lock(&dentry->d_lock); } } - rcu_read_unlock(); - if (skipped) { - smp_rmb(); - if (unlikely(*seq != n)) - goto retry; - } - return res; -} - -static void move_cursor(struct dentry *cursor, struct list_head *after) -{ - struct dentry *parent = cursor->d_parent; - unsigned n, *seq = &parent->d_inode->i_dir_seq; - spin_lock(&parent->d_lock); - for (;;) { - n = *seq; - if (!(n & 1) && cmpxchg(seq, n, n + 1) == n) - break; - cpu_relax(); - } - __list_del(cursor->d_child.prev, cursor->d_child.next); - if (after) - list_add(&cursor->d_child, after); - else - list_add_tail(&cursor->d_child, &parent->d_subdirs); - smp_store_release(seq, n + 2); - spin_unlock(&parent->d_lock); + spin_unlock(&dentry->d_lock); + dput(last); + return found; } loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) @@ -146,35 +149,38 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) switch (whence) { case 1: offset += file->f_pos; + fallthrough; case 0: if (offset >= 0) break; + fallthrough; default: return -EINVAL; } if (offset != file->f_pos) { + struct dentry *cursor = file->private_data; + struct dentry *to = NULL; + + inode_lock_shared(dentry->d_inode); + + if (offset > 2) + to = scan_positives(cursor, &dentry->d_children.first, + offset - 2, NULL); + spin_lock(&dentry->d_lock); + hlist_del_init(&cursor->d_sib); + if (to) + hlist_add_behind(&cursor->d_sib, &to->d_sib); + spin_unlock(&dentry->d_lock); + dput(to); + file->f_pos = offset; - if (file->f_pos >= 2) { - struct dentry *cursor = file->private_data; - struct dentry *to; - loff_t n = file->f_pos - 2; - - inode_lock_shared(dentry->d_inode); - to = next_positive(dentry, &dentry->d_subdirs, n); - move_cursor(cursor, to ? &to->d_child : NULL); - inode_unlock_shared(dentry->d_inode); - } + + inode_unlock_shared(dentry->d_inode); } return offset; } EXPORT_SYMBOL(dcache_dir_lseek); -/* Relationship between i_mode and the DT_xxx types */ -static inline unsigned char dt_type(struct inode *inode) -{ - return (inode->i_mode >> 12) & 15; -} - /* * Directory is locked and all positive dentries in it are safe, since * for ramfs-type trees they can't go away without unlink() or rmdir(), @@ -185,25 +191,32 @@ int dcache_readdir(struct file *file, struct dir_context *ctx) { struct dentry *dentry = file->f_path.dentry; struct dentry *cursor = file->private_data; - struct list_head *p = &cursor->d_child; - struct dentry *next; - bool moved = false; + struct dentry *next = NULL; + struct hlist_node **p; if (!dir_emit_dots(file, ctx)) return 0; if (ctx->pos == 2) - p = &dentry->d_subdirs; - while ((next = next_positive(dentry, p, 1)) != NULL) { + p = &dentry->d_children.first; + else + p = &cursor->d_sib.next; + + while ((next = scan_positives(cursor, p, 1, next)) != NULL) { if (!dir_emit(ctx, next->d_name.name, next->d_name.len, - d_inode(next)->i_ino, dt_type(d_inode(next)))) + d_inode(next)->i_ino, + fs_umode_to_dtype(d_inode(next)->i_mode))) break; - moved = true; - p = &next->d_child; ctx->pos++; + p = &next->d_sib.next; } - if (moved) - move_cursor(cursor, p); + spin_lock(&dentry->d_lock); + hlist_del_init(&cursor->d_sib); + if (next) + hlist_add_before(&cursor->d_sib, &next->d_sib); + spin_unlock(&dentry->d_lock); + dput(next); + return 0; } EXPORT_SYMBOL(dcache_readdir); @@ -229,38 +242,462 @@ const struct inode_operations simple_dir_inode_operations = { }; EXPORT_SYMBOL(simple_dir_inode_operations); -static const struct super_operations simple_super_operations = { - .statfs = simple_statfs, +/* simple_offset_add() never assigns these to a dentry */ +enum { + DIR_OFFSET_FIRST = 2, /* Find first real entry */ + DIR_OFFSET_EOD = S32_MAX, }; -/* - * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that - * will never be mountable) +/* simple_offset_add() allocation range */ +enum { + DIR_OFFSET_MIN = DIR_OFFSET_FIRST + 1, + DIR_OFFSET_MAX = DIR_OFFSET_EOD - 1, +}; + +static void offset_set(struct dentry *dentry, long offset) +{ + dentry->d_fsdata = (void *)offset; +} + +static long dentry2offset(struct dentry *dentry) +{ + return (long)dentry->d_fsdata; +} + +static struct lock_class_key simple_offset_lock_class; + +/** + * simple_offset_init - initialize an offset_ctx + * @octx: directory offset map to be initialized + * + */ +void simple_offset_init(struct offset_ctx *octx) +{ + mt_init_flags(&octx->mt, MT_FLAGS_ALLOC_RANGE); + lockdep_set_class(&octx->mt.ma_lock, &simple_offset_lock_class); + octx->next_offset = DIR_OFFSET_MIN; +} + +/** + * simple_offset_add - Add an entry to a directory's offset map + * @octx: directory offset ctx to be updated + * @dentry: new dentry being added + * + * Returns zero on success. @octx and the dentry's offset are updated. + * Otherwise, a negative errno value is returned. + */ +int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry) +{ + unsigned long offset; + int ret; + + if (dentry2offset(dentry) != 0) + return -EBUSY; + + ret = mtree_alloc_cyclic(&octx->mt, &offset, dentry, DIR_OFFSET_MIN, + DIR_OFFSET_MAX, &octx->next_offset, + GFP_KERNEL); + if (unlikely(ret < 0)) + return ret == -EBUSY ? -ENOSPC : ret; + + offset_set(dentry, offset); + return 0; +} + +static int simple_offset_replace(struct offset_ctx *octx, struct dentry *dentry, + long offset) +{ + int ret; + + ret = mtree_store(&octx->mt, offset, dentry, GFP_KERNEL); + if (ret) + return ret; + offset_set(dentry, offset); + return 0; +} + +/** + * simple_offset_remove - Remove an entry to a directory's offset map + * @octx: directory offset ctx to be updated + * @dentry: dentry being removed + * + */ +void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry) +{ + long offset; + + offset = dentry2offset(dentry); + if (offset == 0) + return; + + mtree_erase(&octx->mt, offset); + offset_set(dentry, 0); +} + +/** + * simple_offset_rename - handle directory offsets for rename + * @old_dir: parent directory of source entry + * @old_dentry: dentry of source entry + * @new_dir: parent_directory of destination entry + * @new_dentry: dentry of destination + * + * Caller provides appropriate serialization. + * + * User space expects the directory offset value of the replaced + * (new) directory entry to be unchanged after a rename. + * + * Returns zero on success, a negative errno value on failure. + */ +int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir); + struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir); + long new_offset = dentry2offset(new_dentry); + + simple_offset_remove(old_ctx, old_dentry); + + if (new_offset) { + offset_set(new_dentry, 0); + return simple_offset_replace(new_ctx, old_dentry, new_offset); + } + return simple_offset_add(new_ctx, old_dentry); +} + +/** + * simple_offset_rename_exchange - exchange rename with directory offsets + * @old_dir: parent of dentry being moved + * @old_dentry: dentry being moved + * @new_dir: destination parent + * @new_dentry: destination dentry + * + * This API preserves the directory offset values. Caller provides + * appropriate serialization. + * + * Returns zero on success. Otherwise a negative errno is returned and the + * rename is rolled back. + */ +int simple_offset_rename_exchange(struct inode *old_dir, + struct dentry *old_dentry, + struct inode *new_dir, + struct dentry *new_dentry) +{ + struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir); + struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir); + long old_index = dentry2offset(old_dentry); + long new_index = dentry2offset(new_dentry); + int ret; + + simple_offset_remove(old_ctx, old_dentry); + simple_offset_remove(new_ctx, new_dentry); + + ret = simple_offset_replace(new_ctx, old_dentry, new_index); + if (ret) + goto out_restore; + + ret = simple_offset_replace(old_ctx, new_dentry, old_index); + if (ret) { + simple_offset_remove(new_ctx, old_dentry); + goto out_restore; + } + + ret = simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry); + if (ret) { + simple_offset_remove(new_ctx, old_dentry); + simple_offset_remove(old_ctx, new_dentry); + goto out_restore; + } + return 0; + +out_restore: + (void)simple_offset_replace(old_ctx, old_dentry, old_index); + (void)simple_offset_replace(new_ctx, new_dentry, new_index); + return ret; +} + +/** + * simple_offset_destroy - Release offset map + * @octx: directory offset ctx that is about to be destroyed + * + * During fs teardown (eg. umount), a directory's offset map might still + * contain entries. xa_destroy() cleans out anything that remains. + */ +void simple_offset_destroy(struct offset_ctx *octx) +{ + mtree_destroy(&octx->mt); +} + +/** + * offset_dir_llseek - Advance the read position of a directory descriptor + * @file: an open directory whose position is to be updated + * @offset: a byte offset + * @whence: enumerator describing the starting position for this update + * + * SEEK_END, SEEK_DATA, and SEEK_HOLE are not supported for directories. + * + * Returns the updated read position if successful; otherwise a + * negative errno is returned and the read position remains unchanged. + */ +static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence) +{ + switch (whence) { + case SEEK_CUR: + offset += file->f_pos; + fallthrough; + case SEEK_SET: + if (offset >= 0) + break; + fallthrough; + default: + return -EINVAL; + } + + return vfs_setpos(file, offset, LONG_MAX); +} + +static struct dentry *find_positive_dentry(struct dentry *parent, + struct dentry *dentry, + bool next) +{ + struct dentry *found = NULL; + + spin_lock(&parent->d_lock); + if (next) + dentry = d_next_sibling(dentry); + else if (!dentry) + dentry = d_first_child(parent); + hlist_for_each_entry_from(dentry, d_sib) { + if (!simple_positive(dentry)) + continue; + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(dentry)) + found = dget_dlock(dentry); + spin_unlock(&dentry->d_lock); + if (likely(found)) + break; + } + spin_unlock(&parent->d_lock); + return found; +} + +static noinline_for_stack struct dentry * +offset_dir_lookup(struct dentry *parent, loff_t offset) +{ + struct inode *inode = d_inode(parent); + struct offset_ctx *octx = inode->i_op->get_offset_ctx(inode); + struct dentry *child, *found = NULL; + + MA_STATE(mas, &octx->mt, offset, offset); + + if (offset == DIR_OFFSET_FIRST) + found = find_positive_dentry(parent, NULL, false); + else { + rcu_read_lock(); + child = mas_find_rev(&mas, DIR_OFFSET_MIN); + found = find_positive_dentry(parent, child, false); + rcu_read_unlock(); + } + return found; +} + +static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + + return dir_emit(ctx, dentry->d_name.name, dentry->d_name.len, + inode->i_ino, fs_umode_to_dtype(inode->i_mode)); +} + +static void offset_iterate_dir(struct file *file, struct dir_context *ctx) +{ + struct dentry *dir = file->f_path.dentry; + struct dentry *dentry; + + dentry = offset_dir_lookup(dir, ctx->pos); + if (!dentry) + goto out_eod; + while (true) { + struct dentry *next; + + ctx->pos = dentry2offset(dentry); + if (!offset_dir_emit(ctx, dentry)) + break; + + next = find_positive_dentry(dir, dentry, true); + dput(dentry); + + if (!next) + goto out_eod; + dentry = next; + } + dput(dentry); + return; + +out_eod: + ctx->pos = DIR_OFFSET_EOD; +} + +/** + * offset_readdir - Emit entries starting at offset @ctx->pos + * @file: an open directory to iterate over + * @ctx: directory iteration context + * + * Caller must hold @file's i_rwsem to prevent insertion or removal of + * entries during this call. + * + * On entry, @ctx->pos contains an offset that represents the first entry + * to be read from the directory. + * + * The operation continues until there are no more entries to read, or + * until the ctx->actor indicates there is no more space in the caller's + * output buffer. + * + * On return, @ctx->pos contains an offset that will read the next entry + * in this directory when offset_readdir() is called again with @ctx. + * Caller places this value in the d_off field of the last entry in the + * user's buffer. + * + * Return values: + * %0 - Complete */ -struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name, - const struct super_operations *ops, const struct xattr_handler **xattr, - const struct dentry_operations *dops, unsigned long magic) +static int offset_readdir(struct file *file, struct dir_context *ctx) +{ + struct dentry *dir = file->f_path.dentry; + + lockdep_assert_held(&d_inode(dir)->i_rwsem); + + if (!dir_emit_dots(file, ctx)) + return 0; + if (ctx->pos != DIR_OFFSET_EOD) + offset_iterate_dir(file, ctx); + return 0; +} + +const struct file_operations simple_offset_dir_operations = { + .llseek = offset_dir_llseek, + .iterate_shared = offset_readdir, + .read = generic_read_dir, + .fsync = noop_fsync, +}; + +struct dentry *find_next_child(struct dentry *parent, struct dentry *prev) +{ + struct dentry *child = NULL, *d; + + spin_lock(&parent->d_lock); + d = prev ? d_next_sibling(prev) : d_first_child(parent); + hlist_for_each_entry_from(d, d_sib) { + if (simple_positive(d)) { + spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(d)) + child = dget_dlock(d); + spin_unlock(&d->d_lock); + if (likely(child)) + break; + } + } + spin_unlock(&parent->d_lock); + dput(prev); + return child; +} +EXPORT_SYMBOL(find_next_child); + +static void __simple_recursive_removal(struct dentry *dentry, + void (*callback)(struct dentry *), + bool locked) +{ + struct dentry *this = dget(dentry); + while (true) { + struct dentry *victim = NULL, *child; + struct inode *inode = this->d_inode; + + inode_lock_nested(inode, I_MUTEX_CHILD); + if (d_is_dir(this)) + inode->i_flags |= S_DEAD; + while ((child = find_next_child(this, victim)) == NULL) { + // kill and ascend + // update metadata while it's still locked + inode_set_ctime_current(inode); + clear_nlink(inode); + inode_unlock(inode); + victim = this; + this = this->d_parent; + inode = this->d_inode; + if (!locked || victim != dentry) + inode_lock_nested(inode, I_MUTEX_CHILD); + if (simple_positive(victim)) { + d_invalidate(victim); // avoid lost mounts + if (callback) + callback(victim); + fsnotify_delete(inode, d_inode(victim), victim); + d_make_discardable(victim); + } + if (victim == dentry) { + inode_set_mtime_to_ts(inode, + inode_set_ctime_current(inode)); + if (d_is_dir(dentry)) + drop_nlink(inode); + if (!locked) + inode_unlock(inode); + dput(dentry); + return; + } + } + inode_unlock(inode); + this = child; + } +} + +void simple_recursive_removal(struct dentry *dentry, + void (*callback)(struct dentry *)) +{ + return __simple_recursive_removal(dentry, callback, false); +} +EXPORT_SYMBOL(simple_recursive_removal); + +void simple_remove_by_name(struct dentry *parent, const char *name, + void (*callback)(struct dentry *)) { - struct super_block *s; struct dentry *dentry; - struct inode *root; - struct qstr d_name = QSTR_INIT(name, strlen(name)); - s = sget_userns(fs_type, NULL, set_anon_super, SB_KERNMOUNT|SB_NOUSER, - &init_user_ns, NULL); - if (IS_ERR(s)) - return ERR_CAST(s); + dentry = lookup_noperm_positive_unlocked(&QSTR(name), parent); + if (!IS_ERR(dentry)) { + simple_recursive_removal(dentry, callback); + dput(dentry); // paired with lookup_noperm_positive_unlocked() + } +} +EXPORT_SYMBOL(simple_remove_by_name); + +/* caller holds parent directory with I_MUTEX_PARENT */ +void locked_recursive_removal(struct dentry *dentry, + void (*callback)(struct dentry *)) +{ + return __simple_recursive_removal(dentry, callback, true); +} +EXPORT_SYMBOL(locked_recursive_removal); + +static const struct super_operations simple_super_operations = { + .statfs = simple_statfs, +}; + +static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc) +{ + struct pseudo_fs_context *ctx = fc->fs_private; + struct inode *root; s->s_maxbytes = MAX_LFS_FILESIZE; s->s_blocksize = PAGE_SIZE; s->s_blocksize_bits = PAGE_SHIFT; - s->s_magic = magic; - s->s_op = ops ? ops : &simple_super_operations; - s->s_xattr = xattr; + s->s_magic = ctx->magic; + s->s_op = ctx->ops ?: &simple_super_operations; + s->s_export_op = ctx->eops; + s->s_xattr = ctx->xattr; s->s_time_gran = 1; + s->s_d_flags |= ctx->s_d_flags; root = new_inode(s); if (!root) - goto Enomem; + return -ENOMEM; + /* * since this is the first inode, make it number 1. New inodes created * after this must take care not to collide with it (by passing @@ -268,23 +705,49 @@ struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name, */ root->i_ino = 1; root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; - root->i_atime = root->i_mtime = root->i_ctime = current_time(root); - dentry = __d_alloc(s, &d_name); - if (!dentry) { - iput(root); - goto Enomem; - } - d_instantiate(dentry, root); - s->s_root = dentry; - s->s_d_op = dops; - s->s_flags |= SB_ACTIVE; - return dget(s->s_root); + simple_inode_init_ts(root); + s->s_root = d_make_root(root); + if (!s->s_root) + return -ENOMEM; + set_default_d_op(s, ctx->dops); + return 0; +} + +static int pseudo_fs_get_tree(struct fs_context *fc) +{ + return get_tree_nodev(fc, pseudo_fs_fill_super); +} -Enomem: - deactivate_locked_super(s); - return ERR_PTR(-ENOMEM); +static void pseudo_fs_free(struct fs_context *fc) +{ + kfree(fc->fs_private); } -EXPORT_SYMBOL(mount_pseudo_xattr); + +static const struct fs_context_operations pseudo_fs_context_ops = { + .free = pseudo_fs_free, + .get_tree = pseudo_fs_get_tree, +}; + +/* + * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that + * will never be mountable) + */ +struct pseudo_fs_context *init_pseudo(struct fs_context *fc, + unsigned long magic) +{ + struct pseudo_fs_context *ctx; + + ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL); + if (likely(ctx)) { + ctx->magic = magic; + fc->fs_private = ctx; + fc->ops = &pseudo_fs_context_ops; + fc->sb_flags |= SB_NOUSER; + fc->global = true; + } + return ctx; +} +EXPORT_SYMBOL(init_pseudo); int simple_open(struct inode *inode, struct file *file) { @@ -298,11 +761,11 @@ int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *den { struct inode *inode = d_inode(old_dentry); - inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); + inode_set_mtime_to_ts(dir, + inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); inc_nlink(inode); ihold(inode); - dget(dentry); - d_instantiate(dentry, inode); + d_make_persistent(dentry, inode); return 0; } EXPORT_SYMBOL(simple_link); @@ -313,7 +776,7 @@ int simple_empty(struct dentry *dentry) int ret = 0; spin_lock(&dentry->d_lock); - list_for_each_entry(child, &dentry->d_subdirs, d_child) { + hlist_for_each_entry(child, &dentry->d_children, d_sib) { spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); if (simple_positive(child)) { spin_unlock(&child->d_lock); @@ -328,13 +791,28 @@ out: } EXPORT_SYMBOL(simple_empty); -int simple_unlink(struct inode *dir, struct dentry *dentry) +void __simple_unlink(struct inode *dir, struct dentry *dentry) { struct inode *inode = d_inode(dentry); - inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); + inode_set_mtime_to_ts(dir, + inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); drop_nlink(inode); - dput(dentry); +} +EXPORT_SYMBOL(__simple_unlink); + +void __simple_rmdir(struct inode *dir, struct dentry *dentry) +{ + drop_nlink(d_inode(dentry)); + __simple_unlink(dir, dentry); + drop_nlink(dir); +} +EXPORT_SYMBOL(__simple_rmdir); + +int simple_unlink(struct inode *dir, struct dentry *dentry) +{ + __simple_unlink(dir, dentry); + d_make_discardable(dentry); return 0; } EXPORT_SYMBOL(simple_unlink); @@ -344,23 +822,70 @@ int simple_rmdir(struct inode *dir, struct dentry *dentry) if (!simple_empty(dentry)) return -ENOTEMPTY; - drop_nlink(d_inode(dentry)); - simple_unlink(dir, dentry); - drop_nlink(dir); + __simple_rmdir(dir, dentry); + d_make_discardable(dentry); return 0; } EXPORT_SYMBOL(simple_rmdir); -int simple_rename(struct inode *old_dir, struct dentry *old_dentry, - struct inode *new_dir, struct dentry *new_dentry, - unsigned int flags) +/** + * simple_rename_timestamp - update the various inode timestamps for rename + * @old_dir: old parent directory + * @old_dentry: dentry that is being renamed + * @new_dir: new parent directory + * @new_dentry: target for rename + * + * POSIX mandates that the old and new parent directories have their ctime and + * mtime updated, and that inodes of @old_dentry and @new_dentry (if any), have + * their ctime updated. + */ +void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + struct inode *newino = d_inode(new_dentry); + + inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir)); + if (new_dir != old_dir) + inode_set_mtime_to_ts(new_dir, + inode_set_ctime_current(new_dir)); + inode_set_ctime_current(d_inode(old_dentry)); + if (newino) + inode_set_ctime_current(newino); +} +EXPORT_SYMBOL_GPL(simple_rename_timestamp); + +int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + bool old_is_dir = d_is_dir(old_dentry); + bool new_is_dir = d_is_dir(new_dentry); + + if (old_dir != new_dir && old_is_dir != new_is_dir) { + if (old_is_dir) { + drop_nlink(old_dir); + inc_nlink(new_dir); + } else { + drop_nlink(new_dir); + inc_nlink(old_dir); + } + } + simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry); + return 0; +} +EXPORT_SYMBOL_GPL(simple_rename_exchange); + +int simple_rename(struct mnt_idmap *idmap, struct inode *old_dir, + struct dentry *old_dentry, struct inode *new_dir, + struct dentry *new_dentry, unsigned int flags) { - struct inode *inode = d_inode(old_dentry); int they_are_dirs = d_is_dir(old_dentry); - if (flags & ~RENAME_NOREPLACE) + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) return -EINVAL; + if (flags & RENAME_EXCHANGE) + return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry); + if (!simple_empty(new_dentry)) return -ENOTEMPTY; @@ -375,15 +900,14 @@ int simple_rename(struct inode *old_dir, struct dentry *old_dentry, inc_nlink(new_dir); } - old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = - new_dir->i_mtime = inode->i_ctime = current_time(old_dir); - + simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry); return 0; } EXPORT_SYMBOL(simple_rename); /** * simple_setattr - setattr for simple filesystem + * @idmap: idmap of the target mount * @dentry: dentry * @iattr: iattr structure * @@ -396,52 +920,51 @@ EXPORT_SYMBOL(simple_rename); * on simple regular filesystems. Anything that needs to change on-disk * or wire state on size changes needs its own setattr method. */ -int simple_setattr(struct dentry *dentry, struct iattr *iattr) +int simple_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + struct iattr *iattr) { struct inode *inode = d_inode(dentry); int error; - error = setattr_prepare(dentry, iattr); + error = setattr_prepare(idmap, dentry, iattr); if (error) return error; if (iattr->ia_valid & ATTR_SIZE) truncate_setsize(inode, iattr->ia_size); - setattr_copy(inode, iattr); + setattr_copy(idmap, inode, iattr); mark_inode_dirty(inode); return 0; } EXPORT_SYMBOL(simple_setattr); -int simple_readpage(struct file *file, struct page *page) +static int simple_read_folio(struct file *file, struct folio *folio) { - clear_highpage(page); - flush_dcache_page(page); - SetPageUptodate(page); - unlock_page(page); + folio_zero_range(folio, 0, folio_size(folio)); + flush_dcache_folio(folio); + folio_mark_uptodate(folio); + folio_unlock(folio); return 0; } -EXPORT_SYMBOL(simple_readpage); -int simple_write_begin(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned flags, - struct page **pagep, void **fsdata) +int simple_write_begin(const struct kiocb *iocb, struct address_space *mapping, + loff_t pos, unsigned len, + struct folio **foliop, void **fsdata) { - struct page *page; - pgoff_t index; + struct folio *folio; - index = pos >> PAGE_SHIFT; + folio = __filemap_get_folio(mapping, pos / PAGE_SIZE, FGP_WRITEBEGIN, + mapping_gfp_mask(mapping)); + if (IS_ERR(folio)) + return PTR_ERR(folio); - page = grab_cache_page_write_begin(mapping, index, flags); - if (!page) - return -ENOMEM; + *foliop = folio; - *pagep = page; + if (!folio_test_uptodate(folio) && (len != folio_size(folio))) { + size_t from = offset_in_folio(folio, pos); - if (!PageUptodate(page) && (len != PAGE_SIZE)) { - unsigned from = pos & (PAGE_SIZE - 1); - - zero_user_segments(page, 0, from, from + len, PAGE_SIZE); + folio_zero_segments(folio, 0, from, + from + len, folio_size(folio)); } return 0; } @@ -449,57 +972,68 @@ EXPORT_SYMBOL(simple_write_begin); /** * simple_write_end - .write_end helper for non-block-device FSes - * @available: See .write_end of address_space_operations - * @file: " + * @iocb: kernel I/O control block * @mapping: " * @pos: " * @len: " * @copied: " - * @page: " + * @folio: " * @fsdata: " * - * simple_write_end does the minimum needed for updating a page after writing is - * done. It has the same API signature as the .write_end of + * simple_write_end does the minimum needed for updating a folio after + * writing is done. It has the same API signature as the .write_end of * address_space_operations vector. So it can just be set onto .write_end for - * FSes that don't need any other processing. i_mutex is assumed to be held. + * FSes that don't need any other processing. i_rwsem is assumed to be held + * exclusively. * Block based filesystems should use generic_write_end(). * NOTE: Even though i_size might get updated by this function, mark_inode_dirty * is not called, so a filesystem that actually does store data in .write_inode * should extend on what's done here with a call to mark_inode_dirty() in the * case that i_size has changed. * - * Use *ONLY* with simple_readpage() + * Use *ONLY* with simple_read_folio() */ -int simple_write_end(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned copied, - struct page *page, void *fsdata) +static int simple_write_end(const struct kiocb *iocb, + struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct folio *folio, void *fsdata) { - struct inode *inode = page->mapping->host; + struct inode *inode = folio->mapping->host; loff_t last_pos = pos + copied; - /* zero the stale part of the page if we did a short copy */ - if (!PageUptodate(page)) { + /* zero the stale part of the folio if we did a short copy */ + if (!folio_test_uptodate(folio)) { if (copied < len) { - unsigned from = pos & (PAGE_SIZE - 1); + size_t from = offset_in_folio(folio, pos); - zero_user(page, from + copied, len - copied); + folio_zero_range(folio, from + copied, len - copied); } - SetPageUptodate(page); + folio_mark_uptodate(folio); } /* * No need to use i_size_read() here, the i_size - * cannot change under us because we hold the i_mutex. + * cannot change under us because we hold the i_rwsem. */ if (last_pos > inode->i_size) i_size_write(inode, last_pos); - set_page_dirty(page); - unlock_page(page); - put_page(page); + folio_mark_dirty(folio); + folio_unlock(folio); + folio_put(folio); return copied; } -EXPORT_SYMBOL(simple_write_end); + +/* + * Provides ramfs-style behavior: data in the pagecache, but no writeback. + */ +const struct address_space_operations ram_aops = { + .read_folio = simple_read_folio, + .write_begin = simple_write_begin, + .write_end = simple_write_end, + .dirty_folio = noop_dirty_folio, +}; +EXPORT_SYMBOL(ram_aops); /* * the inodes created here are not hashed. If you use iunique to generate @@ -510,7 +1044,6 @@ int simple_fill_super(struct super_block *s, unsigned long magic, const struct tree_descr *files) { struct inode *inode; - struct dentry *root; struct dentry *dentry; int i; @@ -529,12 +1062,12 @@ int simple_fill_super(struct super_block *s, unsigned long magic, */ inode->i_ino = 1; inode->i_mode = S_IFDIR | 0755; - inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + simple_inode_init_ts(inode); inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; set_nlink(inode, 2); - root = d_make_root(inode); - if (!root) + s->s_root = d_make_root(inode); + if (!s->s_root) return -ENOMEM; for (i = 0; !files->name || files->name[0]; i++, files++) { if (!files->name) @@ -546,27 +1079,22 @@ int simple_fill_super(struct super_block *s, unsigned long magic, "with an index of 1!\n", __func__, s->s_type->name); - dentry = d_alloc_name(root, files->name); + dentry = d_alloc_name(s->s_root, files->name); if (!dentry) - goto out; + return -ENOMEM; inode = new_inode(s); if (!inode) { dput(dentry); - goto out; + return -ENOMEM; } inode->i_mode = S_IFREG | files->mode; - inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + simple_inode_init_ts(inode); inode->i_fop = files->ops; inode->i_ino = i; - d_add(dentry, inode); + d_make_persistent(dentry, inode); + dput(dentry); } - s->s_root = root; return 0; -out: - d_genocide(root); - shrink_dcache_parent(root); - dput(root); - return -ENOMEM; } EXPORT_SYMBOL(simple_fill_super); @@ -798,7 +1326,7 @@ int simple_attr_open(struct inode *inode, struct file *file, { struct simple_attr *attr; - attr = kmalloc(sizeof(*attr), GFP_KERNEL); + attr = kzalloc(sizeof(*attr), GFP_KERNEL); if (!attr) return -ENOMEM; @@ -838,9 +1366,11 @@ ssize_t simple_attr_read(struct file *file, char __user *buf, if (ret) return ret; - if (*ppos) { /* continued read */ + if (*ppos && attr->get_buf[0]) { + /* continued read */ size = strlen(attr->get_buf); - } else { /* first read */ + } else { + /* first read */ u64 val; ret = attr->get(attr->data, &val); if (ret) @@ -858,11 +1388,11 @@ out: EXPORT_SYMBOL_GPL(simple_attr_read); /* interpret the buffer as a number to call the set function with */ -ssize_t simple_attr_write(struct file *file, const char __user *buf, - size_t len, loff_t *ppos) +static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf, + size_t len, loff_t *ppos, bool is_signed) { struct simple_attr *attr; - u64 val; + unsigned long long val; size_t size; ssize_t ret; @@ -880,7 +1410,12 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf, goto out; attr->set_buf[size] = '\0'; - val = simple_strtoll(attr->set_buf, NULL, 0); + if (is_signed) + ret = kstrtoll(attr->set_buf, 0, &val); + else + ret = kstrtoull(attr->set_buf, 0, &val); + if (ret) + goto out; ret = attr->set(attr->data, val); if (ret == 0) ret = len; /* on success, claim we got the whole input */ @@ -888,8 +1423,62 @@ out: mutex_unlock(&attr->mutex); return ret; } + +ssize_t simple_attr_write(struct file *file, const char __user *buf, + size_t len, loff_t *ppos) +{ + return simple_attr_write_xsigned(file, buf, len, ppos, false); +} EXPORT_SYMBOL_GPL(simple_attr_write); +ssize_t simple_attr_write_signed(struct file *file, const char __user *buf, + size_t len, loff_t *ppos) +{ + return simple_attr_write_xsigned(file, buf, len, ppos, true); +} +EXPORT_SYMBOL_GPL(simple_attr_write_signed); + +/** + * generic_encode_ino32_fh - generic export_operations->encode_fh function + * @inode: the object to encode + * @fh: where to store the file handle fragment + * @max_len: maximum length to store there (in 4 byte units) + * @parent: parent directory inode, if wanted + * + * This generic encode_fh function assumes that the 32 inode number + * is suitable for locating an inode, and that the generation number + * can be used to check that it is still valid. It places them in the + * filehandle fragment where export_decode_fh expects to find them. + */ +int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len, + struct inode *parent) +{ + struct fid *fid = (void *)fh; + int len = *max_len; + int type = FILEID_INO32_GEN; + + if (parent && (len < 4)) { + *max_len = 4; + return FILEID_INVALID; + } else if (len < 2) { + *max_len = 2; + return FILEID_INVALID; + } + + len = 2; + fid->i32.ino = inode->i_ino; + fid->i32.gen = inode->i_generation; + if (parent) { + fid->i32.parent_ino = parent->i_ino; + fid->i32.parent_gen = parent->i_generation; + len = 4; + type = FILEID_INO32_GEN_PARENT; + } + *max_len = len; + return type; +} +EXPORT_SYMBOL_GPL(generic_encode_ino32_fh); + /** * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation * @sb: filesystem to do the file handle conversion on @@ -980,9 +1569,9 @@ int __generic_file_fsync(struct file *file, loff_t start, loff_t end, inode_lock(inode); ret = sync_mapping_buffers(inode->i_mapping); - if (!(inode->i_state & I_DIRTY_ALL)) + if (!(inode_state_read_once(inode) & I_DIRTY_ALL)) goto out; - if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) + if (datasync && !(inode_state_read_once(inode) & I_DIRTY_DATASYNC)) goto out; err = sync_inode_metadata(inode, 1); @@ -1018,7 +1607,7 @@ int generic_file_fsync(struct file *file, loff_t start, loff_t end, err = __generic_file_fsync(file, start, end, datasync); if (err) return err; - return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); + return blkdev_issue_flush(inode->i_sb->s_bdev); } EXPORT_SYMBOL(generic_file_fsync); @@ -1034,13 +1623,17 @@ EXPORT_SYMBOL(generic_file_fsync); int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) { u64 last_fs_block = num_blocks - 1; - u64 last_fs_page = - last_fs_block >> (PAGE_SHIFT - blocksize_bits); + u64 last_fs_page, max_bytes; + + if (check_shl_overflow(num_blocks, blocksize_bits, &max_bytes)) + return -EFBIG; + + last_fs_page = (max_bytes >> PAGE_SHIFT) - 1; if (unlikely(num_blocks == 0)) return 0; - if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT)) + if (blocksize_bits < 9) return -EINVAL; if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || @@ -1060,33 +1653,6 @@ int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) } EXPORT_SYMBOL(noop_fsync); -int noop_set_page_dirty(struct page *page) -{ - /* - * Unlike __set_page_dirty_no_writeback that handles dirty page - * tracking in the page object, dax does all dirty tracking in - * the inode address_space in response to mkwrite faults. In the - * dax case we only need to worry about potentially dirty CPU - * caches, not dirty page cache pages to write back. - * - * This callback is defined to prevent fallback to - * __set_page_dirty_buffers() in set_page_dirty(). - */ - return 0; -} -EXPORT_SYMBOL_GPL(noop_set_page_dirty); - -void noop_invalidatepage(struct page *page, unsigned int offset, - unsigned int length) -{ - /* - * There is no page cache to invalidate in the dax case, however - * we need this callback defined to prevent falling back to - * block_invalidatepage() in do_invalidatepage(). - */ -} -EXPORT_SYMBOL_GPL(noop_invalidatepage); - ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter) { /* @@ -1106,24 +1672,10 @@ void kfree_link(void *p) } EXPORT_SYMBOL(kfree_link); -/* - * nop .set_page_dirty method so that people can use .page_mkwrite on - * anon inodes. - */ -static int anon_set_page_dirty(struct page *page) -{ - return 0; -}; - -/* - * A single inode exists for all anon_inode files. Contrary to pipes, - * anon_inode inodes have no associated per-instance data, so we need - * only allocate one of them. - */ struct inode *alloc_anon_inode(struct super_block *s) { static const struct address_space_operations anon_aops = { - .set_page_dirty = anon_set_page_dirty, + .dirty_folio = noop_dirty_folio, }; struct inode *inode = new_inode_pseudo(s); @@ -1139,12 +1691,16 @@ struct inode *alloc_anon_inode(struct super_block *s) * list because mark_inode_dirty() will think * that it already _is_ on the dirty list. */ - inode->i_state = I_DIRTY; + inode_state_assign_raw(inode, I_DIRTY); + /* + * Historically anonymous inodes don't have a type at all and + * userspace has come to rely on this. + */ inode->i_mode = S_IRUSR | S_IWUSR; inode->i_uid = current_fsuid(); inode->i_gid = current_fsgid(); - inode->i_flags |= S_PRIVATE; - inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + inode->i_flags |= S_PRIVATE | S_ANON_INODE; + simple_inode_init_ts(inode); return inode; } EXPORT_SYMBOL(alloc_anon_inode); @@ -1160,13 +1716,27 @@ EXPORT_SYMBOL(alloc_anon_inode); * All arguments are ignored and it just returns -EINVAL. */ int -simple_nosetlease(struct file *filp, long arg, struct file_lock **flp, +simple_nosetlease(struct file *filp, int arg, struct file_lease **flp, void **priv) { return -EINVAL; } EXPORT_SYMBOL(simple_nosetlease); +/** + * simple_get_link - generic helper to get the target of "fast" symlinks + * @dentry: not used here + * @inode: the symlink inode + * @done: not used here + * + * Generic helper for filesystems to use for symlink inodes where a pointer to + * the symlink target is stored in ->i_link. NOTE: this isn't normally called, + * since as an optimization the path lookup code uses any non-NULL ->i_link + * directly, without calling ->get_link(). But ->get_link() still must be set, + * to mark the inode_operations as being for a symlink. + * + * Return: the symlink target + */ const char *simple_get_link(struct dentry *dentry, struct inode *inode, struct delayed_call *done) { @@ -1187,15 +1757,8 @@ static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, return ERR_PTR(-ENOENT); } -static int empty_dir_getattr(const struct path *path, struct kstat *stat, - u32 request_mask, unsigned int query_flags) -{ - struct inode *inode = d_inode(path->dentry); - generic_fillattr(inode, stat); - return 0; -} - -static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr) +static int empty_dir_setattr(struct mnt_idmap *idmap, + struct dentry *dentry, struct iattr *attr) { return -EPERM; } @@ -1207,9 +1770,7 @@ static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t siz static const struct inode_operations empty_dir_inode_operations = { .lookup = empty_dir_lookup, - .permission = generic_permission, .setattr = empty_dir_setattr, - .getattr = empty_dir_getattr, .listxattr = empty_dir_listxattr, }; @@ -1254,3 +1815,534 @@ bool is_empty_dir_inode(struct inode *inode) return (inode->i_fop == &empty_dir_operations) && (inode->i_op == &empty_dir_inode_operations); } + +#if IS_ENABLED(CONFIG_UNICODE) +/** + * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems + * @dentry: dentry whose name we are checking against + * @len: len of name of dentry + * @str: str pointer to name of dentry + * @name: Name to compare against + * + * Return: 0 if names match, 1 if mismatch, or -ERRNO + */ +int generic_ci_d_compare(const struct dentry *dentry, unsigned int len, + const char *str, const struct qstr *name) +{ + const struct dentry *parent; + const struct inode *dir; + union shortname_store strbuf; + struct qstr qstr; + + /* + * Attempt a case-sensitive match first. It is cheaper and + * should cover most lookups, including all the sane + * applications that expect a case-sensitive filesystem. + * + * This comparison is safe under RCU because the caller + * guarantees the consistency between str and len. See + * __d_lookup_rcu_op_compare() for details. + */ + if (len == name->len && !memcmp(str, name->name, len)) + return 0; + + parent = READ_ONCE(dentry->d_parent); + dir = READ_ONCE(parent->d_inode); + if (!dir || !IS_CASEFOLDED(dir)) + return 1; + + qstr.len = len; + qstr.name = str; + /* + * If the dentry name is stored in-line, then it may be concurrently + * modified by a rename. If this happens, the VFS will eventually retry + * the lookup, so it doesn't matter what ->d_compare() returns. + * However, it's unsafe to call utf8_strncasecmp() with an unstable + * string. Therefore, we have to copy the name into a temporary buffer. + * As above, len is guaranteed to match str, so the shortname case + * is exactly when str points to ->d_shortname. + */ + if (qstr.name == dentry->d_shortname.string) { + strbuf = dentry->d_shortname; // NUL is guaranteed to be in there + qstr.name = strbuf.string; + /* prevent compiler from optimizing out the temporary buffer */ + barrier(); + } + + return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr); +} +EXPORT_SYMBOL(generic_ci_d_compare); + +/** + * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems + * @dentry: dentry of the parent directory + * @str: qstr of name whose hash we should fill in + * + * Return: 0 if hash was successful or unchanged, and -EINVAL on error + */ +int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str) +{ + const struct inode *dir = READ_ONCE(dentry->d_inode); + struct super_block *sb = dentry->d_sb; + const struct unicode_map *um = sb->s_encoding; + int ret; + + if (!dir || !IS_CASEFOLDED(dir)) + return 0; + + ret = utf8_casefold_hash(um, dentry, str); + if (ret < 0 && sb_has_strict_encoding(sb)) + return -EINVAL; + return 0; +} +EXPORT_SYMBOL(generic_ci_d_hash); + +static const struct dentry_operations generic_ci_dentry_ops = { + .d_hash = generic_ci_d_hash, + .d_compare = generic_ci_d_compare, +#ifdef CONFIG_FS_ENCRYPTION + .d_revalidate = fscrypt_d_revalidate, +#endif +}; + +/** + * generic_ci_match() - Match a name (case-insensitively) with a dirent. + * This is a filesystem helper for comparison with directory entries. + * generic_ci_d_compare should be used in VFS' ->d_compare instead. + * + * @parent: Inode of the parent of the dirent under comparison + * @name: name under lookup. + * @folded_name: Optional pre-folded name under lookup + * @de_name: Dirent name. + * @de_name_len: dirent name length. + * + * Test whether a case-insensitive directory entry matches the filename + * being searched. If @folded_name is provided, it is used instead of + * recalculating the casefold of @name. + * + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or + * < 0 on error. + */ +int generic_ci_match(const struct inode *parent, + const struct qstr *name, + const struct qstr *folded_name, + const u8 *de_name, u32 de_name_len) +{ + const struct super_block *sb = parent->i_sb; + const struct unicode_map *um = sb->s_encoding; + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); + struct qstr dirent = QSTR_INIT(de_name, de_name_len); + int res = 0; + + if (IS_ENCRYPTED(parent)) { + const struct fscrypt_str encrypted_name = + FSTR_INIT((u8 *) de_name, de_name_len); + + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) + return -EINVAL; + + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); + if (!decrypted_name.name) + return -ENOMEM; + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, + &decrypted_name); + if (res < 0) { + kfree(decrypted_name.name); + return res; + } + dirent.name = decrypted_name.name; + dirent.len = decrypted_name.len; + } + + /* + * Attempt a case-sensitive match first. It is cheaper and + * should cover most lookups, including all the sane + * applications that expect a case-sensitive filesystem. + */ + + if (dirent.len == name->len && + !memcmp(name->name, dirent.name, dirent.len)) + goto out; + + if (folded_name->name) + res = utf8_strncasecmp_folded(um, folded_name, &dirent); + else + res = utf8_strncasecmp(um, name, &dirent); + +out: + kfree(decrypted_name.name); + if (res < 0 && sb_has_strict_encoding(sb)) { + pr_err_ratelimited("Directory contains filename that is invalid UTF-8"); + return 0; + } + return !res; +} +EXPORT_SYMBOL(generic_ci_match); +#endif + +#ifdef CONFIG_FS_ENCRYPTION +static const struct dentry_operations generic_encrypted_dentry_ops = { + .d_revalidate = fscrypt_d_revalidate, +}; +#endif + +/** + * generic_set_sb_d_ops - helper for choosing the set of + * filesystem-wide dentry operations for the enabled features + * @sb: superblock to be configured + * + * Filesystems supporting casefolding and/or fscrypt can call this + * helper at mount-time to configure default dentry_operations to the + * best set of dentry operations required for the enabled features. + * The helper must be called after these have been configured, but + * before the root dentry is created. + */ +void generic_set_sb_d_ops(struct super_block *sb) +{ +#if IS_ENABLED(CONFIG_UNICODE) + if (sb->s_encoding) { + set_default_d_op(sb, &generic_ci_dentry_ops); + return; + } +#endif +#ifdef CONFIG_FS_ENCRYPTION + if (sb->s_cop) { + set_default_d_op(sb, &generic_encrypted_dentry_ops); + return; + } +#endif +} +EXPORT_SYMBOL(generic_set_sb_d_ops); + +/** + * inode_maybe_inc_iversion - increments i_version + * @inode: inode with the i_version that should be updated + * @force: increment the counter even if it's not necessary? + * + * Every time the inode is modified, the i_version field must be seen to have + * changed by any observer. + * + * If "force" is set or the QUERIED flag is set, then ensure that we increment + * the value, and clear the queried flag. + * + * In the common case where neither is set, then we can return "false" without + * updating i_version. + * + * If this function returns false, and no other metadata has changed, then we + * can avoid logging the metadata. + */ +bool inode_maybe_inc_iversion(struct inode *inode, bool force) +{ + u64 cur, new; + + /* + * The i_version field is not strictly ordered with any other inode + * information, but the legacy inode_inc_iversion code used a spinlock + * to serialize increments. + * + * We add a full memory barrier to ensure that any de facto ordering + * with other state is preserved (either implicitly coming from cmpxchg + * or explicitly from smp_mb if we don't know upfront if we will execute + * the former). + * + * These barriers pair with inode_query_iversion(). + */ + cur = inode_peek_iversion_raw(inode); + if (!force && !(cur & I_VERSION_QUERIED)) { + smp_mb(); + cur = inode_peek_iversion_raw(inode); + } + + do { + /* If flag is clear then we needn't do anything */ + if (!force && !(cur & I_VERSION_QUERIED)) + return false; + + /* Since lowest bit is flag, add 2 to avoid it */ + new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT; + } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); + return true; +} +EXPORT_SYMBOL(inode_maybe_inc_iversion); + +/** + * inode_query_iversion - read i_version for later use + * @inode: inode from which i_version should be read + * + * Read the inode i_version counter. This should be used by callers that wish + * to store the returned i_version for later comparison. This will guarantee + * that a later query of the i_version will result in a different value if + * anything has changed. + * + * In this implementation, we fetch the current value, set the QUERIED flag and + * then try to swap it into place with a cmpxchg, if it wasn't already set. If + * that fails, we try again with the newly fetched value from the cmpxchg. + */ +u64 inode_query_iversion(struct inode *inode) +{ + u64 cur, new; + bool fenced = false; + + /* + * Memory barriers (implicit in cmpxchg, explicit in smp_mb) pair with + * inode_maybe_inc_iversion(), see that routine for more details. + */ + cur = inode_peek_iversion_raw(inode); + do { + /* If flag is already set, then no need to swap */ + if (cur & I_VERSION_QUERIED) { + if (!fenced) + smp_mb(); + break; + } + + fenced = true; + new = cur | I_VERSION_QUERIED; + } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); + return cur >> I_VERSION_QUERIED_SHIFT; +} +EXPORT_SYMBOL(inode_query_iversion); + +ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, + ssize_t direct_written, ssize_t buffered_written) +{ + struct address_space *mapping = iocb->ki_filp->f_mapping; + loff_t pos = iocb->ki_pos - buffered_written; + loff_t end = iocb->ki_pos - 1; + int err; + + /* + * If the buffered write fallback returned an error, we want to return + * the number of bytes which were written by direct I/O, or the error + * code if that was zero. + * + * Note that this differs from normal direct-io semantics, which will + * return -EFOO even if some bytes were written. + */ + if (unlikely(buffered_written < 0)) { + if (direct_written) + return direct_written; + return buffered_written; + } + + /* + * We need to ensure that the page cache pages are written to disk and + * invalidated to preserve the expected O_DIRECT semantics. + */ + err = filemap_write_and_wait_range(mapping, pos, end); + if (err < 0) { + /* + * We don't know how much we wrote, so just return the number of + * bytes which were direct-written + */ + iocb->ki_pos -= buffered_written; + if (direct_written) + return direct_written; + return err; + } + invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT, end >> PAGE_SHIFT); + return direct_written + buffered_written; +} +EXPORT_SYMBOL_GPL(direct_write_fallback); + +/** + * simple_inode_init_ts - initialize the timestamps for a new inode + * @inode: inode to be initialized + * + * When a new inode is created, most filesystems set the timestamps to the + * current time. Add a helper to do this. + */ +struct timespec64 simple_inode_init_ts(struct inode *inode) +{ + struct timespec64 ts = inode_set_ctime_current(inode); + + inode_set_atime_to_ts(inode, ts); + inode_set_mtime_to_ts(inode, ts); + return ts; +} +EXPORT_SYMBOL(simple_inode_init_ts); + +struct dentry *stashed_dentry_get(struct dentry **stashed) +{ + struct dentry *dentry; + + guard(rcu)(); + dentry = rcu_dereference(*stashed); + if (!dentry) + return NULL; + if (IS_ERR(dentry)) + return dentry; + if (!lockref_get_not_dead(&dentry->d_lockref)) + return NULL; + return dentry; +} + +static struct dentry *prepare_anon_dentry(struct dentry **stashed, + struct super_block *sb, + void *data) +{ + struct dentry *dentry; + struct inode *inode; + const struct stashed_operations *sops = sb->s_fs_info; + int ret; + + inode = new_inode_pseudo(sb); + if (!inode) { + sops->put_data(data); + return ERR_PTR(-ENOMEM); + } + + inode->i_flags |= S_IMMUTABLE; + inode->i_mode = S_IFREG; + simple_inode_init_ts(inode); + + ret = sops->init_inode(inode, data); + if (ret < 0) { + iput(inode); + return ERR_PTR(ret); + } + + /* Notice when this is changed. */ + WARN_ON_ONCE(!S_ISREG(inode->i_mode)); + + dentry = d_alloc_anon(sb); + if (!dentry) { + iput(inode); + return ERR_PTR(-ENOMEM); + } + + /* Store address of location where dentry's supposed to be stashed. */ + dentry->d_fsdata = stashed; + + /* @data is now owned by the fs */ + d_instantiate(dentry, inode); + return dentry; +} + +struct dentry *stash_dentry(struct dentry **stashed, struct dentry *dentry) +{ + guard(rcu)(); + for (;;) { + struct dentry *old; + + /* Assume any old dentry was cleared out. */ + old = cmpxchg(stashed, NULL, dentry); + if (likely(!old)) + return dentry; + + /* Check if somebody else installed a reusable dentry. */ + if (lockref_get_not_dead(&old->d_lockref)) + return old; + + /* There's an old dead dentry there, try to take it over. */ + if (likely(try_cmpxchg(stashed, &old, dentry))) + return dentry; + } +} + +/** + * path_from_stashed - create path from stashed or new dentry + * @stashed: where to retrieve or stash dentry + * @mnt: mnt of the filesystems to use + * @data: data to store in inode->i_private + * @path: path to create + * + * The function tries to retrieve a stashed dentry from @stashed. If the dentry + * is still valid then it will be reused. If the dentry isn't able the function + * will allocate a new dentry and inode. It will then check again whether it + * can reuse an existing dentry in case one has been added in the meantime or + * update @stashed with the newly added dentry. + * + * Special-purpose helper for nsfs and pidfs. + * + * Return: On success zero and on failure a negative error is returned. + */ +int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data, + struct path *path) +{ + struct dentry *dentry, *res; + const struct stashed_operations *sops = mnt->mnt_sb->s_fs_info; + + /* See if dentry can be reused. */ + res = stashed_dentry_get(stashed); + if (IS_ERR(res)) + return PTR_ERR(res); + if (res) { + sops->put_data(data); + goto make_path; + } + + /* Allocate a new dentry. */ + dentry = prepare_anon_dentry(stashed, mnt->mnt_sb, data); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + + /* Added a new dentry. @data is now owned by the filesystem. */ + if (sops->stash_dentry) + res = sops->stash_dentry(stashed, dentry); + else + res = stash_dentry(stashed, dentry); + if (IS_ERR(res)) { + dput(dentry); + return PTR_ERR(res); + } + if (res != dentry) + dput(dentry); + +make_path: + path->dentry = res; + path->mnt = mntget(mnt); + VFS_WARN_ON_ONCE(path->dentry->d_fsdata != stashed); + VFS_WARN_ON_ONCE(d_inode(path->dentry)->i_private != data); + return 0; +} + +void stashed_dentry_prune(struct dentry *dentry) +{ + struct dentry **stashed = dentry->d_fsdata; + struct inode *inode = d_inode(dentry); + + if (WARN_ON_ONCE(!stashed)) + return; + + if (!inode) + return; + + /* + * Only replace our own @dentry as someone else might've + * already cleared out @dentry and stashed their own + * dentry in there. + */ + cmpxchg(stashed, dentry, NULL); +} + +/** + * simple_start_creating - prepare to create a given name + * @parent: directory in which to prepare to create the name + * @name: the name to be created + * + * Required lock is taken and a lookup in performed prior to creating an + * object in a directory. No permission checking is performed. + * + * Returns: a negative dentry on which vfs_create() or similar may + * be attempted, or an error. + */ +struct dentry *simple_start_creating(struct dentry *parent, const char *name) +{ + struct qstr qname = QSTR(name); + int err; + + err = lookup_noperm_common(&qname, parent); + if (err) + return ERR_PTR(err); + return start_dirop(parent, &qname, LOOKUP_CREATE | LOOKUP_EXCL); +} +EXPORT_SYMBOL(simple_start_creating); + +/* parent must have been held exclusive since simple_start_creating() */ +void simple_done_creating(struct dentry *child) +{ + inode_unlock(child->d_parent->d_inode); + dput(child); +} +EXPORT_SYMBOL(simple_done_creating); |