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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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SPDX-License-Identifier: GPL-2.0-only/* * fs/libfs.c * Library for filesystems writers. */
#include <linux/blkdev.h>#include <linux/export.h>#include <linux/filelock.h>#include <linux/pagemap.h>#include <linux/slab.h>#include <linux/cred.h>#include <linux/mount.h>#include <linux/vfs.h>#include <linux/quotaops.h>#include <linux/mutex.h>#include <linux/namei.h>#include <linux/exportfs.h>#include <linux/iversion.h>#include <linux/writeback.h>#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(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(&nop_mnt_idmap, request_mask, inode, stat); stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9); return 0;}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; return 0;}EXPORT_SYMBOL(simple_statfs);
/* * Retaining negative dentries for an in-memory filesystem just wastes * memory and lookup time: arrange for them to be deleted immediately. */int always_delete_dentry(const struct dentry *dentry){ return 1;}EXPORT_SYMBOL(always_delete_dentry);
/* * 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. */struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags){ if (dentry->d_name.len > NAME_MAX) return ERR_PTR(-ENAMETOOLONG); 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;
return d_splice_alias(NULL, dentry);}EXPORT_SYMBOL(simple_lookup);
int dcache_dir_open(struct inode *inode, struct file *file){ file->private_data = d_alloc_cursor(file->f_path.dentry);
return file->private_data ? 0 : -ENOMEM;}EXPORT_SYMBOL(dcache_dir_open);
int dcache_dir_close(struct inode *inode, struct file *file){ dput(file->private_data); return 0;}EXPORT_SYMBOL(dcache_dir_close);
/* parent is locked at least shared *//* * 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;
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); } } spin_unlock(&dentry->d_lock); dput(last); return found;}
loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence){ struct dentry *dentry = file->f_path.dentry; 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;
inode_unlock_shared(dentry->d_inode); } return offset;}EXPORT_SYMBOL(dcache_dir_lseek);
/* * 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(), * both impossible due to the lock on directory. */
int dcache_readdir(struct file *file, struct dir_context *ctx){ struct dentry *dentry = file->f_path.dentry; struct dentry *cursor = file->private_data; struct dentry *next = NULL; struct hlist_node **p;
if (!dir_emit_dots(file, ctx)) return 0;
if (ctx->pos == 2) 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, fs_umode_to_dtype(d_inode(next)->i_mode))) break; ctx->pos++; p = &next->d_sib.next; } 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);
ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos){ return -EISDIR;}EXPORT_SYMBOL(generic_read_dir);
const struct file_operations simple_dir_operations = { .open = dcache_dir_open, .release = dcache_dir_close, .llseek = dcache_dir_lseek, .read = generic_read_dir, .iterate_shared = dcache_readdir, .fsync = noop_fsync,};EXPORT_SYMBOL(simple_dir_operations);
const struct inode_operations simple_dir_inode_operations = { .lookup = simple_lookup,};EXPORT_SYMBOL(simple_dir_inode_operations);
/* simple_offset_add() never assigns these to a dentry */enum { DIR_OFFSET_FIRST = 2, /* Find first real entry */ DIR_OFFSET_EOD = S32_MAX,};
/* 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. * * Caller must have grabbed a slot for new_dentry in the maple_tree * associated with new_dir, even if dentry is negative. */void 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);
if (WARN_ON(!new_offset)) return;
simple_offset_remove(old_ctx, old_dentry); offset_set(new_dentry, 0); WARN_ON(simple_offset_replace(new_ctx, old_dentry, new_offset));}
/** * 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;
if (WARN_ON(!old_index || !new_index)) return -EINVAL;
ret = mtree_store(&new_ctx->mt, new_index, old_dentry, GFP_KERNEL); if (WARN_ON(ret)) return ret;
ret = mtree_store(&old_ctx->mt, old_index, new_dentry, GFP_KERNEL); if (WARN_ON(ret)) { mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL); return ret; }
offset_set(old_dentry, new_index); offset_set(new_dentry, old_index); simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry); return 0;}
/** * 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 */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, .setlease = generic_setlease,};
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 dentry *dentry;
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 = 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) 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 * max_reserved of 1 to iunique). */ root->i_ino = 1; root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; 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);}
static void pseudo_fs_free(struct fs_context *fc){ kfree(fc->fs_private);}
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_obj(struct pseudo_fs_context); if (likely(ctx)) { ctx->magic = magic; fc->fs_private = ctx; fc->ops = &pseudo_fs_context_ops; fc->sb_flags |= SB_NOUSER; fc->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; fc->global = true; } return ctx;}EXPORT_SYMBOL(init_pseudo);
int simple_open(struct inode *inode, struct file *file){ if (inode->i_private) file->private_data = inode->i_private; return 0;}EXPORT_SYMBOL(simple_open);
int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry){ struct inode *inode = d_inode(old_dentry);
inode_set_mtime_to_ts(dir, inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); inc_nlink(inode); ihold(inode); d_make_persistent(dentry, inode); return 0;}EXPORT_SYMBOL(simple_link);
int simple_empty(struct dentry *dentry){ struct dentry *child; int ret = 0;
spin_lock(&dentry->d_lock); 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); goto out; } spin_unlock(&child->d_lock); } ret = 1;out: spin_unlock(&dentry->d_lock); return ret;}EXPORT_SYMBOL(simple_empty);
void __simple_unlink(struct inode *dir, struct dentry *dentry){ struct inode *inode = d_inode(dentry);
inode_set_mtime_to_ts(dir, inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); drop_nlink(inode);}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);
int simple_rmdir(struct inode *dir, struct dentry *dentry){ if (!simple_empty(dentry)) return -ENOTEMPTY;
__simple_rmdir(dir, dentry); d_make_discardable(dentry); return 0;}EXPORT_SYMBOL(simple_rmdir);
/** * 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){ int they_are_dirs = d_is_dir(old_dentry);
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;
if (d_really_is_positive(new_dentry)) { simple_unlink(new_dir, new_dentry); if (they_are_dirs) { drop_nlink(d_inode(new_dentry)); drop_nlink(old_dir); } } else if (they_are_dirs) { drop_nlink(old_dir); inc_nlink(new_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 * * Returns 0 on success, -error on failure. * * simple_setattr is a simple ->setattr implementation without a proper * implementation of size changes. * * It can either be used for in-memory filesystems or special files * 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 mnt_idmap *idmap, struct dentry *dentry, struct iattr *iattr){ struct inode *inode = d_inode(dentry); int error;
error = setattr_prepare(idmap, dentry, iattr); if (error) return error;
if (iattr->ia_valid & ATTR_SIZE) truncate_setsize(inode, iattr->ia_size); setattr_copy(idmap, inode, iattr); mark_inode_dirty(inode); return 0;}EXPORT_SYMBOL(simple_setattr);
static int simple_read_folio(struct file *file, struct folio *folio){ folio_zero_range(folio, 0, folio_size(folio)); flush_dcache_folio(folio); folio_mark_uptodate(folio); folio_unlock(folio); return 0;}
int simple_write_begin(const struct kiocb *iocb, struct address_space *mapping, loff_t pos, unsigned len, struct folio **foliop, void **fsdata){ struct folio *folio;
folio = __filemap_get_folio(mapping, pos / PAGE_SIZE, FGP_WRITEBEGIN, mapping_gfp_mask(mapping)); if (IS_ERR(folio)) return PTR_ERR(folio);
*foliop = folio;
if (!folio_test_uptodate(folio) && (len != folio_size(folio))) { size_t from = offset_in_folio(folio, pos);
folio_zero_segments(folio, 0, from, from + len, folio_size(folio)); } return 0;}EXPORT_SYMBOL(simple_write_begin);
/** * simple_write_end - .write_end helper for non-block-device FSes * @iocb: kernel I/O control block * @mapping: " * @pos: " * @len: " * @copied: " * @folio: " * @fsdata: " * * 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_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_read_folio() */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 = folio->mapping->host; loff_t last_pos = pos + copied;
/* zero the stale part of the folio if we did a short copy */ if (!folio_test_uptodate(folio)) { if (copied < len) { size_t from = offset_in_folio(folio, pos);
folio_zero_range(folio, from + copied, len - copied); } folio_mark_uptodate(folio); } /* * No need to use i_size_read() here, the i_size * cannot change under us because we hold the i_rwsem. */ if (last_pos > inode->i_size) i_size_write(inode, last_pos);
folio_mark_dirty(folio); folio_unlock(folio); folio_put(folio);
return copied;}
/* * 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 * unique inode values later for this filesystem, then you must take care * to pass it an appropriate max_reserved value to avoid collisions. */int simple_fill_super(struct super_block *s, unsigned long magic, const struct tree_descr *files){ struct inode *inode; struct dentry *dentry; int i;
s->s_blocksize = PAGE_SIZE; s->s_blocksize_bits = PAGE_SHIFT; s->s_magic = magic; s->s_op = &simple_super_operations; s->s_time_gran = 1;
inode = new_inode(s); if (!inode) return -ENOMEM; /* * because the root inode is 1, the files array must not contain an * entry at index 1 */ inode->i_ino = 1; inode->i_mode = S_IFDIR | 0755; simple_inode_init_ts(inode); inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; set_nlink(inode, 2); 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) continue;
/* warn if it tries to conflict with the root inode */ if (unlikely(i == 1)) printk(KERN_WARNING "%s: %s passed in a files array" "with an index of 1!\n", __func__, s->s_type->name);
dentry = d_alloc_name(s->s_root, files->name); if (!dentry) return -ENOMEM; inode = new_inode(s); if (!inode) { dput(dentry); return -ENOMEM; } inode->i_mode = S_IFREG | files->mode; simple_inode_init_ts(inode); inode->i_fop = files->ops; inode->i_ino = i; d_make_persistent(dentry, inode); dput(dentry); } return 0;}EXPORT_SYMBOL(simple_fill_super);
static DEFINE_SPINLOCK(pin_fs_lock);
int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count){ struct vfsmount *mnt = NULL; spin_lock(&pin_fs_lock); if (unlikely(!*mount)) { spin_unlock(&pin_fs_lock); mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); if (IS_ERR(mnt)) return PTR_ERR(mnt); spin_lock(&pin_fs_lock); if (!*mount) *mount = mnt; } mntget(*mount); ++*count; spin_unlock(&pin_fs_lock); mntput(mnt); return 0;}EXPORT_SYMBOL(simple_pin_fs);
void simple_release_fs(struct vfsmount **mount, int *count){ struct vfsmount *mnt; spin_lock(&pin_fs_lock); mnt = *mount; if (!--*count) *mount = NULL; spin_unlock(&pin_fs_lock); mntput(mnt);}EXPORT_SYMBOL(simple_release_fs);
/** * simple_read_from_buffer - copy data from the buffer to user space * @to: the user space buffer to read to * @count: the maximum number of bytes to read * @ppos: the current position in the buffer * @from: the buffer to read from * @available: the size of the buffer * * The simple_read_from_buffer() function reads up to @count bytes from the * buffer @from at offset @ppos into the user space address starting at @to. * * On success, the number of bytes read is returned and the offset @ppos is * advanced by this number, or negative value is returned on error. **/ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, const void *from, size_t available){ loff_t pos = *ppos; size_t ret;
if (pos < 0) return -EINVAL; if (pos >= available || !count) return 0; if (count > available - pos) count = available - pos; ret = copy_to_user(to, from + pos, count); if (ret == count) return -EFAULT; count -= ret; *ppos = pos + count; return count;}EXPORT_SYMBOL(simple_read_from_buffer);
/** * simple_write_to_buffer - copy data from user space to the buffer * @to: the buffer to write to * @available: the size of the buffer * @ppos: the current position in the buffer * @from: the user space buffer to read from * @count: the maximum number of bytes to read * * The simple_write_to_buffer() function reads up to @count bytes from the user * space address starting at @from into the buffer @to at offset @ppos. * * On success, the number of bytes written is returned and the offset @ppos is * advanced by this number, or negative value is returned on error. **/ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, const void __user *from, size_t count){ loff_t pos = *ppos; size_t res;
if (pos < 0) return -EINVAL; if (pos >= available || !count) return 0; if (count > available - pos) count = available - pos; res = copy_from_user(to + pos, from, count); if (res == count) return -EFAULT; count -= res; *ppos = pos + count; return count;}EXPORT_SYMBOL(simple_write_to_buffer);
/** * memory_read_from_buffer - copy data from the buffer * @to: the kernel space buffer to read to * @count: the maximum number of bytes to read * @ppos: the current position in the buffer * @from: the buffer to read from * @available: the size of the buffer * * The memory_read_from_buffer() function reads up to @count bytes from the * buffer @from at offset @ppos into the kernel space address starting at @to. * * On success, the number of bytes read is returned and the offset @ppos is * advanced by this number, or negative value is returned on error. **/ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, const void *from, size_t available){ loff_t pos = *ppos;
if (pos < 0) return -EINVAL; if (pos >= available) return 0; if (count > available - pos) count = available - pos; memcpy(to, from + pos, count); *ppos = pos + count;
return count;}EXPORT_SYMBOL(memory_read_from_buffer);
/* * Transaction based IO. * The file expects a single write which triggers the transaction, and then * possibly a read which collects the result - which is stored in a * file-local buffer. */
void simple_transaction_set(struct file *file, size_t n){ struct simple_transaction_argresp *ar = file->private_data;
BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
/* * The barrier ensures that ar->size will really remain zero until * ar->data is ready for reading. */ smp_mb(); ar->size = n;}EXPORT_SYMBOL(simple_transaction_set);
char *simple_transaction_get(struct file *file, const char __user *buf, size_t size){ struct simple_transaction_argresp *ar; static DEFINE_SPINLOCK(simple_transaction_lock);
if (size > SIMPLE_TRANSACTION_LIMIT - 1) return ERR_PTR(-EFBIG);
ar = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!ar) return ERR_PTR(-ENOMEM);
spin_lock(&simple_transaction_lock);
/* only one write allowed per open */ if (file->private_data) { spin_unlock(&simple_transaction_lock); kfree(ar); return ERR_PTR(-EBUSY); }
file->private_data = ar;
spin_unlock(&simple_transaction_lock);
if (copy_from_user(ar->data, buf, size)) return ERR_PTR(-EFAULT);
return ar->data;}EXPORT_SYMBOL(simple_transaction_get);
ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos){ struct simple_transaction_argresp *ar = file->private_data;
if (!ar) return 0; return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);}EXPORT_SYMBOL(simple_transaction_read);
int simple_transaction_release(struct inode *inode, struct file *file){ kfree(file->private_data); return 0;}EXPORT_SYMBOL(simple_transaction_release);
/* Simple attribute files */
struct simple_attr { int (*get)(void *, u64 *); int (*set)(void *, u64); char get_buf[24]; /* enough to store a u64 and "\n\0" */ char set_buf[24]; void *data; const char *fmt; /* format for read operation */ struct mutex mutex; /* protects access to these buffers */};
/* simple_attr_open is called by an actual attribute open file operation * to set the attribute specific access operations. */int simple_attr_open(struct inode *inode, struct file *file, int (*get)(void *, u64 *), int (*set)(void *, u64), const char *fmt){ struct simple_attr *attr;
attr = kzalloc_obj(*attr); if (!attr) return -ENOMEM;
attr->get = get; attr->set = set; attr->data = inode->i_private; attr->fmt = fmt; mutex_init(&attr->mutex);
file->private_data = attr;
return nonseekable_open(inode, file);}EXPORT_SYMBOL_GPL(simple_attr_open);
int simple_attr_release(struct inode *inode, struct file *file){ kfree(file->private_data); return 0;}EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
/* read from the buffer that is filled with the get function */ssize_t simple_attr_read(struct file *file, char __user *buf, size_t len, loff_t *ppos){ struct simple_attr *attr; size_t size; ssize_t ret;
attr = file->private_data;
if (!attr->get) return -EACCES;
ret = mutex_lock_interruptible(&attr->mutex); if (ret) return ret;
if (*ppos && attr->get_buf[0]) { /* continued read */ size = strlen(attr->get_buf); } else { /* first read */ u64 val; ret = attr->get(attr->data, &val); if (ret) goto out;
size = scnprintf(attr->get_buf, sizeof(attr->get_buf), attr->fmt, (unsigned long long)val); }
ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);out: mutex_unlock(&attr->mutex); return ret;}EXPORT_SYMBOL_GPL(simple_attr_read);
/* interpret the buffer as a number to call the set function with */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; unsigned long long val; size_t size; ssize_t ret;
attr = file->private_data; if (!attr->set) return -EACCES;
ret = mutex_lock_interruptible(&attr->mutex); if (ret) return ret;
ret = -EFAULT; size = min(sizeof(attr->set_buf) - 1, len); if (copy_from_user(attr->set_buf, buf, size)) goto out;
attr->set_buf[size] = '\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 */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 * @fid: file handle to convert * @fh_len: length of the file handle in bytes * @fh_type: type of file handle * @get_inode: filesystem callback to retrieve inode * * This function decodes @fid as long as it has one of the well-known * Linux filehandle types and calls @get_inode on it to retrieve the * inode for the object specified in the file handle. */struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len, int fh_type, struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)){ struct inode *inode = NULL;
if (fh_len < 2) return NULL;
switch (fh_type) { case FILEID_INO32_GEN: case FILEID_INO32_GEN_PARENT: inode = get_inode(sb, fid->i32.ino, fid->i32.gen); break; }
return d_obtain_alias(inode);}EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
/** * generic_fh_to_parent - generic helper for the fh_to_parent export operation * @sb: filesystem to do the file handle conversion on * @fid: file handle to convert * @fh_len: length of the file handle in bytes * @fh_type: type of file handle * @get_inode: filesystem callback to retrieve inode * * This function decodes @fid as long as it has one of the well-known * Linux filehandle types and calls @get_inode on it to retrieve the * inode for the _parent_ object specified in the file handle if it * is specified in the file handle, or NULL otherwise. */struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, int fh_len, int fh_type, struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen)){ struct inode *inode = NULL;
if (fh_len <= 2) return NULL;
switch (fh_type) { case FILEID_INO32_GEN_PARENT: inode = get_inode(sb, fid->i32.parent_ino, (fh_len > 3 ? fid->i32.parent_gen : 0)); break; }
return d_obtain_alias(inode);}EXPORT_SYMBOL_GPL(generic_fh_to_parent);
/** * simple_fsync_noflush - generic fsync implementation for simple filesystems * * @file: file to synchronize * @start: start offset in bytes * @end: end offset in bytes (inclusive) * @datasync: only synchronize essential metadata if true * * This function is an fsync handler for simple filesystems. It writes out * dirty data, inode (if dirty), but does not issue a cache flush. */int simple_fsync_noflush(struct file *file, loff_t start, loff_t end, int datasync){ struct inode *inode = file->f_mapping->host; int err; int ret = 0;
err = file_write_and_wait_range(file, start, end); if (err) return err;
if (!(inode_state_read_once(inode) & I_DIRTY_ALL)) goto out; if (datasync && !(inode_state_read_once(inode) & I_DIRTY_DATASYNC)) goto out;
ret = sync_inode_metadata(inode, 1);out: /* check and advance again to catch errors after syncing out buffers */ err = file_check_and_advance_wb_err(file); if (ret == 0) ret = err; return ret;}EXPORT_SYMBOL(simple_fsync_noflush);
/** * simple_fsync - fsync implementation for simple filesystems with flush * @file: file to synchronize * @start: start offset in bytes * @end: end offset in bytes (inclusive) * @datasync: only synchronize essential metadata if true * * This function is an fsync handler for simple filesystems. It writes out * dirty data, inode (if dirty), and issues a cache flush. */int simple_fsync(struct file *file, loff_t start, loff_t end, int datasync){ struct inode *inode = file->f_mapping->host; int err;
err = simple_fsync_noflush(file, start, end, datasync); if (err) return err; return blkdev_issue_flush(inode->i_sb->s_bdev);}EXPORT_SYMBOL(simple_fsync);
/** * generic_check_addressable - Check addressability of file system * @blocksize_bits: log of file system block size * @num_blocks: number of blocks in file system * * Determine whether a file system with @num_blocks blocks (and a * block size of 2**@blocksize_bits) is addressable by the sector_t * and page cache of the system. Return 0 if so and -EFBIG otherwise. */int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks){ u64 last_fs_block = num_blocks - 1; 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) return -EINVAL;
if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || (last_fs_page > (pgoff_t)(~0ULL))) { return -EFBIG; } return 0;}EXPORT_SYMBOL(generic_check_addressable);
/* * No-op implementation of ->fsync for in-memory filesystems. */int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync){ return 0;}EXPORT_SYMBOL(noop_fsync);
ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter){ /* * iomap based filesystems support direct I/O without need for * this callback. However, it still needs to be set in * inode->a_ops so that open/fcntl know that direct I/O is * generally supported. */ return -EINVAL;}EXPORT_SYMBOL_GPL(noop_direct_IO);
/* Because kfree isn't assignment-compatible with void(void*) ;-/ */void kfree_link(void *p){ kfree(p);}EXPORT_SYMBOL(kfree_link);
struct inode *alloc_anon_inode(struct super_block *s){ static const struct address_space_operations anon_aops = { .dirty_folio = noop_dirty_folio, }; struct inode *inode = new_inode_pseudo(s);
if (!inode) return ERR_PTR(-ENOMEM);
inode->i_ino = get_next_ino(); inode->i_mapping->a_ops = &anon_aops;
/* * Mark the inode dirty from the very beginning, * that way it will never be moved to the dirty * list because mark_inode_dirty() will think * that it already _is_ on the dirty list. */ 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 | S_ANON_INODE; simple_inode_init_ts(inode); return inode;}EXPORT_SYMBOL(alloc_anon_inode);
/** * 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){ return inode->i_link;}EXPORT_SYMBOL(simple_get_link);
const struct inode_operations simple_symlink_inode_operations = { .get_link = simple_get_link,};EXPORT_SYMBOL(simple_symlink_inode_operations);
/* * Operations for a permanently empty directory. */static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags){ return ERR_PTR(-ENOENT);}
static int empty_dir_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr){ return -EPERM;}
static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size){ return -EOPNOTSUPP;}
static const struct inode_operations empty_dir_inode_operations = { .lookup = empty_dir_lookup, .setattr = empty_dir_setattr, .listxattr = empty_dir_listxattr,};
static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence){ /* An empty directory has two entries . and .. at offsets 0 and 1 */ return generic_file_llseek_size(file, offset, whence, 2, 2);}
static int empty_dir_readdir(struct file *file, struct dir_context *ctx){ dir_emit_dots(file, ctx); return 0;}
static const struct file_operations empty_dir_operations = { .llseek = empty_dir_llseek, .read = generic_read_dir, .iterate_shared = empty_dir_readdir, .fsync = noop_fsync,};
void make_empty_dir_inode(struct inode *inode){ set_nlink(inode, 2); inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO; inode->i_uid = GLOBAL_ROOT_UID; inode->i_gid = GLOBAL_ROOT_GID; inode->i_rdev = 0; inode->i_size = 0; inode->i_blkbits = PAGE_SHIFT; inode->i_blocks = 0;
inode->i_op = &empty_dir_inode_operations; inode->i_opflags &= ~IOP_XATTR; inode->i_fop = &empty_dir_operations;}
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_ENCRYPTIONstatic 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){ end_creating(child);}EXPORT_SYMBOL(simple_done_creating);