diff options
Diffstat (limited to 'fs/kernfs')
| -rw-r--r-- | fs/kernfs/dir.c | 111 | ||||
| -rw-r--r-- | fs/kernfs/file.c | 10 | ||||
| -rw-r--r-- | fs/kernfs/inode.c | 9 | ||||
| -rw-r--r-- | fs/kernfs/kernfs-internal.h | 9 | ||||
| -rw-r--r-- | fs/kernfs/mount.c | 94 | ||||
| -rw-r--r-- | fs/kernfs/symlink.c | 6 |
6 files changed, 197 insertions, 42 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index db5900aaa55a..89d1dc19340b 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -21,6 +21,7 @@ DEFINE_MUTEX(kernfs_mutex); static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */ static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */ +static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */ #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) @@ -507,6 +508,10 @@ void kernfs_put(struct kernfs_node *kn) struct kernfs_node *parent; struct kernfs_root *root; + /* + * kernfs_node is freed with ->count 0, kernfs_find_and_get_node_by_ino + * depends on this to filter reused stale node + */ if (!kn || !atomic_dec_and_test(&kn->count)) return; root = kernfs_root(kn); @@ -533,7 +538,9 @@ void kernfs_put(struct kernfs_node *kn) simple_xattrs_free(&kn->iattr->xattrs); } kfree(kn->iattr); - ida_simple_remove(&root->ino_ida, kn->ino); + spin_lock(&kernfs_idr_lock); + idr_remove(&root->ino_idr, kn->id.ino); + spin_unlock(&kernfs_idr_lock); kmem_cache_free(kernfs_node_cache, kn); kn = parent; @@ -542,7 +549,7 @@ void kernfs_put(struct kernfs_node *kn) goto repeat; } else { /* just released the root kn, free @root too */ - ida_destroy(&root->ino_ida); + idr_destroy(&root->ino_idr); kfree(root); } } @@ -559,7 +566,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) if (d_really_is_negative(dentry)) goto out_bad_unlocked; - kn = dentry->d_fsdata; + kn = kernfs_dentry_node(dentry); mutex_lock(&kernfs_mutex); /* The kernfs node has been deactivated */ @@ -567,7 +574,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) goto out_bad; /* The kernfs node has been moved? */ - if (dentry->d_parent->d_fsdata != kn->parent) + if (kernfs_dentry_node(dentry->d_parent) != kn->parent) goto out_bad; /* The kernfs node has been renamed */ @@ -587,14 +594,8 @@ out_bad_unlocked: return 0; } -static void kernfs_dop_release(struct dentry *dentry) -{ - kernfs_put(dentry->d_fsdata); -} - const struct dentry_operations kernfs_dops = { .d_revalidate = kernfs_dop_revalidate, - .d_release = kernfs_dop_release, }; /** @@ -610,8 +611,9 @@ const struct dentry_operations kernfs_dops = { */ struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) { - if (dentry->d_sb->s_op == &kernfs_sops) - return dentry->d_fsdata; + if (dentry->d_sb->s_op == &kernfs_sops && + !d_really_is_negative(dentry)) + return kernfs_dentry_node(dentry); return NULL; } @@ -620,6 +622,8 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, unsigned flags) { struct kernfs_node *kn; + u32 gen; + int cursor; int ret; name = kstrdup_const(name, GFP_KERNEL); @@ -630,11 +634,25 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, if (!kn) goto err_out1; - ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL); + idr_preload(GFP_KERNEL); + spin_lock(&kernfs_idr_lock); + cursor = idr_get_cursor(&root->ino_idr); + ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC); + if (ret >= 0 && ret < cursor) + root->next_generation++; + gen = root->next_generation; + spin_unlock(&kernfs_idr_lock); + idr_preload_end(); if (ret < 0) goto err_out2; - kn->ino = ret; + kn->id.ino = ret; + kn->id.generation = gen; + /* + * set ino first. This barrier is paired with atomic_inc_not_zero in + * kernfs_find_and_get_node_by_ino + */ + smp_mb__before_atomic(); atomic_set(&kn->count, 1); atomic_set(&kn->active, KN_DEACTIVATED_BIAS); RB_CLEAR_NODE(&kn->rb); @@ -666,6 +684,54 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, return kn; } +/* + * kernfs_find_and_get_node_by_ino - get kernfs_node from inode number + * @root: the kernfs root + * @ino: inode number + * + * RETURNS: + * NULL on failure. Return a kernfs node with reference counter incremented + */ +struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root, + unsigned int ino) +{ + struct kernfs_node *kn; + + rcu_read_lock(); + kn = idr_find(&root->ino_idr, ino); + if (!kn) + goto out; + + /* + * Since kernfs_node is freed in RCU, it's possible an old node for ino + * is freed, but reused before RCU grace period. But a freed node (see + * kernfs_put) or an incompletedly initialized node (see + * __kernfs_new_node) should have 'count' 0. We can use this fact to + * filter out such node. + */ + if (!atomic_inc_not_zero(&kn->count)) { + kn = NULL; + goto out; + } + + /* + * The node could be a new node or a reused node. If it's a new node, + * we are ok. If it's reused because of RCU (because of + * SLAB_TYPESAFE_BY_RCU), the __kernfs_new_node always sets its 'ino' + * before 'count'. So if 'count' is uptodate, 'ino' should be uptodate, + * hence we can use 'ino' to filter stale node. + */ + if (kn->id.ino != ino) + goto out; + rcu_read_unlock(); + + return kn; +out: + rcu_read_unlock(); + kernfs_put(kn); + return NULL; +} + /** * kernfs_add_one - add kernfs_node to parent without warning * @kn: kernfs_node to be added @@ -875,13 +941,14 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, if (!root) return ERR_PTR(-ENOMEM); - ida_init(&root->ino_ida); + idr_init(&root->ino_idr); INIT_LIST_HEAD(&root->supers); + root->next_generation = 1; kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO, KERNFS_DIR); if (!kn) { - ida_destroy(&root->ino_ida); + idr_destroy(&root->ino_idr); kfree(root); return ERR_PTR(-ENOMEM); } @@ -984,7 +1051,7 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir, unsigned int flags) { struct dentry *ret; - struct kernfs_node *parent = dentry->d_parent->d_fsdata; + struct kernfs_node *parent = dir->i_private; struct kernfs_node *kn; struct inode *inode; const void *ns = NULL; @@ -1001,8 +1068,6 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir, ret = NULL; goto out_unlock; } - kernfs_get(kn); - dentry->d_fsdata = kn; /* attach dentry and inode */ inode = kernfs_get_inode(dir->i_sb, kn); @@ -1039,7 +1104,7 @@ static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry, static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) { - struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_node *kn = kernfs_dentry_node(dentry); struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; int ret; @@ -1059,7 +1124,7 @@ static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags) { - struct kernfs_node *kn = old_dentry->d_fsdata; + struct kernfs_node *kn = kernfs_dentry_node(old_dentry); struct kernfs_node *new_parent = new_dir->i_private; struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; int ret; @@ -1572,7 +1637,7 @@ static struct kernfs_node *kernfs_dir_next_pos(const void *ns, static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) { struct dentry *dentry = file->f_path.dentry; - struct kernfs_node *parent = dentry->d_fsdata; + struct kernfs_node *parent = kernfs_dentry_node(dentry); struct kernfs_node *pos = file->private_data; const void *ns = NULL; @@ -1589,7 +1654,7 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) const char *name = pos->name; unsigned int type = dt_type(pos); int len = strlen(name); - ino_t ino = pos->ino; + ino_t ino = pos->id.ino; ctx->pos = pos->hash; file->private_data = pos; diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index e6c8954a4e89..9698e51656b1 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -616,7 +616,7 @@ static void kernfs_put_open_node(struct kernfs_node *kn, static int kernfs_fop_open(struct inode *inode, struct file *file) { - struct kernfs_node *kn = file->f_path.dentry->d_fsdata; + struct kernfs_node *kn = inode->i_private; struct kernfs_root *root = kernfs_root(kn); const struct kernfs_ops *ops; struct kernfs_open_file *of; @@ -768,7 +768,7 @@ static void kernfs_release_file(struct kernfs_node *kn, static int kernfs_fop_release(struct inode *inode, struct file *filp) { - struct kernfs_node *kn = filp->f_path.dentry->d_fsdata; + struct kernfs_node *kn = inode->i_private; struct kernfs_open_file *of = kernfs_of(filp); if (kn->flags & KERNFS_HAS_RELEASE) { @@ -835,7 +835,7 @@ void kernfs_drain_open_files(struct kernfs_node *kn) static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait) { struct kernfs_open_file *of = kernfs_of(filp); - struct kernfs_node *kn = filp->f_path.dentry->d_fsdata; + struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry); struct kernfs_open_node *on = kn->attr.open; if (!kernfs_get_active(kn)) @@ -895,7 +895,7 @@ repeat: * have the matching @file available. Look up the inodes * and generate the events manually. */ - inode = ilookup(info->sb, kn->ino); + inode = ilookup(info->sb, kn->id.ino); if (!inode) continue; @@ -903,7 +903,7 @@ repeat: if (parent) { struct inode *p_inode; - p_inode = ilookup(info->sb, parent->ino); + p_inode = ilookup(info->sb, parent->id.ino); if (p_inode) { fsnotify(p_inode, FS_MODIFY | FS_EVENT_ON_CHILD, inode, FSNOTIFY_EVENT_INODE, kn->name, 0); diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c index fb4b4a79a0d6..a34303981deb 100644 --- a/fs/kernfs/inode.c +++ b/fs/kernfs/inode.c @@ -112,7 +112,7 @@ int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr) int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr) { struct inode *inode = d_inode(dentry); - struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_node *kn = inode->i_private; int error; if (!kn) @@ -154,7 +154,7 @@ static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata, ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size) { - struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_node *kn = kernfs_dentry_node(dentry); struct kernfs_iattrs *attrs; attrs = kernfs_iattrs(kn); @@ -203,8 +203,8 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode) int kernfs_iop_getattr(const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { - struct kernfs_node *kn = path->dentry->d_fsdata; struct inode *inode = d_inode(path->dentry); + struct kernfs_node *kn = inode->i_private; mutex_lock(&kernfs_mutex); kernfs_refresh_inode(kn, inode); @@ -220,6 +220,7 @@ static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode) inode->i_private = kn; inode->i_mapping->a_ops = &kernfs_aops; inode->i_op = &kernfs_iops; + inode->i_generation = kn->id.generation; set_default_inode_attr(inode, kn->mode); kernfs_refresh_inode(kn, inode); @@ -265,7 +266,7 @@ struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn) { struct inode *inode; - inode = iget_locked(sb, kn->ino); + inode = iget_locked(sb, kn->id.ino); if (inode && (inode->i_state & I_NEW)) kernfs_init_inode(kn, inode); diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index 2d5144ab4251..0f260dcca177 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -70,6 +70,13 @@ struct kernfs_super_info { }; #define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info)) +static inline struct kernfs_node *kernfs_dentry_node(struct dentry *dentry) +{ + if (d_really_is_negative(dentry)) + return NULL; + return d_inode(dentry)->i_private; +} + extern const struct super_operations kernfs_sops; extern struct kmem_cache *kernfs_node_cache; @@ -98,6 +105,8 @@ int kernfs_add_one(struct kernfs_node *kn); struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, const char *name, umode_t mode, unsigned flags); +struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root, + unsigned int ino); /* * file.c diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index d5b149a45be1..95a7c88baed9 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -16,6 +16,7 @@ #include <linux/pagemap.h> #include <linux/namei.h> #include <linux/seq_file.h> +#include <linux/exportfs.h> #include "kernfs-internal.h" @@ -33,7 +34,7 @@ static int kernfs_sop_remount_fs(struct super_block *sb, int *flags, char *data) static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry) { - struct kernfs_root *root = kernfs_root(dentry->d_fsdata); + struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry)); struct kernfs_syscall_ops *scops = root->syscall_ops; if (scops && scops->show_options) @@ -43,7 +44,7 @@ static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry) static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry) { - struct kernfs_node *node = dentry->d_fsdata; + struct kernfs_node *node = kernfs_dentry_node(dentry); struct kernfs_root *root = kernfs_root(node); struct kernfs_syscall_ops *scops = root->syscall_ops; @@ -64,6 +65,78 @@ const struct super_operations kernfs_sops = { .show_path = kernfs_sop_show_path, }; +/* + * Similar to kernfs_fh_get_inode, this one gets kernfs node from inode + * number and generation + */ +struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root, + const union kernfs_node_id *id) +{ + struct kernfs_node *kn; + + kn = kernfs_find_and_get_node_by_ino(root, id->ino); + if (!kn) + return NULL; + if (kn->id.generation != id->generation) { + kernfs_put(kn); + return NULL; + } + return kn; +} + +static struct inode *kernfs_fh_get_inode(struct super_block *sb, + u64 ino, u32 generation) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct inode *inode; + struct kernfs_node *kn; + + if (ino == 0) + return ERR_PTR(-ESTALE); + + kn = kernfs_find_and_get_node_by_ino(info->root, ino); + if (!kn) + return ERR_PTR(-ESTALE); + inode = kernfs_get_inode(sb, kn); + kernfs_put(kn); + if (!inode) + return ERR_PTR(-ESTALE); + + if (generation && inode->i_generation != generation) { + /* we didn't find the right inode.. */ + iput(inode); + return ERR_PTR(-ESTALE); + } + return inode; +} + +static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type) +{ + return generic_fh_to_dentry(sb, fid, fh_len, fh_type, + kernfs_fh_get_inode); +} + +static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type) +{ + return generic_fh_to_parent(sb, fid, fh_len, fh_type, + kernfs_fh_get_inode); +} + +static struct dentry *kernfs_get_parent_dentry(struct dentry *child) +{ + struct kernfs_node *kn = kernfs_dentry_node(child); + + return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent)); +} + +static const struct export_operations kernfs_export_ops = { + .fh_to_dentry = kernfs_fh_to_dentry, + .fh_to_parent = kernfs_fh_to_parent, + .get_parent = kernfs_get_parent_dentry, +}; + /** * kernfs_root_from_sb - determine kernfs_root associated with a super_block * @sb: the super_block in question @@ -159,6 +232,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic) sb->s_magic = magic; sb->s_op = &kernfs_sops; sb->s_xattr = kernfs_xattr_handlers; + if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP) + sb->s_export_op = &kernfs_export_ops; sb->s_time_gran = 1; /* get root inode, initialize and unlock it */ @@ -176,8 +251,6 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic) pr_debug("%s: could not get root dentry!\n", __func__); return -ENOMEM; } - kernfs_get(info->root->kn); - root->d_fsdata = info->root->kn; sb->s_root = root; sb->s_d_op = &kernfs_dops; return 0; @@ -283,7 +356,6 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags, void kernfs_kill_sb(struct super_block *sb) { struct kernfs_super_info *info = kernfs_info(sb); - struct kernfs_node *root_kn = sb->s_root->d_fsdata; mutex_lock(&kernfs_mutex); list_del(&info->node); @@ -295,7 +367,6 @@ void kernfs_kill_sb(struct super_block *sb) */ kill_anon_super(sb); kfree(info); - kernfs_put(root_kn); } /** @@ -330,7 +401,16 @@ struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns) void __init kernfs_init(void) { + + /* + * the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino + * can access the slab lock free. This could introduce stale nodes, + * please see how kernfs_find_and_get_node_by_ino filters out stale + * nodes. + */ kernfs_node_cache = kmem_cache_create("kernfs_node_cache", sizeof(struct kernfs_node), - 0, SLAB_PANIC, NULL); + 0, + SLAB_PANIC | SLAB_TYPESAFE_BY_RCU, + NULL); } diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c index 1684af4a8b9b..08ccabd7047f 100644 --- a/fs/kernfs/symlink.c +++ b/fs/kernfs/symlink.c @@ -98,9 +98,9 @@ static int kernfs_get_target_path(struct kernfs_node *parent, return 0; } -static int kernfs_getlink(struct dentry *dentry, char *path) +static int kernfs_getlink(struct inode *inode, char *path) { - struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_node *kn = inode->i_private; struct kernfs_node *parent = kn->parent; struct kernfs_node *target = kn->symlink.target_kn; int error; @@ -124,7 +124,7 @@ static const char *kernfs_iop_get_link(struct dentry *dentry, body = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!body) return ERR_PTR(-ENOMEM); - error = kernfs_getlink(dentry, body); + error = kernfs_getlink(inode, body); if (unlikely(error < 0)) { kfree(body); return ERR_PTR(error); |