diff options
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/Makefile | 2 | ||||
| -rw-r--r-- | fs/overlayfs/namei.c | 267 | ||||
| -rw-r--r-- | fs/overlayfs/overlayfs.h | 34 | ||||
| -rw-r--r-- | fs/overlayfs/ovl_entry.h | 51 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 529 | ||||
| -rw-r--r-- | fs/overlayfs/util.c | 235 |
6 files changed, 572 insertions, 546 deletions
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile index 900daed3e91d..99373bbc1478 100644 --- a/fs/overlayfs/Makefile +++ b/fs/overlayfs/Makefile @@ -4,4 +4,4 @@ obj-$(CONFIG_OVERLAY_FS) += overlay.o -overlay-objs := super.o inode.o dir.o readdir.o copy_up.o +overlay-objs := super.o namei.o util.o inode.o dir.o readdir.o copy_up.o diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c new file mode 100644 index 000000000000..f4057fcb0246 --- /dev/null +++ b/fs/overlayfs/namei.c @@ -0,0 +1,267 @@ +/* + * Copyright (C) 2011 Novell Inc. + * Copyright (C) 2016 Red Hat, Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + */ + +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/xattr.h> +#include "overlayfs.h" +#include "ovl_entry.h" + +static struct dentry *ovl_lookup_real(struct dentry *dir, + const struct qstr *name) +{ + struct dentry *dentry; + + dentry = lookup_one_len_unlocked(name->name, dir, name->len); + if (IS_ERR(dentry)) { + if (PTR_ERR(dentry) == -ENOENT) + dentry = NULL; + } else if (!dentry->d_inode) { + dput(dentry); + dentry = NULL; + } else if (ovl_dentry_weird(dentry)) { + dput(dentry); + /* Don't support traversing automounts and other weirdness */ + dentry = ERR_PTR(-EREMOTE); + } + return dentry; +} + +static bool ovl_is_opaquedir(struct dentry *dentry) +{ + int res; + char val; + + if (!d_is_dir(dentry)) + return false; + + res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1); + if (res == 1 && val == 'y') + return true; + + return false; +} + +/* + * Returns next layer in stack starting from top. + * Returns -1 if this is the last layer. + */ +int ovl_path_next(int idx, struct dentry *dentry, struct path *path) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + BUG_ON(idx < 0); + if (idx == 0) { + ovl_path_upper(dentry, path); + if (path->dentry) + return oe->numlower ? 1 : -1; + idx++; + } + BUG_ON(idx > oe->numlower); + *path = oe->lowerstack[idx - 1]; + + return (idx < oe->numlower) ? idx + 1 : -1; +} + +struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + struct ovl_entry *oe; + const struct cred *old_cred; + struct ovl_entry *poe = dentry->d_parent->d_fsdata; + struct path *stack = NULL; + struct dentry *upperdir, *upperdentry = NULL; + unsigned int ctr = 0; + struct inode *inode = NULL; + bool upperopaque = false; + bool stop = false; + bool isdir = false; + struct dentry *this; + unsigned int i; + int err; + + old_cred = ovl_override_creds(dentry->d_sb); + upperdir = ovl_upperdentry_dereference(poe); + if (upperdir) { + this = ovl_lookup_real(upperdir, &dentry->d_name); + err = PTR_ERR(this); + if (IS_ERR(this)) + goto out; + + if (this) { + if (unlikely(ovl_dentry_remote(this))) { + dput(this); + err = -EREMOTE; + goto out; + } + if (ovl_is_whiteout(this)) { + dput(this); + this = NULL; + stop = upperopaque = true; + } else if (!d_is_dir(this)) { + stop = true; + } else { + isdir = true; + if (poe->numlower && ovl_is_opaquedir(this)) + stop = upperopaque = true; + } + } + upperdentry = this; + } + + if (!stop && poe->numlower) { + err = -ENOMEM; + stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL); + if (!stack) + goto out_put_upper; + } + + for (i = 0; !stop && i < poe->numlower; i++) { + struct path lowerpath = poe->lowerstack[i]; + + this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name); + err = PTR_ERR(this); + if (IS_ERR(this)) { + /* + * If it's positive, then treat ENAMETOOLONG as ENOENT. + */ + if (err == -ENAMETOOLONG && (upperdentry || ctr)) + continue; + goto out_put; + } + if (!this) + continue; + if (ovl_is_whiteout(this)) { + dput(this); + break; + } + /* + * If this is a non-directory then stop here. + */ + if (!d_is_dir(this)) { + if (isdir) { + dput(this); + break; + } + stop = true; + } else { + /* + * Only makes sense to check opaque dir if this is not + * the lowermost layer. + */ + if (i < poe->numlower - 1 && ovl_is_opaquedir(this)) + stop = true; + } + + stack[ctr].dentry = this; + stack[ctr].mnt = lowerpath.mnt; + ctr++; + } + + oe = ovl_alloc_entry(ctr); + err = -ENOMEM; + if (!oe) + goto out_put; + + if (upperdentry || ctr) { + struct dentry *realdentry; + struct inode *realinode; + + realdentry = upperdentry ? upperdentry : stack[0].dentry; + realinode = d_inode(realdentry); + + err = -ENOMEM; + if (upperdentry && !d_is_dir(upperdentry)) { + inode = ovl_get_inode(dentry->d_sb, realinode); + } else { + inode = ovl_new_inode(dentry->d_sb, realinode->i_mode, + realinode->i_rdev); + if (inode) + ovl_inode_init(inode, realinode, !!upperdentry); + } + if (!inode) + goto out_free_oe; + ovl_copyattr(realdentry->d_inode, inode); + } + + revert_creds(old_cred); + oe->opaque = upperopaque; + oe->__upperdentry = upperdentry; + memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); + kfree(stack); + dentry->d_fsdata = oe; + d_add(dentry, inode); + + return NULL; + +out_free_oe: + kfree(oe); +out_put: + for (i = 0; i < ctr; i++) + dput(stack[i].dentry); + kfree(stack); +out_put_upper: + dput(upperdentry); +out: + revert_creds(old_cred); + return ERR_PTR(err); +} + +bool ovl_lower_positive(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + struct ovl_entry *poe = dentry->d_parent->d_fsdata; + const struct qstr *name = &dentry->d_name; + unsigned int i; + bool positive = false; + bool done = false; + + /* + * If dentry is negative, then lower is positive iff this is a + * whiteout. + */ + if (!dentry->d_inode) + return oe->opaque; + + /* Negative upper -> positive lower */ + if (!oe->__upperdentry) + return true; + + /* Positive upper -> have to look up lower to see whether it exists */ + for (i = 0; !done && !positive && i < poe->numlower; i++) { + struct dentry *this; + struct dentry *lowerdir = poe->lowerstack[i].dentry; + + this = lookup_one_len_unlocked(name->name, lowerdir, + name->len); + if (IS_ERR(this)) { + switch (PTR_ERR(this)) { + case -ENOENT: + case -ENAMETOOLONG: + break; + + default: + /* + * Assume something is there, we just couldn't + * access it. + */ + positive = true; + break; + } + } else { + if (this->d_inode) { + positive = !ovl_is_whiteout(this); + done = true; + } + dput(this); + } + } + + return positive; +} diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index db28512165c5..f6e4d3539a25 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -9,8 +9,6 @@ #include <linux/kernel.h> -struct ovl_entry; - enum ovl_path_type { __OVL_PATH_UPPER = (1 << 0), __OVL_PATH_MERGE = (1 << 1), @@ -138,37 +136,39 @@ static inline struct inode *ovl_inode_real(struct inode *inode, bool *is_upper) return (struct inode *) (x & ~OVL_ISUPPER_MASK); } +/* util.c */ +int ovl_want_write(struct dentry *dentry); +void ovl_drop_write(struct dentry *dentry); +struct dentry *ovl_workdir(struct dentry *dentry); +const struct cred *ovl_override_creds(struct super_block *sb); +struct ovl_entry *ovl_alloc_entry(unsigned int numlower); +bool ovl_dentry_remote(struct dentry *dentry); +bool ovl_dentry_weird(struct dentry *dentry); enum ovl_path_type ovl_path_type(struct dentry *dentry); -u64 ovl_dentry_version_get(struct dentry *dentry); -void ovl_dentry_version_inc(struct dentry *dentry); void ovl_path_upper(struct dentry *dentry, struct path *path); void ovl_path_lower(struct dentry *dentry, struct path *path); enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); -int ovl_path_next(int idx, struct dentry *dentry, struct path *path); struct dentry *ovl_dentry_upper(struct dentry *dentry); struct dentry *ovl_dentry_lower(struct dentry *dentry); struct dentry *ovl_dentry_real(struct dentry *dentry); -struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode, - bool is_upper); struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry); void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache); -struct dentry *ovl_workdir(struct dentry *dentry); -int ovl_want_write(struct dentry *dentry); -void ovl_drop_write(struct dentry *dentry); bool ovl_dentry_is_opaque(struct dentry *dentry); -bool ovl_lower_positive(struct dentry *dentry); bool ovl_dentry_is_whiteout(struct dentry *dentry); void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque); -bool ovl_is_whiteout(struct dentry *dentry); -const struct cred *ovl_override_creds(struct super_block *sb); void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry); +void ovl_inode_init(struct inode *inode, struct inode *realinode, + bool is_upper); void ovl_inode_update(struct inode *inode, struct inode *upperinode); -struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, - unsigned int flags); +void ovl_dentry_version_inc(struct dentry *dentry); +u64 ovl_dentry_version_get(struct dentry *dentry); +bool ovl_is_whiteout(struct dentry *dentry); struct file *ovl_path_open(struct path *path, int flags); -struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry, - struct kstat *stat, const char *link); +/* namei.c */ +int ovl_path_next(int idx, struct dentry *dentry, struct path *path); +struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags); +bool ovl_lower_positive(struct dentry *dentry); /* readdir.c */ extern const struct file_operations ovl_dir_operations; diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h new file mode 100644 index 000000000000..3b7ba59ad27e --- /dev/null +++ b/fs/overlayfs/ovl_entry.h @@ -0,0 +1,51 @@ +/* + * + * Copyright (C) 2011 Novell Inc. + * Copyright (C) 2016 Red Hat, Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + */ + +struct ovl_config { + char *lowerdir; + char *upperdir; + char *workdir; + bool default_permissions; +}; + +/* private information held for overlayfs's superblock */ +struct ovl_fs { + struct vfsmount *upper_mnt; + unsigned numlower; + struct vfsmount **lower_mnt; + struct dentry *workdir; + long lower_namelen; + /* pathnames of lower and upper dirs, for show_options */ + struct ovl_config config; + /* creds of process who forced instantiation of super block */ + const struct cred *creator_cred; +}; + +/* private information held for every overlayfs dentry */ +struct ovl_entry { + struct dentry *__upperdentry; + struct ovl_dir_cache *cache; + union { + struct { + u64 version; + bool opaque; + }; + struct rcu_head rcu; + }; + unsigned numlower; + struct path lowerstack[]; +}; + +struct ovl_entry *ovl_alloc_entry(unsigned int numlower); + +static inline struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) +{ + return lockless_dereference(oe->__upperdentry); +} diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 212e746320b3..011482e74096 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -9,283 +9,25 @@ #include <linux/fs.h> #include <linux/namei.h> -#include <linux/pagemap.h> #include <linux/xattr.h> -#include <linux/security.h> #include <linux/mount.h> -#include <linux/slab.h> #include <linux/parser.h> #include <linux/module.h> -#include <linux/sched.h> #include <linux/statfs.h> #include <linux/seq_file.h> #include <linux/posix_acl_xattr.h> #include "overlayfs.h" +#include "ovl_entry.h" MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); MODULE_DESCRIPTION("Overlay filesystem"); MODULE_LICENSE("GPL"); -struct ovl_config { - char *lowerdir; - char *upperdir; - char *workdir; - bool default_permissions; -}; - -/* private information held for overlayfs's superblock */ -struct ovl_fs { - struct vfsmount *upper_mnt; - unsigned numlower; - struct vfsmount **lower_mnt; - struct dentry *workdir; - long lower_namelen; - /* pathnames of lower and upper dirs, for show_options */ - struct ovl_config config; - /* creds of process who forced instantiation of super block */ - const struct cred *creator_cred; -}; struct ovl_dir_cache; -/* private information held for every overlayfs dentry */ -struct ovl_entry { - struct dentry *__upperdentry; - struct ovl_dir_cache *cache; - union { - struct { - u64 version; - bool opaque; - }; - struct rcu_head rcu; - }; - unsigned numlower; - struct path lowerstack[]; -}; - #define OVL_MAX_STACK 500 -static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe) -{ - return oe->numlower ? oe->lowerstack[0].dentry : NULL; -} - -enum ovl_path_type ovl_path_type(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - enum ovl_path_type type = 0; - - if (oe->__upperdentry) { - type = __OVL_PATH_UPPER; - - /* - * Non-dir dentry can hold lower dentry from previous - * location. - */ - if (oe->numlower && d_is_dir(dentry)) - type |= __OVL_PATH_MERGE; - } else { - if (oe->numlower > 1) - type |= __OVL_PATH_MERGE; - } - return type; -} - -static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) -{ - return lockless_dereference(oe->__upperdentry); -} - -void ovl_path_upper(struct dentry *dentry, struct path *path) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - struct ovl_entry *oe = dentry->d_fsdata; - - path->mnt = ofs->upper_mnt; - path->dentry = ovl_upperdentry_dereference(oe); -} - -enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) -{ - enum ovl_path_type type = ovl_path_type(dentry); - - if (!OVL_TYPE_UPPER(type)) - ovl_path_lower(dentry, path); - else - ovl_path_upper(dentry, path); - - return type; -} - -struct dentry *ovl_dentry_upper(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - return ovl_upperdentry_dereference(oe); -} - -struct dentry *ovl_dentry_lower(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - return __ovl_dentry_lower(oe); -} - -struct dentry *ovl_dentry_real(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - struct dentry *realdentry; - - realdentry = ovl_upperdentry_dereference(oe); - if (!realdentry) - realdentry = __ovl_dentry_lower(oe); - - return realdentry; -} - -static void ovl_inode_init(struct inode *inode, struct inode *realinode, - bool is_upper) -{ - WRITE_ONCE(inode->i_private, (unsigned long) realinode | - (is_upper ? OVL_ISUPPER_MASK : 0)); -} - -struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode, - bool is_upper) -{ - if (is_upper) { - struct ovl_fs *ofs = inode->i_sb->s_fs_info; - - return ofs->upper_mnt; - } else { - return oe->numlower ? oe->lowerstack[0].mnt : NULL; - } -} - -struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - return oe->cache; -} - -void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - oe->cache = cache; -} - -void ovl_path_lower(struct dentry *dentry, struct path *path) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL }; -} - -int ovl_want_write(struct dentry *dentry) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - return mnt_want_write(ofs->upper_mnt); -} - -void ovl_drop_write(struct dentry *dentry) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - mnt_drop_write(ofs->upper_mnt); -} - -struct dentry *ovl_workdir(struct dentry *dentry) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - return ofs->workdir; -} - -bool ovl_dentry_is_opaque(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - return oe->opaque; -} - -bool ovl_dentry_is_whiteout(struct dentry *dentry) -{ - return !dentry->d_inode && ovl_dentry_is_opaque(dentry); -} - -void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) -{ - struct ovl_entry *oe = dentry->d_fsdata; - oe->opaque = opaque; -} - -void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode)); - WARN_ON(oe->__upperdentry); - /* - * Make sure upperdentry is consistent before making it visible to - * ovl_upperdentry_dereference(). - */ - smp_wmb(); - oe->__upperdentry = upperdentry; -} - -void ovl_inode_update(struct inode *inode, struct inode *upperinode) -{ - WARN_ON(!upperinode); - WARN_ON(!inode_unhashed(inode)); - WRITE_ONCE(inode->i_private, - (unsigned long) upperinode | OVL_ISUPPER_MASK); - if (!S_ISDIR(upperinode->i_mode)) - __insert_inode_hash(inode, (unsigned long) upperinode); -} - -void ovl_dentry_version_inc(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - WARN_ON(!inode_is_locked(dentry->d_inode)); - oe->version++; -} - -u64 ovl_dentry_version_get(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - WARN_ON(!inode_is_locked(dentry->d_inode)); - return oe->version; -} - -bool ovl_is_whiteout(struct dentry *dentry) -{ - struct inode *inode = dentry->d_inode; - - return inode && IS_WHITEOUT(inode); -} - -const struct cred *ovl_override_creds(struct super_block *sb) -{ - struct ovl_fs *ofs = sb->s_fs_info; - - return override_creds(ofs->creator_cred); -} - -static bool ovl_is_opaquedir(struct dentry *dentry) -{ - int res; - char val; - - if (!d_is_dir(dentry)) - return false; - - res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1); - if (res == 1 && val == 'y') - return true; - - return false; -} static void ovl_dentry_release(struct dentry *dentry) { @@ -395,275 +137,6 @@ static const struct dentry_operations ovl_reval_dentry_operations = { .d_weak_revalidate = ovl_dentry_weak_revalidate, }; -static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) -{ - size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); - struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); - - if (oe) - oe->numlower = numlower; - - return oe; -} - -static bool ovl_dentry_remote(struct dentry *dentry) -{ - return dentry->d_flags & - (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | - DCACHE_OP_REAL); -} - -static bool ovl_dentry_weird(struct dentry *dentry) -{ - return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | - DCACHE_MANAGE_TRANSIT | - DCACHE_OP_HASH | - DCACHE_OP_COMPARE); -} - -static inline struct dentry *ovl_lookup_real(struct dentry *dir, - const struct qstr *name) -{ - struct dentry *dentry; - - dentry = lookup_one_len_unlocked(name->name, dir, name->len); - if (IS_ERR(dentry)) { - if (PTR_ERR(dentry) == -ENOENT) - dentry = NULL; - } else if (!dentry->d_inode) { - dput(dentry); - dentry = NULL; - } else if (ovl_dentry_weird(dentry)) { - dput(dentry); - /* Don't support traversing automounts and other weirdness */ - dentry = ERR_PTR(-EREMOTE); - } - return dentry; -} - -/* - * Returns next layer in stack starting from top. - * Returns -1 if this is the last layer. - */ -int ovl_path_next(int idx, struct dentry *dentry, struct path *path) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - BUG_ON(idx < 0); - if (idx == 0) { - ovl_path_upper(dentry, path); - if (path->dentry) - return oe->numlower ? 1 : -1; - idx++; - } - BUG_ON(idx > oe->numlower); - *path = oe->lowerstack[idx - 1]; - - return (idx < oe->numlower) ? idx + 1 : -1; -} - -struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, - unsigned int flags) -{ - struct ovl_entry *oe; - const struct cred *old_cred; - struct ovl_entry *poe = dentry->d_parent->d_fsdata; - struct path *stack = NULL; - struct dentry *upperdir, *upperdentry = NULL; - unsigned int ctr = 0; - struct inode *inode = NULL; - bool upperopaque = false; - bool stop = false; - bool isdir = false; - struct dentry *this; - unsigned int i; - int err; - - old_cred = ovl_override_creds(dentry->d_sb); - upperdir = ovl_upperdentry_dereference(poe); - if (upperdir) { - this = ovl_lookup_real(upperdir, &dentry->d_name); - err = PTR_ERR(this); - if (IS_ERR(this)) - goto out; - - if (this) { - if (unlikely(ovl_dentry_remote(this))) { - dput(this); - err = -EREMOTE; - goto out; - } - if (ovl_is_whiteout(this)) { - dput(this); - this = NULL; - stop = upperopaque = true; - } else if (!d_is_dir(this)) { - stop = true; - } else { - isdir = true; - if (poe->numlower && ovl_is_opaquedir(this)) - stop = upperopaque = true; - } - } - upperdentry = this; - } - - if (!stop && poe->numlower) { - err = -ENOMEM; - stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL); - if (!stack) - goto out_put_upper; - } - - for (i = 0; !stop && i < poe->numlower; i++) { - struct path lowerpath = poe->lowerstack[i]; - - this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name); - err = PTR_ERR(this); - if (IS_ERR(this)) { - /* - * If it's positive, then treat ENAMETOOLONG as ENOENT. - */ - if (err == -ENAMETOOLONG && (upperdentry || ctr)) - continue; - goto out_put; - } - if (!this) - continue; - if (ovl_is_whiteout(this)) { - dput(this); - break; - } - /* - * If this is a non-directory then stop here. - */ - if (!d_is_dir(this)) { - if (isdir) { - dput(this); - break; - } - stop = true; - } else { - /* - * Only makes sense to check opaque dir if this is not - * the lowermost layer. - */ - if (i < poe->numlower - 1 && ovl_is_opaquedir(this)) - stop = true; - } - - stack[ctr].dentry = this; - stack[ctr].mnt = lowerpath.mnt; - ctr++; - } - - oe = ovl_alloc_entry(ctr); - err = -ENOMEM; - if (!oe) - goto out_put; - - if (upperdentry || ctr) { - struct dentry *realdentry; - struct inode *realinode; - - realdentry = upperdentry ? upperdentry : stack[0].dentry; - realinode = d_inode(realdentry); - - err = -ENOMEM; - if (upperdentry && !d_is_dir(upperdentry)) { - inode = ovl_get_inode(dentry->d_sb, realinode); - } else { - inode = ovl_new_inode(dentry->d_sb, realinode->i_mode, - realinode->i_rdev); - if (inode) - ovl_inode_init(inode, realinode, !!upperdentry); - } - if (!inode) - goto out_free_oe; - ovl_copyattr(realdentry->d_inode, inode); - } - - revert_creds(old_cred); - oe->opaque = upperopaque; - oe->__upperdentry = upperdentry; - memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); - kfree(stack); - dentry->d_fsdata = oe; - d_add(dentry, inode); - - return NULL; - -out_free_oe: - kfree(oe); -out_put: - for (i = 0; i < ctr; i++) - dput(stack[i].dentry); - kfree(stack); -out_put_upper: - dput(upperdentry); -out: - revert_creds(old_cred); - return ERR_PTR(err); -} - -bool ovl_lower_positive(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - struct ovl_entry *poe = dentry->d_parent->d_fsdata; - const struct qstr *name = &dentry->d_name; - unsigned int i; - bool positive = false; - bool done = false; - - /* - * If dentry is negative, then lower is positive iff this is a - * whiteout. - */ - if (!dentry->d_inode) - return oe->opaque; - - /* Negative upper -> positive lower */ - if (!oe->__upperdentry) - return true; - - /* Positive upper -> have to look up lower to see whether it exists */ - for (i = 0; !done && !positive && i < poe->numlower; i++) { - struct dentry *this; - struct dentry *lowerdir = poe->lowerstack[i].dentry; - - this = lookup_one_len_unlocked(name->name, lowerdir, - name->len); - if (IS_ERR(this)) { - switch (PTR_ERR(this)) { - case -ENOENT: - case -ENAMETOOLONG: - break; - - default: - /* - * Assume something is there, we just couldn't - * access it. - */ - positive = true; - break; - } - } else { - if (this->d_inode) { - positive = !ovl_is_whiteout(this); - done = true; - } - dput(this); - } - } - - return positive; -} - -struct file *ovl_path_open(struct path *path, int flags) -{ - return dentry_open(path, flags | O_NOATIME, current_cred()); -} - static void ovl_put_super(struct super_block *sb) { struct ovl_fs *ufs = sb->s_fs_info; diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c new file mode 100644 index 000000000000..0d45a84468d2 --- /dev/null +++ b/fs/overlayfs/util.c @@ -0,0 +1,235 @@ +/* + * Copyright (C) 2011 Novell Inc. + * Copyright (C) 2016 Red Hat, Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + */ + +#include <linux/fs.h> +#include <linux/mount.h> +#include <linux/slab.h> +#include <linux/xattr.h> +#include "overlayfs.h" +#include "ovl_entry.h" + +int ovl_want_write(struct dentry *dentry) +{ + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; + return mnt_want_write(ofs->upper_mnt); +} + +void ovl_drop_write(struct dentry *dentry) +{ + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; + mnt_drop_write(ofs->upper_mnt); +} + +struct dentry *ovl_workdir(struct dentry *dentry) +{ + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; + return ofs->workdir; +} + +const struct cred *ovl_override_creds(struct super_block *sb) +{ + struct ovl_fs *ofs = sb->s_fs_info; + + return override_creds(ofs->creator_cred); +} + +struct ovl_entry *ovl_alloc_entry(unsigned int numlower) +{ + size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); + struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); + + if (oe) + oe->numlower = numlower; + + return oe; +} + +bool ovl_dentry_remote(struct dentry *dentry) +{ + return dentry->d_flags & + (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | + DCACHE_OP_REAL); +} + +bool ovl_dentry_weird(struct dentry *dentry) +{ + return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | + DCACHE_MANAGE_TRANSIT | + DCACHE_OP_HASH | + DCACHE_OP_COMPARE); +} + +enum ovl_path_type ovl_path_type(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + enum ovl_path_type type = 0; + + if (oe->__upperdentry) { + type = __OVL_PATH_UPPER; + + /* + * Non-dir dentry can hold lower dentry from previous + * location. + */ + if (oe->numlower && d_is_dir(dentry)) + type |= __OVL_PATH_MERGE; + } else { + if (oe->numlower > 1) + type |= __OVL_PATH_MERGE; + } + return type; +} + +void ovl_path_upper(struct dentry *dentry, struct path *path) +{ + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; + struct ovl_entry *oe = dentry->d_fsdata; + + path->mnt = ofs->upper_mnt; + path->dentry = ovl_upperdentry_dereference(oe); +} + +void ovl_path_lower(struct dentry *dentry, struct path *path) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL }; +} + +enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) +{ + enum ovl_path_type type = ovl_path_type(dentry); + + if (!OVL_TYPE_UPPER(type)) + ovl_path_lower(dentry, path); + else + ovl_path_upper(dentry, path); + + return type; +} + +struct dentry *ovl_dentry_upper(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + return ovl_upperdentry_dereference(oe); +} + +static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe) +{ + return oe->numlower ? oe->lowerstack[0].dentry : NULL; +} + +struct dentry *ovl_dentry_lower(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + return __ovl_dentry_lower(oe); +} + +struct dentry *ovl_dentry_real(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + struct dentry *realdentry; + + realdentry = ovl_upperdentry_dereference(oe); + if (!realdentry) + realdentry = __ovl_dentry_lower(oe); + + return realdentry; +} + +struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + return oe->cache; +} + +void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + oe->cache = cache; +} + +bool ovl_dentry_is_opaque(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + return oe->opaque; +} + +bool ovl_dentry_is_whiteout(struct dentry *dentry) +{ + return !dentry->d_inode && ovl_dentry_is_opaque(dentry); +} + +void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) +{ + struct ovl_entry *oe = dentry->d_fsdata; + oe->opaque = opaque; +} + +void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode)); + WARN_ON(oe->__upperdentry); + /* + * Make sure upperdentry is consistent before making it visible to + * ovl_upperdentry_dereference(). + */ + smp_wmb(); + oe->__upperdentry = upperdentry; +} + +void ovl_inode_init(struct inode *inode, struct inode *realinode, bool is_upper) +{ + WRITE_ONCE(inode->i_private, (unsigned long) realinode | + (is_upper ? OVL_ISUPPER_MASK : 0)); +} + +void ovl_inode_update(struct inode *inode, struct inode *upperinode) +{ + WARN_ON(!upperinode); + WARN_ON(!inode_unhashed(inode)); + WRITE_ONCE(inode->i_private, + (unsigned long) upperinode | OVL_ISUPPER_MASK); + if (!S_ISDIR(upperinode->i_mode)) + __insert_inode_hash(inode, (unsigned long) upperinode); +} + +void ovl_dentry_version_inc(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + WARN_ON(!inode_is_locked(dentry->d_inode)); + oe->version++; +} + +u64 ovl_dentry_version_get(struct dentry *dentry) +{ + struct ovl_entry *oe = dentry->d_fsdata; + + WARN_ON(!inode_is_locked(dentry->d_inode)); + return oe->version; +} + +bool ovl_is_whiteout(struct dentry *dentry) +{ + struct inode *inode = dentry->d_inode; + + return inode && IS_WHITEOUT(inode); +} + +struct file *ovl_path_open(struct path *path, int flags) +{ + return dentry_open(path, flags | O_NOATIME, current_cred()); +} |