Merge branch 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi: "This relaxes the requirements on the lower layer filesystem: now ones that implement .d_revalidate, such as NFS, can be used. Upper layer filesystems still has the "no .d_revalidate" requirement. Also a bad interaction with jffs2 locking has been fixed" * 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: lookup whiteouts outside iterate_dir() ovl: allow distributed fs as lower layer ovl: don't traverse automount points
This commit is contained in:
Linus Torvalds
commit
320cd413fa
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@ -23,6 +23,7 @@ struct ovl_cache_entry {
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u64 ino;
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struct list_head l_node;
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struct rb_node node;
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struct ovl_cache_entry *next_maybe_whiteout;
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bool is_whiteout;
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char name[];
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};
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@ -39,7 +40,7 @@ struct ovl_readdir_data {
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struct rb_root root;
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struct list_head *list;
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struct list_head middle;
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struct dentry *dir;
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struct ovl_cache_entry *first_maybe_whiteout;
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int count;
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int err;
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};
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@ -79,7 +80,7 @@ static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
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return NULL;
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}
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static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir,
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static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
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const char *name, int len,
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u64 ino, unsigned int d_type)
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{
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@ -98,29 +99,8 @@ static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir,
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p->is_whiteout = false;
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if (d_type == DT_CHR) {
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struct dentry *dentry;
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const struct cred *old_cred;
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struct cred *override_cred;
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override_cred = prepare_creds();
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if (!override_cred) {
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kfree(p);
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return NULL;
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}
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/*
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* CAP_DAC_OVERRIDE for lookup
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*/
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cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
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old_cred = override_creds(override_cred);
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dentry = lookup_one_len(name, dir, len);
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if (!IS_ERR(dentry)) {
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p->is_whiteout = ovl_is_whiteout(dentry);
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dput(dentry);
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}
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revert_creds(old_cred);
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put_cred(override_cred);
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p->next_maybe_whiteout = rdd->first_maybe_whiteout;
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rdd->first_maybe_whiteout = p;
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}
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return p;
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}
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@ -148,7 +128,7 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
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return 0;
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}
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p = ovl_cache_entry_new(rdd->dir, name, len, ino, d_type);
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p = ovl_cache_entry_new(rdd, name, len, ino, d_type);
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if (p == NULL)
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return -ENOMEM;
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@ -169,7 +149,7 @@ static int ovl_fill_lower(struct ovl_readdir_data *rdd,
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if (p) {
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list_move_tail(&p->l_node, &rdd->middle);
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} else {
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p = ovl_cache_entry_new(rdd->dir, name, namelen, ino, d_type);
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p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
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if (p == NULL)
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rdd->err = -ENOMEM;
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else
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@ -219,6 +199,43 @@ static int ovl_fill_merge(struct dir_context *ctx, const char *name,
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return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type);
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}
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static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)
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{
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int err;
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struct ovl_cache_entry *p;
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struct dentry *dentry;
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const struct cred *old_cred;
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struct cred *override_cred;
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override_cred = prepare_creds();
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if (!override_cred)
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return -ENOMEM;
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/*
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* CAP_DAC_OVERRIDE for lookup
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*/
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cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
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old_cred = override_creds(override_cred);
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err = mutex_lock_killable(&dir->d_inode->i_mutex);
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if (!err) {
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while (rdd->first_maybe_whiteout) {
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p = rdd->first_maybe_whiteout;
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rdd->first_maybe_whiteout = p->next_maybe_whiteout;
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dentry = lookup_one_len(p->name, dir, p->len);
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if (!IS_ERR(dentry)) {
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p->is_whiteout = ovl_is_whiteout(dentry);
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dput(dentry);
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}
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}
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mutex_unlock(&dir->d_inode->i_mutex);
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}
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revert_creds(old_cred);
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put_cred(override_cred);
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return err;
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}
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static inline int ovl_dir_read(struct path *realpath,
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struct ovl_readdir_data *rdd)
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{
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@ -229,7 +246,7 @@ static inline int ovl_dir_read(struct path *realpath,
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if (IS_ERR(realfile))
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return PTR_ERR(realfile);
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rdd->dir = realpath->dentry;
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rdd->first_maybe_whiteout = NULL;
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rdd->ctx.pos = 0;
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do {
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rdd->count = 0;
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@ -238,6 +255,10 @@ static inline int ovl_dir_read(struct path *realpath,
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if (err >= 0)
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err = rdd->err;
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} while (!err && rdd->count);
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if (!err && rdd->first_maybe_whiteout)
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err = ovl_check_whiteouts(realpath->dentry, rdd);
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fput(realfile);
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return err;
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@ -273,10 +273,57 @@ static void ovl_dentry_release(struct dentry *dentry)
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}
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}
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static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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unsigned int i;
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int ret = 1;
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for (i = 0; i < oe->numlower; i++) {
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struct dentry *d = oe->lowerstack[i].dentry;
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if (d->d_flags & DCACHE_OP_REVALIDATE) {
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ret = d->d_op->d_revalidate(d, flags);
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if (ret < 0)
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return ret;
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if (!ret) {
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if (!(flags & LOOKUP_RCU))
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d_invalidate(d);
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return -ESTALE;
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}
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}
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}
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return 1;
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}
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static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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unsigned int i;
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int ret = 1;
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for (i = 0; i < oe->numlower; i++) {
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struct dentry *d = oe->lowerstack[i].dentry;
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if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
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ret = d->d_op->d_weak_revalidate(d, flags);
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if (ret <= 0)
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break;
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}
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}
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return ret;
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}
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static const struct dentry_operations ovl_dentry_operations = {
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.d_release = ovl_dentry_release,
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};
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static const struct dentry_operations ovl_reval_dentry_operations = {
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.d_release = ovl_dentry_release,
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.d_revalidate = ovl_dentry_revalidate,
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.d_weak_revalidate = ovl_dentry_weak_revalidate,
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};
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static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
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{
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size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
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@ -288,6 +335,20 @@ static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
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return oe;
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}
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static bool ovl_dentry_remote(struct dentry *dentry)
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{
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return dentry->d_flags &
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(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
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}
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static bool ovl_dentry_weird(struct dentry *dentry)
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{
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return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
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DCACHE_MANAGE_TRANSIT |
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DCACHE_OP_HASH |
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DCACHE_OP_COMPARE);
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}
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static inline struct dentry *ovl_lookup_real(struct dentry *dir,
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struct qstr *name)
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{
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@ -303,6 +364,10 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir,
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} else if (!dentry->d_inode) {
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dput(dentry);
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dentry = NULL;
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} else if (ovl_dentry_weird(dentry)) {
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dput(dentry);
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/* Don't support traversing automounts and other weirdness */
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dentry = ERR_PTR(-EREMOTE);
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}
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return dentry;
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}
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@ -350,6 +415,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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goto out;
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if (this) {
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if (unlikely(ovl_dentry_remote(this))) {
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dput(this);
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err = -EREMOTE;
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goto out;
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}
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if (ovl_is_whiteout(this)) {
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dput(this);
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this = NULL;
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@ -694,25 +764,6 @@ static void ovl_unescape(char *s)
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}
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}
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static bool ovl_is_allowed_fs_type(struct dentry *root)
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{
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const struct dentry_operations *dop = root->d_op;
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/*
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* We don't support:
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* - automount filesystems
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* - filesystems with revalidate (FIXME for lower layer)
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* - filesystems with case insensitive names
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*/
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if (dop &&
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(dop->d_manage || dop->d_automount ||
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dop->d_revalidate || dop->d_weak_revalidate ||
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dop->d_compare || dop->d_hash)) {
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return false;
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}
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return true;
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}
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static int ovl_mount_dir_noesc(const char *name, struct path *path)
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{
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int err = -EINVAL;
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@ -727,7 +778,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path)
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goto out;
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}
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err = -EINVAL;
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if (!ovl_is_allowed_fs_type(path->dentry)) {
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if (ovl_dentry_weird(path->dentry)) {
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pr_err("overlayfs: filesystem on '%s' not supported\n", name);
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goto out_put;
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}
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@ -751,13 +802,21 @@ static int ovl_mount_dir(const char *name, struct path *path)
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if (tmp) {
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ovl_unescape(tmp);
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err = ovl_mount_dir_noesc(tmp, path);
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if (!err)
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if (ovl_dentry_remote(path->dentry)) {
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pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
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tmp);
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path_put(path);
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err = -EINVAL;
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}
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kfree(tmp);
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}
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return err;
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}
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static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
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int *stack_depth)
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int *stack_depth, bool *remote)
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{
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int err;
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struct kstatfs statfs;
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@ -774,6 +833,9 @@ static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
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*namelen = max(*namelen, statfs.f_namelen);
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*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
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if (ovl_dentry_remote(path->dentry))
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*remote = true;
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return 0;
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out_put:
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@ -827,6 +889,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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unsigned int numlower;
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unsigned int stacklen = 0;
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unsigned int i;
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bool remote = false;
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int err;
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err = -ENOMEM;
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@ -900,7 +963,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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lower = lowertmp;
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for (numlower = 0; numlower < stacklen; numlower++) {
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err = ovl_lower_dir(lower, &stack[numlower],
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&ufs->lower_namelen, &sb->s_stack_depth);
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&ufs->lower_namelen, &sb->s_stack_depth,
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&remote);
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if (err)
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goto out_put_lowerpath;
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@ -958,7 +1022,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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if (!ufs->upper_mnt)
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sb->s_flags |= MS_RDONLY;
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sb->s_d_op = &ovl_dentry_operations;
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if (remote)
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sb->s_d_op = &ovl_reval_dentry_operations;
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else
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sb->s_d_op = &ovl_dentry_operations;
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err = -ENOMEM;
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oe = ovl_alloc_entry(numlower);
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